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Author Topic: Is time an illusion?  (Read 53858 times)

Offline yor_on

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Re: Is time an illusion?
« Reply #25 on: 14/03/2012 04:17:19 »
"and geometry according to Einstein's field equations, is directly linked to the curvature (the geometry) of space and time."

Yep, it's called SpaceTime for a reason :)

As for Julian Barbour I tried to read him some year or so ago, but found it to intricate for my taste. I prefer simpler explanations :) as most of us , or maybe it's me  getting senile :)

 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #26 on: 19/03/2012 21:10:59 »
As an ordained priest in the church of orthodox physics, my answer would be,

"Who's Julian Barbour?"

(In other words, his ideas haven't made much of an impact on physics.)

Well, the subject he tackles is actually well known. It is called timelessness in GR and is born from the WDW equation. His approach was brilliant in removing time and only dealing with real observables.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #27 on: 20/03/2012 07:13:07 »
Quote Julian Barbour.
"I believe that a theory of the universe should explain why entropy increases."

Simple, Entropy increases because that is the preferred 'ground state' of the Universe.
The ground state being the most stable configuration possible.

Entropy is therefore the main arrow of time.  All other arrows of time are essentially entropic in nature.

Change involves an increase in entropy and involves causality.  We call this time.

Quote Julian Barbour.
 "but the equations of physics are symmetric with respect to the direction of time? The equations of physics allow not only the shattering of a cup that is dropped on the floor but also the re-assembly of the pieces. However, that is never observed."

Hypothetically, an antimatter universe could exist in which the arrow of time is reversed in comparison to our universe.  Time would still flow forward as observed by beings in that universe.  This would allow time to be symmetric but still without re-assembly of the pieces. (Unless viewed by us)

Quote Julian Barbour.
"If we could stand outside the universe and ‘see it as it is’, it would appear to be static."

Assuming we viewed it from a similar and equivalent time frame why would it appear to be static.  If you could manipulate your own time frame then you could appear to make it seem static but what would be the point?

Quotes are from
http://platonia.com/books.html
« Last Edit: 20/03/2012 08:03:37 by MikeS »
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #28 on: 20/03/2012 07:31:41 »
What is a ground state though? (Rhetorical question). How do we know the universe did not appear in some excited state? It did afterall appear in one superdense past which is a high energy phenomenon.

 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #29 on: 20/03/2012 07:33:32 »
Plus. I think if you qoute doctor Barbour, you should give a reference so we can measure up exactly why he asked this question. Is it from his paper on time?
 

Offline MikeS

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Re: Is time an illusion?
« Reply #30 on: 20/03/2012 07:47:55 »
Have modified above message to give source of quotes.

"The ground state of a quantum mechanical system is its lowest-energy state; the energy of the ground state is known as the zero-point energy of the system."
http://en.wikipedia.org/wiki/Ground_state

Regardless of the universes starting conditions this is where it is heading.
It can do this in either one or the other of two ways.
The universe could expand until energy has completely dissipated.
or
The universe could contract into a black hole.  Either way entropy is satisfied.

The ground state must have been the starting point prior to the start of the universe but talking about a starting point prior to the starting point is really meaningless.  If you follow...
« Last Edit: 20/03/2012 07:58:33 by MikeS »
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #31 on: 20/03/2012 08:05:39 »
Quote Julian Barbour.
"I believe that a theory of the universe should explain why entropy increases."

Simple, Entropy increases because that is the preferred 'ground state' of the Universe.
The ground state being the most stable configuration possible.

Entropy is therefore the main arrow of time.  All other arrows of time are essentially entropic in nature.

Change involves an increase in entropy and involves causality.  We call this time.

Quote Julian Barbour.
 "but the equations of physics are symmetric with respect to the direction of time? The equations of physics allow not only the shattering of a cup that is dropped on the floor but also the re-assembly of the pieces. However, that is never observed."

Hypothetically, an antimatter universe could exist in which the arrow of time is reversed in comparison to our universe.  Time would still flow forward as observed by beings in that universe.  This would allow time to be symmetric but still without re-assembly of the pieces.

Quote Julian Barbour.
"If we could stand outside the universe and ‘see it as it is’, it would appear to be static."

