Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
1 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   What is Time and Space
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 159 of 204 (311696)
05-13-2006 5:37 AM
Reply to: Message 155 by GDR
05-08-2006 11:53 PM


A relevant (long overdue) response to Sidelined
If we take the position that the universe always existed I assume this is the same as saying that time never had a beginning which seems to me to be impossible for the reason that without a beginning how can any point in time ever be arrived at?
Ok, first read my post above. You'll see the problem with thinking of time-flow a fundemental property of the universe. If you read through the Penrose stuff that GDR quotes, you'll see the idea that time is intimately wrapped up in conciousness. I have a lot of sympathy for this idea.
So there is no time variable that montonically increases... there is just a fixed, possibly infinite, time dimension. Part of the four dimensional mess of matter that makes up the universe are these sub-structures that we call humans, although we are more familiar with dealing with single cross-sections of these humans. These strcutures are sufficiently complex that somehow (don't ask me how) this thing known as conciousness arises, and appears as a dynamic 3-d process within the static 4d structure. How this conciousness makes sense of a temporal order is difficult to determine but certainly the thermodynamic arrow of time is involved.
Does this start to answer your question?

This message is a reply to:
 Message 155 by GDR, posted 05-08-2006 11:53 PM GDR has replied

Replies to this message:
 Message 160 by GDR, posted 05-14-2006 4:46 PM cavediver has replied
 Message 165 by sidelined, posted 05-15-2006 3:18 PM cavediver has replied
 Message 180 by GDR, posted 09-05-2006 1:48 AM cavediver has not replied

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


Message 161 of 204 (311796)
05-14-2006 7:18 PM
Reply to: Message 160 by GDR
05-14-2006 4:46 PM


Re: A relevant (long overdue) response to Sidelined
Yes, I had read through your posts. I must admit that I am a little skeptical about the relevance of our perceived passage of time to the deeper notions of the connections of conciousness and time. I'm fairly sure tests have shown that a perceived minute doesn't change much over our lifetime, once we have a good idea of what a minute is. This is really just a function of processing speed. The larger scale perception of time passing seems more to do with the ratio of information gathered to information stored. I would describe both of these as high-level, cognitive issues, and would be true whether time-flow existed completely independent of conciousness or not. Well, that's my thoughts anyway...

This message is a reply to:
 Message 160 by GDR, posted 05-14-2006 4:46 PM GDR has replied

Replies to this message:
 Message 162 by GDR, posted 05-15-2006 12:41 AM cavediver has replied

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


Message 163 of 204 (311876)
05-15-2006 5:29 AM
Reply to: Message 162 by GDR
05-15-2006 12:41 AM


Re: A relevant (long overdue) response to Sidelined
Can you tell me what you believe would be left if all consciousness ceased to exist. Presumably time would cease but would matter exist? Is the suggestion then that the existance of the entire universe depends on consciousness?
Hmmm, starting to stray into Strong Anthropic territory here.
This is a GR-"solution"-inspired view:
The universe does not depend upon conciousness. It just is. It has no dynamics, it does not evolve. Every slice that we think of as a moment in time is fixed and exists "always".
However, us theoretical physicists tend to revere consistency above all else. And so far our only datapoint is that a consistent universe involves conciousness...

This message is a reply to:
 Message 162 by GDR, posted 05-15-2006 12:41 AM GDR has replied

Replies to this message:
 Message 164 by GDR, posted 05-15-2006 10:33 AM cavediver has not replied

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


Message 166 of 204 (312150)
05-15-2006 7:22 PM
Reply to: Message 165 by sidelined
05-15-2006 3:18 PM


Re: A relevant (long overdue) response to Sidelined
Typical, you're picking up on the "other" stuff about conciousness I wasn't really going there...
Penrose is not suggesting a new force, but he starts with the idea that our conciousness can come up with non/un-computable stuff like Godel Incompleteness, P/NP, etc and hence conciousness must be more than computation. He suggests quantum computation through the micro-tubule stuff.
Now Roger's difficulties with classical emergence (collapse of the wave-function) have always confused me as he spent a reasonable amount of time with Chris Isham and should be satisfied with de-coherence as an excellent approach to the problem (Isham being a pioneer of this with Jim Hartle). But then Roger is a mathematician pretending to be a physicist unlike the rest of us who are physicists pretending to be mathematicians.
To be honest, none of this is what I was discussing. I'm not so much interested in the origins of conciousness (for this particular debate) but rather the role of conciousness in "flow of time" - generating or merely observing. I'm at least 50% with generating... i.e. the "flow of time" is as much an observer dependent quantity as "red" or "Emaj7". That said, I am at least 25% convinced that conciousness is a necessary element of what we call existence (note, nothing of my religious beliefs intrudes here.)
If the universe must, according to some imbalance or difference in potential,move in a given direction as to effect an arrow of time is it necessary that we discover the mechanism as a consequence of the quantum physics or is the problwem of finding a suitable means of testing by experiment to settle the question?
The arrow of time does not in itself imply a flow of time, merely an ordering of the fixed four dimensional solution. Statitsical, thermodynamic considerations lead to the arrow but they do not imply "flow".
Ionce read on the paradox about the wave particle duality and in that same book the author was implying that the wave aspect is simply a measure of the probability of a particle and the particle aspect was the actual matter point itself.
NO! This is very naive and shows the lack of understanding by many who profess to know and then to teach! Neither description is correct, but both suffice in different situations. The particle is better described as a quite complex (quantum) excitation of a field.
Edited by cavediver, : Does there have to be a reason?

