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Author Topic: Does Time have a Direction Without Gravity?  (Read 13356 times)

Offline yor_on

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Re: Does Time have a Direction Without Gravity?
« Reply #25 on: 17/02/2012 13:45:47 »
Imaatfaal, you wrote "I don't believe there are any reactions/interactions that are not time reversible; ie which make just as much sense going in one direction as the other. " and I referred you too CPT (Charge, Parity, and Time Reversals). I gave you one example of it (weak nuclear force) but I expect there to be more to be found. It would be nice if the symmetry(ies) couldn't be questioned, but it/they can. That may mean that there are some deeper definition of it which must be symmetric, or it may be that what we see is a result of us living in a universe where most is arranged as a symmetry by 'chance/probability' although not coming out so at all times. I don't know, although I would really like to know what 'time' and its arrow really, and I do mean, R e a l l y, is/are myself?

Spontaneous CPT asymmetry of the Universe (Free)

CPT violation and particle-antiparticle asymmetry in cosmology.

Just interesting :)
 

Offline yor_on

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Re: Does Time have a Direction Without Gravity?
« Reply #26 on: 17/02/2012 13:53:27 »
I better point out, before we get too deep into this, that if any interaction is found to be asymmetric it has to be found so inside the arrow we have, as I see it. And so all CPT interactions not 'reversible' also falls under the arrow of time. But this is my own view. But logically you can't discuss an interaction without involving the arrow, except as a 'emergence' of course.

In that case we are discussing what we see coming up from the fountains 'origin', as I see it, also what I mean by 'deeper definition'  and in that case I would call it 'time' myself, instead of a arrow.
 

Offline imatfaal

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Re: Does Time have a Direction Without Gravity?
« Reply #27 on: 17/02/2012 17:34:51 »
Imaatfaal, you wrote "I don't believe there are any reactions/interactions that are not time reversible; ie which make just as much sense going in one direction as the other. " and I referred you too CPT (Charge, Parity, and Time Reversals). I gave you one example of it (weak nuclear force) but I expect there to be more to be found. It would be nice if the symmetry(ies) couldn't be questioned, but it/they can. That may mean that there are some deeper definition of it which must be symmetric, or it may be that what we see is a result of us living in a universe where most is arranged as a symmetry by 'chance/probability' although not coming out so at all times. I don't know, although I would really like to know what 'time' and its arrow really, and I do mean, R e a l l y, is/are myself?

Spontaneous CPT asymmetry of the Universe (Free)

CPT violation and particle-antiparticle asymmetry in cosmology.

Just interesting :)

Yoron - to the best of reading (and thats not too hot) these are theoretical and deal with the possible ramification of CP and T breaking.  They also rely on the sakharov conditions which involve breaking T thermodynamically in large systerms

Read here http://hyperphysics.phy-astr.gsu.edu/hbase/particles/cpt.html#c3
 

Offline Phractality

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Re: Does Time have a Direction Without Gravity?
« Reply #28 on: 17/02/2012 19:41:44 »
Turbulence around an object moving thru a fluid is a good illustration of the irreversibility of time.

Reversing time puts the turbulence on upwind side of the windmills.
 

Offline yor_on

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Re: Does Time have a Direction Without Gravity?
« Reply #29 on: 18/02/2012 23:48:39 »
Yes, nice one Phractality. And yes Imatfaal, it's different views. If we have a 'box' then you might expect everything to reversible. If we don't have that universal box, the way we look at it, define it, now then there will be violations found. It's also a matter of our definitions as it seems to me, it's very possible we might find better descriptions for the 'box' than those we have now.
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #30 on: 27/02/2012 07:45:14 »
So yes you can ignore time dilation by either doing the experiment within the frame of the interaction or by compensating for frame differences.  The time dilation does not affect the reaction - it affects the observation of it.
Thinking about it, I believe you are wrong.  It affects the amount of energy required to do the reaction and results in higher entropy.

The time dilation factor does affect the reaction in as much as entropy increases at a higher rate in a greater time dilation than in a lesser one.  You need more energy to do anything (including any chemical reaction, experiment etc.) in a greater time dilated (higher gravitational) potential than in a lower time dilated (lower gravitational) potential.  This is the answer I was looking for but had as then not found in answer to Soul Surfer  and JP earlier in this thread.

