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Author Topic:   What is Time and Space
nipok
Inactive Member


Message 181 of 204 (347498)
09-08-2006 3:55 AM
Reply to: Message 180 by GDR
09-05-2006 1:48 AM


Time
Of every post I've made in the last week or so I can only hope that some of you whose interests have been peaked can grasp this simple concept. It deals with time and everything we currently think about time. So much emphasis has been put on the possible point singularity from which all that we see has expanded from. To this end we feel the same singularity that created the matter we see also created the time we feel. The problem is that although they are intricately related they both have no smallest or largest unit of measure. They exist in all directions both inwards and outwards for an infinite chain of larger or smaller measurements and they both can be visualized and measured as relative absolutes. If one can fathom the likely probability that time and space are infinite in all directions then one can see how silly it is to think that the same singularity (or event) that started the process of our expanding universe also created the interwoven time that we use to perceive it upon. Time is an absolute and can have no beginning or end. Some may try to argue otherwise but that’s because they base their deductions on a house of cards that can easily blow over with a sneeze.

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Replies to this message:
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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 182 of 204 (347500)
09-08-2006 4:28 AM
Reply to: Message 181 by nipok
09-08-2006 3:55 AM


Re: Time
So much emphasis has been put on the possible point singularity
In an infinite universe, the singularity is not a point but infinite in extent.
If one can fathom the likely probability that time and space are infinite in all directions then one can see how silly it is to think that the same singularity (or event) that started the process of our expanding universe also created the interwoven time that we use to perceive it upon.
In physics, we do not use terms like "silly". They have no place. We use terms such as "consistent with" or "implied by". Some of the most sensible sounding ideas are nonsense and some of the most outlandish ideas have been shown to be true.
Time is an absolute and can have no beginning or end. Some may try to argue otherwise but that’s because they base their deductions on a house of cards that can easily blow over with a sneeze.
Einstein's theory of General Relativity argues otherwise. So far, it is the only theory of time we have and also stands as the most accurately tested theory in the history of science. It wil be superceded by a deeper, more unified theory at some stage, but it will never be superceded by aimless waffle and random terminology such as I see in this thread.

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Replies to this message:
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GDR
Member
Posts: 6202
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.9


Message 183 of 204 (347535)
09-08-2006 11:17 AM
Reply to: Message 182 by cavediver
09-08-2006 4:28 AM


Re: Time
One term I can't seem to understand is "universe". You said that the term means everything that is but what is a universe when Julian Barbour suggests that every moment in time is an eternal universe? If a moment is a planck time that would mean that there is a lot of universes out there.

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Replies to this message:
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1.61803
Member (Idle past 1504 days)
Posts: 2928
From: Lone Star State USA
Joined: 02-19-2004


Message 184 of 204 (347566)
09-08-2006 1:58 PM
Reply to: Message 183 by GDR
09-08-2006 11:17 AM


Re: Time
"The universe is all there ever was, all there is, and all there ever will be." Carl Sagen
He was pretty ambitious.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 185 of 204 (347570)
09-08-2006 2:11 PM
Reply to: Message 183 by GDR
09-08-2006 11:17 AM


Re: Time
You have to remember that Barbour's stuff is very advanced conceptually. It's a real struggle how to explain this without introducing innumerable other concepts that each need explaining
Ok, let's try a super-brief version: imagine all possible variations of the universe at a fixed time - a sort of universe cross-section(ignore relativistic objections to this concept for now), in an Everrett many-worlds sort of way. Stick them all in one big super-universe - a universe of universe-cross-sections. They will be arranged by "smoothness" - universes very similar will be close together, universes less similar will be further apart. Given the infinite number of degrees of difference you could have, this super-universe is infinite-dimensional. Now, pick a path through these universe-cross-sections. This gives us "our universe". There will be certain rules that restrict the possible directions of this path, and that gives us time.
Far from perfect, but a start.

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 Message 183 by GDR, posted 09-08-2006 11:17 AM GDR has replied

Replies to this message:
 Message 186 by GDR, posted 09-08-2006 3:17 PM cavediver has replied
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GDR
Member
Posts: 6202
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.9


Message 186 of 204 (347586)
09-08-2006 3:17 PM
Reply to: Message 185 by cavediver
09-08-2006 2:11 PM


Re: Time
I'm sorry to be slow but when you say "imagine all possible variations of the universe at a fixed time " I can't come up with more than one. That is my basic problem. I don't understand what it means to have multiple or infinite universes. It may be that there is no way to understand it outside of mathematics.
Is a universe one precise organization of all matter at one precise time?(I only use Barbour because his theory is more definitive than just proposing multiple or infinite universes.)
In what way would universes be similar?
When you say in the last sentence "our universe" are you speaking about a universe that is the one that all of us experience?

This message is a reply to:
 Message 185 by cavediver, posted 09-08-2006 2:11 PM cavediver has replied

Replies to this message:
 Message 187 by cavediver, posted 09-08-2006 3:23 PM GDR has replied
 Message 198 by nipok, posted 09-12-2006 2:22 AM GDR has not replied

  
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 187 of 204 (347588)
09-08-2006 3:23 PM
Reply to: Message 186 by GDR
09-08-2006 3:17 PM


Re: Time
when you say "imagine all possible variations of the universe at a fixed time " I can't come up with more than one
Sure you can. Look around you. Imagine slight changes that would still seem to be consistent with the laws of phsyics. From my desk, I can imagine my mouse slightly to the right, a bit more to the right, perhaps slighlty to the left. Perhaps the fan in my PC has a slighlty lower voltage, the drawer to my left is shut rather than open. These all give rise to similar universes centered around the one I am experiencing.
Is a universe one precise organization of all matter at one precise time?
In my super-simplifed version, yes.
When you say in the last sentence "our universe" are you speaking about a universe that is the one that all of us experience?
Could be, or perhaps individualistic... the model's not sufficiently well defined on that point! Take you pick...

