Theory of Relativity

[cacian]

How do I explain this theory to a child without getting myslef too hyped up about it?

I got as far as the univers expanding and time dilating.:svengo:
Anyone here with a simplifier?
Thanks!

[cafolini]

How do I explain this theory to a child without getting myslef too hyped up about it?

I got as far as the univers expanding and time dilating.:svengo:
Anyone here with a simplifier?
Thanks!

The imagination is important, but an imagination without knowledge is like a toilet without water. ~ C A Cafolini

[/dev/null]

Trains. Then conformal diagrams.

[cacian]

Trains. Then conformal diagrams.

Woud you mind explaining a bit more dev/null ?:p
Trains is movement but diagrams are shapes.
Is it something shapes move?


The imagination is important, but an imagination without knowledge is like a toilet without water. ~ C A Cafolini

Ouch!

[Charles Darnay]

Depending on how old the person is, introduce him/her to this (http://www.amazon.com/Einsteins-Dreams-Alan-Lightman/dp/140007780X/ref=sr_1_1?ie=UTF8&qid=1346943142&sr=8-1&keywords=einstein%27s+dreams):

[My2cents]

According to a PBS presentation, it boils down to the idea that time and space aren't mutually exclusive. Ergo if you're moving in space, then time actually slows down. I'm grossly simplifying things, so here's a link to possible enlightenment:

http://www.pbs.org/wgbh/nova/physics/special-relativity-nutshell.html

[cafolini]

Ouch!

Actually time does not dilate. But time is a variable. So, if there is a compression because the object is pushing through some density, you might want to interpret that time dilated. It's useless.

[cacian]

Depending on how old the person is, introduce him/her to this (http://www.amazon.com/Einsteins-Dreams-Alan-Lightman/dp/140007780X/ref=sr_1_1?ie=UTF8&qid=1346943142&sr=8-1&keywords=einstein%27s+dreams):
Thank you Charles the book looks interesting. Have you read it?

According to a PBS presentation, it boils down to the idea that time and space aren't mutually exclusive. Ergo if you're moving in space, then time actually slows down. I'm grossly simplifying things, so here's a link to possible enlightenment:

http://www.pbs.org/wgbh/nova/physics/special-relativity-nutshell.html
Time is pointless in space right?
Thanks for the link!


Actually time does not dilate. But time is a variable. So, if there is a compression because the object is pushing through some density, you might want to interpret that time dilated. It's useless.

Could this link with this question:
Is everything one sees real?

[Charles Darnay]

Thank you Charles the book looks interesting. Have you read it?


Yes. I really like it.




Time is pointless in space right?



No, no it is definitely not.

[Mutatis-Mutandis]

How do I explain this theory to a child without getting myslef too hyped up about it?

The same way you'd explain your thoughts on biology, surely.

[Anton Hermes]

The same way you'd explain your thoughts on biology, surely.
:lol:

"Who needs books? Ponder away, kid."

[cacian]

The same way you'd explain your thoughts on biology, surely.

I guess I would try it my way if I did not understand it the other way.
You cannot blame me if Darwin failed to make it clear to me.

[Anton Hermes]

You cannot blame me if Darwin failed to make it clear to me.

If Darwin and everyone in this thread failed to make it clear to you, it's safe to say where the blame lies.

[Volya]

Seriously guys (Mutatis, Anton), why bother bringing that up here.

[Mutatis-Mutandis]

I guess I would try it my way if I did not understand it the other way.
You cannot blame me if Darwin failed to make it clear to me.

Of course I can. Who better to blame, really? Darwin made it quite clear for millions of people. If one person doesn't understand it, the fault is with that one person more than it is with Darwin.


Seriously guys (Mutatis, Anton), why bother bringing that up here.

I felt it relevant to remind people what kind of reactions they'd get if they actually decided to take the time to truly explain the theory of relativity to cacian.

[cacian]

Of course I can. Who better to blame, really? Darwin made it quite clear for millions of people. If one person doesn't understand it, the fault is with that one person more than it is with Darwin.



I felt it relevant to remind people what kind of reactions they'd get if they actually decided to take the time to truly explain the theory of relativity to cacian.

I somehow differ on the view that Darwin has clearly demonstrated his thoughts on this subject.
It is down to the master to lead by examples and demonstrates capabilities to those who wish to learn.
Unfortunately in this particular example the knowledgable master has failed the tasks to issue a clear pervoyance upon my will to understand and therefore the failures is with him and him alone for not having achieved knowledge to base.
A child learns from adult. I take it that would the same similaritie between a Darwin and a mere person.

[Summer M]

Back to the topic:
How old is the child? How brilliant is the child? Are we talking about the special theory or the general? Does the child know basic Newtonian mechanics? If not, why bother with relativity just yet?

[cacian]

Back to the topic:
How old is the child? How brilliant is the child? Are we talking about the special theory or the general? Does the child know basic Newtonian mechanics? If not, why bother with relativity just yet?

Hi Summer back to topic indeed.
The child between seven and eight.
I am talking any theory general or specific.
I am looking for an ouversture a simplified one to give a basic generals about this theory sets out be.
For example something like this

I will explain to a child that I want to reach number 8 using numerals and so will ask what mathematicals rethorics is one to use to reach that number.
The child should conclude that one needs to use 'adding' to do so.
I will leave the multiply and division for later on.

So I am after logical steps to give the child an image like the number 8 is an image.

[Scheherazade]

Are you home schooling your child?

[cacian]

Are you home schooling your child?

No this came up in a conversation with some children and so I could not explain it because I do not understand myself.

[Summer M]

Forget about the general theory, as it is way too difficult. I'd say forget about the special, too, but if you insist, I'd say look at Brian Greene's The Elegant Universe, which explains the rudiments quite well. But really, at eight years old there is plenty to learn before relativity.

[YesNo]

How do I explain this theory to a child without getting myslef too hyped up about it?


I sometimes wonder how to explain it to myself, but here is something to go on and what I would use as a reference:

http://en.wikipedia.org/wiki/Theory_of_relativity

It might be an interesting challenge to see how one would actually say this to a child.

[cafolini]

I sometimes wonder how to explain it to myself, but here is something to go on and what I would use as a reference:

http://en.wikipedia.org/wiki/Theory_of_relativity

It might be an interesting challenge to see how one would actually say this to a child.

Einstein didn't win the Nobel for the theory of relativity. And when it came to that, there was very little that was his in that stuff.
For the rest, he was as retarded as his professors said he was. For the special as well as the general.

[Anymodal]

Explain to him the general outline of the thought process that Einstein had.


Start talking about light. Ask him if he ever wondered if when he switched on the lights, the light was inmediatly in all the room or it traveled too fast to tell. If he never thought of that explain him that light actually travels (you figure it out how, remember the example of the sun, etc). Highlight the point that - therefore- it has a certain speed.
Now, long time ago people aknowledged this, and for many centuries scientist have been trying it to calculate or messure the speed somehow. Astronomers came up with a way to messure it with some aproximation.

Now explain to him a little bit what happens with velocities. It's intuitive actually: Imagine that you get in a train. Now you start running in the hallway in the same direction than the train does. You run at 10km/h. The train moves at 20km/h. Then you are moving 30km/h respect to the ground. Conclusion:Velocities add up.

Now what is to expect is that in the same situation, but standing still in the hallway, if you switch on a flashlight pointing again at the same direction than the train, the beam of light will move at c (c= the speed of light) PLUS 20km/h respect to the ground.

In 1887 an experiment took place in the USA. It involves light and its speed. The results of the experiment contradicted the principle of addition of velocities, because they meassured the same speed of light respect to the ground for a beam that came from a source standing still and from a beam that came from a source in motion. (This is a lie, it's all simplified and adapted).

So at first scientist thought the experiment was a failure. But Einstein asked himself: What if the experiment was correct? What would it mean? Why didn't the speed of light added up with the speed of it's source?
"Mmmhh my best guess -he said to himself- is that, maybe, there is a universal limit to how fast something can travel, like a speed limit, and it happens to be the speed of light, and that explains why the velocities didn't add up in the experiment"

Now, why would there be a universal speed limit?: "I don't know! For some obscure underlying reason. But lets suspend this questioning, because I can't keep too many lines of thought at the same time. Let's pretend my guess is right and figure out what consecuenses it would have. Maybe I can deal with that later"


(To be continued...)

[cafolini]

Explain to him the general outline of the thought process that Einstein had.


Start talking about light. Ask him if he ever wondered if when he switched on the lights, the light was inmediatly in all the room or it traveled too fast to tell. If he never thought of that explain him that light actually travels (you figure it out how, remember the example of the sun, etc). Highlight the point that - therefore- it has a certain speed.
Now, long time ago people aknowledged this, and for many centuries scientist have been trying it to calculate or messure the speed somehow. Astronomers came up with a way to messure it with some aproximation.

Now explain to him a little bit what happens with velocities. It's intuitive actually: Imagine that you get in a train. Now you start running in the hallway in the same direction than the train does. You run at 10km/h. The train moves at 20km/h. Then you are moving 30km/h respect to the ground. Conclusion:Velocities add up.

Now what is to expect is that in the same situation, but standing still in the hallway, if you switch on a flashlight pointing again at the same direction than the train, the beam of light will move at c (c= the speed of light) PLUS 20km/h respect to the ground.

In 1887 an experiment took place in the USA. It involves light and its speed. The results of the experiment contradicted the principle of addition of velocities, because they meassured the same speed of light respect to the ground for a beam that came from a source standing still and from a beam that came from a source in motion. (This is a lie, it's all simplified and adapted).

So at first scientist thought the experiment was a failure. But Einstein asked himself: What if the experiment was correct? What would it mean? Why didn't the speed of light added up with the speed of it's source?
"Mmmhh my best guess -he said to himself- is that, maybe, there is a universal limit to how fast something can travel, like a speed limit, and it happens to be the speed of light, and that explains why the velocities didn't add up in the experiment"

Now, why would there be a universal speed limit?: "I don't know! For some obscure underlying reason. But lets suspend this questioning, because I can't keep too many lines of thought at the same time. Let's pretend my guess is right and figure out what consecuenses it would have. Maybe I can deal with that later"


(To be continued...)

At this point in my life, the subject of Einstein bores me to dead. There were days in my youth when I got entangled with it and I figure him out one by one. Have fun.

[Anymodal]

I don't think I will ever get bored of relativity. And I already understand it quite well by the way :yesnod:. I stoped the explanation because I just got lazy of thinking how to explain it to an 8 year old.. but then I'll continue :D

[YesNo]

Well, if you were going to explain it to someone, whether 7 or 70, you would probably have to start out by explaining that physical laws are supposedly independent of the velocity of any particular frame of reference, otherwise they wouldn't be physical laws. That goes back to Galileo.

Then you would have to say that a physical law related to the velocity of light was discovered, namely, that nothing can go faster than it. That goes back to the Michelson-Morley experiment that failed to find the speed of the ether.

Since the speed of light as a maximum speed is a physical law, it must be independent of the velocity of any particular frame of reference. So every frame of reference, no matter whether it is rushing toward the light source or rushing away from the light source, will have to come up with the same measure for the velocity of the light source.

[mal4mac]

Check out "Mr Tompkins in Paperback" by George Gamow. I read it when I was about 10 and found it very inspirational.

Simon Singh's "Big Bang" has some very good explanations and diagrams - it's really aimed at adults, but might inspire you to some good explanations.

I second Brian Greene's The Elegant Universe.

Careful of Wikipedia - it gets hard very quickly! Encyclopedia Britannica is more straightforward.

[cacian]

I sometimes wonder how to explain it to myself, but here is something to go on and what I would use as a reference:

http://en.wikipedia.org/wiki/Theory_of_relativity

It might be an interesting challenge to see how one would actually say this to a child.
Indeed. Thnak you YesNo it is all an adult world out there.

Einstein didn't win the Nobel for the theory of relativity. And when it came to that, there was very little that was his in that stuff.
For the rest, he was as retarded as his professors said he was. For the special as well as the general.

Einstein retarded? Now that is a first for me.
Since when?:p


I don't think I will ever get bored of relativity. And I already understand it quite well by the way :yesnod:. I stoped the explanation because I just got lazy of thinking how to explain it to an 8 year old.. but then I'll continue :D


Please do. I have to admit I kept up reading up to a point and I felt a headache coming on.
I wondered about someone running on a train that is already running.
Is that a possibility to run that fast on a train that is already very fast?


Well, if you were going to explain it to someone, whether 7 or 70, you would probably have to start out by explaining that physical laws are supposedly independent of the velocity of any particular frame of reference, otherwise they wouldn't be physical laws. That goes back to Galileo.

One could use speed rather then velocity because velo-city is composed of two words velo=bike and city= city. It can be misleading for a French speaker like me. I can't help but stop the velo in there.
It is almost half french and english this word.
The other thing what about buyancy interms of speed? Is there anything in there about in relativity?

Then you would have to say that a physical law related to the velocity of
light was discovered, namely, that nothing can go faster than it. That goes back to the Michelson-Morley experiment that failed to find the speed of the ether.

Since the speed of light as a maximum speed is a physical law, it must be independent of the velocity of any particular frame of reference. So every frame of reference, no matter whether it is rushing toward the light source or rushing away from the light source, will have to come up with the same measure for the velocity of the light source.
Ouch that is too much information for me haha. :p
How about a simple drawing just to settle a picture in one's mind haha.

[YesNo]

One could use speed rather then velocity because velo-city is composed of two words velo=bike and city= city. It can be misleading for a French speaker like me. I can't help but stop the velo in there.
It is almost half french and english this word.
The other thing what about buyancy interms of speed? Is there anything in there about in relativity?

In English, I've learned that "velocity" means speed with a direction. The main reason I use it is to make me look as if I know what I'm talking about. If I wrote, "speed", some reader would think, "Oh, the dummy doesn't know the correct term is 'velocity'". For the purposes of this thread, however, I suspect speed is just as good.

What do you use in French to distinguish these ideas?

The speeds of these frames of reference have to be so smooth that any people in them doing science would not feel that they are moving at all. So there wouldn't be any buoyancy or bumpiness.



Ouch that is too much information for me haha. :p
How about a simple drawing just to settle a picture in one's mind haha.

I find it strange also, but I think the core of the strangeness has to do with finding a law of physics related to the maximum speed something can go.

In all these frames of reference, their relative speeds are supposed to be irrelevant in the verifications of the laws of physics done by someone in that frame of reference, but here is a law saying that there is a maximum possible speed. Here is a law about speed itself. Since it is a law of physics, I can verify it and I should come up with the same value no matter if I am moving toward the light source or away from the light source from the relative perspective of someone in a different frame of reference.

Of course, I don't think I'm moving at all in my own frame of reference. It is the other guy watching me who's moving and, oddly, getting the same value for the speed of light that I did.

[mal4mac]

I think with an 8 year old kid you need to follow Gamow and try and imagine that relativity applies to the everyday, practical world the kid knows about. Imagine a particle of light as a spacehopper*. Ask the kid what it would be like to jump on that particle. Then tell him the spacehopper will be moving at 'the speed of light', so how could he jump on? If says he would run and catch it, tell him it will always be moving at the same speed away from him however fast he runs!

* Do 8 year old kids know what spacehoppers are these days?

[cacian]

I think with an 8 year old kid you need to follow Gamow and try and imagine that relativity applies to the everyday, practical world the kid knows about. Imagine a particle of light as a spacehopper*. Ask the kid what it would be like to jump on that particle. Then tell him the spacehopper will be moving at 'the speed of light', so how could he jump on? If says he would run and catch it, tell him it will always be moving at the same speed away from him however fast he runs!

* Do 8 year old kids know what spacehoppers are these days?

Hey mal4mac yes eight year olds do know what a space hooper is.
Thank you for the post. I explained what you have just said but there is one one question they asked:
what is making the spacehopper run so fast and will it ever stop because it should eventually.
In other word the space hopper will eventually slow down to a stop right? :p

[mal4mac]

Hey mal4mac yes eight year olds do know what a space hooper is.
Thank you for the post. I explained what you have just said but there is one one question they asked:
what is making the spacehopper run so fast and will it ever stop because it should eventually.
In other word the space hopper will eventually slow down to a stop right? :p

No! The speed of light is a constant. We don't know what is making it a constant, it's just a universal law of nature that we must accept (like bedtime rules...)