Mike this is getting bizarre. 

Quote
.... in a greater time dilated (higher gravitational) potential than in a lower time dilated (lower gravitational) potential.
Even ignoring the claim about energy needed this sentence is wrong.  gravitational potential goes up as you leave the gravity well of a massive body - clocks at a high gravitational potential run faster than those at a low gravitational potential.  You are making claims of a subject you really do not understand.

Please at least read the wikipage on this subject http://en.wikipedia.org/wiki/Gravitational_time_dilation

If you drop a weight onto ice, the energy released will cause a certain amont of ice to turn into water.  If you repeat the same experiment in a higher gravity environment a greater amount of ice will turn into water.  The explanation being it took more energy to raise the weight in the higher gravitational environment.  Even ignoring the amount of ice turned to water, it will still require more energy to raise the weight in a higher gravity environment.  Therefore gravity cannot be ignored in the experiment and as the time dilation factor is tied to gravity, neither can time dilation be ignored. 

When I refer to gravitational potential I am refering to the gravitational strength in that environment.  The gravitational strength increases closer to the mass.  This is the oposite of what you are refering to which is gravitational potential energy.  I do understand the subject and my claim is correct.

I would have replied earlier but my PC demonstrated times arrow by dying and I have just got it back.
« Last Edit: 27/02/2012 08:02:35 by MikeS »
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #31 on: 27/02/2012 07:56:06 »
I believe, in the proverbial "closed system", radioactive decay must proceed in the direction of increasing entropy. You start with uranium and end up with lead, and that is independent of gravity. You can't go from lead to uranium without a low-entropy input from outside the system.

In my own model, the direction of time is determined by the expansion of space, with alternate scale-wise universes running in alternate directions.

Nothing is independent of gravity and certainly nothing that has mass.
 

Offline Phractality

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Re: Does Time have a Direction Without Gravity?
« Reply #32 on: 27/02/2012 20:50:38 »
I believe, in the proverbial "closed system", radioactive decay must proceed in the direction of increasing entropy. You start with uranium and end up with lead, and that is independent of gravity. You can't go from lead to uranium without a low-entropy input from outside the system.

In my own model, the direction of time is determined by the expansion of space, with alternate scale-wise universes running in alternate directions.

Nothing is independent of gravity and certainly nothing that has mass.
The electroweak force is like 44 orders of magnitude stronger than gravity. I doubt if gravity can have much of an influence inside a nucleus.
« Last Edit: 28/02/2012 06:28:35 by Phractality »
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #33 on: 28/02/2012 07:02:54 »
Phrac

Radioactive decay proceeds at a given rate.  Therefore time plays a roll in the process and the time dilation factor is affected by the gravitational field.

Presumably radioactive decay could be used as a clock.  The time dilation factor of that clock will vary depending upon its hight within the gravitational gradient. So it would seem that gravity by affecting time dilation does play a part even at the nuclear level.
 

Offline Phractality

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Re: Does Time have a Direction Without Gravity?
« Reply #34 on: 29/02/2012 18:19:36 »
Phrac

Radioactive decay proceeds at a given rate.  Therefore time plays a roll in the process and the time dilation factor is affected by the gravitational field.

Presumably radioactive decay could be used as a clock.  The time dilation factor of that clock will vary depending upon its hight within the gravitational gradient. So it would seem that gravity by affecting time dilation does play a part even at the nuclear level.
Where gravity does dilate time, yes; I believe it affects the rate of radioactive decay, but not the direction. I thought we were talking about absence of gravity, except, of course the gravity among nucleons of a single atom. It takes a lot of atoms to warp space-time significantly.

Anyway, aren't we talking about the direction of time? Gravity dilates time; it doesn't affect the direction of time, at least not in Einstein's general relativity. I believe, when we get around to unifying GR with quantum mechanics, we're going to have to treat the nuclear forces in the same way that we treat gravity. At nuclear distances, the strong and weak forces (and perhaps the Higgs force) will warp space-time, but to a far greater extent than gravity does. A quark may resemble a tiny black hole, due to the way those forces warp space-time inside the subatomic particles. Outside the nucleus, those forces cancel each other out, so they don't warp space-time. I expect them to dilate time, also, but not alter its direction.

