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Author Topic: Is time an illusion?  (Read 53994 times)

Offline yor_on

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Re: Is time an illusion?
« Reply #200 on: 29/12/2012 08:39:38 »
I can't see how to ignore times arrow? Not here and now anyway. We have the idea of quantum computers as well as how all paths are take simultaneously with only one path 'left' to us finally (by its probability) and this could maybe been seen as a 'state' of timelessness. But it's not here, we live by outcomes, and those define all physics.
 

Offline Pmb

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Re: Is time an illusion?
« Reply #201 on: 29/12/2012 10:29:13 »
I would like to know what orthodox physicists think of Julian Barbour's radical ideas about time.  This also relates to he quantum mechanics theories that i also have a post about.
"Barbour argues that we live in a universe which has neither past nor future. A strange new world in which we are alive and dead in the same instant. In this eternal present, our sense of the passage of time is nothing more than a giant cosmic illusion." Discover Mag.
He says that there is no time, only change.Does he have a following?
Ignore Julian Barbour. From what I read of his work he only uses semantics to argue his point. I.e. he chooses specific definitions of things like "real" and "exist" etc and then makes arguements such that using his basic assumptions he gets the answers he wanted to arrive at.

Time is simply a concept we use to describe the fact the things in nature change in more than a merely spatial manner. Making more of it than that is merely a way to come up with little ideas to sell books and publish etc. In the end what does it give you?
 

Offline Bill S

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Re: Is time an illusion?
« Reply #202 on: 03/01/2013 18:03:31 »
This is a long thread, and my time is very limited, so if in what follows I repeat someone else's thoughts, I apologise.

I struggled with Barbour's "The End of Time", and wondered if the impression I had that he was at times creating definitions to suit his arguments arose from my lack of understanding.

However, I was fascinated by his concept of “Platonia”, presented as a timeless “land” in which nothing happens, but everything exists.  (I apologise to Julian Barbour if this is a misrepresentation of Platonia or if I should have seen more through the coloured mists that shroud that land).  The particular reason for my interest was that there seemed to be considerable similarity between the concept of Platonia and the idea of a cosmos that was infinite, timeless and changeless, at which I had arrived, albeit by a much less scientific path, some time ago. 

The two ideas share some problems.  The difficulties of describing a timeless arena are comparable to those of describing an infinite arena.  In both cases it seems that time-dependent descriptions become unavoidable.  Barbour talks about experiencing instants, one at a time.  The idea of experiencing instants “one at a time” surely implies a passage of time.  I accept that the passage of time may be only in our perception, but how do we distinguish between “reality” and our perceptions of reality?  Is there, in fact, any difference?

 Linked to the difficulty of distinguishing between perception and reality is the difficulty of imagining our world of three spatial dimensions embedded in a universe of many, or even infinite, dimensions.  Barbour says:

“….when we think we see motion at some instant, the underlying reality is that our brain at that instant contains data corresponding to several different positions of the object perceived to be in motion.  My brain contains, at any one instant, several ‘snapshots’ at once.  The brain, through the way in which it presents data to consciousness, somehow ‘plays the movie’ for me.” 

What I believe we have to acknowledge is that, even if we accept Barbour’s idea that time and motion are all in our heads, our perception is, and has to be, our reality.   So, if our perception is our reality; progression from one snapshot to another must be real.

    The same sort of problem arises with the idea of regarding time as a series of “snapshots”. David Deutsch and Barbour both make use of these snapshots, but in order to make distinctly different points.  However, in both cases, some degree of sequential experience must be assumed in order to (in Deutsch’s case) realise the universe you are in, and (in Barbour’s case) to produce the impression of motion, or the passage of time, where none is actually present.

Of course, the same problem arises if one tries to distinguish any two points in an infinite “landscape”, so it will be obvious that I am not trying to use these examples in order to detract from Barbour’s basic idea; because as I pointed out above, it does seem to jibe with my own thoughts, which is always gratifying.  However, I think it is important to stress the difficulties involved in trying to describe either the infinite, or the timeless, without recourse to finite and time-dependent terminology, since our lives are intimately entwined in both time and finite dimensions. 



   
 

Offline Pmb

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Re: Is time an illusion?
« Reply #203 on: 16/10/2013 12:37:13 »
Quote from: imatfaal
In quantum mechanics every variable (position, momentum,  angular momentum, spin, energy, and many tothers) is able to be represented by a Hermitian operator ...
Sorry for commenting on an old post but I just came across this one while reviewing the thread.