And we must accept it because it agrees with all the theories of clever physics dudes like Einstein. Thousands of experiments have either shown or assumed that the speed of light is a constant, and none of these experiments have been shown to be wrong. It's as certain as a spacehopper bouncing...

A photon might be absorbed by an atom in your retina, but whenever there's a photon around it's scurrying off at a constant speed. A light photon does not "slow down" upon entering a medium. The apparent decrease in speed in the atmosphere is because it "bounces" between particles. It's still going at the "universal constant" speed c.

(Einstein's special theory of relativity says that any particle with zero mass must always appear to move at the speed of light in any frame of reference.)

[YesNo]

Your thread, cacian, has got me reading Richard Wolfson's Simply Einstein. He tries to explain relativity to anyone. He probably assumes his audience is older than 7, however.

One thing I would add to my original description, based on Wolfson's text, is to explain why people prior to Galileo did not feel the need for a principle of relativity. They experienced in their daily lives only one frame of reference, the earth, which was not moving while the sun, moon and constellations of stars were moving in a circular pattern around this frame of reference.

A relativity principle requires one to have at least two frames of reference.

[cafolini]

Your thread, cacian, has got me reading Richard Wolfson's Simply Einstein. He tries to explain relativity to anyone. He probably assumes his audience is older than 7, however.

One thing I would add to my original description, based on Wolfson's text, is to explain why people prior to Galileo did not feel the need for a principle of relativity. They experienced in their daily lives only one frame of reference, the earth, which was not moving while the sun, moon and constellations of stars were moving in a circular pattern around this frame of reference.

A relativity principle requires one to have at least two frames of reference.

False. Galileo's was relativity. Newton clearly stated that it is impossible to establish velocity 0. Galileo had as many frames of reference as he wished.

Regarding acceleration, a very important Einstenian retardation, two spaceships traveling together, nearby, can consult each other to see if the acceleration read is external or internal.

[cacian]

Your thread, cacian, has got me reading Richard Wolfson's Simply Einstein. He tries to explain relativity to anyone. He probably assumes his audience is older than 7, however.

One thing I would add to my original description, based on Wolfson's text, is to explain why people prior to Galileo did not feel the need for a principle of relativity. They experienced in their daily lives only one frame of reference, the earth, which was not moving while the sun, moon and constellations of stars were moving in a circular pattern around this frame of reference.

A relativity principle requires one to have at least two frames of reference.

Thank you YesNo.
So one requires to have at least two but why in the grandest scheme of things?
In other words in what way does a frame of reference help me advance?

[YesNo]

False. Galileo's was relativity. Newton clearly stated that it is impossible to establish velocity 0. Galileo had as many frames of reference as he wished.

Regarding acceleration, a very important Einstenian retardation, two spaceships traveling together, nearby, can consult each other to see if the acceleration read is external or internal.

I think we are in agreement.

The single frame of reference applies to the science done before Galileo's time. With Galileo one gets at least a second frame of reference, either the sun or Jupiter with its moons. Once you have two frames of reference that number would expand to as many as one wished to have.

The main credit for the idea of relativity belongs to Galileo, as I see it. Einstein did little more than affirm it for electromagnetic waves.

Although I think I read somewhere that there could be "infinitely" many frames of reference, I think that is an exaggeration. There are not even infinitely many subatomic particles in the universe nor with quantized time and space, infinitely many "points" of space-time.

[YesNo]

Thank you YesNo.
So one requires to have at least two but why is the grandest scheme of things?
In other in what way does a frame of reference help me advance?

The way Wolfson describes the relativity of a frame of reference is to consider the motion behavior of playing tennis or the electromagnetic behavior of cooking a meal in a microwave oven.

Would we expect to play tennis differently on a planet in a galaxy traveling very fast away from us? If we were on that planet, would we expect to heat up a meal differently? The principle of relativity claims that we wouldn't have to do anything differently. The laws of physics, both the motion laws as well as the electromagnetic laws, are the same in that planet's frame of reference as our own.

[mal4mac]

One thing I would add to my original description, based on Wolfson's text, is to explain why people prior to Galileo did not feel the need for a principle of relativity. They experienced in their daily lives only one frame of reference, the earth, which was not moving while the sun, moon and constellations of stars were moving in a circular pattern around this frame of reference.

What about a ship? In fact, Galileo used a ship to explain his theory of relativity. And they had ships before Galileo! So you, or Wolfson, need to explain why people didn't think of this before Galileo. I can't see that Galileo had more "need" to explain this than other people. Given the Spanish Inquisition perhaps more of a need not to :angel:

http://physics.ucr.edu/~wudka/Physics7/Notes_www/node47.html

[cafolini]

I think the validity of infinity resides in division by two and is inescapable. There cannot occur an object without some measure of inside or, in the macro, some measure of beyond. by inference, or what has been named "weak proof." I don't see it as weak. But, of course, you can't get a baby to have a natural vocation for imaginary Cheerios, except if it is a convenient way of gaining the actual, occurring, Cheerios in three dimensions.
In the large scheme of things we could find as little solution as in the microscopic. This will always trigger unending and useless speculation as to where God is hiding, is, exists, or occurs.
But we must accept that as scientists we only can be annoyed at the impossibility of postulating occurrence other than as being and existence in the imagination. But because of these vicious, circular arguments I am exposing, where the existence or being of God couldn't possibly help science, beyond the mental kind, why should but a psychologist elebarote on it. The rest of the people is subjected to faith as the only solution and the psychologist as a volunteer at the mental stage. Don't forget to have some fun and firm faith in love and hope.

[YesNo]

What about a ship? In fact, Galileo used a ship to explain his theory of relativity. And they had ships before Galileo! So you, or Wolfson, need to explain why people didn't think of this before Galileo. I can't see that Galileo had more "need" to explain this than other people. Given the Spanish Inquisition perhaps more of a need not to :angel:

http://physics.ucr.edu/~wudka/Physics7/Notes_www/node47.html
I think you're right that there was opportunity to come up with a principle of relativity long before Galileo. Perhaps some cultures actually did.

The following about infinite speeds in a vacuum and everything naturally slowing down from the article are things I didn't know about Aristotle's mechanics, but I don't know much about Aristotle.


This directly contradicts the Aristotelian philosophy which claimed that

all objects on Earth, being imperfect, will naturally slow down,
that in a vacuum infinite speeds would ensue,
and that perfect celestial bodies must move in circles.

I can see the part about things naturally slowing down, but why the infinite speeds in a vacuum?

[YesNo]

I think the validity of infinity resides in division by two and is inescapable.

As far as mathematics goes, that makes sense. One could keep dividing by two as often as one liked and get closer and closer to having a pile with an infinite number of smaller and smaller pieces.

However, if one actually wanted to have that infinite pile of pieces one would have to assume that one could complete such an infinite process of dividing something even if that something were imaginary. I think that assumption was labelled the "axiom of choice", but it has been a while.

[cacian]

The way Wolfson describes the relativity of a frame of reference is to consider the motion behavior of playing tennis or the electromagnetic behavior of cooking a meal in a microwave oven.

Would we expect to play tennis differently on a planet in a galaxy traveling very fast away from us? If we were on that planet, would we expect to heat up a meal differently? The principle of relativity claims that we wouldn't have to do anything differently. The laws of physics, both the motion laws as well as the electromagnetic laws, are the same in that planet's frame of reference as our own.

Thank YesNo for explaining this most helpful and I am now beginning to have a feel for it.
If I may add then, this simply platonic reasoning because using a microwave or playing tennis in a different planet/ galaxy is not going to happen.
Unless of course one wishes to make a film out of it to demonstrate what one means.

[mal4mac]

As far as mathematics goes, that makes sense. One could keep dividing by two as often as one liked and get closer and closer to having a pile with an infinite number of smaller and smaller pieces.

However, if one actually wanted to have that infinite pile of pieces one would have to assume that one could complete such an infinite process of dividing something even if that something were imaginary. I think that assumption was labelled the "axiom of choice", but it has been a while.

I think the problem with this argument begins before the "completion of an infinite process" problem.

Doesn't mathematics only make sense in "our world"? And in our world you can't just keep chopping things in half. How would you chop a Higgs boson in half?

[cafolini]

As far as mathematics goes, that makes sense. One could keep dividing by two as often as one liked and get closer and closer to having a pile with an infinite number of smaller and smaller pieces.

However, if one actually wanted to have that infinite pile of pieces one would have to assume that one could complete such an infinite process of dividing something even if that something were imaginary. I think that assumption was labelled the "axiom of choice", but it has been a while.

True. However, if it were possible, or you found the means and the technique to do it, you would. That there is a smallest particle is a worse assumption. Humanity has been claiming smallest particles for ages and always found smaller ones. They can't pull that one anymore against historical evidence of their scoundrelship.

[YesNo]

I'll have to look at some quantum physics text to see if makes sense that those leptons and quarks are as small as one can get. I wonder if "particle" is even a good metaphor to use to describe them. With the detection of the Higgs boson recently, that theory is probably on firm ground, but I don't know much about it.


I think the problem with this argument begins before the "completion of an infinite process" problem.

Doesn't mathematics only make sense in "our world"? And in our world you can't just keep chopping things in half. How would you chop a Higgs boson in half?

I think you are right about the problem. There is a difference between the process of getting closer and closer to an infinite collection of something and actually finishing that process and having the infinite collection to work with.

If one assumes one can actually have infinite sets of things then one can use logic to see what consequences follow even if in the real world infinite sets of things don't exist.


Thank YesNo for explaining this most helpful and I am now beginning to have a feel for it.
If I may add then, this simply platonic reasoning because using a microwave or playing tennis in a different planet/ galaxy is not going to happen.
Unless of course one wishes to make a film out of it to demonstrate what one means.
We won't be able to reach that galaxy to test out whether we would need to do anything special or not to play tennis or use a microwave oven. However, from the point of view of anyone on that galaxy moving away from us, we are in that situation right now. They think we're moving away from them at a fast speed.

[mal4mac]

I'll have to look at some quantum physics text to see if makes sense that those leptons and quarks are as small as one can get. I wonder if "particle" is even a good metaphor to use to describe them. With the detection of the Higgs boson recently, that theory is probably on firm ground, but I don't know much about it.

In theory you can go as small as you like, in fact, particles are usually considered to be point particles in quantum physics texts - that is, infinitely small, but the uncertainty principle would make them look like fuzzy balls, if we could see them, which we can't.

The smallest things we can see (or, actually, feel!) are atoms:

http://www.nanooze.org/english/articles/article5_powerfulmicroscope.html

(That nanooze site looks a good one for kids into science...)

[cacian]

I admire you lot for such great patience towards particles atoms and whatnot.
I totally follow that chain of thought no matter how hard I would like to.
The point of quantum is that it does not matter where you are can still see it but cannot quiet define if one was not aware of it.
I mean humans must be quantums themselves if we were observed by partilcles or atoms.
In other words if atoms had eyes they would describe a human going about his or her bunsiness as a quantums of an earthal dimension. Juts a reversed psychology there for a minute haha.

[YesNo]

In theory you can go as small as you like, in fact, particles are usually considered to be point particles in quantum physics texts - that is, infinitely small, but the uncertainty principle would make them look like fuzzy balls, if we could see them, which we can't.

The smallest things we can see (or, actually, feel!) are atoms:

http://www.nanooze.org/english/articles/article5_powerfulmicroscope.html

(That nanooze site looks a good one for kids into science...)

I didn't realize that there were "atomic force microscopes" which sound pretty interesting nor that an electron microscope would not be able to see colors, which makes sense now that I think about it.

On a theoretical level the spacetime grid seems like it should be flat and allow one to go out to infinity in both the space and time dimensions since nothing logically stops us from doing do. Also we should be able to break up any world line into points that correspond to the rational numbers and the irrational numbers. Those sets of points would be disjoint and both would be infinite sets although they would be different sized infinities. So there is logically smoothness and infinity all over the place.

However, once one starts looking at the spacetime grid as populated with matter and energy upon which one can perform experiments, one finds that the universe has to be finite or we couldn't survive in it and general relativity turns up the possibility of black holes representing singularities in the spacetime grid. With the big bang, time loses its infinite property on the grid. With quantum mechanics, spacetime itself might not be able to make sense below the Planck length. I hear that this quantum approach to spacetime might provide a solution to Zeno's paradoxes or those paradoxes might imply the necessity of something like the Planck length: http://barang.sg/index.php?view=achilles&part=8

Actually, I don't know.

I did finish Wolfson's text and found another by Chad Orzel called How to Teach Relativity to Your Dog. I didn't check it out, but it looks like he has upped the challenge somewhat.

[cacian]

Hi YesNo I have just thought of another way to the theory.
I would ask this:

Why would anyone want to teach the theory of relativity to?
I am looking for a reason.

For example I teach myself cooking because I wish to feed myself first and foremost.

[YesNo]

I think the main reasons to teach this are to explain gravity and what the consequences are with having an upper speed limit that light can achieve.

One would either have to teach the Newtonian gravity as a force acting instantaneously through a distance or Einstein's understanding of gravity as the way spacetime is shaped around objects. Einstein's approach is more satisfying because it explains more observable phenomena, such as Mercury's orbit, and does not require that force be transmitted faster than the speed of light.

[cacian]

I think the main reasons to teach this are to explain gravity and what the consequences are with having an upper speed limit that light can achieve.
This is information that I need to think about a bit more.
I am considering the next which to define movement.
In other words what is a movement and why is there light?


One would either have to teach the Newtonian gravity as a force acting instantaneously through a distance or Einstein's understanding of gravity as the way spacetime is shaped around objects. Einstein's approach is more satisfying because it explains more observable phenomena, such as Mercury's orbit, and does not require that force be transmitted faster than the speed of light.
In this paragraph I am going to have to go with the word for a minute.
I need to define force and what it means in relation to speed and movement.
When I think of gravity I think a spaceman hoping/floating around space with no force to lead him.
The question I am after is what does make someone float in space and not why he/she floats?

[cafolini]

I think the main reasons to teach this are to explain gravity and what the consequences are with having an upper speed limit that light can achieve.

One would either have to teach the Newtonian gravity as a force acting instantaneously through a distance or Einstein's understanding of gravity as the way spacetime is shaped around objects. Einstein's approach is more satisfying because it explains more observable phenomena, such as Mercury's orbit, and does not require that force be transmitted faster than the speed of light.

That people chose to try to explain Newtonian gravity as forces at a distance and cast it in bronze, does not mean that Newton or Galileo ate that tangerine. Neither do we eat the super darn stringettas. And the unified field pee?
The future lies in the understanding of densities and objects moving through them. The speed of light could be any. We'll proceed to eliminate the ridiculousness of weak proof (axion of choice), the idiocy of forces at a distance, or Italian cheese and stringettas, unified pee and the like. There is not enough magic, no enough elegance, not enough theater in all that poor man's stuff. Magic is a science.

[Volya]

In this paragraph I am going to have to go with the word for a minute.
I need to define force and what it means in relation to speed and movement.
When I think of gravity I think a spaceman hoping/floating around space with no force to lead him.
The question I am after is what does make someone float in space and not why he/she floats?

They float due to lack of gravity. All bodies exert gravitational pull, if you have a larger mass the force will be stronger. Hence why on Earth we walk 'normally', on the moon spacemen can sorta 'bounce' along, as the moon has a smaller mass.

[mal4mac]

I didn't realize that there were "atomic force microscopes"...

You could have some great kids activities based around that idea. Blindfold them, give them a stick and see if they can "see" objects by feeling them with the stick. Could lead to some really cool questions, like: Are blind people really blind?



On a theoretical level the spacetime grid seems like it should be flat and allow one to go out to infinity in both the space and time dimensions since nothing logically stops us from doing so.


Why should it be flat? Einstein's GR predicted three possible states - flat, closed curvature, open curvature. Flat and open go to infinity, closed is a three dimensional spherical surface in a four dimensional space. Head off in a spaceship and you don't go to infinity you come back to where you started (like flying a plane away from your city...)

That said, observational astronomers are now pretty certain the space is flat, and that the universe will expand forever so it looks like space and time are indeed infinite as you say.




I did finish Wolfson's text and found another by Chad Orzel called How to Teach Relativity to Your Dog.

Now that's just silly!