In the absence of gravity other than that between nucleons of a single atom, without a major modification of GR, radioactive decay proceeds in the same direction as it does near a black hole. Inside a black hole, all bets are off.

The one thing in my model that reverses the direction of time is scale, with many orders of magnitude defining the scales of successive universes. At present, there are roughly 59 orders of magnitude difference between our universe and the next larger-scale universe, and that number is increasing. Between our universe and the next smaller-scale universe, the scale factor is probably unknowable and decreasing from our point of view, while increasing from a sub-universe point of view.
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #35 on: 01/03/2012 09:45:50 »
Phrac

Radioactive decay proceeds at a given rate.  Therefore time plays a roll in the process and the time dilation factor is affected by the gravitational field.

Presumably radioactive decay could be used as a clock.  The time dilation factor of that clock will vary depending upon its hight within the gravitational gradient. So it would seem that gravity by affecting time dilation does play a part even at the nuclear level.
Where gravity does dilate time, yes; I believe it affects the rate of radioactive decay, but not the direction. I thought we were talking about absence of gravity, except, of course the gravity among nucleons of a single atom. It takes a lot of atoms to warp space-time significantly.

Anyway, aren't we talking about the direction of time? Gravity dilates time; it doesn't affect the direction of time, at least not in Einstein's general relativity. I believe, when we get around to unifying GR with quantum mechanics, we're going to have to treat the nuclear forces in the same way that we treat gravity. At nuclear distances, the strong and weak forces (and perhaps the Higgs force) will warp space-time, but to a far greater extent than gravity does. A quark may resemble a tiny black hole, due to the way those forces warp space-time inside the subatomic particles. Outside the nucleus, those forces cancel each other out, so they don't warp space-time. I expect them to dilate time, also, but not alter its direction.

In the absence of gravity other than that between nucleons of a single atom, without a major modification of GR, radioactive decay proceeds in the same direction as it does near a black hole. Inside a black hole, all bets are off.

The one thing in my model that reverses the direction of time is scale, with many orders of magnitude defining the scales of successive universes. At present, there are roughly 59 orders of magnitude difference between our universe and the next larger-scale universe, and that number is increasing. Between our universe and the next smaller-scale universe, the scale factor is probably unknowable and decreasing from our point of view, while increasing from a sub-universe point of view.

I don't believe that Einstein precluded the possibility of time reversal.
At the event horizon of a black hole time virtually stands still according to a distant observer but the arrow remains in the same direction.  It is still open to experimental proof whether or not antimatter and matter are gravitationally attractive or repulsive.  If repulsive then in an antimatter universe the arrow of time would point in the opposite direction.  If that is true then matter causes the arrow of time to point in one direction and antimatter causes it to point in the other. Until such time as this experiment can be done it must remain open to question whether or not this is the case.

However, it is certainly true that gravity defines the direction of the arrow of time.  If you drop a tea cup it shatters.  This is an example of entropy, the main arrow of time. 
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #36 on: 02/03/2012 07:02:31 »
An increase in gravitational strength dilates time.  The EH of a black hole dilates time to the point where it (effectively) stops.  Although the passage of time has stopped the arrow of time remains but the clock never ticks.

Do we all agree or disagree?
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #37 on: 02/03/2012 07:20:50 »
An increase in gravitational strength dilates time.  The EH of a black hole dilates time to the point where it (effectively) stops.  Although the passage of time has stopped the arrow of time remains but the clock never ticks.


imatfaal is probably going to point out that this is true only for a distant observer.  For an observer in the EH (lets call him Fred), time passes as normal as perceived by him and recorded by his clock.

Fred does not notice the slowing of time as perceived by a distant observer.  As time stops so Fred's thought processes stop.  Fred's watch stops.

When Fred's watch stops, time really has stopped both for Fred and the distant observer.

 

Offline imatfaal

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Re: Does Time have a Direction Without Gravity?
« Reply #38 on: 02/03/2012 13:26:49 »
An increase in gravitational strength dilates time.  The EH of a black hole dilates time to the point where it (effectively) stops.  Although the passage of time has stopped the arrow of time remains but the clock never ticks.


imatfaal is probably going to point out that this is true only for a distant observer.  For an observer in the EH (lets call him Fred), time passes as normal as perceived by him and recorded by his clock.

