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Author Topic: Is time an illusion?  (Read 54028 times)

Offline annie123

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Is time an illusion?
« on: 11/02/2012 20:12:59 »
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?
« Last Edit: 10/03/2012 20:29:05 by annie123 »


 

Offline JP

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Re: Is time an illusion?
« Reply #1 on: 12/02/2012 16:29:33 »
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.)
 

Offline Bored chemist

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Re: Is time an illusion?
« Reply #2 on: 12/02/2012 17:06:29 »
I think half the quote is missing
"time is an illusion: lunchtime doubly so"

http://en.wikiquote.org/wiki/The_Hitchhiker's_Guide_to_the_Galaxy#Chapter_2
 

Offline yor_on

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Re: Is time an illusion?
« Reply #3 on: 12/02/2012 22:20:51 »
'Time' itself can't be illusion. What I see the debate to be about is what we should relate the 'arrow of time' to. And there thermo dynamics and entropy are two strong runners. Think of it Annie :) when that second hand moves, why does it do so?
« Last Edit: 12/02/2012 22:44:02 by yor_on »
 

Offline Soul Surfer

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Re: Is time an illusion?
« Reply #4 on: 12/02/2012 22:23:10 »
Presumably annie123 is talking about the book  "The End of Time" by Julian Barbour 

Julian Barbour  is a respected cosmologist and philosopher.  I have had the book for some years and read it a couple of times  His book includes a good general introduction.

It takes an interesting approach to making sense of the quantum approach to physics where the universe effectively "samples" all possible states on the way to settling down for an "observation" which is the sort of thing that we see or another particle interacts with.

This fits with the equations that describe the events which are in effect infinite integrals over all space and time.

The full reality is that both space and time are emergent properties of our universe which is fundamentally built out of energy and momentum but this is so unfamiliar that most people have great difficulty in coming to terms with it.

As always with these books the ideas when put into an extreme situation seem weird but have absolutely no effect on our own perceptions of "reality"  describing something in terms of mathematics which works and produces very accurate predictions does not change the universe from what it IS in any way.
 

Offline Geezer

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Re: Is time an illusion?
« Reply #5 on: 13/02/2012 02:36:15 »
It's probably not legit to talk about time as a discrete thingy. It's certainly not in any way absolute. It's really just a property of space-time.

I make this all quite clear in my book.
 

Offline annie123

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Re: Is time an illusion?
« Reply #6 on: 18/02/2012 23:16:17 »
SOul Surfer, you could tell JP a thing or two.  But how do you know what the universe IS? I'd like to know.  Unless it is just a name given to what we have learned so far about it. But how do we know that's all there is to know? After all, we only 'know' very little given all the theories about dark matter/energy etc.
To JP, Discover Magazine has a very long article about Julian Barbour this month. And yes, The End of Time is one of his books.
 

Offline Soul Surfer

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Re: Is time an illusion?
« Reply #7 on: 22/02/2012 15:06:08 »
Annie to find out what the universe IS you need to search back to find what are the most fundamental physical laws.  We are aware that space can be bent to create gravity and time can be different for different observers.  So it follows that although these are pretty stable under the conditions of normal life they may not be totally fundamental.

A very deep mathematical relationship exists between symmetries in nature and conservation laws. This is called Noether's theorem (look it up in wikipedia for more indformation). This is that all important symmetries have an associated conservation law.  Now for an understandable universe the physical laws should not change arbitrarily according to where you are how you move about and in what direction you are looking

These simple "symmetry" requirements lead to the most fundamental conservation laws in our (or probably any) universe these are the conservation of energy, momentum and angular momentum respectively.  It therefore follows that our universe is built from energy and momentum continually interacting with each other and locked together to create the more familiar aspects of space, time and matter.
« Last Edit: 22/02/2012 15:07:51 by Soul Surfer »
 

Offline Durgesh Dubhashi

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Re: Is time an illusion?
« Reply #8 on: 28/02/2012 13:36:03 »
Two Different Ways of Seeing Things.. Time is a dimension created by Man to Ans the Question When? As for Barbour's Illusion, its an example of Elephant and Ant. The time period of an Ant would be Big enough for itself but to an Elephant it is nothing.. Similarly when we compare Universe's life to that of our, time is an illusion.
 