They float due to lack of gravity. All bodies exert gravitational pull, if you have a larger mass the force will be stronger. Hence why on Earth we walk 'normally', on the moon spacemen can sorta 'bounce' along, as the moon has a smaller mass.

You're right about the 'bouncing' moon men, but not right, or at least not clear enough for a twelve year old, about floating being due to 'lack of gravity'. So how to explain floating astronauts to a twelve year old? Here's an attempt:

There is only "zero gravity" at special points in space where gravity cancels out - if the moon and the earth were the same size that would be the mid-point between them.

The reason astronauts in earth orbit seem to float is that they are in free fall.

Imagine an aircraft's engines cut out and it just free falls to Earth. The passengers would fall at the same speed as the plane and appear to be floating. In a spacecraft it's exactly the same thing, but the forward velocity of the spacecraft means that it never hits ground, it just remains in orbit.

On firing the rockets and heading to the moon the astronauts feel a force "like gravity" due to the acceleration. But on turning off the rockets they free fall to the moon - the rocket and the astronauts fall at the same speed towards the moon, and therefore the astronauts seem to be floating. But there is no "lack of gravity". The gravitational field of the moon and the Earth are acting, and there is a pull towards the Earth or moon, depending on the distance from either.

[cacian]

They float due to lack of gravity. All bodies exert gravitational pull, if you have a larger mass the force will be stronger. Hence why on Earth we walk 'normally', on the moon spacemen can sorta 'bounce' along, as the moon has a smaller mass.

I am not so sure about size and mass because it is relative.
Man earth Man moon mass/size way is proportionate .
A man bouncing on a moon is like a tennis ball bouncing on the floor.
The same idea.
I am thinking along the line of earth is populated and moon is not.
Earth weighs more then moon.
The bouncing effect is to the 'empty 'effect.
There is weight distinction between empty space and man. The element of air plays a role too.
Man breaths on earth but does not on the moon. This indicates something. The reason I am guessing that men bounce on the moon just like a tennis ball on earth is because of lack of oxygen in both their system.

[Volya]

No cacian. The moon just simply 'weighs less' than the earth effectively.

[YesNo]

You could have some great kids activities based around that idea. Blindfold them, give them a stick and see if they can "see" objects by feeling them with the stick. Could lead to some really cool questions, like: Are blind people really blind?

It is amazing that we can get more information about something than we might expect we could.



Why should it be flat? Einstein's GR predicted three possible states - flat, closed curvature, open curvature. Flat and open go to infinity, closed is a three dimensional spherical surface in a four dimensional space. Head off in a spaceship and you don't go to infinity you come back to where you started (like flying a plane away from your city...)

That said, observational astronomers are now pretty certain the space is flat, and that the universe will expand forever so it looks like space and time are indeed infinite as you say.


I was trying to think of what space and time might be like without matter or energy. I doubt that space and time could really exist without them, however.

Now that the universe has started, does it go on forever or will matter and energy decay at some point into nothing destroying space and time when it is all gone?



The reason astronauts in earth orbit seem to float is that they are in free fall.

Right. That seems like the normal frame of reference that general relativity claims all physical laws have to be valid in.

[YesNo]

That people chose to try to explain Newtonian gravity as forces at a distance and cast it in bronze, does not mean that Newton or Galileo ate that tangerine. Neither do we eat the super darn stringettas. And the unified field pee?
The future lies in the understanding of densities and objects moving through them. The speed of light could be any. We'll proceed to eliminate the ridiculousness of weak proof (axion of choice), the idiocy of forces at a distance, or Italian cheese and stringettas, unified pee and the like. There is not enough magic, no enough elegance, not enough theater in all that poor man's stuff. Magic is a science.

I don't know what they might have accepted.

If magic is in some way repeatable, I suspect it could be a science. People would probably not call it magic anymore.

[cafolini]

I don't know what they might have accepted.

If magic is in some way repeatable, I suspect it could be a science. People would probably not call it magic anymore.

It is well known that magic is a science borrowing from many fields. You should dig into it. I'll close this case with that. It's irrelevant what people that cannot grasp it call it. For those who are magicians, it is more magic than ever.

[cacian]

I'll have to look at some quantum physics text to see if makes sense that those leptons and quarks are as small as one can get. I wonder if "particle" is even a good metaphor to use to describe them. With the detection of the Higgs boson recently, that theory is probably on firm ground, but I don't know much about it.



I think you are right about the problem. There is a difference between the process of getting closer and closer to an infinite collection of something and actually finishing that process and having the infinite collection to work with.

If one assumes one can actually have infinite sets of things then one can use logic to see what consequences follow even if in the real world infinite sets of things don't exist.



We won't be able to reach that galaxy to test out whether we would need to do anything special or not to play tennis or use a microwave oven. However, from the point of view of anyone on that galaxy moving away from us, we are in that situation right now. They think we're moving away from them at a fast speed.

May I ask what galaxy is this?
What I am trying to say is who is THEY in the galaxy?
How does one know there is anyone in that galaxy and if so how can one reach such conclusions if they have never actually experienced it themselves?

[mal4mac]

I was trying to think of what space and time might be like without matter or energy. I doubt that space and time could really exist without them, however.


Why? Max Tegmark suggested the ultimate multiverse idea that any universe you can think of actually exists. You've just thought of a universe without mass or energy but space and time. So it exists! Even without Max's zany ideas surely in principle it could exist. Why not? Pretty boring place, though :)



Now that the universe has started, does it go on forever or will matter and energy decay at some point into nothing destroying space and time when it is all gone?


The big, basic unbreakable rule of physics is conservation of mass energy - matter and energy CANNOT dissolve into nothing - have you heard of the heat death of the universe? That's been a standard "end of it all" explanation for many decades and it's still basically what the average cosmologist expects. As the universe expands the uniform distribution of energy, "heat", just gets, more and more diffuse tending to nothing - "death".

Any "loose matter" - us, the remnants of our sun after supernova, etc, get sucked into black holes. But as black holes evaporate (according to Hawking) eventually you will have just weakening energy permeating space. I think space and time will still be there, though.

I've never seen it suggested than vanishing small energy levels will result in the destruction of space & time.

Dark energy and dark matter may still be around - we have no idea what they are, so who knows what they will get up to in the distant future. I think the best guess is that they'll just "be there", like now, while "normal" mass energy just gets on with getting more homogenous, and weaker.

[YesNo]

Why? Max Tegmark suggested the ultimate multiverse idea that any universe you can think of actually exists. You've just thought of a universe without mass or energy but space and time. So it exists! Even without Max's zany ideas surely in principle it could exist. Why not? Pretty boring place, though :)

I don't know if thinking something exists makes it exist except as a thought, but that is an interesting idea.



The big, basic unbreakable rule of physics is conservation of mass energy - matter and energy CANNOT dissolve into nothing - have you heard of the heat death of the universe? That's been a standard "end of it all" explanation for many decades and it's still basically what the average cosmologist expects. As the universe expands the uniform distribution of energy, "heat", just gets, more and more diffuse tending to nothing - "death".

Any "loose matter" - us, the remnants of our sun after supernova, etc, get sucked into black holes. But as black holes evaporate (according to Hawking) eventually you will have just weakening energy permeating space. I think space and time will still be there, though.

I've never seen it suggested than vanishing small energy levels will result in the destruction of space & time.

I think you are right that the likely end of the universe is some sort of heat death. Since the energy is still present, the space-time would be as well, but I think you are claiming that space-time can exist without energy. The reason I think it cannot is because it gets distorted by the presence of energy which makes me think it is dependent on energy.

[cafolini]

I don't know if thinking something exists makes it exist except as a thought, but that is an interesting idea.


I think you are right that the likely end of the universe is some sort of heat death. Since the energy is still present, the space-time would be as well, but I think you are claiming that space-time can exist without energy. The reason I think it cannot is because it gets distorted by the presence of energy which makes me think it is dependent on energy.

"The imagination is important. But the imagination without knowledge is like a toilet without water." ~ C A Cafolini

[mal4mac]

The reason I think it cannot is because it gets distorted by the presence of energy which makes me think it is dependent on energy.

I don't see it - think of the trampoline metaphor for GR - you can think of the trampoline as space and balls lying on the trampoline as planets "distorting" that space. The planets curve space. But take away the planets, and every other "mass-energy ball", and the trampoline (space) is still there.

Why need space be dependent on energy?

Show me the equations my old prof. would say. And those equations would have to predict every known result of physics and some more...

Then again...

By talking about "distorting space" I'm thinking you are are in the realms of GR. But if you are thinking in quantum terms you might have something - but it's already been "discovered" - the concept of "vacuum energy of empty space" (= dark energy?)

[cafolini]

I don't see it - think of the trampoline metaphor for GR - you can think of the trampoline as space and balls lying on the trampoline as planets "distorting" that space. The planets curve space. But take away the planets, and every other "mass-energy ball", and the trampoline (space) is still there.

Why need space be dependent on energy?

Show me the equations my old prof. would say. And those equations would have to predict every known result of physics and some more...

Then again...

By talking about "distorting space" I'm thinking you are are in the realms of GR. But if you are thinking in quantum terms you might have something - but it's already been "discovered" - the concept of "vacuum energy of empty space" (= dark energy?)

It is energy that's dependent on having space. Energy is and will remain an ability of mass to do work. It is the ability of mass to force a displacement. Forget the tranpolin and that stuff. Space doesn't get curved. That would be ridiculous. Space is there for displacement to occur.

[cacian]

The next question that came to mind is this

When does big becomes big? In relation to what?
If we are and we must bear in mind that there is nothing bigger then the universe itself.
In other words when does size becomes a size?

[YesNo]

I don't see it - think of the trampoline metaphor for GR - you can think of the trampoline as space and balls lying on the trampoline as planets "distorting" that space. The planets curve space. But take away the planets, and every other "mass-energy ball", and the trampoline (space) is still there.

Why need space be dependent on energy?

Show me the equations my old prof. would say. And those equations would have to predict every known result of physics and some more...

Then again...

By talking about "distorting space" I'm thinking you are are in the realms of GR. But if you are thinking in quantum terms you might have something - but it's already been "discovered" - the concept of "vacuum energy of empty space" (= dark energy?)

I need to see the equations also to be convinced, but I don't know what they are. The problem with equations is that they may be just approximations to reality especially around singularities.

I went back to the library to look for Orzel's How to Teach Relativity to Your Dog, but it was checked out. So, I'm reading Joseph Mazur's The Motion Paradox instead. It is also a survey written for the curious, but supposedly it will point in some interesting direction since it is more specifically about time and space.

The distorting space concept would come from general relativity. I guess I don't know what space is without the stuff in it to define it.

Cacian asks what "big" is. I assume the space of the universe is finite and expanding, but I wonder if that assumes it is dependent on matter. Cafolini doesn't think space gets curved by matter so then we are back to Newton's force of gravity acting instantaneously over a distance.

[cafolini]

I need to see the equations also to be convinced, but I don't know what they are. The problem with equations is that they may be just approximations to reality especially around singularities.

I went back to the library to look for Orzel's How to Teach Relativity to Your Dog, but it was checked out. So, I'm reading Joseph Mazur's The Motion Paradox instead. It is also a survey written for the curious, but supposedly it will point in some interesting direction since it is more specifically about time and space.

The distorting space concept would come from general relativity. I guess I don't know what space is without the stuff in it to define it.

Cacian asks what "big" is. I assume the space of the universe is finite and expanding, but I wonder if that assumes it is dependent on matter. Cafolini doesn't think space gets curved by matter so then we are back to Newton's force of gravity acting instantaneously over a distance.

No. Actually we are not back to forces acting at a distantce. That would be ridiculous. There has to be physical contact. Forces at-a-distance do not provide it. Newton did not claim the action of forces at-at-a-distance. His model was one of behaviour, based on Kepler's descriptions. And so were Halley's predictions.
Stringettas with papal cheese were an invention to fake the appearance of physical contact. A funny cardinalia myth established to keep going with the BS.
The M&M experiment was another funny idiocy if taken as scientific. Aristrotle spoke of the Aither (the ether they went to test). That's similar to the palpitations of some freak that suspects there is someone at the door, goes to check and not finding anyone says "he wasn't there. So, there has to be a principle based on why he wasn't there." Ridiculous.
What's going on is based on travelling through densities. That's dynamic, and that's where the answers are and have been found. The speed of light or ANY other matter could be ANY based on the density of the area they are travelling. And this is no longer a static situation measured by matter/volume, but a very dynamic one where V (the full vector) play a part. Density encountered changes with V. Jesus knew this and that's why he walked on water. The pigmies of Africa learn how to run over swamps. Mythbusters walked over a swiming pool where the density of its water was increased with corn starch. Have fun. :nopity:

[cacian]

No. Actually we are not back to forces acting at a distantce. That would be ridiculous. There has to be physical contact. Forces at-a-distance do not provide it. Newton did not claim the action of forces at-at-a-distance. His model was one of behaviour, based on Kepler's descriptions. And so were Halley's predictions.
Stringettas with papal cheese were an invention to fake the appearance of physical contact. A funny cardinalia myth established to keep going with the BS.
The M&M experiment was another funny idiocy if taken as scientific. Aristrotle spoke of the Aither (the ether they went to test). That's similar to the palpitations of some freak that suspects there is someone at the door, goes to check and not finding anyone says "he wasn't there. So, there has to be a principle based on why he wasn't there." Ridiculous.
What's going on is based on travelling through densities. That's dynamic, and that's where the answers are and have been found. The speed of light or ANY other matter could be ANY based on the density of the area they are travelling. And this is no longer a static situation measured by matter/volume, but a very dynamic one where V (the full vector) play a part. Density encountered changes with V. Jesus knew this and that's why he walked on water. The pigmies of Africa learn how to run over swamps. Mythbusters walked over a swiming pool where the density of its water was increased with corn starch. Have fun. :nopity:

Jesus did not walk on water cafolini.
If you believe that you believe anything.
Jesus was a person just like you and mme and so he did not cure diseases either. He did not have magic hands.
And he most definetely did not turn water into wine. I thought he walked on it.

[cacian]

I need to see the equations also to be convinced, but I don't know what they are. The problem with equations is that they may be just approximations to reality especially around singularities.

I went back to the library to look for Orzel's How to Teach Relativity to Your Dog, but it was checked out. So, I'm reading Joseph Mazur's The Motion Paradox instead. It is also a survey written for the curious, but supposedly it will point in some interesting direction since it is more specifically about time and space.

The distorting space concept would come from general relativity. I guess I don't know what space is without the stuff in it to define it.

Cacian asks what "big" is. I assume the space of the universe is finite and expanding, but I wonder if that assumes it is dependent on matter. Cafolini doesn't think space gets curved by matter so then we are back to Newton's force of gravity acting instantaneously over a distance.

Do you know YesNo I personally do not believe gravity exists. I have my own reasons to think that.
I think the apple fell because it was ready/ripe to fall. When a fruit is a ripe it falls off the tree.

Another point when does distance becomes distance? It is perspective rather then further or closer away.
I am not sure.
It is the same as the size issue.

[YesNo]

I agree with you that the apple falls when it is ripe.

Daniel Chamovitz's What a Plant Knows: A Field Guide to the Sense is a survey of what is known about plant sensation. If I recall correctly, plants will ripen their fruit when they detect a certain "smell". Since they do not have noses, their sense of smell functions differently than ours. What Chamovitz does is finds correlations between our sensations and plant sensations and then shows if there is scientific evidence that plants actually do have such sensations. The only comparable sensation that he could not find was hearing.

I finished Mazur's The Motion Paradox. It was a history of the ideas of motion and illusion from Zeno to the present day. Zeno claims that a continuous space and time, which is what our senses perceive and our mathematics models with the continuous number line, implies change is an illusion. The continuous model of space and time has had to be patched with the discovery that space and time are relative and the speed of light is constant, the discovery that dense mass increases the curvature of space and the discovery that the smallest particles behave also as waves fluctuating through quanta and not continuously. The search for a unified theory of quantum mechanics and gravitation is an attempt to replace the patched mathematical model of space-time with a new model.

[cacian]

YesNo thank you for the post.
Here is my next thought

does weightlessness exists ?
Because if it does not then stilness cannot be either.

[YesNo]

I don't really have any answers, just some ideas of what makes sense to me at the moment based on reading and trusting, perhaps too eagerly, what I've read.