Not all variables in quantum mechanics can be represented by a Hermitian operator. Only those corresponding to observables are Hermitian.

A good example of a variable which is not an observable and therefore has no corresponding QM operator is a phasor.
 

Offline webplodder

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Re: Is time an illusion?
« Reply #204 on: 19/10/2013 15:11:00 »
I can't see how to ignore times arrow? Not here and now anyway. We have the idea of quantum computers as well as how all paths are take simultaneously with only one path 'left' to us finally (by its probability) and this could maybe been seen as a 'state' of timelessness. But it's not here, we live by outcomes, and those define all physics.

How do we really know that event b is an outcome of event a? What if, instead, events a and b are somehow "paired" together or correlated such that they are predetermined to occur within some frame of reference and that their causal relationship is just an illusion? Commonsense has taught us that if we drop an apple it falls to earth but why should the order of these events always be from the same direction? Why can't we introduce the idea of "negative time" where the causal relationship is reversed? It seems to me that it is because we separate things out from one another that the concept of causality arises and at a fundamental level reality may be non-local and unified so that every event exists now and time has no meaning. Could "spooky action at a distance" be pointing to this?
« Last Edit: 19/10/2013 15:16:03 by webplodder »
 

Offline Bill S

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Re: Is time an illusion?
« Reply #205 on: 19/10/2013 15:49:05 »
Quote from: Webplodder
Why can't we introduce the idea of "negative time" where the causal relationship is reversed? It seems to me that it is because we separate things out from one another that the concept of causality arises and at a fundamental level reality may be non-local and unified so that every event exists now and time has no meaning. Could "spooky action at a distance" be pointing to this?

I suspect that negative time would raise some complications, as well as upsetting “Bill Ockham”.

You could achieve the same thing, e.g. explaining "spooky action at a distance", by arguing that our Universe is a finite Universe “embedded” in an infinite cosmos.  The problem with both approaches is that they require assumptions that scientists have problems with.  :)

I think the idea of negative time could provoke some interesting discussion though.  Go for it, Webplodder! 

 

Offline Pmb

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Re: Is time an illusion?
« Reply #206 on: 22/10/2013 07:19:37 »
Quote from: webplodder
How do we really know that event b is an outcome of event a?
That can only be answered in specific instances. We develope laws of cause and effect by experimentation and observation. Then we postulate causes and effects. Saying that we "know" them as such gets deep into sematics and epistemology.

Quote from: webplodder
What if, instead, events a and b are somehow "paired" together or correlated such that they are predetermined to occur within some frame of reference and that their causal relationship is just an illusion?
I'm sure that happens a great deal of the time. But that's outside the laws of nature and now you're talking about something else.

Quote from: webplodder
Commonsense has taught us that if we drop an apple it falls to earth but why should the order of these events always be from the same direction?
What do you mean when you speak of events being from a direction?

Quote from: webplodder
Why can't we introduce the idea of "negative time" where the causal relationship is reversed?
You're confusing the ordering of events with the causality of the events. I see no reason to do so. I'm also not clear on what you mean by negative time.
 

Offline webplodder

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Re: Is time an illusion?
« Reply #207 on: 22/10/2013 10:25:48 »
Quote
We develope laws of cause and effect by experimentation and observation. Then we postulate causes and effects. Saying that we "know" them as such gets deep into sematics and epistemology.

The problem with this is that when we attempt to trace such causes and effects backwards in time we find we can never find an original moment that gave rise to causality since we can always ask:"what happened before that?", which gets us into a universe with no beginning, leading to the problem of explaining where causality came from. This model is so contradictory that perhaps we should consider other models of reality where time does not "flow" in a forward direction but only appears to exist as an emergent property of consciousness. Dispensing with the " arrow of time" concept frees us from having to deal with infinities and we are left with a multiverse which is fundamentally non-local in nature, time and space being appearances that we human beings have evolved to navigate through in the interests of survival. With this model it is unnecessary to ask about where the universe came from because time becomes irrelevant at the most fundamental level. It also means causality is an illusion since time is not real, leading to the conclusion that events are really part of a much greater whole that is inseparable. What we really see when we witness one event apparently following another is different aspects of this greater whole, not one being a consequence of another but both existing at the same time. It is our human psychology that is telling us event a) causes event b) and this is quite understandable when we see the usefulness of this approach in the history of our (and indeed other) species in adapting to the environment. This is where " common sense" has its practical value but is not reliable when attempting to probe the true nature of reality.
« Last Edit: 22/10/2013 10:28:57 by webplodder »
 

Offline webplodder

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Re: Is time an illusion?
« Reply #208 on: 22/10/2013 10:43:18 »
Quote
You're confusing the ordering of events with the causality of the events. I see no reason to do so. I'm also not clear on what you mean by negative time.

