does time travel?

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Originally Posted by MorpheusSandman

Based on what?

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Newtonian physics.

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Our looking changes how we interact with other quantum entities; even if we assume that there is a dead-cat world and alive-cat world before we look, we don't know what world we're in until we look, so we "experience" the cat as "alive and dead." This is the same thing with particles. When we're not measuring them, they display the quality of existing in all possible states at once. Once we look, they behave like ordinary matter, one thing or another, not everything simultaneously. In Schrodinger's Cat, the cat is like a particle until we look. This is because we ourselves, as quantum entities, become entangled with other quantum entities. So while our observation is not a "cause" of anything (it doesn't affect the cat), it very much affects how we experience the cat. So, while MW has an answer to what's happening with Schrodinger's Cat, I wouldn't say it "eliminates the problem" (if it even ever was a problem, since it was merely meant to illustrate our observations of particle behavior on a macro level).

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Schrodinger's Cat demonstrated uncertainty. The uncertainty no longer exists. There is no need to look to see whether the cat is alive or dead; it is alive in one universe and dead in another.

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Originally Posted by PeterL

Newtonian physics.

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Newtonian physics is wrong. It's a mere approximation that couldn't even account for the orbit of Mercury. General Relativity is better yet, but even it can't account for quantum events. Quantum math can scale to GR's levels, though (minus gravity). Its minute accuracy is reason enough not to doubt it. But saying "Newtonian physics" as a reason for doubting Quantum math is rather laughable.

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Originally Posted by PeterL

Schrodinger's Cat demonstrated uncertainty. The uncertainty no longer exists. There is no need to look to see whether the cat is alive or dead; it is alive in one universe and dead in another.

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The uncertainty was always on the observer's (our) side, so it still exists until the observer looks. The only thing the observer can say for certain is that both the alive and dead worlds are real (because possible) and they will find themselves in one or the other once they look. You're making a similar mistake to those that Copenhagen makes, and that's taking the observer out of the equation. Even if the observer doesn't effect the world the object ends up in (as in Copenhagen, who also denies the reality of the other worlds), the observer does effect how the observer ends up in each world.

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Originally Posted by cacian

I do not believe there is an ether. the reason for that is that I can only believe in what I can perceive see or feel.

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I don't believe in it either.

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Originally Posted by cacian

I do not understand energy fields and what they are about. space is energetic because of the planets including earth and humans. we are energy and what surrounds us immediately is what activates the energy within us. energy can only work both ways . it need give and take it circular in that sense. energy is activated upon another sourced one. humans are one source of energy light is another.

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Space would be some relationship between objects which generate fields and time would be the change of those objects. I don't understand energy fields either. I was trying to get away from thinking that space-time is something real rather than just a coordinate system for a formula to use.

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Originally Posted by PeterL

All of the predictions of relativity, both special and general hold true in Aether Theory, and there are some predictions of Aether that aare true but are not predicted by relativity. The Michelson-Morley experiment was repeated many times, and was found that there is aether drift, but it is different from what the theory predicted. Dayton Miller was one of the more noted people in the field, but there have been others sinece then who have found more evidence for Aether theory.
You might start from this article:

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

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Looking at the link, it seems that Shankland could not confirm Miller's results suggesting there were some kind of ether. However, I think it is worth testing physical constants to see just how constant they are. Ultimately that might bring up the notion of an ether indirectly.

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Originally Posted by PeterL

Nearly all physical processes are reversible (I can't recall the one that isn't), and that may indicate that everything is actually reversible. Yes, reversing an atomic process is not the same as sending me back to 20,000 BCE, but the principal is the same.

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I assume you would accept that our lives are physical processes going from birth to death. Are they reversible (outside of some science fiction tale)?

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Originally Posted by YesNo

Looking at the link, it seems that Shankland could not confirm Miller's results suggesting there were some kind of ether. However, I think it is worth testing physical constants to see just how constant they are. Ultimately that might bring up the notion of an ether indirectly.


I assume you would accept that our lives are physical processes going from birth to death. Are they reversible (outside of some science fiction tale)?

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Our lives involve chemical processes too, which are not always reversible.

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Originally Posted by Volya

Our lives involve chemical processes too, which are not always reversible.

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That's a good point. There are physical/chemical changes (processes) that are considered to be either reversible or non-reversible, depending
on the laws of thermodynamics applied to specific situations. The Second Law of Thermodynamics states that the global (i.e. system and its
surroundings) change in entropy of any spontaneous process is greater than or equal to zero. It's never a negative number.

In most situations entropy increases because there is some loss of "useful" energy that is "wasted" in the form of "heat" dissipation. In
mechanical systems, for example, energy is lost through friction. This is a major reason why we haven't been able to make "perpetual
motion" machines. The best that we can hope for in spontaneous physical processes is zero total entropy change. We can't expect that
it will be possible for a physical process to decrease total entropy. It is possible to have a LOCAL decrease in entropy, but this will always
come at a cost of TOTAL (i.e. "universal") entropy. Maxwell described a famous thought experiment, "Maxwell's Demon," that proposed
a plausible way to violate the Second Law. There has been a lot of discussion about why the Demon could not do what he was tasked to
do (i.e. violate the Second Law).

One of the reasons why so many folks believe that the Second Law explains the "unidirectionality" of time is that the 2nd Law states that
entropy is always greater than or equal to zero.

systems

What would a spontaneous physical process with zero total entropy change be? Perhaps the earth's motion around the sun? I assume a reversible physical process would have to have zero total entropy change.

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Originally Posted by YesNo

What would a spontaneous physical process with zero total entropy change be? Perhaps the earth's motion around the sun? I assume a reversible physical process would have to have zero total entropy change.

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You ask about two different things: 1) spontaneous processes; and, 2) reversible processes. Spontaneous processes are those for which the Gibbs Free Energy, defined by the equation deltaG=deltaH-TdeltaS is negative. G=Gibbs Free Energy, H=enthalpy, T=temperature, and S=entropy....and delta="change in." Reversible processes are those for which the change in entropy is zero.

Since entropy is the only physical quantity we currently know about that seems to always result in a greater than or equal to zero result when the total "system" is considered, it seems to be a plausible explanation for the unidirectionality of "the arrow of time." The recent discovery of the Higg's Boson may offer other explanations for that...

I am beginning to see the difference. Thanks for the explanation.

"Spontaneous processes" ( http://en.wikipedia.org/wiki/Spontaneous_process ) would not be reversible because there is increased entropy involved.

A "reversible process" ( http://en.wikipedia.org/wiki/Reversi...hermodynamics) ) is a "quasistatic process" ( http://en.wikipedia.org/wiki/Quasistatic_processes ). Here is one quote from the reversible article:

Since it would take an infinite amount of time for the reversible process to finish, perfectly reversible processes are impossible.

Although I don't understand the "infinite amount of time" part, it looks like reversible processes generally don't exist.

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Originally Posted by YesNo

What would a spontaneous physical process with zero total entropy change be? Perhaps the earth's motion around the sun? I assume a reversible physical process would have to have zero total entropy change.

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Using the Gibbs Free Energy equation (deltaG=deltaH-TdeltaS) along with the requirement that a spontaneous process requires that deltaG be negative, we require that deltaH be negative, since TdeltaS is zero if deltaS is zero.

The earth's rotation around the sun is a spontaneous process, but it is not reversible. The motion of the earth-sun system is driven by gravity. The orbital motion of the earth around the sun has been going on for a very long time, and it might seem to some sort of perpetual motion machine, but it isn't. deltaS is a positive quantity for this process.