Weightlessness is what one would experience in "free fall" which is the inertial frame of reference that general relativity claims the laws of physics should be verifiable in. Special relativity only holds for frames of reference where the relative motion of the frame is uniform, what the Mars rover was in while en route to Mars. Although it is called a kind of "fall", it is what one would experience orbiting the earth, weightless and motionless.

I don't know what you mean by "stillness cannot be either". It sounds like what one would experience when one does not have fear or desires. I think one could experience that while on earth with the earth keeping us grounded.

[mal4mac]

The distorting space concept would come from general relativity. I guess I don't know what space is without the stuff in it to define it.


Why does it need "stuff in it" to define it? The inside of a watering can is not defined by water ... or the can ... or air. It's just space.



Cacian asks what "big" is. I assume the space of the universe is finite and expanding, but I wonder if that assumes it is dependent on matter.

One should never make assumptions with this crazy stuff :) Read what the crazy cosmologists write. The current favoured model is an infinite, expanding space. The infinite space was created at the moment of the Big Bang... note it's now thought to be "flat", a nice 3D space, so nice and easy to visualise (?)

As infinite space was "just there" after the Big bang, I can't see matter had much to do with it. In any case, one could imagine a universe that is just flat and infinite without matter. Couldn't one?

Anyway, matter is just an impermanent fluctuation in the quantum vortex... when it's all been swallowed into exploding mini Black holes and there will just be energy.. and that will (due to expansion) attenuate into a level indistinguishable from vacuum quantum fluctuations... so space will indeed by all there is (unless you want to count quantum vacuum fluctuations...)

[cacian]

Why does it need "stuff in it" to define it? The inside of a watering can is not defined by water ... or the can ... or air. It's just space.



One should never make assumptions with this crazy stuff :) Read what the crazy cosmologists write. The current favoured model is an infinite, expanding space. The infinite space was created at the moment of the Big Bang... note it's now thought to be "flat", a nice 3D space, so nice and easy to visualise (?)

As infinite space was "just there" after the Big bang, I can't see matter had much to do with it. In any case, one could imagine a universe that is just flat and infinite without matter. Couldn't one?

Anyway, matter is just an impermanent fluctuation in the quantum vortex... when it's all been swallowed into exploding mini Black holes and there will just be energy.. and that will (due to expansion) attenuate into a level indistinguishable from vacuum quantum fluctuations... so space will indeed by all there is (unless you want to count quantum vacuum fluctuations...)

This makes me think

What is the edge of earth and does infinity equal space?
I think infinity and space are not the same.

[YesNo]

One should never make assumptions with this crazy stuff :) Read what the crazy cosmologists write. The current favoured model is an infinite, expanding space. The infinite space was created at the moment of the Big Bang... note it's now thought to be "flat", a nice 3D space, so nice and easy to visualise (?)

As infinite space was "just there" after the Big bang, I can't see matter had much to do with it. In any case, one could imagine a universe that is just flat and infinite without matter. Couldn't one?


What do you recommend that I read?

I see space or space-time as a coordinate system with a metric defined on it to measure distance between objects. So it is just a model, not the reality. If the model doesn't work to explain gravitation, for example, one changes it to claim that the model is now "curved". It makes the observations of the orbit of Mercury work better, but it is still a model. An infinite coordinate system does avoid the need to find an edge to the universe.

In looking for some validation for this, the Wikipedia article on the metric expansion of space somewhat helps: http://en.wikipedia.org/wiki/Metric_expansion_of_space The first paragraph makes sense to me although I don't think I understand what this "intrinsic expansion" of space really means. The rising bread image somewhat helps.


The metric expansion of space is the increase of the distance between two distant parts of the universe with time. It is an intrinsic expansion — that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space as, for example, an explosion of matter. The universe is not expanding "into" anything.

But later it talks about an infinite space to avoid the idea of an edge for which there is as yet no evidence:


At present, observations are consistent with the universe being infinite in extent and simply connected, though we are limited in distinguishing between simple and more complicated proposals by cosmological horizons. The universe could be infinite in extent or it could be finite; but the evidence that leads to the inflationary model of the early universe also implies that the "total universe" is much larger than the observable universe, and so any edges or exotic geometries or topologies would not be directly observable as light has not reached scales on which such aspects of the universe, if they exist, are still allowed. For all intents and purposes, it is safe to assume that the universe is infinite in spatial extent, without edge or strange connectedness.

[mal4mac]

What do you recommend that I read?

Ricard's "Happiness" or Maupassant's short stories:)

But if it must be cosmology then Hawking's "A Briefer History of Time" is pretty good, and Greene's "The Fabric of Reality" - but anybody in the local library who's an actual professor of cosmology might be just as good. So browse - just avoid obvious kooks and hard books (Penrose springs to mind... his "The Road to Reality" was harder than my MSc course work!)


I see space or space-time as a coordinate system with a metric defined on it to measure distance between objects. So it is just a model, not the reality. If the model doesn't work to explain gravitation, for example, one changes it to claim that the model is now "curved". It makes the observations of the orbit of Mercury work better, but it is still a model. An infinite coordinate system does avoid the need to find an edge to the universe.


Have you read, "The Grand Design" by Stephen Hawking, he takes this model approach and runs with it - I agree with you and Hawking about this approach - but it does take some of the glory away. "Space is Curved" sounds a lot grander than "my model of space is curved". In fact my acceptance of this position has led me to explore subjectivity & consciousness far more than cosmology these days hence Ricard and Maupassant...)



In looking for some validation for this, the Wikipedia article on the metric expansion of space somewhat helps: http://en.wikipedia.org/wiki/Metric_expansion_of_space The first paragraph makes sense to me although I don't think I understand what this "intrinsic expansion" of space really means. The rising bread image somewhat helps.


I refuse to look at Wikipedia articles, so please don't quote them, it upsets my digestions. It's just a bunch of graduate students showing off, and to h*ll with the general public - or even fellow physicists (!) I tried simplifying a few articles so that my gran could read them and they got upset. You'd be far better off reading professors who are writing for the general public.

The metric expansion of space is the increase of the distance between *any and all* parts of the universe with time. The old balloon metaphor is the best to start with - think of space as the two dimnensional surface of an expanding ballion, and ink dots on the ballon as galaxies. You blow up the ballon and space expands "intrinsically". The ink spots move further apart - just as the galaxies are observed to move apart.

But, remember, space is now thought to be flat and infinite in extent so instead of the ballon think of an infinite flat rubbery sheet like the surface of the ballon - and think of it still expanding like the balloon surface. Ink spots go apart in exactly the same way!

Now think back to the big bang - the infinite sheet was created in the first moment, and matter/energy distributed uniformly across the sheet. Matter collapsed into galaxies and 'cause the universe is only 14.7 billion years old we can only see some galaxies - not the whole inrfinite collection of them on the sheet. Check out:

http://www.atlasoftheuniverse.com/bigbang.html

[YesNo]

Ricard's "Happiness" or Maupassant's short stories:)

But if it must be cosmology then Hawking's "A Briefer History of Time" is pretty good, and Greene's "The Fabric of Reality" - but anybody in the local library who's an actual professor of cosmology might be just as good. So browse - just avoid obvious kooks and hard books (Penrose springs to mind... his "The Road to Reality" was harder than my MSc course work!)

Have you read, "The Grand Design" by Stephen Hawking, he takes this model approach and runs with it - I agree with you and Hawking about this approach - but it does take some of the glory away. "Space is Curved" sounds a lot grander than "my model of space is curved". In fact my acceptance of this position has led me to explore subjectivity & consciousness far more than cosmology these days hence Ricard and Maupassant...)

I'll see if I can find the Grand Design. I think I've seen it in the library.

For special relativity where one has the physical reality of the speed of light being constant, that forces the spacetime model to be what it is. For general relativity, we have replaced an unlikely explanation of gravity being a force instantaneously transmitted to what looks to me like rigging the spacetime coordinate system to get the right results. It doesn't explain why spacetime is curved around matter.



I refuse to look at Wikipedia articles, so please don't quote them, it upsets my digestions. It's just a bunch of graduate students showing off, and to h*ll with the general public - or even fellow physicists (!) I tried simplifying a few articles so that my gran could read them and they got upset. You'd be far better off reading professors who are writing for the general public.

I don't often get the question I'm most interested in answered by the Wikipedia articles either, but they are shorter than a book and usually lead to something else.



Now think back to the big bang - the infinite sheet was created in the first moment, and matter/energy distributed uniformly across the sheet. Matter collapsed into galaxies and 'cause the universe is only 14.7 billion years old we can only see some galaxies - not the whole inrfinite collection of them on the sheet. Check out:

http://www.atlasoftheuniverse.com/bigbang.html

If there were an infinite number of potential stars created during the Big Bang, it is a good thing space is expanding faster than the speed of light so we can only see a finite number of them since the photons of an infinite number of stars bombarding earth would mean the night sky would be bright.

Interesting site that you referenced.

[cacian]

YesNo the issue with the bigbang is that it is too random not as in why and how but as in the time it happened.
It is very easy to imagine what happened but not so easy to imagine why it happened the time it happened.
Time is still a puzzle issue here.

[mal4mac]

For general relativity, we have replaced an unlikely explanation of gravity being a force instantaneously transmitted to what looks to me like rigging the spacetime coordinate system to get the right results. It doesn't explain why spacetime is curved around matter.


Physics doesn't give ultimate explanations - GR experts just accept that spacetime curves around matter, they do not reason why. Stringy types might come up with an explanation using stringy things, but you are still left with "Why stringy things?"




I don't often get the question I'm most interested in answered by the Wikipedia articles either, but they are shorter than a book and usually lead to something else.


.. yes to more unreadable pages. It's far better browsing in the library and looking up stuff in the index of likely looking books.



If there were an infinite number of potential stars created during the Big Bang, it is a good thing space is expanding faster than the speed of light so we can only see a finite number of them since the photons of an infinite number of stars bombarding earth would mean the night sky would be bright.

Interesting site that you referenced.[/QUOTE]

[mal4mac]

If there were an infinite number of potential stars created during the Big Bang, it is a good thing space is expanding faster than the speed of light so we can only see a finite number of them since the photons of an infinite number of stars bombarding earth would mean the night sky would be bright.

I don't think that's all there is to it.

The universe has been in existence for only 13.7 billion years, so we wouldn't see the light from the infinite number of galaxies that are more than 13.7 billion light years from us, even if space wasn't expanding. Interestingly, the universe would get brighter as more and more light started reach us! But...

Following your argument, the edge of the visible universe *is* expanding at greater than the speed of light, so we will never see the light from those distant galaxies.

Worse, because the expansion of the universe is accelerating, most galaxies will eventually cross a cosmological event horizon where any light they emit past that point will never be able to reach us.

So there will be an infinite number of galaxies but we will not be able to see any (except for the local group... and until the heat death...)

[Calidore]

If the speed of light is a hard limit, how can space be expanding faster, not to mention accelerating?

[cacian]

If there is a sound barrier then there must be a speed barrier and so this does not make sense.

[Cioran]

If the speed of light is a hard limit, how can space be expanding faster, not to mention accelerating?

The speed of light limit is a limit on information transfer. Also, special relativity is strictly a false theory. It applies only to local, idealized flat regions of spacetime. It does not apply to the universe as a whole, where general relativity takes over. But the information transfer limit of SR holds in GR.

The universe can and has expanded much faster than light speed because this expansion does not enable faster than light signaling. In the same way, quantum entanglement takes place across arbitrarily vast distances, even across the whole universe instantaneously, but since this phenomenon cannot be exploited to send information, the speed of light limit on information transfer holds.

[YesNo]

YesNo the issue with the bigbang is that it is too random not as in why and how but as in the time it happened.
It is very easy to imagine what happened but not so easy to imagine why it happened the time it happened.
Time is still a puzzle issue here.

I agree. I don't know of any explanation that makes sense to me that the big bang should have happened 13.7 billion years ago and not, say 12.5 billion years ago.

I suppose the way around this is to model that big bangs are happening all the time and we just happen to be on one that started 13.7 billion years ago. Conveniently for such random models, we can't see these other universes so these models are not falsifiable. That would make them more of a belief system rather than a scientific model.

[cacian]

Indeed and the other time how could we be exact with our timing and numbering because time I am thinking back then was either non existand or simply pointless. What I mean 13.7 measures up exact but then there was no such thing as exact. Our seconds were presumably nothing compare to how fast it was then.
A bigbang is as a result of a very fast wind up . Is see it as winding a clock but faster then it is set up that is the only time a proper explosion happens as a result of faster elements going even faster their atmospheric elements.
That nothingness before that must have been much faster in comparison to our timescale in fact it would have burst our timescale to have been a bigbang.

[YesNo]

ave you read, "The Grand Design" by Stephen Hawking, he takes this model approach and runs with it - I agree with you and Hawking about this approach - but it does take some of the glory away. "Space is Curved" sounds a lot grander than "my model of space is curved". In fact my acceptance of this position has led me to explore subjectivity & consciousness far more than cosmology these days hence Ricard and Maupassant...)


I finished Hawking and Mlodinow's The Grand Design. I have read Deepak Chopra and Leonard Mlodinow's War of the Worldviews in the past which was also entertaining.

Regarding infinity, they do mention the need to avoid unbounded results in a model, although I suspect they accept an actual infinite quantity of objects in the universe. Unlike an unbounded result for a sum, one can easily skip over an infinite quantity, but I think it poses other questions such as which infinity one is talking about, the infinity that counts the set of natural numbers, or the larger one that counts the set of real numbers, or the even larger one of the set of all functions on a real domain or perhaps an even larger infinity? That is one of the reasons why one should avoid an infinite quantity of anything in a scientific model.

On the last page is their praise for M-theory that seems to suggest that the universe could be finite in their view:


M-theory is the most general supersymmetric theory of gravity. For these reasons M-theory is the only candidate for a complete theory of the universe. If it is finite--and this has yet to be proved--it will be a model of a universe that creates itself. We must be part of this universe, because there is no other consistent model.
Although I think supergravity would make an expansion of space more substantial than an arbitrary expansion of a coordinate system, the way they put this sounds like too much authority talking and not enough evidence to me. For what it's worth, this is what Wikipedia says about M-theory: http://en.wikipedia.org/wiki/M-theory


M-theory (and string theory) has been criticized for lacking predictive power or being untestable. Further work continues to find mathematical constructs that join various surrounding theories. However, the tangible success of M-theory can be questioned, given its current incompleteness and limited predictive power.

[YesNo]

Indeed and the other time how could we be exact with our timing and numbering because time I am thinking back then was either non existand or simply pointless. What I mean 13.7 measures up exact but then there was no such thing as exact. Our seconds were presumably nothing compare to how fast it was then.
A bigbang is as a result of a very fast wound up . Is see it as wounding a clock but faster then it is set up that is the only time a proper explosion happens as a result of faster elements going even faster their atmospheric elements.
That nothingness before that must have been much faster in comparison to our timescale in fact it would have burst our timescale to have been a bigbang.

If one were pure energy traveling at the speed of light with respect to any massive, aka inertial, frame of reference, would there be any time or space? I suspect there wouldn't, but I don't know what a physicist would say about that.

[KillCarneyKlans]

If a tree falls in the woods and no one is around to hear it, does it make a sound?

A meteor in the vacuum of space makes no sound? If it crashes into a planet, would the resultant impact produce ... a crater?


I thought time was considered a fourth dimension. Is there a school of thought that has it caused by three-dimensional physical motion

Cartoons are 2D they understand time too!

© 1993-2003 ENCARTA Microsoft Corporation. All rights reserved.

Time, conscious experience of duration, the period during which an action or event occurs. Time is also a dimension representing a succession of such actions or events. Time is one of the fundamental quantities of the physical world, similar to length and mass in this respect. The concept that time is a fourth dimension—on a par with the three dimensions of space: length, width, and depth—is one of the foundations of modern physics.

The word relativity derives from the fact that the appearance of the world depends on the observer’s state of motion and is relative to the observer ... Time is distorted in regions of large masses, such as stars and black holes. The general theory of relativity predicts that a massive rotating body will drag space and time around with it as it moves. This effect is called frame dragging.