If the model I have expounded above is correct then it should be (at least, theoretically) possible to treat an event we appear to observe as causing another event as, itself, a consequence of that other event. It may be because we are so "hard-wired" to see time as a unidirectional flow that we have built our scientific theories to reflect this, however, such theories are ultimately based upon observational data which, of course, rely on our human perceptions to events developed over evolutionary time which enabled living things to survive.
 

Offline Pmb

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Re: Is time an illusion?
« Reply #209 on: 22/10/2013 17:07:45 »
Quote from: webplodder
The problem with this is that when we attempt to trace such causes and effects backwards in time we find we can never find an original moment that gave rise to causality since we can always ask:"what happened before that?", which gets us into a universe with no beginning, leading to the problem of explaining where causality came from.
Why? Who said that we couldn’t ask what happened before the big bang? I recall when I was an undergraduate and the subject of what happened before the big bang came up one day and the often quoted response “You can’t ask that question <=” Also came up along with it. My physics advisor commented, and I’ll never forget this, that such a comment was a terrible thing to say since there’s nothing wrong with asking questions like that. People who make those kinds of statements didn’t learn from the history of physics. Now, almost 25 years later, he’s proven to be quite right! :)

Quote from: webplodder
This model is so contradictory …..
I’m going to stop right here until we clear this assertion up.

Please provide your arguments as to why this is the case since I don’t see it in the least.
 

Offline AndroidNeox

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Re: Is time an illusion?
« Reply #210 on: 22/10/2013 22:05:48 »
Relativity requires that all past and future events exist within spacetime. This is because different observers must agree on what events take place (causality) but not on when or even what sequence they take place. Regarding the fact that entropy increases with time, it's easy to show that sequences can only be observer within systems of increasing entropy. To observer a sequence (which is what we always do when we observe time) one needs to retain information from previous states. The longer the sequence, the more information must be retained. The entropy of a system is the same as the information quantity of the system. Whether time "flows" doesn't matter... it can only be observed within causal systems of increasing entropy.
 

Offline Pmb

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Re: Is time an illusion?
« Reply #211 on: 22/10/2013 22:59:05 »
Quote from: AndroidNeox
Relativity requires that all past and future events exist within spacetime.
Since spacetime is actually defined as the set of all events your statement is only tautologically true.


Quote from: AndroidNeox
This is because different observers must agree on what events take place (causality) but not on when or even what sequence they take place.
That does not hold true in general. The spacetime separation determines whether two events can be causally related or not.

Quote from: AndroidNeox
Regarding the fact that entropy increases with time, it's easy to show that sequences can only be observer within systems of increasing entropy.
Okay. Since it’s so easy please show this. Thanks.

Quote from: AndroidNeox
To observer a sequence (which is what we always do when we observe time) one needs to retain information from previous states.
Please post an example of this.
 

Offline AndroidNeox

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Re: Is time an illusion?
« Reply #212 on: 23/10/2013 00:29:02 »
Quote from: AndroidNeox
Relativity requires that all past and future events exist within spacetime.
Since spacetime is actually defined as the set of all events your statement is only tautologically true.


Quote from: AndroidNeox
This is because different observers must agree on what events take place (causality) but not on when or even what sequence they take place.
That does not hold true in general. The spacetime separation determines whether two events can be causally related or not.

Quote from: AndroidNeox
Regarding the fact that entropy increases with time, it's easy to show that sequences can only be observer within systems of increasing entropy.
Okay. Since it’s so easy please show this. Thanks.

Quote from: AndroidNeox
To observer a sequence (which is what we always do when we observe time) one needs to retain information from previous states.
Please post an example of this.

"Since spacetime is actually defined as the set of all events your statement is only tautologically true."
No, this isn't just a tautology. It's a requirement of Relativity. It concerned Einstein because he felt it left no room for free will.

