how do they correlate?
to define speed of light one must define movement
Printable View
how do they correlate?
to define speed of light one must define movement
My knowledge of physics may be amateur at best, but the answer is 'yes'. That's the whole point of Einstein's concept of mass-energy equivalence, so recently beautifully proven by the detection of gravity waves.
We now know that E=mc2, at least on a macroscopic level. 'c', which is the speed of light in a vacuum, is a universal constant by which we calculate movement.
I agree with Lokasenna.
Also I can't remember if I ever had a physics course or not, so I would be in the amateur category as well. However, one doesn't need much physics to construct a reasonably accurate modern myth or story of what is going on. Once we hear what physicists come up with we will inevitably start this mythopoetic process.
So here is the myth I currently believe in:
First, when one is talking about "speed", one is talking about "movement". This implies there exists something corresponding to space and time.
Second, the reason the speed of light is important is because nothing within space and time can be measured going faster than the speed of light. That is called the "locality" property.
Third, but the big bang and the existence of quantum entangled particles affecting each other across distances faster than the speed of light imply that not everything is "local". If the universe had a beginning, there must be something outside of our space and time, perhaps other universes. If the effects of entangled particles occur faster than the speed of light that non-locality would not be occurring within our space and time.
Fourth, that's as far as I've got.
Einstein's mass-energy equivalence has many more points - you can calculate the heat released by the breaking of chemical bonds (i.e., the amount of potential energy that has translated into heat) in a nuclear bomb or even a common garden fire. I don't think 'macroscopic' is quite the word here, though, as generally the amount of mass disappearing is anything but.
It's also good to remember that while the speed of light in a vacuum is a constant, in various media it slows considerably down, and light can be stopped at a temperature close to absolute zero.
https://www.youtube.com/watch?v=-8Nj2uTZc10
It is interesting that Lene Hau was able to stop light, North Star.
There is the claim in the text that this is something "Einstein theorized was impossible". I wonder why it would be impossible. If light can be slowed down in a medium, stopping it seems possible.
I wonder what to the form of light..ie the shape.Quote:
Originally Posted by YesNo
is light linear circular or simply binary
in this thread I should have added
what about artificial light in retrospect to static objects.
can light encourage movement of a static object when to the naked eye it is not visible?
to put it differently static versus light.
Stopping it completely would probably require that the system is in absolute zero. Trouble is, that photon is going to create some heat when it hits something.Quote:
Originally Posted by YesNo
Erm... what? Light is either electromagnetic radiation or (well, and) particles, i.e. photons. Light travels from A to B the fastest possible route, and it goes straight in all directions. A photon would be circular in shape, but often it's more helpful to think of it in terms of straight rays.Quote:
Originally Posted by cacian
Light (photons) can translate into energy and move an electron to a higher orbital, or even break chemical bonds. If you are on top of a frozen lake during winter, and wait there for long enough, sunlight will move you to the bottom of the lake...Quote:
in this thread I should have added
what about artificial light in retrospect to static objects.
can light encourage movement of a static object when to the naked eye it is not visible?
to put it differently static versus light.
I wish I knew.Quote:
Originally Posted by cacian
Light is puzzling. It doesn't have any mass. From its perspective, if it makes sense to even talk about that, can space and time be more than a single point?
I've heard of some pickup trucks ice-fishermen use for which that has actually happened. :)Quote:
Originally Posted by North Star
I hope I have some knowledge that will help satisfy some curiosity--or better yet spark more.
In response to the OP: motion has a definition in physics: change in position with respect to time.
Speed also has a definition which is subtly distinct from velocity. Velocity is a vector, which means it has magnitude and direction. Speed is a scalar and only has magnitude. Thus, 10 m/s going left and 10 m/s going right are different velocities which have the same speed of 10 m/s.
Acceleration is a change in velocity (not speed). Most people naturally think that acceleration always implies a change in speed, but this is not true because velocity can change if only the direction changes. Thus things like turning also count as forms of acceleration. It also follows that while the speed of light is constant it can still undergo acceleration if it changes direction, which it does, of course, due to the force of gravity. I have seen a few people get confused by this and think that since turning is acceleration and (wrongly believe) that acceleration implies change in speed, the idea that the speed of light is constant cannot possibly be correct.
Maybe I'll also add the brain-bending idea that, while there is no such thing as absolute motion, there is probably absolute acceleration. You can see this when you think about something like the twin's paradox. Though for both twins the relative changes in motion, speed, etc. are identical, only one twin experiences time dilation.
If acceleration, force, or action were also relative it would imply a separate universe for each twin. To the twin in the spaceship, his brother on the ground would be the one accelerating and experiencing time dilation; to the twin on the ground, his brother on the spaceship would be experiencing time dilation. If this is how it worked, then following the spaceman's reference frame would show our earthling brother aging more slowly as we traveled farther and farther away as the spaceman's rate of aging stayed constant; and following the earthling's reference frame would show the spaceman aging more and more slowly as he traveled away while the earthling's stayed constant. In one frame the earthling gets old while the spaceman stays young, in the other the opposite happens. This would require the universe to "split" to accommodate two incompatible realities. In any case, this isn't how it works. The reference frame which had the force applied to it is the one which experiences time dilation and this seems to imply that something like acceleration or action must be an absolute.
Unfortunately entanglement doesn't seem to work like this.Quote:
Third, but the big bang and the existence of quantum entangled particles affecting each other across distances faster than the speed of light imply that not everything is "local". If the universe had a beginning, there must be something outside of our space and time, perhaps other universes. If the effects of entangled particles occur faster than the speed of light that non-locality would not be occurring within our space and time.
I'll use Leonard Susskind's simplified way of explaining entanglement. It's sort of like having two coins, where if you bring them really close together one always goes heads and the other always goes tails. Now if you do this and give one coin to one person and the other to another, you can have one person walk out of the room and look at his coin, and whether it's heads or tails he knows instantly that the other coin is the opposite. However, if he "flips" his coin over, or interacts with his side of the system, the other coin does not also instantaneously flip too. It just stays in whatever state it was in before. The system simply becomes disentangled.
The concept of entanglement is essentially not much more than this, believe it or not. I know there's a lot of misinformation circulating around (I'm looking at you What the Bleep do we Know?!) about it, but it seems that entanglement has never actually allowed for information to travel faster than the speed of light.
Light was only "stopped" on a macroscopic scale, just like light "slows down" when it passes through a medium like glass, water, or air. What's really happening is the light is being absorbed and emitted by particles in such a way that it's getting bounced back and forth between them. But while it travels between particles it's going at the speed of light. You probably already knew this, though...Quote:
It is interesting that Lene Hau was able to stop light, North Star.
I'm not familiar with the specifics of Hau's publication and what claims she makes but I sort of doubt that she ever really claims that Einstein was somehow fundamentally wrong.
While a photon is a particle it doesn't have a definite shape like an atom or a proton. It's a common misconception to think that all basic particles have definite shapes.Quote:
I wonder what to the form of light..ie the shape.
Light interacts with matter electromagnetically. If light didn't interact with matter the sun would not be able to heat up a black car, for example. Remember that heat is essentially just movement of mass particles.Quote:
can light encourage movement of a static object when to the naked eye it is not visible?