Immanuel Kant, have proposed that newborn babies may experience the passage of time ... Henri Bergson thought of time as something entirely derived from experience. In Time and Free Will (1889; translated 1910), he proposed that time is a matter of subjective experience, [and that] an infant would not experience time directly but rather would have to learn ,,, how to experience it.

Scientists disagree on whether it is a closed curve (such as a sphere) or an open curve (such as a cylinder or a bowl with sides of infinite height). The theory of relativity leads to the possibility that the universe is expanding; this is the most likely theoretical explanation of the experimentally observed fact that the spectral lines of all distant nebulae are shifted to the red; on the other hand the expanding-universe theory also supplies other possible explanations. The latter theory makes it reasonable to assume that the past history of the universe is finite, but it also leads to alternative possibilities.

Contributed By: Clifford A. Pickover Ph.D; IBM Reasearch Staff Member; Author of Time: A Traveler's Guide and and Strange Brains and Genius
Contributed By: Lawrence A. Bornstein Dept. of Physics NYU; Author of A Contemporary View of Elementary Physics and Calculus for the Physical Sciences.

[cacian]

Well if you take babies they are like a capsule of time they increase they are born then again decrease then death.
It is a capsule of time that grows a certain length then come into being grows even more then dies.
Time in this sense in finite. Non?
Or is this not time but something else?

[mal4mac]

If the speed of light is a hard limit, how can space be expanding faster, not to mention accelerating?

I agree with what Cioran said about "information transfer", this is "standard Bible".

Why expansion of space is accelerating was a big mystery last time I looked - do a search for "dark energy" to see the latest on this.

[mal4mac]

I agree. I don't know of any explanation that makes sense to me that the big bang should have happened 13.7 billion years ago and not, say 12.5 billion years ago.

I suppose the way around this is to model that big bangs are happening all the time and we just happen to be on one that started 13.7 billion years ago. Conveniently for such random models, we can't see these other universes so these models are not falsifiable. That would make them more of a belief system rather than a scientific model.

String theorists have a "landscape model" where each Big Bang model can be thought of as a point in the landscape. This landscape model comes out of basic theory, so I think it qualifies as a scientific theory. It's just there's no experimental proof. But it's no worse a theory than general Relativity was around 1915 - before the experimental proof started to come in (Eddington's solar eclipse mission, etc...)

String theorists talk about "brane collisions" - each Big Bang is contained on a "membrane", these might interact at some points, and we *might* see these interactions writ large across the sky in distortions of galactic & MBR patterns.

Maybe CERN will come up with some ideas and see some trace of multiverses in the LHC? It's not a case of "The unicorns will never be seen. It's just a belief system". We might get lucky... or clever...

[mal4mac]

If one were pure energy traveling at the speed of light with respect to any massive, aka inertial, frame of reference, would there be any time or space? I suspect there wouldn't, but I don't know what a physicist would say about that.

If one were pure energy travelling at the speed of light, one would be very dead, so the experiment would not be possible. That's why Scottie gets all upset when the transport starts to malfunction... Then again Kirk and gang did encounter pure energy beings... ask one of them...

Imagining that I'm a pure energy being, for the moment, imagine if I blast off to the stars at the speed of light than come back to report to you twenty years later (in your time!) Using the old twin-paradox observations, at the limit, I'd not be a nano-second older. Expanding on this, if I continued always moving at the speed of light, every moment would be the same for me forever. I could be at the stars (and every other star... and every point...) at the same moment (for me). Space would be nothing to me... I'd be everywhere in this moment (and there's only this moment... ) I'll stop now... I'm starting to sound like an E.E. "Doc" Simth novel...

In summary, I think you're wrong... there would be time and space, but only one moment, and all of space would be the same, that is, reduced to one point.

[YesNo]

If one were pure energy travelling at the speed of light, one would be very dead, so the experiment would not be possible. That's why Scottie gets all upset when the transport starts to malfunction... Then again Kirk and gang did encounter pure energy beings... ask one of them...

Imagining that I'm a pure energy being, for the moment, imagine if I blast off to the stars at the speed of light than come back to report to you twenty years later (in your time!) Using the old twin-paradox observations, at the limit, I'd not be a nano-second older. Expanding on this, if I continued always moving at the speed of light, every moment would be the same for me forever. I could be at the stars (and every other star... and every point...) at the same moment (for me). Space would be nothing to me... I'd be everywhere in this moment (and there's only this moment... ) I'll stop now... I'm starting to sound like an E.E. "Doc" Simth novel...

In summary, I think you're wrong... there would be time and space, but only one moment, and all of space would be the same, that is, reduced to one point.

That there would be only one point in the coordinate system is reasonable to me and is all I would be looking for.

I agree that mass cannot move at that speed. As I understand it trying to accelerate mass not only increases the velocity but also the inertia or mass of the object. Since the object also gets massive as well as increases velocity an incremental change in velocity requires increasing amounts of energy.

I found this site called "Ask a physicist/mathematician". Here are some questions they answered that were related to what we discussed:

1) Do time and distance exist in a completely empty universe? http://www.askamathematician.com/2012/01/q-do-time-and-distance-exist-in-a-completely-empty-universe/ Unless I misread, they left the answer ambiguous.

2) Does light experience time? http://www.askamathematician.com/2011/07/q-does-light-experience-time/ The answer is no, which is what we agree on.

They also answered questions such has "How many mathematicians does it take to screw in a light bulb?", which I didn't read.

[YesNo]

String theorists have a "landscape model" where each Big Bang model can be thought of as a point in the landscape. This landscape model comes out of basic theory, so I think it qualifies as a scientific theory. It's just there's no experimental proof. But it's no worse a theory than general Relativity was around 1915 - before the experimental proof started to come in (Eddington's solar eclipse mission, etc...)

String theorists talk about "brane collisions" - each Big Bang is contained on a "membrane", these might interact at some points, and we *might* see these interactions writ large across the sky in distortions of galactic & MBR patterns.

Maybe CERN will come up with some ideas and see some trace of multiverses in the LHC? It's not a case of "The unicorns will never be seen. It's just a belief system". We might get lucky... or clever...

I would place a belief system, such as the unicorn one you mention, that has no experimental evidence for it, on one side. I would place on the other side a scientific theory, such as relativity, that has evidence in favor of it, on the other side. Between them there are a lot of models and theories and beliefs. It might be possible to come up with some indirect evidence for the multiverse and we need to look for it because the model has been presented, but until there is some evidence, it is not a scientific theory, but a speculation.

[YesNo]

Well if you take babies they are like a capsule of time they increase they are born then again decrease then death.
It is a capsule of time that grows a certain length then come into being grows even more then dies.
Time in this sense in finite. Non?
Or is this not time but something else?

At least two things people thought were infinite have turned out to be finite.

Time was believed to be infinite in extent into the past prior to the big bang. Now it is finite. Although time may be assumed to continue indefinitely into the future, that is a different kind of infinity. We haven't reached it yet and so it is not realized.

Matter was considered to be infinitely divisible in a continuous space modeled by real coordinates of mathematics. Now that we have finite quanta of matter and energy, that coordinate system is only useful as a convenience. It does not represent reality, but our illusion of a continuous space-time.

I think it is safe to assume that a scientific model should not include any realized infinities. If the mathematics leads to an unbounded state, the scientific theory is no longer valid there.

[KillCarneyKlans]

I was thinking about a book I use to have ... Hawkins on Quatum stuff and describing the quarks as cards ... and spinning them at various turns to reveal the card ... and that got me thinking ... Hey I just saw Groom Lake ... Shatner saved this alien ... that travels at near light speed ... by turning into a gas, gas expands ... so you decide ?!?

http://en.wikipedia.org/wiki/Spin_%28physics%29
Quantum mechanics states that component of angular momentum measured along any direction can only take a number of discrete values. The most convenient quantum mechanical description of particle's spin is therefore with a set of complex numbers corresponding to amplitudes of finding a given value of projection of its intrinsic angular momentum on a given axis.

The spin vector ... is easy to picture classically. For instance, quantum mechanical spin can exhibit phenomena analogous to classical gyroscopic effects. For example, one can exert a kind of >"torque"< on an electron by putting it in a magnetic field (the field acts upon the electron's intrinsic magnetic dipole moment). The result is that the spin vector undergoes precession, just like a classical gyroscope. This phenomenon is used in nuclear magnetic resonance sensing.

Mathematically, quantum mechanical spin is not described by vectors as in classical angular momentum, but by objects known as spinors. There are subtle differences between the behavior of spinors and vectors under coordinate rotations. For example, rotating a spin-1/2 particle by 360 degrees does not bring it back to the same quantum state, but to the state with the opposite quantum phase;

http://en.wikipedia.org/wiki/Spin-%C2%BD
In quantum mechanics, spin is an intrinsic property of all elementary particles. Fermions, the particles that constitute ordinary matter, have half-integer spin ... Particles having net spin ½ include the proton, neutron, electron, neutrino, and quarks. The dynamics of spin-½ objects cannot be accurately described using classical physics; they are among the simplest systems which require quantum mechanics to describe them. As such, the study of the behavior of spin-½ systems forms a central part of quantum mechanics.

One consequence of the generalized uncertainty principle is that the spin projection operators (which measure the spin along a given direction like x, y, or z), cannot be measured simultaneously. Physically, this means that it is ill defined what axis a particle is spinning about. A measurement of the z-component of spin destroys any information about the x and y components that might previously have been obtained.

http://en.wikipedia.org/wiki/Lagrangian
The Lagrangian formulation of mechanics is important not just for its broad applications, but also for its role in advancing deep understanding of physics. Although Lagrange only sought to describe classical mechanics, the action principle that is used to derive the Lagrange equation was later recognized to be applicable to quantum mechanics as well.

Physical action and quantum-mechanical phase are related via Planck's constant, and the principle of stationary action can be understood in terms of constructive interference of wave functions.

The same principle, and the Lagrangian formalism, are tied closely to Noether's theorem, which connects physical conserved quantities to continuous symmetries of a physical system.

Lagrangian mechanics and Noether's theorem together yield a natural formalism for first quantization by including commutators between certain terms of the Lagrangian equations of motion for a physical system.

In classical mechanics, the natural form of the Lagrangian is defined as the kinetic energy, T, of the system . minus its potential energy, V ... If the Lagrangian of a system is known, then the equations of motion of the system may be obtained by a direct substitution of the expression for the Lagrangian into the >EULER<–Lagrange equation. The Lagrangian of a given system is not unique, but solving any equivalent Lagrangians will give the same equations of motion.

[YesNo]

... that travels at near light speed ...

Traveling at light speed implies one has no mass, but it also means space-time is a single point for what is traveling that fast. It makes me wonder if what is traveling at the speed of light could also be considered to be outside space-time.

I'm reading John S. Rigden's Einstein 1905: The Standard of Greatness now. The goal of the thread is to explain relativity to a child. I'm having a hard time explaining it even to myself. Maybe this book will help.

[mal4mac]

Traveling at light speed implies one has no mass...

But light has energy and therefore, according to E=mc2, it has mass.



... but it also means space-time is a single point for what is traveling that fast.

If something is a single point how can it be anything?

String theorists think of particles, ultimately, as one dimensional strings.



It makes me wonder if what is traveling at the speed of light could also be considered to be outside space-time.

Aren't we all outside space time? We can only experience what happens in the present, so we are "outside" the future and the past, therefore outside time. Also conciousness has no location, so it is outside space.

[YesNo]

But light has energy and therefore, according to E=mc2, it has mass.

If light had mass, it couldn't travel at the speed it does. Having mass puts us in an inertial frame of reference with respect to light. That means when we measure light's speed we come up with the same value because of special relativity. Light is not in an inertial frame of reference since it has no inertia. It can't measure the speed of light.




If something is a single point how can it be anything?


That's what I'm wondering about now, but from the perspective of energy, we already agreed that such energy experiences no space-time. It's coordinate system is a single point. That also seems to be what others acknowledge as well.



Aren't we all outside space time? We can only experience what happens in the present, so we are "outside" the future and the past, therefore outside time. Also conciousness has no location, so it is outside space.

I would agree with that, but I don't want to go beyond what science is presenting with evidence to back it up.

[Cioran]

If light had mass, it couldn't travel at the speed it does. Having mass puts us in an inertial frame of reference with respect to light. That means when we measure light's speed we come up with the same value because of special relativity. Light is not in an inertial frame of reference since it has no inertia. It can't measure the speed of light.

Photons have mass as given by Einstein's equation. They just don't have rest mass.

[YesNo]

Photons have mass as given by Einstein's equation. They just don't have rest mass.

OK, I can accept that. Could a photon be considered to have an inertial frame of reference?

[Cioran]

OK, I can accept that. Could a photon be considered to have an inertial frame of reference?

Not sure I understand the question. An inertial frame is one in constant uniform motion. That was nothing new with Einstein. It is actually called Galilean relativity, because it goes back to Mr. G. He noted that if you were in constant uniform motion, there is no physical experiment that you could perform that would distinguish this condition from a "rest" state. "Rest" goes in quotes because actually everything is in motion, but some frames are in rest relative to others in motion. The only thing Einstein added to Galilean relativity was the postulate that the speed of light was the same when measured by all inertial frames.

In the case of light, if light could be said to have a "point of view," the whole history of the world would happen instantaneously, and there would be no distance between any two places. So time and space would collapse away in the photonic frame, as best as I understand it.

[YesNo]

So time and space would collapse away in the photonic frame, as best as I understand it.

Yes, that is how I see it as well. It is tempting to think of such energy as being outside space-time. I am not sure that is the way a physicist would see it, however.

[mal4mac]

Photons have mass as given by Einstein's equation. They just don't have rest mass.

I agree with Cioran, this answer is "standard bible".

I see you're near Chicago, YesNo, do the physics department at the University of Chicago do evening classes? It has world-leading renown for general relativity, Robert Wald, for instance.

"Special Relativity" by French was one of my better UG textbooks - you might want to take a crack at that. Another good one is the classic "Spacetime Physics" by Edwin F. Taylor and John Archibald Wheeler.

[YesNo]

I could take a class, but it is more entertaining just discussing it. Thanks for the references. I'll keep them in mind when I'm at the library.

So, do we disagree on anything at the moment?

Ultimately, the goal is how to explain relativity to a 7 year old.

[cacian]

Disagreement is what seems to be driving this whole theory of relativity to something less obvious then I thought.
I don't think I could still manage an explanation to a 7 year old because it is all not that clear.

[Cioran]

The Dog School of Mathematics: Special Relativity (http://conduit9sr.tripod.com/SR2.html)

Actually, my link was to Chapter 2. You should start with Chapter One. (http://conduit9sr.tripod.com/SR1.html)

[cacian]

Cioran this is great thank you.

Let see this bit from the link:
''In physics what you measure is what you get'''

Ok we could define physics then define measurement if we wanted to but two words come to mind:
Photographic memory.
Enough said.

[VERONIQUE]

Is this thread theory,? or I am I living in a 10 dimensional multiverse? is Brian Greene from another Planet and have the Chicago Bears any real chance in our newtonian classical universe, any timespace soon?

[Calidore]

Hey, a question I can answer.


have the Chicago Bears any real chance in our newtonian classical universe, any timespace soon?

Yes, because they aren't the Cubs.

[cacian]

Is this thread theory,? or I am I living in a 10 dimensional multiverse? is Brian Greene from another Planet and have the Chicago Bears any real chance in our newtonian classical universe, any timespace soon?

LOL well let's put it this way it is all melting pot.
Anything falls under relativity hence the OP.

[cacian]

Hi YesNo I was just thinking let's talk space for a minute.
What is the temperature in space?
I am trying to understand why when I put a jacket potatoe without pricking it in the oven, I forgot, it exploded.
I guessed it was because the heat causes pressure and pressure causes explosion.
It is not a fire as such but the actual heat.
Now Galileo thought the center of the universe is the sun. It can't be for this very reason.
Am I right?

[YesNo]

I didn't follow the reason why Galileo was wrong, cacian. Is it because heat exists somewhere other than the sun?

[cacian]

I didn't follow the reason why Galileo was wrong, cacian. Is it because heat exists somewhere other than the sun?

Hi YesNo sorry If I am not clear here.
What I am trying to say is that the center of the earth is not hot otherwise it would cause pressure.
I was wondering about space atmosphere.

[YesNo]

The earth has volcanoes and so is active unlike the moon which is not anymore. So, the center of the earth is hot and the pressure would be the volcanic action. I guess it is a good thing the earth doesn't explode like a potato.