Assuming we viewed it from a similar and equivalent time frame why would it appear to be static.  If you could manipulate your own time frame then you could appear to make it seem static but what would be the point?

Quote are from
http://platonia.com/books.html

''Hypothetically, an antimatter universe could exist in which the arrow of time is reversed in comparison to our universe.  Time would still flow forward as observed by beings in that universe.  This would allow time to be symmetric but still without re-assembly of the pieces.''

This isn't really Julians point. His point is that motion is a symmetry of the theory. True time evolution does not exist in GR. The past and future are only artefacts of a theory we have developed, if you like it has some kind of psychological arrow which implies a directionality to time, a past then a future state. But in GR wordlines are static. There is no past or future. There is, only the present.

This is also true with our direct experience of the world. We may ''feel'' like a time has past, but we don't actually experience a past, nor do we ever experience a future.

''Assuming we viewed it from a similar and equivalent time frame why would it appear to be static.  If you could manipulate your own time frame then you could appear to make it seem static but what would be the point?''

 It has something to do with weak measurements. It would be like an atom. An atom ripe to radiate energy can be suspended in time by making a series of observations on the system - this is called the Zeno Effect.



By the way, when I said:

''What is a ground state though? (Rhetorical question). ''

I never intended you link a ground state. I am well aware of what a ground state is. I am saying your assumption that ground state systems alone answers for the origin of entropy does not add up.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #32 on: 20/03/2012 08:06:44 »
''The ground state must have been the starting point prior to the start of the universe ''

I disgree. Before the Big Bang, there was nothing.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #33 on: 20/03/2012 08:13:55 »
I am saying your assumption that ground state systems alone answers for the origin of entropy does not add up.

Why?

''The ground state must have been the starting point prior to the start of the universe ''

I disgree. Before the Big Bang, there was nothing.

Try taking it in context.
What I said was.
The ground state must have been the starting point prior to the start of the universe but talking about a starting point prior to the starting point is really meaningless.  If you follow...
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #34 on: 20/03/2012 08:25:17 »
You ask why saying something in a ground state answers for entropy is not enough?

Call it a matter of conjecture. Your point is a conjecture. It isn't theory. It doesn't answer for instance, why entropy would be driven by a ground state, in let's say something preferential to an excited state.

Entropy, is in a loose way of speaking, a measure of change. You will find change most prominently in an excited state atom, ready to give up energy. That is a form of entropy as well.

''The ground state must have been the starting point prior to the start of the universe...''

You seem to be having a mental block - there was no ''prior state'' to the big bang. Ground, excited, give or take a little space, time nothing, nada, the big goose egg. If anything, there might have been a potential for a universe to come into existence (Such as a Hartle-Hawking Universe), but I've never fully understood that concept as it makes little sense when you are dealing with a non-system.

''but talking about a starting point prior to the starting point is really meaningless.''

Right.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #35 on: 20/03/2012 08:25:30 »
''The ground state must have been the starting point prior to the start of the universe ''

I disgree. Before the Big Bang, there was nothing.

In some sense that is debatable.  If there was nothing then where did the universe come from?  It is certainly true to say before the big bang there was no universe and that includes such concepts as time, distance and thought.  Assuming the big bang to be correct of course.

I guess it depends on what you mean by nothing.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #36 on: 20/03/2012 08:29:39 »
The ground state must have been the starting point prior to the start of the universe but talking about a starting point prior to the starting point is really meaningless.  If you follow...

It was a kind of 'tongue in cheek joke'.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #37 on: 20/03/2012 08:33:03 »
Assuming the big bang is correct, which I don't think it is, but that is neither here nor there, then there was nothing we can attribute to as the four fundamental ingredients, such as space, time, energy or matter. Nothing exists outside the universe either, according to relativity, so we must assume that if the universe was not around, there could have been nothing before it.

There maybe reasons why the beginning is such. There is a theory right now which scientists are eager over called the Transactional Interpretation which can put a new spin on the beginning of things. Essentially, we could adopt the idea that the future cone of the universe is shaping up the past - the beginning is being formed by actions in our future horizon. So the future creates the past. There is actually experimental varification of this.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #38 on: 20/03/2012 09:10:52 »
You ask why saying something in a ground state answers for entropy is not enough?