Offline yor_on

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Re: Is time an illusion?
« Reply #9 on: 28/02/2012 23:18:13 »
There is a arrow of time. You are born and you die. Split your lifespan into even chunks and you get the 'clock'. That arrow does not point from your demise to your birth, it has one way for you only. And the same goes for all objects you ever will meet. So the 'arrow' exist.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #10 on: 29/02/2012 07:44:06 »
I haven't read the book but time is no illusion.  The term 'Time' is something not invented but named by man.  We exist in the present and the past and future are concepts that we can only remember or visualise but cannot visit.  The arrow of time is very real.  Gravity is an expression of entropy and entropy is the main arrow of time.
 

Offline Soul Surfer

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Re: Is time an illusion?
« Reply #11 on: 03/03/2012 22:24:40 »
Mike   Julian Barbour is not suggesting that time is in any way an illusion.  It is very real and important from our point of view.  However from the point of view of the mathematics of quantum mechanics our universe is continually visiting every state that can possibly exist and moving between the ones that have the best probability based on all the states that have occurred. making time an emergent property of the energy and momentum states possible in the universe.  I would extend this and say space is also an emergent property as well but I am not sure if anyone has gone that far.
 

Offline MikeS

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Re: Is time an illusion?
« Reply #12 on: 04/03/2012 07:10:28 »
Mike   Julian Barbour is not suggesting that time is in any way an illusion.  It is very real and important from our point of view.  However from the point of view of the mathematics of quantum mechanics our universe is continually visiting every state that can possibly exist and moving between the ones that have the best probability based on all the states that have occurred. making time an emergent property of the energy and momentum states possible in the universe.  I would extend this and say space is also an emergent property as well but I am not sure if anyone has gone that far.


I would agree with that.  I believe that the size of the universe (the space it contains is mostly down to the amount of free energy [radiation] that it contains.)  If for example the Universe were to be consumed by a black hole then as mass and energy were consumed so space would shrink.
 

Offline yor_on

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Re: Is time an illusion?
« Reply #13 on: 04/03/2012 18:17:04 »
'Emergences' is a nice concept SoulSurfer, reminding me of 'fields'. A sort of natural symmetry to those two.

Emergences, fields, excitations and all possible from there being an arrow to experience it in. So what came first :)

I say the arrow.
=

No arrow, nothing to discuss.
 

Offline Soul Surfer

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Re: Is time an illusion?
« Reply #14 on: 08/03/2012 22:40:10 »
Annie knowing a little of the mind of Neilep level members I think he (she or it ) was cracking a joke  :)  Baa

« Last Edit: 08/03/2012 22:45:36 by Soul Surfer »
 

Offline Geezer

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Re: Is time an illusion?
« Reply #15 on: 08/03/2012 23:44:45 »
Blimey! I've been rumbled. (Queue feet running towards exit.)
 

Offline Livewire

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Re: Is time an illusion?
« Reply #16 on: 09/03/2012 00:01:37 »
time is a man made invention the universe moves forward with out it. It will move even after your body can no longer sustain life as for no future its our present actions that determine future events.
 

Offline Bill S

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Re: Is time an illusion?
« Reply #17 on: 09/03/2012 16:28:43 »
I agree that, in spite of the title, "The End of Time", JB is not throwing time out of the window.

   He believes that you can question the reality of time, without throwing out general relativity.  He expresses his belief in relativity, and says:  “I am not claiming that the description of space-time given by Einstein and Minkowski is wrong.  Far from it – they got it right ….”  However, he adds a proviso:  “…. but they described the finished product, and the complete story must also include the construction of the product.”

I think it would be difficult to accept GR without according some significance to time.

As far as the arrow of time is concerned, we have to distinguish between the idea of an arrow that flies through the air, and one that is painted on a sign to point the way.  Obviously this brings in the arguments about tensed and untensed time, but without that distinction discussions tend to go round in circles.
 

Offline yor_on

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Re: Is time an illusion?
« Reply #18 on: 11/03/2012 01:51:51 »
Now I'm feeling stupid Bill.

What is 'tensed and untensed time,'?
 

Offline Geezer

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Re: Is time an illusion?
« Reply #19 on: 11/03/2012 04:24:48 »

Obviously this brings in the arguments about tensed and untensed time, but without that distinction discussions tend to go round in circles.