The idea of space puzzles me. On the one hand there is the coordinate system which is just a model and on the other hand there is the reality of an expanding space in which light is bent around inertial objects. I suspect the theory would say that the universe doesn't have a center. That would just be the origin of a coordinate system used to model the reality.

[cacian]

The earth has volcanoes and so is active unlike the moon which is not anymore. So, the center of the earth is hot and the pressure would be the volcanic action. I guess it is a good thing the earth doesn't explode like a potato.

The idea of space puzzles me. On the one hand there is the coordinate system which is just a model and on the other hand there is the reality of an expanding space in which light is bent around inertial objects. I suspect the theory would say that the universe doesn't have a center. That would just be the origin of a coordinate system used to model the reality.

I am not so sure about center but more the peripheries because a center does not help long term in terms of determining positions and spheres.
What helps is understanding peripheries and how the extend and to where.
Space is space and peripheries is what makes space hollow and expandable.
Centers are irrelevant in my views.

[mal4mac]

Hi YesNo I was just thinking let's talk space for a minute.
What is the temperature in space?

Space is permeated by the Microwave bakcground Radiation, which is at a temperature of about 3K (yawn...)

It is now more fun talking about it, I read too many of pop sci books in my youth... it tends to be yawn, here we go again,... or I get angry when they don't explain things well (too often the usual case...) The reason I recommend hawking to friends is at least he's short* and his books have lots of pretty pictures, so I probably won't get accused of boring my friends...

I would take cacian's approach to explaining it to a seven year old - you'd both have lots of laughs and that's the main thing. Have you read Calvino's "Cosmicomics"?

Have you tried your 7 year old with Hawking? Try "A Briefer History of Time" for bed time reading and see how it goes. Get the hardback, it's really nice and should last till he's 14 and you want to encourage him to do GCSE physics... (note the "briefer" it's been made easier since "brief" - Mblobdinow is a co-author and he used to right Star Trek episodes ... careful your 7 year old doesn't become a little know-all Wesley Crusher... ("Come on dad, it's obvious,the dilithium crystals are overstretched, so it can't go into warp drive...")

*It's the wheelchair

[mal4mac]

Hi YesNo sorry If I am not clear here.
What I am trying to say is that the center of the earth is not hot otherwise it would cause pressure.
I was wondering about space atmosphere.

No it has to be hot otherwise we would freeze when the Sun was on the other side of the Earth, and Emperor Penguins would rule.

Space must have an atmosphere, because Fred Hoyle said there were viruses in space, and viruses need an atmosphere to get a party going.

[mal4mac]

The idea of space puzzles me. On the one hand there is the coordinate system which is just a model and on the other hand there is the reality of an expanding space in which light is bent around inertial objects. I suspect the theory would say that the universe doesn't have a center. That would just be the origin of a coordinate system used to model the reality.

The standard model of the universe doesn't have a centre - we talk about galaxies being "so many" parsecs from Earth, never form the "centre of the universe".

The big bang happened everywhere, everywhere is the centre.

Where is the centre of the balloon's surface? Please don't say the middle of the balloon - all we know of is the balloon surface and, as Wittgenstein said, we need to be silent about things we don't know - the clown's breath is a figment of your fantastic imagination.

Is expanding space a reality or just our best guess?

Hindus suggest that everything is a dream, i.e., everything is a model. Why not?

[cacian]

Space is permeated by the Microwave bakcground Radiation, which is at a temperature of about 3K (yawn...)

It is now more fun talking about it, I read too many of pop sci books in my youth... it tends to be yawn, here we go again,... or I get angry when they don't explain things well (too often the usual case...) The reason I recommend hawking to friends is at least he's short* and his books have lots of pretty pictures, so I probably won't get accused of boring my friends...

I would take cacian's approach to explaining it to a seven year old - you'd both have lots of laughs and that's the main thing. Have you read Calvino's "Cosmicomics"?

Have you tried your 7 year old with Hawking? Try "A Briefer History of Time" for bed time reading and see how it goes. Get the hardback, it's really nice and should last till he's 14 and you want to encourage him to do GCSE physics... (note the "briefer" it's been made easier since "brief" - Mblobdinow is a co-author and he used to right Star Trek episodes ... careful your 7 year old doesn't become a little know-all Wesley Crusher... ("Come on dad, it's obvious,the dilithium crystals are overstretched, so it can't go into warp drive...")

*It's the wheelchair
Haha hi mal4mac thank you the lengthy post very very helpful. It is weird I never imagined we were set up like a microwave with radiations at the back. I think the reason is that I think radiation I think danger.
In my mind I had it that space was just round and safe place with airvent to circulate oxgen and regulate carbon so that breathing is permeated and radiation are something man made.
I have not read Calvino but will have a look.


No it has to be hot otherwise we would freeze when the Sun was on the other side of the Earth, and Emperor Penguins would rule.

Space must have an atmosphere, because Fred Hoyle said there were viruses in space, and viruses need an atmosphere to get a party going.

Holy what !!!:eek: viruses in space? that is really new to me. Why would they be viruses in space?
The other thing I had it in my head, again that is me in my little world, that the center of the earth was like a vaccum , in French I would describe it as a centrifuge, circular and hollow in order to circulate movement and regulate temperatures. A bit like a cold and hot oven with an air vent that keeps check on temperatures.
Volcanos however are like little heating systems to keep the earth and atmosphere in balance with the extreme cold.
How else would one explain the presence of volcanos?
Again I obviously had it planned out differently.
Anyway this is how I have written and drawn in my story I am working on called the a history of the earth. Haha I much prefer my version because it is easier to draw on a map.

[YesNo]

The standard model of the universe doesn't have a centre - we talk about galaxies being "so many" parsecs from Earth, never form the "centre of the universe".

The big bang happened everywhere, everywhere is the centre.

Where is the centre of the balloon's surface? Please don't say the middle of the balloon - all we know of is the balloon surface and, as Wittgenstein said, we need to be silent about things we don't know - the clown's breath is a figment of your fantastic imagination.

Is expanding space a reality or just our best guess?

Hindus suggest that everything is a dream, i.e., everything is a model. Why not?

The part about Wittgenstein I feel safe to ignore.

Otherwise, I agree with most of what you said up to the final sentence. That part I am still trying to clarify for myself. The exercise of trying to explain relativity to a 7 year old may help me understand the relationships between Hinduism and science better.

By the way, I'm reading Amir D. Aczel's Entaglement, The Greatest Mystery in Physics to get a better understanding what is the scientific evidence for non-local events. It has more substance than the Hawking and Mlodinow's The Grand Design, but it is not very technical.

[Cioran]

No it has to be hot otherwise we would freeze when the Sun was on the other side of the Earth, and Emperor Penguins would rule.

Space must have an atmosphere, because Fred Hoyle said there were viruses in space, and viruses need an atmosphere to get a party going.

1, Outer space does not have an atmosphere.

2. Fred Hoyle's panspermia/virus thesis depends on such entities being transported by comets. There is zero (0, nada, zilch) evidence to support the claim of viruses or any living thing coming from space to earth.

3. In general, Hoyle was nuts.

[cacian]

1, Outer space does not have an atmosphere.

2. Fred Hoyle's panspermia/virus thesis depends on such entities being transported by comets. There is zero (0, nada, zilch) evidence to support the claim of viruses or any living thing coming from space to earth.

3. In general, Hoyle was nuts.

LOL I thought viruses only lived amongst humans. To think they exist in outer space sounds rather scary is .
I thought outter space is too clean to withhold any viruses of any sort.

[mal4mac]

Haha hi mal4mac thank you the lengthy post very very helpful. It is weird I never imagined we were set up like a microwave with radiations at the back. I think the reason is that I think radiation I think danger.

And it's not like meteors, this radiation does make it down to Earth. Tin foil hat anyone? No stop panicking - it's very mild and hard to detect - it was actually detected by accident by Bell Telephone labs in New Jersey, by Penzias & Wilson, ... It's what finally blew Fred Hoyle's steady state theory out of the water. He couldn't stand the laughter when besides suggesting that protons just appear everywhere from nowhere, microwave radiation "just happens" as well.


In my mind I had it that space was just round and safe place with airvent to circulate oxgen and regulate carbon so that breathing is permeated and radiation are something man made.



I have not read Calvino but will have a look.


The earlier stories are better - I borrowed the "complete" from the library and they tailed off a bit. But the early ones are really funny.




Holy what !!!:eek: viruses in space? that is really new to me. Why would they be viruses in space?


Why not?

The idea is still in common use, never mind what others say here. For instance, Channel 4 has "Apocolypse" running at the moment, where mad mind bender Derran Brown is convincing some poor Sid that the apopocolypse is actually happening.. employing full Hollywood special effects, and false newscasts. The story is that meteors are falling down destroying everything, PLUS they are full of viruses that turn people into zombies.

I should be so nuts as Fred Hoyle... look up his Wikipedia page, if you must, and see all the accepted stuff he has done, even his bad ideas are good ideas, 'cause they get others to think better - like the Big Bang lot.


The part about Wittgenstein I feel safe to ignore.

Otherwise, I agree with most of what you said up to the final sentence. That part I am still trying to clarify for myself. The exercise of trying to explain relativity to a 7 year old may help me understand the relationships between Hinduism and science better.

By the way, I'm reading Amir D. Aczel's Entaglement, The Greatest Mystery in Physics to get a better understanding what is the scientific evidence for non-local events.

It's good.

There, I just saved you reading the book!

I'm tempted to read up more on Hinduism, especially Vedanta.

I just re-read Huxley's "the Perrenial Philosophy" which is good on all this mystical stuff - Christian, Buddhist, Hindu... is there a broader overview? All the Christian stuff got a bit tedious, though. All this "God, I see you God!" stuff only drew a "There's no one there, you daft bat!" response from my skeptical self (the one in control...) Is Vedanata the most appealing religion?

No soul, or atman, that is the question.

No soul seems a bit harsh, but atman too good to be true. Time to re-read "My Gurus and his Disciple" by Christopher Isherwood methinks...

I read Capra's "The Tao of Physics" when it first came out and kept thinking "why isn't my course as interesting as this" - I think it's still rated quite highly (by some) and might give it a re-read.

P.S. I've given up on Wittgenstein as well (Tractatus, what's that all about?) I throw in his name & twopenny ideas, now and again, so that people think I'm Mr Big Philosopher. {JBI/MM: "No one would make that mistake...", there you are, saved you making the post, you cynics :)

[YesNo]

It's good.

There, I just saved you reading the book!

:)

I've actually read the Tractatus or whatever it's called. I understand even Wittgenstein thought it was wrong and wrote his next book opposing it, which I didn't read.

Although I read the Tractatus, I didn't understand the book. However, I read parts of it to my wife and we both laughed at it. It had some use-value.



I'm tempted to read up more on Hinduism, especially Vedanta.

I just re-read Huxley's "the Perrenial Philosophy" which is good on all this mystical stuff - Christian, Buddhist, Hindu... is there a broader overview? All the Christian stuff got a bit tedious, though. All this "God, I see you God!" stuff only drew a "There's no one there, you daft bat!" response from my skeptical self (the one in control...) Is Vedanata the most appealing religion?

No soul, or atman, that is the question.

No soul seems a bit harsh, but atman too good to be true. Time to re-read "My Gurus and his Disciple" by Christopher Isherwood methinks...

I read Capra's "The Tao of Physics" when it first came out and kept thinking "why isn't my course as interesting as this" - I think it's still rated quite highly (by some) and might give it a re-read.


I don't know much about Hinduism. I realized when I argued with Paulclem in some thread about the non-atman idea in Buddhism, that I don't know much about any of these religions.

The Isherwood book sounds interesting.

[KillCarneyKlans]

http://www.online-literature.com/forums/entry.php?12644-Theory-of-Relativity-thread-Niotes
Short version Below ...

© 1993-2003 ENCARTA Microsoft Corporation. All rights reserved.
The energy of a photon is equal to the product of a constant number [h] called Planck’s multiplied by the frequency [v], or number of vibrations per second [E=hv] ... Photons that are visible to the human eye have energy levels around 1 electron volt (eV) and frequencies from 1014 to 1015 Hz ...

http://www.nasa.gov/mission_pages/GLAST/news/dark-matter-insights.html
"One of the best places to look for these faint gamma-ray signals is in dwarf spheroidal galaxies, small satellites of our own Milky Way galaxy that we know possess large amounts of dark matter," Siegal-Gaskins explained. "[Boring] astrophysical ... systems, with little gas or star formation and no objects like pulsars or supernova remnants that emit gamma rays." ... many dwarfs lie far away from the plane of our galaxy, which produces a broad band of diffuse gamma-ray emission that stretches all around the sky.

http://www.nasa.gov/mission_pages/GLAST/main/index.html
Fermi is a powerful space observatory that will open a wide window on the universe. Gamma rays are the highest-energy form of light ... Fermi data will enable scientists to answer persistent questions across a broad range of topics, including supermassive black-hole systems, pulsars, the origin of cosmic rays, and searches for signals of new physics.

http://www.abovetopsecret.com/forum/thread895027/pg1
... Research [is focused] on revealing the properties of dark matter using observational probes such as gamma rays and other high-energy particles ... NASA['s] "revelation" on Thursday will be exciting in that we have discovered some very important details [forms stars] about the 70% of Dark Matter that exists in our universe by looking at our own Milky Way Galaxy.

http://www.nasa.gov/mission_pages/GLAST/news/highest-energy.html
During a powerful solar blast on March 7, NASA's Fermi Gamma-ray Space Telescope detected the highest-energy light ever associated with an eruption on the sun. The discovery heralds Fermi's new role as a solar observatory ... The flux of high-energy gamma rays, defined as those with energies beyond 100 million electron volts (MeV), was 1,000 times greater than the sun's steady output ... Fermi's LAT detected high-energy gamma rays for about 20 hours ... "Seeing the rise and fall of this brief flare in both instruments allowed us to determine that some of these particles were accelerated to two-thirds of the speed of light in as little as 3 seconds."

http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20120302.html
NASA's Cassini spacecraft has "sniffed" molecular oxygen ions around Saturn's icy moon Dione ... Dione's oxygen appears to derive from either solar photons or energetic particles from space bombarding the moon's water ice surface and liberating oxygen molecules.

http://www.nasa.gov/mission_pages/GLAST/news/fermi-thunderstorms.html
Scientists using NASA's Fermi Gamma-ray Space Telescope have detected beams of antimatter produced above thunderstorms on Earth

http://www.nasa.gov/mission_pages/GLAST/news/new-structure.html
NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy. "What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center" ...

http://www.nasa.gov/images/content/498888main1_DF3_Fermi_bubble_art_labels-226x163.jpghttp://www.nasa.gov/images/content/498892main1_DF1_Fermi_all-sky_1-10_GeV-226x127.jpg

[cafolini]

http://www.online-literature.com/forums/entry.php?12644-Theory-of-Relativity-thread-Niotes
Short version Below ...