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 Message 186 by GDR, posted 09-08-2006 3:17 PM GDR has replied

Replies to this message:
 Message 188 by GDR, posted 09-08-2006 4:03 PM cavediver has not replied
 Message 190 by nwr, posted 09-09-2006 8:31 AM cavediver has replied
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GDR
Member
Posts: 6202
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.9


Message 188 of 204 (347592)
09-08-2006 4:03 PM
Reply to: Message 187 by cavediver
09-08-2006 3:23 PM


Re: Time
Thanks cavediver. That's helpful. I'm curious to know what the impact of relativity is on the model as if we all have different times how can we all be in one universe at any given moment.
I'm out the door for the afternoon so that will give me time to think about it. It's great to have you back.

Everybody is entitled to my opinion.

This message is a reply to:
 Message 187 by cavediver, posted 09-08-2006 3:23 PM cavediver has not replied

  
GDR
Member
Posts: 6202
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.9


Message 189 of 204 (347733)
09-09-2006 2:20 AM
Reply to: Message 185 by cavediver
09-08-2006 2:11 PM


Re: Time
cavediver writes:
Now, pick a path through these universe-cross-sections. This gives us "our universe". There will be certain rules that restrict the possible directions of this path, and that gives us time.
I assume that each individual picks their own path. Wouldn't that mean then that everyone has their own universe?

This message is a reply to:
 Message 185 by cavediver, posted 09-08-2006 2:11 PM cavediver has replied

Replies to this message:
 Message 192 by cavediver, posted 09-10-2006 5:30 PM GDR has replied

  
nwr
Member
Posts: 6408
From: Geneva, Illinois
Joined: 08-08-2005
Member Rating: 5.1


Message 190 of 204 (347757)
09-09-2006 8:31 AM
Reply to: Message 187 by cavediver
09-08-2006 3:23 PM


Re: Time
Imagine slight changes that would still seem to be consistent with the laws of phsyics.
Why assume that what we know as the laws of physics should be relevant to a different universe?

This message is a reply to:
 Message 187 by cavediver, posted 09-08-2006 3:23 PM cavediver has replied

Replies to this message:
 Message 191 by Son Goku, posted 09-10-2006 5:11 PM nwr has seen this message but not replied
 Message 193 by cavediver, posted 09-10-2006 5:33 PM nwr has seen this message but not replied

  
Son Goku
Inactive Member


Message 191 of 204 (347969)
09-10-2006 5:11 PM
Reply to: Message 190 by nwr
09-09-2006 8:31 AM


Re: Time
I personally don't know much about Barbour's theories, but ideas similar to this already occur in physics.
For instance in the path integral approach one sums over the different paths a particle can take between point A and point B to obtain the the amplitude (which is squared to obtain the probability) for the particle to go from A to B.
Each path is essentially the path the particle would take in a world with different laws of classical mechanics.
You don't assume this though, it follows from other things in QM.
It is a different calculational technique with an unusual picture associated with it.
In essence they aren't really other universes, it's just that one can consider a quantum mechanical process in our quantum mechanical universe as a weighted sum of classical processes from slightly different (and continously different) purely classical universes.
Barbour's idea probably contains a similar idea of "universe".
Edited by Son Goku, : Slight edit and expansion.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 192 of 204 (347972)
09-10-2006 5:30 PM
Reply to: Message 189 by GDR
09-09-2006 2:20 AM


Re: Time
I assume that each individual picks their own path
No, I don't think so. What makes the individual is the path that is taken. That path would probably be determined by some minimisation of some "action"-like quantity... as in the principle of least action.

This message is a reply to:
 Message 189 by GDR, posted 09-09-2006 2:20 AM GDR has replied

Replies to this message:
 Message 195 by GDR, posted 09-10-2006 6:54 PM cavediver has not replied

  
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 193 of 204 (347973)
09-10-2006 5:33 PM
Reply to: Message 190 by nwr
09-09-2006 8:31 AM


Re: Time
Why assume that what we know as the laws of physics should be relevant to a different universe?
In this concept, there are no "different universes", just an infinitude of possible slices that could make up a universe. There will be some over-arching laws that govern this super-space, that give rise to our observed laws.
But in terms of the quote, I was merely trying to get GDR to appreciate what I meant by possible universes.
Edited by AdminJar, : close quotebox

This message is a reply to:
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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 194 of 204 (347975)
09-10-2006 5:35 PM
Reply to: Message 191 by Son Goku
09-10-2006 5:11 PM


Re: Time
For instance in the path integral approach
This is actually more closely related to moduli-space work than to PI formalism. Check out some of Nick Manton's soliton dyanmics, for example.

This message is a reply to:
 Message 191 by Son Goku, posted 09-10-2006 5:11 PM Son Goku has not replied

  
GDR
Member
Posts: 6202
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.9


Message 195 of 204 (347985)
09-10-2006 6:54 PM
Reply to: Message 192 by cavediver
09-10-2006 5:30 PM


Re: Time
cavediver writes:
That path would probably be determined by some minimisation of some "action"-like quantity... as in the principle of least action.
I'm sorry, but that is over my head. It may be as low as you can get it in which case I think I'm out of luck.
Edited by GDR, : No reason given.

This message is a reply to:
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Replies to this message:
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