Should we then be referring to the boomerang of time, rather than the arrow?
 

Offline yor_on

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Re: Is time an illusion?
« Reply #20 on: 12/03/2012 20:15:18 »
Is it this you were referring to Bill?

"Consider this one issue upon which philosophers are deeply divided: What sort of ontological differences are there among the present, past and future? There are three competing theories. Presentists argue that necessarily only present objects and present experiences are real, and we conscious beings recognize this in the special “vividness” of our present experience. The dinosaurs have slipped out of reality. However, according to the growing-universe or growing-block theory, the past and present are both real, but the future is not real because the future is indeterminate or merely potential. Dinosaurs are real, but our death is not. The third and more popular theory is that there are no significant ontological differences among present, past, and future because the differences are merely subjective. This view is called “the block universe theory” or “eternalism.”

That controversy raises the issue of tenseless versus tensed theories of time. The block universe theory implies a tenseless theory. The earliest version of this theory implied that tensed terminology can be replaced adequately with tenseless terminology. For example, the future-tensed sentence, “The Lakers will win the basketball game” might be analyzed as, “The Lakers do win at time t, and time t happens after the time of this utterance.” Notice that the future tense has been removed, and the new verb phrases “do win” and “happens after” are tenseless logically, although they are grammatically in the present tense. (Similarly, the present-tense verb “is” in “seven plus five is twelve” isn’t only about the present.) Advocates of a tensed theory object and say that tenseless terminology is not semantically basic but should be analyzed in tensed terms, and that tensed facts are needed to make tensed statements be true. For example, a tensed theory might imply that no adequate account of the present tensed fact that it is now midnight can be given without irreducible tensed properties such as presentness or now-ness. So, the philosophical debate is over whether tensed concepts have semantical priority over untensed concepts, and whether tensed facts have ontological priority over untensed facts." By Bradley Dowden in "Time" (IEP)
« Last Edit: 12/03/2012 20:19:35 by yor_on »
 

Offline MikeS

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Re: Is time an illusion?
« Reply #21 on: 12/03/2012 20:58:44 »
Well I read it but that was (tensed) a waste of time.
 

Offline Soul Surfer

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Re: Is time an illusion?
« Reply #22 on: 13/03/2012 10:49:32 »
This deals with linguistic expressions of things unfortunately science is (or should be) independent of the language in which we express it.  The best language for this is probably mathematics
 

Offline Æthelwulf

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Re: Is time an illusion?
« Reply #23 on: 13/03/2012 19:16:29 »
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?

Julian Barbour is absolutely correct. I have most appreciated his understanding of time over the last two years has it has been formulated http://www.fqxi.org/data/essay-contest-files/Barbour_The_Nature_of_Time.pdf?phpMyAdmin=0c371ccdae9b5ff3071bae814fb4f9e9 into Markoupoulou's title of the Problem of Time on the FQXI team and forum http://www.fqxi.org/data/essay-contest-files/Markopoulou_SpaceDNE.pdf , that space can be understood in a unique way in a model called Geometrogenesis: The intricate understanding that space is a low energy phenomenon - so it happens late in the universes history, and geometry according to Einstein's field equations, is directly linked to the curvature (the geometry) of space and time.

Timelessness may exist, according to Barbour. In Fotini Markoupoulou's interpretation, we can keep time by removing space. Her model is revolutionary but faulty - time will not exist either, for using her same methodologies, time would have no appearance at the big bang. Geometry is not concerned with high energy phenomena, atleast in the fundamental sense - geometry appears late in the universes history as an indication itself that not only the normal spatial geometry comes into question when you unify physics into absurdly small places, but you also get a problem in time as well since geometry according to the ''Minkowski'' view of space, was to be coupled to a fourth dimension of space.

But space at big bang did not exist, since there was no space since big bang happened at an infinitessimal point. So how can current theory tackle the prevailing truth?
« Last Edit: 13/03/2012 19:19:00 by Æthelwulf »
 

Offline Æthelwulf

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Re: Is time an illusion?
« Reply #24 on: 13/03/2012 21:51:27 »
I should state that Julian neither places bold assertions on wehether a universe contains a past or future. To understand these things, one must first understand the wheeler de-witt equation then come to terms that worldlines are indeed static.


As I said, he was right.
 

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Re: Is time an illusion?
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