© 1993-2003 ENCARTA Microsoft Corporation. All rights reserved.
The energy of a photon is equal to the product of a constant number [h] called Planck’s multiplied by the frequency [v], or number of vibrations per second [E=hv] ... Photons that are visible to the human eye have energy levels around 1 electron volt (eV) and frequencies from 1014 to 1015 Hz ...

http://www.nasa.gov/mission_pages/GLAST/news/dark-matter-insights.html
"One of the best places to look for these faint gamma-ray signals is in dwarf spheroidal galaxies, small satellites of our own Milky Way galaxy that we know possess large amounts of dark matter," Siegal-Gaskins explained. "[Boring] astrophysical ... systems, with little gas or star formation and no objects like pulsars or supernova remnants that emit gamma rays." ... many dwarfs lie far away from the plane of our galaxy, which produces a broad band of diffuse gamma-ray emission that stretches all around the sky.

http://www.nasa.gov/mission_pages/GLAST/main/index.html
Fermi is a powerful space observatory that will open a wide window on the universe. Gamma rays are the highest-energy form of light ... Fermi data will enable scientists to answer persistent questions across a broad range of topics, including supermassive black-hole systems, pulsars, the origin of cosmic rays, and searches for signals of new physics.

http://www.abovetopsecret.com/forum/thread895027/pg1
... Research [is focused] on revealing the properties of dark matter using observational probes such as gamma rays and other high-energy particles ... NASA['s] "revelation" on Thursday will be exciting in that we have discovered some very important details [forms stars] about the 70% of Dark Matter that exists in our universe by looking at our own Milky Way Galaxy.

http://www.nasa.gov/mission_pages/GLAST/news/highest-energy.html
During a powerful solar blast on March 7, NASA's Fermi Gamma-ray Space Telescope detected the highest-energy light ever associated with an eruption on the sun. The discovery heralds Fermi's new role as a solar observatory ... The flux of high-energy gamma rays, defined as those with energies beyond 100 million electron volts (MeV), was 1,000 times greater than the sun's steady output ... Fermi's LAT detected high-energy gamma rays for about 20 hours ... "Seeing the rise and fall of this brief flare in both instruments allowed us to determine that some of these particles were accelerated to two-thirds of the speed of light in as little as 3 seconds."

http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20120302.html
NASA's Cassini spacecraft has "sniffed" molecular oxygen ions around Saturn's icy moon Dione ... Dione's oxygen appears to derive from either solar photons or energetic particles from space bombarding the moon's water ice surface and liberating oxygen molecules.

http://www.nasa.gov/mission_pages/GLAST/news/fermi-thunderstorms.html
Scientists using NASA's Fermi Gamma-ray Space Telescope have detected beams of antimatter produced above thunderstorms on Earth

http://www.nasa.gov/mission_pages/GLAST/news/new-structure.html
NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy. "What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center" ...

http://www.nasa.gov/images/content/498888main1_DF3_Fermi_bubble_art_labels-226x163.jpghttp://www.nasa.gov/images/content/498892main1_DF1_Fermi_all-sky_1-10_GeV-226x127.jpg

You might as well use astrology, and many do. You are looking many many light years into the future. You are putting on a cosmicomical proposition, trying to guarantee that things today look the same as in so many millions of conventional years in the past. Ludicrous!!

[KillCarneyKlans]

You are putting on a cosmicomical proposition, trying to guarantee that things today look the same as in so many millions of conventional years in the past

How so? I never stated such a thing ... the laws of physics aren't changed ... at least in this universe ... This is just the latest findings on Gamma Ray [The most intense form of light] detection ... While flying over the earth ... instruments detected TGF's in lightning storms ... pretty solid stuff ... a few million is nothing to evolution ?? As far I know 95% of the [unknown] universe isn't going away soon.

"These signals are the first direct evidence that thunderstorms make antimatter particle beams ... Fermi is designed to monitor gamma rays, the highest energy form of light.

[YesNo]

I usually make the same mistake that cafolini warns against. I assume that the picture of the gamma ray emitting bubbles is how the universe is now, not simply how is looks now. The most that can be said is that is how it was a million years ago or however long it took those gamma rays to reach us. We are just now getting the information.

I started reading Christopher Isherwood's My Guru and his His Disciple based on mal4mac's recommendation. One thing in there that seemed related to this thread on relativity is the following sentence describing Gerald's religious practice of mindfulness from the first chapter:


Whenever your awareness weakened, you slipped back into acceptance of the unreal situation, which is experienced as space-time and which imposes disbelief in "this thing" and belief in individual separateness.

But can we can actually experience Einstein's space-time?

Although we can use space-time calculations in our technology, our experience is only of space and time as separate dimensions. That is part of the "unreal situation" Gerald is trying to escape. My current suspicion is that not only should meditation help us past these illusions, but science should be helpful also.

I am glad that KillCarneyKlans posted the information about gamma rays. I'm also interested in the Mars Rover's search for past or current microbial life on that planet.

[mal4mac]

I think Gerald is just saying that our everyday (unreal) situation is one in which we "see" time passing, e.g. by looking at a clock(!), and experience space, i.e., we walk cross the room and we experience movement in space. Nothing more fancy than that, I don't know why he used the term "space-time" if he just meant "everyday space & time". Wants to sound like a guru maybe :)

Mindfulness is all about being aware of the present moment, the "now", which is timeless, as it happens in consciousness, there is also no spatial dimension. So Newtonian space & time, Einsteinian space-time, any space+time actually loses all meaning in states of deep meditation. At least I think that's what he means - I haven't read the book for decades, must read it again soon! If you want to get up to date on Mindfulness, which is very big in meditation circles these days, try "Mindfulness for Beginners" by Kabat-Zinn - it's a great quick start and has a superb bibliography.

[YesNo]

I think Gerald is just saying that our everyday (unreal) situation is one in which we "see" time passing, e.g. by looking at a clock(!), and experience space, i.e., we walk cross the room and we experience movement in space. Nothing more fancy than that, I don't know why he used the term "space-time" if he just meant "everyday space & time". Wants to sound like a guru maybe :)

Yes, that's all he's saying and the "space-time" part was to sound modern. Consciousness can also be viewed as eternal, being only in the here and now. However, from a space-time perspective, a photon could be viewed as eternal also since it only has a here and now. From a Newtonian space and time perspective it could not be so considered.

[cacian]

consciousness is in the now here with us. We are only to establish what we are aware of and therefore to call it eternal is not quite right in my view.

[YesNo]

I am probably going into the area of belief when I associated the here and now with what is eternal. It may not be the case. I don't think that material objects are eternal because they persist in space-time and not just in the here-now.

I define "eternal" as whatever is outside space-time. That may not be correct. With that definition I would then assume that consciousness is outside space-time based on various religious traditions that seem to suggest it is. Consciousness would also be within space-time because we are conscious within space-time and that is an empirical fact. With the assumption and the fact, consciousness becomes a portal between space-time and the eternal.

For those who think that consciousness is derived from matter somehow then consciousness would not be eternal, but wholly contained within the non-eternal space-time. With such an assumption about consciousness it could not function as such a portal. This is not the simplest way to deal with consciousness since the evidence of near and shared death experiences suggest that there is more to it than that.

That relativity allows the photon, for example, to have a single-point space-time reality makes me think there is another portal between the eternal and space-time besides consciousness. That would be energy itself.

[cacian]

The standard model of the universe doesn't have a centre - we talk about galaxies being "so many" parsecs from Earth, never form the "centre of the universe".

The word centrifuges comes to mind. What 'standard' universe?


The big bang happened everywhere, everywhere is the centre.

I thought parallelism and centre correlate. 'Everywhere' does not seem right to be called a centre. There is a start a finish. A start cannot be everywhere.


Where is the centre of the balloon's surface? Please don't say the middle of the balloon - all we know of is the balloon surface and,

Interesting. A balloon surface? A balloon is shape. A shape that one makes/draws has a start and a finish and thus a centre is.


as Wittgenstein said, we need to be silent about things we don't know -
I thought the only thing about silence is 'the right to remain silent'. I thought no talking about something one does not know exist is obvious.


the clown's breath is a figment of your fantastic imagination.
I do not understand this. Why a clown's breath? and not a person's breath for example?


Is expanding space a reality or just our best guess?

I am not sure about a space that expends. I thought that something that increases also decreases too if it is a shape and space is a shape.


Hindus suggest that everything is a dream, i.e.,

Well Hinduism is suggesting is also a dream then .


everything is a model. Why not?
To model something you need an original. Modelling is copying something right?

[mal4mac]

[

The word centrifuges comes to mind.



Why? Could a centrifugal model of the universe explain Dark Energy? I can't see why I'm forced against the wall in fairground centrifuges - is this dark energy? Am I spinning or is the universe rotating around me, very quickly?


There is a start a finish. A start cannot be everywhere.


Blow up a balloon. Where does the balloon start expanding? Everywhere! There need be no finish. Why finish blowing up the balloon?




Interesting. A balloon surface? A balloon is shape. A shape that one makes/draws has a start and a finish and thus a centre is.


If you draw a circle the centre is not where you start to draw. The "start" could be anywhere on the circle. A million artists could draw one point of the circle, then the circle would start and finish everywhere, at the same time.



To model something you need an original. Modelling is copying something right?

I had a model spaceship as a kid and it wasn't a copy of anything that existed. Shame :( The original could supposedly go faster than light...

I also had a model of a Saturn V rocket - but it was a very rough copy of the original. I tried putting fuel in it, but it didn't take off, just burned a hole in my desk :( Our models of the universe are just very rough copies of the original, I guess.

[mal4mac]

I am probably going into the area of belief when I associated the here and now with what is eternal. It may not be the case. I don't think that material objects are eternal because they persist in space-time and not just in the here-now.

Mass-energy is conserved, it was created at the "beginning" (along with time), the universe is expanding "for ever", therefore mass-energy is eternal.



I define "eternal" as whatever is outside space-time.

Isn't "outside" a spatial concept? If the "eternal" doesn't concern space, how can you use "outside"? Is it better to say consciousness doesn't have space-time attributes? Where is consciousness in space? Point to it.

[YesNo]

Mass-energy is conserved, it was created at the "beginning" (along with time), the universe is expanding "for ever", therefore mass-energy is eternal.

The way I look at "eternal" is that it does not have space or time associated with it except for a here-now to allow access to space-time. So even if the universe expanded forever, that would not make it eternal.

However, I suspect energy could be eternal only because of the single point of its relativistic frame of reference. What the beginning of the universe becomes is energy taking on a manifestation as matter and creating space-time in the process.



Isn't "outside" a spatial concept? If the "eternal" doesn't concern space, how can you use "outside"? Is it better to say consciousness doesn't have space-time attributes? Where is consciousness in space? Point to it.

It is better not to use the word "outside" as you suggest. I should have said that consciousness doesn't have space-time attributes except for here-now.

[mal4mac]

What the beginning of the universe becomes is energy taking on a manifestation as matter and creating space-time in the process.

There's also a problem with "beginning" of the universe. Things begin in time. How can time begin in time? The universe just begins, it doesn't begin in time, because time is created at the moment of the Big Bang. (Rats, I used "begin" again... and "moment"... how do we get away from time-dependent terms so we can talk about a time without time (!)?)

[cacian]

Why? Could a centrifugal model of the universe explain Dark Energy? I can't see why I'm forced against the wall in fairground centrifuges - is this dark energy? Am I spinning or is the universe rotating around me, very quickly?
Dark energy? That is the first I have heard of. I am not aware of what dark energy is.

Blow up a balloon. Where does the balloon start expanding? Everywhere! There need be no finish. Why finish blowing up the balloon?
Blowing up a balloon is pumping air into an already established shape that is round or whatever. The air traverses in circular according to the shape in order to fill the balloon up.
If one does not finish blowing up a balloon then there is no balloon yet. The start and the finish is what conclude a shape.






If you draw a circle the centre is not where you start to draw. The "start" could be anywhere on the circle. A million artists could draw one point of the circle, then the circle would start and finish everywhere, at the same time.

Drawing a circular shape on a piece of paper depends on the start and finish and not before that. The center then becomes relative to when one starts and finishes. Time and space relativity applies meaning the center is where your lines and movements are with relation to space and time.
In other words the center is circular following the movements whilst the shape is being drawn. Theory of relativity applies.
There is only one way of dressing a shape and that is according to where one starts and finishes and center is its movement.


I had a model spaceship as a kid and it wasn't a copy of anything that existed. Shame :( The original could supposedly go faster than light...

I also had a model of a Saturn V rocket - but it was a very rough copy of the original. I tried putting fuel in it, but it didn't take off, just burned a hole in my desk :( Our models of the universe are just very rough copies of the original, I guess.
Sorry to hear about your model aeroplane.
A spaceship is a model because it is modelled around space and time program.
Making a spaceship is modelling a ship to adapt to a new environment it is going to be in.

[mal4mac]

Dark energy? That is the first I have heard of. I am not aware of what dark energy is.


Where you been cacian? That's 3/4 of the Universe you have missed.

Dark energy is the most accepted hypothesis to explain the observations that the universe is expanding at an accelerating rate. So not only is the balloon being blown up, the clown is blowing harder as time goes on!

Dark energy accounts for 73% of the total mass–energy of the universe.



If one does not finish blowing up a balloon then there is no balloon yet. The start and the finish is what conclude a shape.


If the clown lets go of the balloon so the kids can laugh at it going round the room does he say "look at the thing go" kids, or "Look at the balloon go"? If he said thing and told children off for calling it a balloon I'd not hire him for another children's party.

Clown's a have a very dark energy, but I think that's a different sort of dark energy.

[cacian]

[QUOTE=mal4mac;1183086]Where you been cacian? That's 3/4 of the Universe you have missed.
Dark energy is the most accepted hypothesis to explain the observations that the universe is expanding at an accelerating rate. So not only is the balloon being blown up, the clown is blowing harder as time goes on!

Dark energy accounts for 73% of the total mass–energy of the universe.
Haha oh well may that is because I have been living on cloud9. I am too busy down here on earth to contemplate dark forces or energies taking over the universe.
On a serious note mal4mac I understood energy to be anything but dark because energy for me means a boost which can only be positive. Without energy we are nothing.
The issue with the balloon being blown up is that at some stage it will either have to blow up pressures builds up or go beyond its capacity and the only way is down once we let go.
A universe is a shape and shape increases and decreases otherwise it would not be called a shape. You blow a balloon up it goes back to its initial state inertia if you like.
Take the sponge theory you squeeze it then you let go it goes back to its normal shape. That is the exact opposite of what balloon does pumps up it takes shape then returns back to where it started.
Hence start and the finish is what it is all about.


If the clown lets go of the balloon so the kids can laugh at it going round the room does he say "look at the thing go" kids, or "Look at the balloon go"? If he said thing and told children off for calling it a balloon I'd not hire him for another children's party.
I thought the idea is that initially it is the clown that makes people laugh not a balloon. I am not sure I get this.
A balloon here is not needed because one has a clown already. I ask myself this: if at a birthday children party an adult lets go of the balloon would the children laugh at the balloon for decreasing and dwindling or would they laugh because the adult let the balloon fly? Here the idea that the balloon escaped from being held.

Clown's a have a very dark energy, but I think that's a different sort of dark energy.
I totally do not get this. An energy being dark because it is a clown?
Then we must all have some kind of energy right?

[mal4mac]

I thought the idea is that initially it is the clown that makes people laugh not a balloon. I am not sure I get this.
A balloon here is not needed because one has a clown already. I ask myself this: if at a birthday children party an adult lets go of the balloon would the children laugh at the balloon for decreasing and dwindling or would they laugh because the adult let the balloon fly? Here the idea that the balloon escaped from being held.


Yeah the kids would be laughing at the adult, cruel kids. That's why clowns have such a dark energy, they are sad because kids are always being cruel to them.

I agree that the balloon on its own is not *that* funny. But it's a great prop! the clown can pretend to have trouble blowing up the balloon - getting out of breath, losing the grip on the balloon and chasing it round the room. I hypothesise that a balloon with a clown is like a clown squared, that, is e = mc2, the comic energy of the clown with a balloon is equal to the mass of balloon times the comic energy of a propless clown squared.

I need an experimentalist to dress as a clown, get some balloons, and prove this... come on YesNo, you have a seven year old, your job...

[YesNo]

I think you're doing a good job explaining this, mal4mac, and cacian is making me realize that the challenge might be more difficult than I realized, but worth the effort.

[cacian]

Yeah the kids would be laughing at the adult, cruel kids. That's why clowns have such a dark energy, they are sad because kids are always being cruel to them.

I am not sure. I think children laugh because they find something funny. They do not laugh at the clown they laugh at the whole thing together.


I agree that the balloon on its own is not *that* funny. But it's a great prop! the clown can pretend to have trouble blowing up the balloon - getting out of breath, losing the grip on the balloon and chasing it round the room. I hypothesise that a balloon with a clown is like a clown squared, that, is e = mc2, the comic energy of the clown with a balloon is equal to the mass of balloon times the comic energy of a propless clown squared.
I sure don't mix maths/physics/numbers with people. It don't get it.
I think you would find that any person dressed or not dressed up would make children laugh if they know how to.
Children get humour naturally and quicker then adults. I think it is the adult that thinks that dressing up that will add to humour.
Children would laugh at the balloon because it dwindled as it took off.
That is the humour I understand.

[YesNo]

I think the balloon concept is a way to explain how space expands. So on top of the motion away from us of the furthest galaxies, space is also creating distances between us and these galaxies like the stretching surface of a balloon or, to use a different image, the surface of a loaf of bread that is rising in the oven. The dark energy is like the yeast in the bread that makes it rise.