"That does not hold true in general. The spacetime separation determines whether two events can be causally related or not."
It's true that different observers must agree on what events take place but not time or sequence. While that may not be relevant for humans living on Earth, my statement is most definitely true.

"Okay. Since it’s so easy please show this. Thanks."

I explained it but will try again. Observation of time is observation of sequence. Observation of sequence requires retaining information from prior states. Retaining information from prior states yields increase in entropy. Hence, time is only observable when the observer's system is increasing in entropy.

Simple enough?
 

Offline webplodder

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Re: Is time an illusion?
« Reply #213 on: 23/10/2013 09:01:04 »
Quote from: webplodder
The problem with this is that when we attempt to trace such causes and effects backwards in time we find we can never find an original moment that gave rise to causality since we can always ask:"what happened before that?", which gets us into a universe with no beginning, leading to the problem of explaining where causality came from.
Why? Who said that we couldn’t ask what happened before the big bang? I recall when I was an undergraduate and the subject of what happened before the big bang came up one day and the often quoted response “You can’t ask that question <=” Also came up along with it. My physics advisor commented, and I’ll never forget this, that such a comment was a terrible thing to say since there’s nothing wrong with asking questions like that. People who make those kinds of statements didn’t learn from the history of physics. Now, almost 25 years later, he’s proven to be quite right! :)

Quote from: webplodder
This model is so contradictory …..
I’m going to stop right here until we clear this assertion up.

Please provide your arguments as to why this is the case since I don’t see it in the least.


I'm sorry, it appears we are at cross-purposes here. I wasn't just talking about before the Big Bang but whatever gave rise to that and whatever gave rise to that and so on. The central point here is that once you accept time is a continuous flow in one direction you are forced into an infinite model of reality which throws up contradictions surrounding causality. How can cause-and-effect be valid in a universe that has no cause? No matter how far back you go it is always possible to ask what went before, so it is an exercise in futility. For this reason, I reject the idea of "the arrow of time" and am forced into the conclusion that time and space exist as a unified, unbroken whole where time and space are simply emergent properties experienced as "real" by conscious observers such as us and other sentient beings.
« Last Edit: 23/10/2013 10:30:06 by webplodder »
 

Offline yor_on

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Re: Is time an illusion?
« Reply #214 on: 30/10/2013 20:31:15 »
Annie, I think it depends on your definitions. We can talk about a 'inside' and a 'outside' of a universe. What we make measurements on is the 'inside', and we do it from the precise same 'inside'. Inside we have a arrow, the arrow defines us and the universe we see. 'Outside' is another thing, the point is that we can't really define what that would be, we can only guess on it.  My own guess is that what we have is a construction, very well done and logical, in it we find principles following, as well as demanding, a arrow to make our logic. It's a little like life, it needs to be done.
 

Offline AndroidNeox

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Re: Is time an illusion?
« Reply #215 on: 05/11/2013 23:09:59 »
I'm sorry, it appears we are at cross-purposes here. I wasn't just talking about before the Big Bang but whatever gave rise to that and whatever gave rise to that and so on. The central point here is that once you accept time is a continuous flow in one direction you are forced into an infinite model of reality which throws up contradictions surrounding causality. How can cause-and-effect be valid in a universe that has no cause? No matter how far back you go it is always possible to ask what went before, so it is an exercise in futility. For this reason, I reject the idea of "the arrow of time" and am forced into the conclusion that time and space exist as a unified, unbroken whole where time and space are simply emergent properties experienced as "real" by conscious observers such as us and other sentient beings.

Personally, I think this is the most interesting question facing physics. All our knowledge and observations of physical reality show it to be causal. No violations of physical conservation symmetries, ever. Except when we look back 13.8 billion years to time = zero, when causality breaks down entirely.

Suppose the prior condition was non-causal? What would be the characteristics of a non-causal condition? There would be no conserved quantities. There would be no observable sequences so no time. Perhaps the ancients were right that our orderly reality sprung from chaos.
 

Offline yor_on

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Re: Is time an illusion?
« Reply #216 on: 08/11/2013 23:50:24 »
Or suppose that what we call order is a arrangement, 'emergence', through scales, and ? Constants? Forces? Meaning that this process is never finished, and in a way never 'here' either. The order we find seems defined in symmetries, 'emergences', using a arrow. In a way a opposite of decoherence.
=

Or a symmetry to decoherence, if one like.
 

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Re: Is time an illusion?
« Reply #216 on: 08/11/2013 23:50:24 »

 

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