This message is a reply to:
 Message 165 by sidelined, posted 05-15-2006 3:18 PM sidelined has replied

Replies to this message:
 Message 167 by sidelined, posted 05-23-2006 1:06 PM cavediver has replied
 Message 168 by GDR, posted 05-23-2006 4:49 PM cavediver has replied

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


Message 171 of 204 (314720)
05-23-2006 7:08 PM
Reply to: Message 167 by sidelined
05-23-2006 1:06 PM


Re: A relevant (long overdue) response to Sidelined
Is it sufficient to say that these two measurements are similar to a description of a cone...
Yes, a good analogy, and closer to the truth that you realise. When I ask, "what is the position of the particle?" I am projecting the wave-function in a particular way that gives me a position-like answer. When I ask about the momentum of the particle, I am projecting the wave-function in a different way, just like your "side" or "end-on" projections of your cone. Notice how the two projected aspects, position and momentum, cannot possibly be observed simulataneously by the same observer...
Is the difficulty in the ability of our brains to concieve of a geometry that allows these two descriptions to co-exist without the seeming paradox?
It probably plays a large part, yes. We are so used to "things" sitting in space and "processes" applied to "things" at our length scale. This is so unlike the quantum field picture.

This message is a reply to:
 Message 167 by sidelined, posted 05-23-2006 1:06 PM sidelined has replied

Replies to this message:
 Message 179 by sidelined, posted 05-31-2006 2:07 AM cavediver has not replied

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


Message 172 of 204 (314723)
05-23-2006 7:15 PM
Reply to: Message 168 by GDR
05-23-2006 4:49 PM


Re: A relevant (long overdue) response to Sidelined
Do you agree with him that most physicists would agree with his statement?
Well I agree with his statement, and I think most physicists in our field would as well. Outside our field, I wouldn't be so sure.
What does he mean by illusion? If time is just a series of nows that are eternal I'm wondering if that would qualify as an illusion.
The illusion is the "time-flow", or passing of time. To me, every moment exists, it is just my conciousness only revealing a slice at a time.
Is Penrose's thinking on this consistent with Julian Barbour?
In general, yes. But my description depicts a static 4d universe, with all the time layers neatly ordered. Barbour sees a collection of possible states of 3d spaces that are brought together or picked out to form the 4d universe.
How come all you guys that seem to write about this come from the UK?
It's the tea Too bad you chucked all of yours into the sea a while back

This message is a reply to:
 Message 168 by GDR, posted 05-23-2006 4:49 PM GDR has replied

Replies to this message:
 Message 173 by GDR, posted 05-23-2006 9:18 PM cavediver has replied

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


Message 174 of 204 (314805)
05-24-2006 4:21 AM
Reply to: Message 173 by GDR
05-23-2006 9:18 PM


Re: A relevant (long overdue) response to Sidelined
That would be our good friends to the south
I was going to excuse myself by saying I thought I was replying to Sidelined, then just checked his location
So... what is it that makes the Canucks ask all the awkward questions?

This message is a reply to:
 Message 173 by GDR, posted 05-23-2006 9:18 PM GDR has replied

Replies to this message:
 Message 175 by GDR, posted 05-24-2006 11:04 AM cavediver has replied

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


Message 176 of 204 (314871)
05-24-2006 11:28 AM
Reply to: Message 175 by GDR
05-24-2006 11:04 AM


Re: A relevant (long overdue) response to Sidelined
Yeah, I know Don a little He was Hawking's sidekick before my time so I only ever met him on his visits. He's done some interesting work in his time.
not only will we eventually find that time is an illusion but so is space
This is very much the picture from something as "mundane" as classic string theory, when looked at from the relativist/mathematical viewpoint (as opposed to the particle physicists). In this case, reality is only two dimensional and our 4d universe and everything in it inlcuding us is a projection.

This message is a reply to:
 Message 175 by GDR, posted 05-24-2006 11:04 AM GDR has not replied

Replies to this message:
 Message 177 by Son Goku, posted 05-24-2006 12:59 PM cavediver has not replied

  
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.

This message is a reply to:
 Message 181 by nipok, posted 09-08-2006 3:55 AM nipok has not replied

Replies to this message:
 Message 183 by GDR, posted 09-08-2006 11:17 AM cavediver has replied

  
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.

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

This message is a reply to:
 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
 Message 199 by GDR, posted 10-04-2006 12:03 AM cavediver has not replied

  
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:
 Message 190 by nwr, posted 09-09-2006 8:31 AM nwr has seen this message but not replied

  
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

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


Message 202 of 204 (465458)
05-07-2008 4:43 AM
Reply to: Message 201 by john6zx
05-07-2008 12:10 AM


Re: Uniform Time
So do you think that MR. Green is saying that time is basically a concept?
I guess that must depend on what you mean by 'concept'. Off the top of my head, 'time' refers colloquially to at least three different concepts in General Relativity, and mixing these up is at the heart of most of confusion in this topic. Time is a dimension, it is a coordinate, it is a path through space-time, it is a rate (of affine parameterisation) along that path - ah, that's four...

This message is a reply to:
 Message 201 by john6zx, posted 05-07-2008 12:10 AM john6zx has replied

Replies to this message:
 Message 203 by john6zx, posted 05-13-2008 1:26 AM cavediver has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024