[cacian]

I think the balloon concept is a way to explain how space expands.
Hi YesNo I hope you could bear with me. I am having trouble visualising the balloon concept for the simple reason that a balloon can only go as far pressure takes it before it explodes or shrinks to its initial point.
That is the issue I am having I don't get how one uses a balloon, which is a shape, to compare it with a dark energy which takes all shapes and directions. Energy is free movement and goes billions of directions. It is not attainable into one shape like a balloon. Energy is shapeless a free agent. A balloon is not.
We know that a shape always returns to its initial position. The universe is a shape too that is kept within other exisiting shapes around. One shapes makes another shape and another. There is a link between each abject galaxies and space.
They are all interrelated. They all expand and then decrease. That is the nature of shapes.
Energy for it to be is all around and never at one point.


So on top of the motion away from us of the furthest galaxies, space is also creating distances between us and these galaxies like the stretching surface of a balloon or

I understand what you are saying but the stretching of surface of a balloon does not last for very long. Once a surface is over stretched then it wrecks.
The distance between a stretching balloon and I is not that very far because of what I have explained above.

to use a different image, the surface of a loaf of bread that is rising in the oven. The dark energy is like the yeast in the bread that makes it rise.
A dark energy I understand to be some kind unknown phenomena hence dark.
Yeast is a natural process that is naturally found in bread. It is a reactive agent to water. Yeast is only reactive when in contact with water. So it is by that a natural process to make bread. No water no yeast.
One cannot contain energy y because it explodes if it is just like wind. One cannot have wind in a bottle or into a shape it is not possible.
And then dark usually indicate unknown not quite figured out.
The universe is far as I know perfect and works in harmony around other perfects planets and galaxies.
I don't know I am not really making sense forgive me.
I have never been good at physics and science to be honest haha.

[YesNo]

Hi YesNo I hope you could bear with me.

No problem. Thanks for starting the thread, by the way. Please bear with me as well. I don't understand the concepts well, but when one tries to explain something, it helps.



I am having trouble visualising the balloon concept for the simple reason that a balloon can only go as far pressure takes it before it explodes or shrinks to its initial point.

The concept only works for how the surface is stretching. Put two marks on a balloon and then measure how far apart they are. Then blow up the balloon. If you measure how far apart the marks are now, the distance between them should increase. That is all the idea of the balloon is good for illustrating. I don't know if the universe will actually shrink in the future or not, but the only thing the balloon concept is illustrating is that the marks separate when the balloon expands.



That is the issue I am having I don't get how one uses a balloon, which is a shape, to compare it with a dark energy which takes all shapes and directions. Energy is free movement and goes billions of directions. It is not attainable into one shape like a balloon. Energy is shapeless a free agent. A balloon is not.
We know that a shape always returns to its initial position. The universe is a shape too that is kept within other exisiting shapes around. One shapes makes another shape and another. There is a link between each abject galaxies and space.
They are all interrelated. They all expand and then decrease. That is the nature of shapes.
Energy for it to be is all around and never at one point.

I understand what you are saying but the stretching of surface of a balloon does not last for very long. Once a surface is over stretched then it wrecks.
The distance between a stretching balloon and I is not that very far because of what I have explained above.

At this point the balloon doesn't help explain anything anymore.


A dark energy I understand to be some kind unknown phenomena hence dark.

That is how I see it as well.


Yeast is a natural process that is naturally found in bread. It is a reactive agent to water. Yeast is only reactive when in contact with water. So it is by that a natural process to make bread. No water no yeast.
One cannot contain energy y because it explodes if it is just like wind. One cannot have wind in a bottle or into a shape it is not possible.
And then dark usually indicate unknown not quite figured out.
The universe is far as I know perfect and works in harmony around other perfects planets and galaxies.
I don't know I am not really making sense forgive me.
I have never been good at physics and science to be honest haha.

At this point the bread concept no longer works either. It is only good to show that something can expand and when that happens points on the surface will spread apart. It is not good for anything else.

I only took one physics class in high school. I don't recall doing very well in the class but that has been a long time ago. Most of what I'm saying here, I've learned from books and talking about it to reinforce the ideas.

[mal4mac]

I am not sure. I think children laugh because they find something funny. They do not laugh at the clown they laugh at the whole thing together.

Maybe some cruel kids laugh at the clown? Or, even if all the kids are only laughing at the situation, the clown might think they are laughing at him. If the clown let go of the balloon on purpose then the cruel clown might be laughing at the kids because they are so stupid at thinking he did this by accident. If he let go of the balloon 'cause he's clumsy then he may be a sad clown 'cause he realises he's bad at clowning, and the kids' laughter hurts.

There is a well know phobia for clowns, like arachnophobia for spiders. That's why they have a dark energy for many people.

Children would laugh at the balloon because it dwindled as it took off.
That is the humour I understand.

Maybe slightly - especially the sudden collapse. I think it's more the farty sound and the random anarchy of it's motion (and the discomfort of the clown... at least for some...) Even funnier if the clown blows the balloon up too much an dit expldes - sudden shcok can be funny (timid kids might cry though... nice kids might cry if the clown pretends to be hurt... many will laugh at his pain, though... cruelty comes naturally to mankind...)

[mal4mac]

I think the balloon concept is a way to explain how space expands. So on top of the motion away from us of the furthest galaxies, space is also creating distances between us and these galaxies like the stretching surface of a balloon or, to use a different image, the surface of a loaf of bread that is rising in the oven. The dark energy is like the yeast in the bread that makes it rise.

I think you're slightly mis-using the bread metaphor. It's usually used to bring three dimensionality into the situation. The surface of the bread takes us no further than the balloon.

Imagine galaxies as raisins in the bread - you can (just about) visualise the raisins all becoming further from each other as the bread expands - like the ink spots in the surface of the balloon but now we have 3D. I like yeast being used as the metaphor for dark energy though...

For the seven year old I'd start with the balloon metaphor, though, and sympathise with any difficulty in visualising the bread metaphor. Maybe actually bake the bread and measure distances between raisins! In "Universe in a Nutshell" Hawking admits that he can't visualise *every* situation fully in 3D - only in 2 dimensions, or, at a stretch, 21/2 dimensions... made me feel at a lot happier about my limitations in visualising things...

P.S. as space actually is "flat", according to the most accepted standard model, the bread model is a precise model of the expanding universe. A bright 7 year old might complain about using the balloon model, as the universe obviously isn't 2D! Like using a cardboard cut out instead of a 3D action man - just wrong. The bread model gets round that...

[YesNo]

The Dog School of Mathematics: Special Relativity (http://conduit9sr.tripod.com/SR2.html)

Actually, my link was to Chapter 2. You should start with Chapter One. (http://conduit9sr.tripod.com/SR1.html)

The page on focal-plane shutter cameras from this series was interesting: http://conduit9sr.tripod.com/SR12.html

In the link is a photo of a car at a race where the type of camera used, the fact that the photographer moved the camera and the speed of the car created a distorted image. The goal was to use the picture to show how relativity made a person looking at an object in motion would see time dilation or shorter lengths than expected.

This does involve light and motion and, like the balloon or raisin bread ideas that mal4mac and I have been using, may have something that can mislead as well as illustrate.

The car's speed however is not even close to the speed of light although the distortion of the wheel is obvious.


There's also a problem with "beginning" of the universe. Things begin in time. How can time begin in time? The universe just begins, it doesn't begin in time, because time is created at the moment of the Big Bang. (Rats, I used "begin" again... and "moment"... how do we get away from time-dependent terms so we can talk about a time without time (!)?)

I suspect, because it happened once, the Big Bang happened many times. Our space-time starts when matter is transformed from energy to become a universe, but that doesn't mean it is the only universe that exists. These other universes need not be connected nor overlap since they create their own space-time upon expansion. It may not be possible to get experimental evidence from within one to detect the other.

The problem with the beginning of our particular universe is that it requires a cause of some sort. That cause either involves a conscious choice or not making the cause a justification of either theism or atheism. Whether the cause is conscious or not, it is hard to make sense of a cause that triggers a space-time to start. Usually a cause has a temporal component to it.

I also finished a quick reading of Aczel's Entanglement which is an historical survey of the confirmation that quantum theory implies non-local behavior.

Entanglement is when two quantum objects are created in such a way that when the spin is detected as either "up" or "down" in one, the opposite spin is determined in the other. Prior to detection, the spin is random. It could be either up or down. This spin determination occurs across large distances that light could not travel in time to let the entangled object know that the spin of its partner had been detected and so its spin is now determined.

Although it is not information or mass transmission, this determination happens instantaneously. I don't think there is any speed associated with it at all. That is, it happens faster than the speed of light.

Einstein, Podolsky and Rosen challenged physicists to either accept non-local behavior or acknowledge that quantum theory was incomplete in 1935. John Bell re-formulated the challenge between 1964 and 1966 so that it could be experimentally tested. The non-local behavior of quantum theory was confirmed later in the last century.

Just something more to try to tell the 7-year old.

[mal4mac]

I suspect, because it happened once, the Big Bang happened many times. Our space-time starts when matter is transformed from energy to become a universe, but that doesn't mean it is the only universe that exists.

The standard model assumes that space-time and energy start at the moment of the Big Bang. I can't see what "energy *then* matter and s-t" gives you! Not even sure it' s thinkable - if it's kinetic energy then motion happens in time... I can't see how you can get away from time being the first thing to appear... maybe along with other things...



These other universes need not be connected nor overlap since they create their own space-time upon expansion. It may not be possible to get experimental evidence from within one to detect the other.


That looks like standard M theory, where M can stand for Membrane, each universe on a different membrane. Brian Greene is quite good on that theory. Last I heard they were looking for distortions in the MWBR that might indicate a brane collision.



The problem with the beginning of our particular universe is that it requires a cause of some sort.


Does it? Why?





Entanglement is when two quantum objects are created in such a way that when the spin is detected as either "up" or "down"...

I think the key points are (i) that the particle system acts like one object, (ii) everything in the system acts at the same time. So why not, instead of all these boring spin particles, talk about an "entangled toy robot". If you turn on the switch on its back, it says "Hello, Jack Robinson. Danger! Danger!" (or whatever). Take the switch off its back and place it on the moon, mars, Andromeda galaxy, wherever, turn it on and in that instant the robot still comes alive just as if the switch was on its back! But you can only get pictures of the Robot responding much later, due to the limit of the speed of light, hence information cannot travel faster than light, but you can get an entangled system that acts as one thing, and makes it seem like faster than light 'something' is going on. But as entangled objects act in the same "now" I don't think it helps much to talk about faster than light anything going between them... anything going between objects requires time to go between them doesn't it? Also, we haven't spotted any strange radiation going between objects in "now" time...

I think going on about Bell's proof should be left until he's 22 :)

[YesNo]

The standard model assumes that space-time and energy start at the moment of the Big Bang. I can't see what "energy *then* matter and s-t" gives you! Not even sure it' s thinkable - if it's kinetic energy then motion happens in time... I can't see how you can get away from time being the first thing to appear... maybe along with other things...

Kinetic energy would be within space-time. From within any particular space-time universe, the Big Bang was when energy-matter was created. Because energy moving at the speed of light has only a hear-now space-time makes me think that this energy may have a reality separate from any space-time.

I guess I don't like seeing things being created out of nothing.




That looks like standard M theory, where M can stand for Membrane, each universe on a different membrane. Brian Greene is quite good on that theory. Last I heard they were looking for distortions in the MWBR that might indicate a brane collision.

In that case the brane collision would link the two universes together if that actually happened. However, in general I don't see why two separate space-times each with their own Big Bang should ever have contact with each other. They create their own space-times. They don't consume the space-time of a separate universe and so should never have occasion to collide with another one.



I think the key points are (i) that the particle system acts like one object, (ii) everything in the system acts at the same time. So why not, instead of all these boring spin particles, talk about an "entangled toy robot". If you turn on the switch on its back, it says "Hello, Jack Robinson. Danger! Danger!" (or whatever). Take the switch off its back and place it on the moon, mars, Andromeda galaxy, wherever, turn it on and in that instant the robot still comes alive just as if the switch was on its back! But you can only get pictures of the Robot responding much later, due to the limit of the speed of light, hence information cannot travel faster than light, but you can get an entangled system that acts as one thing, and makes it seem like faster than light 'something' is going on. But as entangled objects act in the same "now" I don't think it helps much to talk about faster than light anything going between them... anything going between objects requires time to go between them doesn't it? Also, we haven't spotted any strange radiation going between objects in "now" time...

Putting the switch on the moon would require some time before the robot realized it was turned on. However, what you mention about happening in the same here-now does seem to explain how entangled photons could influence each other across great distances. From their perspective, it is no distance at all.

[mal4mac]

Putting the switch on the moon would require some time before the robot realized it was turned on. However, what you mention about happening in the same here-now does seem to explain how entangled photons could influence each other across great distances. From their perspective, it is no distance at all.

It would take some time to take the switch to the moon, by some Russian space craft maybe, but once there the switch would act just as if it was on the robot's back - we are assuming the switch and the robot are "entangled", of course, so we would have to create an entirely new technology. Do you think the Dragons would give us £100K to R&D this? :)

[YesNo]

It we assume things that large could get quantum entangled, then flipping the switch on the moon should instantaneously make the robot move.

However, that does seem like information transfer faster than the speed of light. Now I'm aware that the non-local quantum behavior is supposed to avoid any violation of special relativity, but I am beginning to wonder why that is claimed to be the case. Suppose the state of one entangled photon is observed, the state of the other is now determined, but how does that other photon know that it's state has been determined? That looks like information transfer faster than the speed of light.

[mal4mac]

It we assume things that large could get quantum entangled, then flipping the switch on the moon should instantaneously make the robot move.

However, that does seem like information transfer faster than the speed of light. Now I'm aware that the non-local quantum behavior is supposed to avoid any violation of special relativity, but I am beginning to wonder why that is claimed to be the case. Suppose the state of one entangled photon [A] is observed, the state of the other is now determined, but how does that other photon [B] know that it's state has been determined? That looks like information transfer faster than the speed of light.

Observer of A (OA) assumes that the state of B is determined, that is, OA knows, if his theory is correct, that because A is "down", B must be "up". But he can only know this *for sure* by getting a message from OB, and that message has to travel at light speed.

Therefore information, which must be actual experimental verification, is limited by the speed of light.

If OB measures B as "up" he has no idea if A is "down", or anything about A, until OA tells him, and that "telling" is also limited by the speed of light.

[YesNo]

I agree. From the observers' perspective they cannot communicate faster than the speed of light using entangled particles. I guess that is the "no-communication theorem": http://en.wikipedia.org/wiki/No-communication_theorem

However, if the particles are entangled, there is something known about a distant location that happened instantaneously. Suppose two particles have been entangled and are now a light-day away from each other. Bob measures one of the particles to have the "up" property. Immediately, Bob knows that Alice's particle is "down" whether she has already measured it or not. This is not because Bob's particle was always "up". It was not "up" until the first measurement occurred which Alice might have already made. It could just as easily have been measured "down". It is true that Bob and Alice would have to wait a day to get confirmation of the non-locality result, but if the non-locality theory has been established, they would just invoke it and not bother asking the other what their measurement was. They would already know.

Because of the time component, it makes one wonder, as Cioran mentioned in a separate thread, in whose frame of reference do we say that Bob made the measurement first or Alice made the measurement first? That would be the relativity question for this thread. :)

In any case, this is one way for Bob and Alice to individually flip a coin and get information on the results faster than the speed of light. They don't know what the results will be until they perform the flip, but once one of them does, the coin flip has been determined for both across potentially vast distances of space.

[cacian]

I think I would see it this way.
The universe is the origin to a simple question:
''Where do we begin?'' and not ''how did we begin?''
Only for the simple reasons that my probabilities of finding the answer to the first question is more likely to lead me to many possibilities.
Eventuality is a fact of life. Durability is not so because each individual life span is relative and that is enough.
And so the second question is less pressing because it contains many insolvencies and takes me nowhere.

A similar example to clarify the above post is bit like this:
I look at bird and I wonder:
'Where does it fly to' and not 'how does it fly'.The where is the origin.
The how is pointless.

[YesNo]

"How" does seem to dwell on the past. "Where" seems open to the future.