Fred does not notice the slowing of time as perceived by a distant observer.  As time stops so Fred's thought processes stop.  Fred's watch stops.

When Fred's watch stops, time really has stopped both for Fred and the distant observer.



Because you post hundreds of messages on gravitational potential time dilation without understanding it.  Fred will feel the pain as tidal forces rip him to pieces and we can only pray he is unconscious first; but he will not repeat NOT be insensible due to time slowing for him.  He will know that it is slowing because the signals from his mate in the accelerated frame of reference will be more and more blueshifted - but he will not be able to sense it in his local frame.  His mate will look at his signals and think that it is taking a huge time for his to cross the EH.

And it is gravitational potential  - not gravitational strength; there is a difference.

You keep on about the arrow of time remaining - how do we test for that? 
 

Offline MikeS

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Re: Does Time have a Direction Without Gravity?
« Reply #39 on: 11/03/2012 07:58:18 »
An increase in gravitational strength dilates time.  The EH of a black hole dilates time to the point where it (effectively) stops.  Although the passage of time has stopped the arrow of time remains but the clock never ticks.


imatfaal is probably going to point out that this is true only for a distant observer.  For an observer in the EH (lets call him Fred), time passes as normal as perceived by him and recorded by his clock.

Fred does not notice the slowing of time as perceived by a distant observer.  As time stops so Fred's thought processes stop.  Fred's watch stops.

When Fred's watch stops, time really has stopped both for Fred and the distant observer.



Because you post hundreds of messages on gravitational potential time dilation without understanding it.  Fred will feel the pain as tidal forces rip him to pieces and we can only pray he is unconscious first; but he will not repeat NOT be insensible due to time slowing for him.  He will know that it is slowing because the signals from his mate in the accelerated frame of reference will be more and more blueshifted - but he will not be able to sense it in his local frame. His mate will look at his signals and think that it is taking a huge time for his to cross the EH.

And it is gravitational potential  - not gravitational strength; there is a difference.

You keep on about the arrow of time remaining - how do we test for that? 
I think that I do understand it and you have yet to convince me otherwise.  Give me proof of what I have got wrong that's all I ask.

I thought that was obvious and in this thought experiment it was irrelevant to state it.

That's exactly what I said "For an observer in the EH (lets call him Fred), time passes as normal as perceived by him and recorded by his clock."

We have had this discussion in a different thread over the confusion of the terms 'gravitational potential' and 'gravitational potential energy'.  Some people and web sites use both terms to mean 'gravitational potential energy'.  To get rid of the confusion I have mentioned this before in the hope that we can speak a common language on the subject but you have not answered my post.

I assume by 'gravitational potential' you are referring to the gravitational constant like on the surface of the Earth for instance?  Not GPE.  The 'gravitational potential' at any particular place is the same thing as it's 'gravitational strength' as far as I can see.  If, on the other hand you are using the term 'gravitational potential' to mean 'gravitational potential energy' then this is not the same as 'gravitational strength'.  We need to clarify this.


You probably can't test for it as a test involves the passage of time but you can be aware of it as I have mentioned many times before in previous threads.  Whilst we can't as yet test for it we can do a thought experiment as mentioned below.

A plumb bob (weight on a piece of string) points down being the direction it would travel through space-time if released.  Its a static indication of the arrow of time.  To be a demonstration it only needs to be dropped.  When I say static indication it's a relative term.  The plumb bob when stationary in space is still moving through time. 

How to prove the arrow of time still exists if there is no 'passage' of time' (time is infinitely dilated).

Imagine this plumb bob to be on a very long piece of string and the plumb bob itself to be held 'stationary' in the event horizon of a black hole.  The plumb bob points toward the singularity.  Being in the Event Horizon the 'passage' of time is stationary but the arrow of time still exists.  This could be interpreted as whilst the passage of time is zero, 'space' is flowing into the black hole at the speed of light.  However, this still shows that the 'arrow' of time still exists even without the 'passage' of time.
« Last Edit: 11/03/2012 08:04:05 by MikeS »
 

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Re: Does Time have a Direction Without Gravity?
« Reply #39 on: 11/03/2012 07:58:18 »

 

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