Call it a matter of conjecture. Your point is a conjecture. It isn't theory. It doesn't answer for instance, why entropy would be driven by a ground state, in let's say something preferential to an excited state.


It is self evident that the Universe is driven by energy.  As energy 'does work' so the entropy of the Universe increases.  Ultimately the Universe will run out of energy and entropy will be at a maximum.  This will be as close to the ground state as possible.

No it's not theory, neither is it conjecture.  It is fact.
 

Offline Nizzle

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Re: Is time an illusion?
« Reply #39 on: 20/03/2012 09:49:16 »
He says that there is no time, only change.Does he have a following?

This is like saying "There is no distance, only centimetres" or "There is no volume, only litres"....
Time is a physical property, like distance and volume. Change is one of the ways to measure it..
So he's contradicting himself in one short sentence. Not an easy feat. ;)
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #40 on: 20/03/2012 09:54:35 »
You ask why saying something in a ground state answers for entropy is not enough?

Call it a matter of conjecture. Your point is a conjecture. It isn't theory. It doesn't answer for instance, why entropy would be driven by a ground state, in let's say something preferential to an excited state.


It is self evident that the Universe is driven by energy.  As energy 'does work' so the entropy of the Universe increases.  Ultimately the Universe will run out of energy and entropy will be at a maximum.  This will be as close to the ground state as possible.

No it's not theory, neither is it conjecture.  It is fact.

Saying entropy is caused by a Ground State is about as enlightening as an unplugged Christmas Tree. As I have explained, it doesn't answer it at all. It answer it as much as an excited state would. It's pointless, meaningless speculation.

I was being kind when I said conjecture. All you are stating is a speculation, with no reason other than you thinking it sounding good.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #41 on: 20/03/2012 09:55:20 »
He says that there is no time, only change.Does he have a following?

This is like saying "There is no distance, only centimetres" or "There is no volume, only litres"....
Time is a physical property, like distance and volume. Change is one of the ways to measure it..
So he's contradicting himself in one short sentence. Not an easy feat. ;)

Time is not physical. How can it be physical?

Physical things purport to Observables. Time is NOT an Observable.
 

Offline Nizzle

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Re: Is time an illusion?
« Reply #42 on: 20/03/2012 10:07:32 »
He says that there is no time, only change.Does he have a following?

This is like saying "There is no distance, only centimetres" or "There is no volume, only litres"....
Time is a physical property, like distance and volume. Change is one of the ways to measure it..
So he's contradicting himself in one short sentence. Not an easy feat. ;)

Time is not physical. How can it be physical?

Physical things purport to Observables. Time is NOT an Observable.

So for you, wind is not physical either? Cause you can't see wind?

EDIT: I meant "Time is a physical quantity" not "property". It's a language thing, I'm not a native english speaker..
« Last Edit: 20/03/2012 10:11:40 by Nizzle »
 

Offline MikeS

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Re: Is time an illusion?
« Reply #43 on: 20/03/2012 11:17:40 »
You ask why saying something in a ground state answers for entropy is not enough?

Call it a matter of conjecture. Your point is a conjecture. It isn't theory. It doesn't answer for instance, why entropy would be driven by a ground state, in let's say something preferential to an excited state.


It is self evident that the Universe is driven by energy.  As energy 'does work' so the entropy of the Universe increases.  Ultimately the Universe will run out of energy and entropy will be at a maximum.  This will be as close to the ground state as possible.

No it's not theory, neither is it conjecture.  It is fact.

Saying entropy is caused by a Ground State is about as enlightening as an unplugged Christmas Tree.

I never actually said that.
The ground state is reached when entropy is at a maximum.

Sorry you don't like it but that's the way it is.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #44 on: 20/03/2012 20:09:20 »
He says that there is no time, only change.Does he have a following?

This is like saying "There is no distance, only centimetres" or "There is no volume, only litres"....
Time is a physical property, like distance and volume. Change is one of the ways to measure it..
So he's contradicting himself in one short sentence. Not an easy feat. ;)

Time is not physical. How can it be physical?

Physical things purport to Observables. Time is NOT an Observable.

So for you, wind is not physical either? Cause you can't see wind?

EDIT: I meant "Time is a physical quantity" not "property". It's a language thing, I'm not a native english speaker..

Wind is made of molecules, atoms. Charged particles.

What is time made of, but the ethereal experience of it?

Seriously dude, go learn some physics before you make statements you can't support. Time should not be physical. Just because it is part of an understanding Minkowski made years and years ago that by treating it as a dimension has left physics following a wrong path - a deluded idea that perhaps time is also physical, that it is part of the manifold we call space. Sure, calculationally-wise, time is very useful when thought of as a dimension. Other than that, it has no physical appearance. Time is not an observable. It is not tangible.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #45 on: 20/03/2012 20:11:37 »
You ask why saying something in a ground state answers for entropy is not enough?

Call it a matter of conjecture. Your point is a conjecture. It isn't theory. It doesn't answer for instance, why entropy would be driven by a ground state, in let's say something preferential to an excited state.


It is self evident that the Universe is driven by energy.  As energy 'does work' so the entropy of the Universe increases.  Ultimately the Universe will run out of energy and entropy will be at a maximum.  This will be as close to the ground state as possible.

No it's not theory, neither is it conjecture.  It is fact.

Saying entropy is caused by a Ground State is about as enlightening as an unplugged Christmas Tree.

I never actually said that.
The ground state is reached when entropy is at a maximum.

Sorry you don't like it but that's the way it is.

What's that supposed to mean anyway, ''when entropy is at a maximum'', I don't get it. Either a system is changing or not.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #46 on: 20/03/2012 20:13:02 »
The biggest fall I seem to be seeing right now, is people making

Time = Change

Time does not necesserily mean change at all. In fact, if anyone can follow the math of Julian Barbour, he shows you can deal with real observable things and omit time from the equations. Change can happen with real observables, the way physics should be.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #47 on: 20/03/2012 23:51:23 »
You ask why saying something in a ground state answers for entropy is not enough?

Call it a matter of conjecture. Your point is a conjecture. It isn't theory. It doesn't answer for instance, why entropy would be driven by a ground state, in let's say something preferential to an excited state.


It is self evident that the Universe is driven by energy.  As energy 'does work' so the entropy of the Universe increases.  Ultimately the Universe will run out of energy and entropy will be at a maximum.  This will be as close to the ground state as possible.

No it's not theory, neither is it conjecture.  It is fact.

Saying entropy is caused by a Ground State is about as enlightening as an unplugged Christmas Tree.

I never actually said that.
The ground state is reached when entropy is at a maximum.

Sorry you don't like it but that's the way it is.

Reading this back, my brain has boggled in what you have meant... until now. You aren't perhaps talking about the relationship between the least action principle and the principle of maximum entropy... Well, since a least action is one which uses the least amount of energy (Ground State) I suppose this is what you are talking about.

In which case I have little add. I don't know this relationship well.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #48 on: 21/03/2012 05:35:57 »
Quote from: Ęthelwulf link=topic=43056.msg383435#msg383435
clip
Time [i
"has no physical appearance. Time is not an observable. It is not tangible."[/i]

Two identical clocks, one on the Earths surface and one in orbit above the Earth will show a different passage of time.  Time passing faster for the clock in orbit.

That's observable and tangible enough for me.  You may not be able to see time directly but you can certainly see both the arrow and passage of time.
 

Offline Ęthelwulf

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Re: Is time an illusion?
« Reply #49 on: 21/03/2012 06:45:18 »
Quote from: Ęthelwulf link=topic=43056.msg383435#msg383435
clip
Time [i
"has no physical appearance. Time is not an observable. It is not tangible."[/i]

Two identical clocks, one on the Earths surface and one in orbit above the Earth will show a different passage of time.  Time passing faster for the clock in orbit.

That's observable and tangible enough for me.  You may not be able to see time directly but you can certainly see both the arrow and passage of time.

Time isn't an observable, and dilation is an effect.
 

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Re: Is time an illusion?
« Reply #49 on: 21/03/2012 06:45:18 »

 

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