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Author Topic:   Julian Barbour on Time
GDR
Member
Posts: 4365
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.8


Message 1 of 39 (231974)
08-10-2005 3:42 PM


I am wondering if there is anyone on the forum that is familiar with and has an opinion on the theories of Julian Barbour. He wrote a book called “The End of Time”, in which he claims that time does not exist. He claims as I understand it that we function in a series of nows, and that each now exists forever. This is an excerpt from a book review.

Julian Barbour writes:

Specifically, DeWitt hijacked the Schrödinger equation, named for the great
Austrian physicist who created it. In its original form, the equation reveals how
the arrangement of electrons determines the geometrical shapes of atoms and
molecules. As modified by DeWitt, the equation describes different possible
shapes for the entire universe and the position of everything in it. The key
difference between Schrödinger's quantum and DeWitt's cosmic version of the
equation— besides the scale of the things involved— is that atoms, over time,
can interact with other atoms and change their energies. But the universe has
nothing to interact with except itself and has only a fixed total energy. Because
the energy of the universe doesn't change with time, the easiest of the many
ways to solve what has become known as the Wheeler-DeWitt equation is to
eliminate time.
Most physicists balk at that solution, believing it couldn't possibly describe the
real universe. But a number of respected theorists, Barbour and Stephen
Hawking among them, take DeWitt's work seriously. Barbour sees it as the
best path to a real theory of everything, even with its staggering implication that
we live in a universe without time, motion, or change of any kind.
Strolling in the meadows of oxford's Christ Church College with Julian Barbour,
time and motion seem undeniable. Towering cumulus clouds float overhead,
ferried by a gentle breeze. Children run and shout in the same field where Alice
Liddell, the girl who inspired Lewis Carroll's Alice's Adventures in
Wonderland, often played. How can there be no time, no movement? Barbour
settles his tall, lean frame into the grass, readying himself for a long explanation
to yet another skeptic. He begins with what seems a most straightforward
proposition: Time is nothing but a measure of the changing positions of objects.
A pendulum swings, the hands on a clock advance. Objects— and their
positions— he argues, are therefore more fundamental than time. The universe
at any given instant simply consists of many different objects in many different
positions.
That sounds reasonable, as it should, coming from a thoughtful gentleman like
Barbour. But the next part of his argument— the crux of his view— is much
harder to swallow: Every possible configuration of the universe, past, present,
and future, exists separately and eternally. We don't live in a single universe that
passes through time. Instead, we— or many slightly different versions of
ourselves— simultaneously inhabit a multitude of static, everlasting tableaux that
include everything in the universe at any given moment. Barbour calls each of
these possible still-life configurations a "Now." Every Now is a complete,
self-contained, timeless, unchanging universe. We mistakenly perceive the
Nows as fleeting, when in fact each one persists forever. Because the word
universe seems too small to encompass all possible Nows, Barbour coined a
new word for it: Platonia. The name honors the ancient Greek philosopher who
argued that reality is composed of eternal and changeless forms, even though
the physical world we perceive through our senses appears to be in constant
flux.

The following is another quote from the review on the reaction of some of his peers.

interviewer writes:

How does the physics community react to such ideas? Physicists who know
Barbour's work agree that it shouldn't be dismissed out of hand. At a physics
conference in Spain, Barbour conducted an informal poll. He asked how many
of the physicists believed that time would not be a part of a final, complete
description of the universe. A majority were inclined to agree.
Don Page, a cosmologist at the University of Alberta in Edmonton who
frequently collaborates with Stephen Hawking, raised his hand that day. "I think
Julian's work clears up a lot of misconceptions," says Page. "Physicists might
not need time as much as we might have thought before. He is really
questioning the basic nature of time, its nonexistence. You can't make technical
advances if you're stuck in a conceptual muddle." Strangely enough, Page feels
that Barbour might actually be too conservative. When physicists finally iron
out a new theory of the universe, Page suspects that time won't be the only
casualty. "I think space will go too," he says cryptically.

Here is the link:
http://www.discover.com/issues/dec-00/cover/

I realize that I should develop this more than I have, but I don’t have the personal knowledge to make any type of intelligent comment. I would just like to know what the opinion is of those who do know what they’re talking about.
I suggest that this should be posted under "Big Bang and Cosmology"


Replies to this message:
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Message 2 of 39 (232526)
08-12-2005 7:51 AM


Thread moved here from the Proposed New Topics forum.
    
cavediver
Member (Idle past 1255 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 3 of 39 (232541)
08-12-2005 8:17 AM
Reply to: Message 1 by GDR
08-10-2005 3:42 PM


Hmmm, a difficult one to discuss here. I'd like to see his books to see how he makes the stuff accessible. I almost ended up working on a variant of this, as I was invited to take my PhD under Chris Isham at Imperial studying the "problem of time in decoherent histories".

I keep trying to describe what this is about, but it requires describing so many precursors that it will take longer than I have at the moment. But it isn't as way out as it sounds. Well, compared to string theory, it's weird, but then all the great ideas in quantum gravity sound weird. And it actually addresses the problem of time, which is not touched upon in string/M-theory.


This message is a reply to:
 Message 1 by GDR, posted 08-10-2005 3:42 PM GDR has responded

Replies to this message:
 Message 4 by GDR, posted 08-12-2005 10:49 PM cavediver has responded

  
GDR
Member
Posts: 4365
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.8


Message 4 of 39 (232829)
08-12-2005 10:49 PM
Reply to: Message 3 by cavediver
08-12-2005 8:17 AM


I kinda thought this topic wouldn't produce a huge response but I wanted to get an idea of whether Barbour was generally accepted and it sounds as if he is. Also I just wanted to hear what someone with your expertise would have to say about him.

Thanks for the response cavediver. (I am curious about your name by the way. :) )


Everybody is entitled to my opinion. :)
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cavediver
Member (Idle past 1255 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 5 of 39 (232919)
08-13-2005 4:42 AM
Reply to: Message 4 by GDR
08-12-2005 10:49 PM


I think "generally accepted" is a bit strong. He's ceretianly not a mainstream quantum gravity guy, but he is respected and his ideas have merit... I have heard far more outlandish ideas from, for example, the world authority on black-holes. I was quite shocked :)

I'll come back to this and try to talk about it later...


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cavediver
Member (Idle past 1255 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 6 of 39 (232930)
08-13-2005 7:30 AM
Reply to: Message 4 by GDR
08-12-2005 10:49 PM


I am curious about your name by the way.

What? cavediver... it's what I do. Followed the wrong track to be an astronaut, so this is the next best thing. And believe me, at the extreme end, it can get close :)

At age 4 I decided I was going to be one of three things: astronaut, astronomer, or astronautical engineer. I achieved one some time ago, and I still have aspirations on the other two :)


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 Message 4 by GDR, posted 08-12-2005 10:49 PM GDR has responded

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GDR
Member
Posts: 4365
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.8


Message 7 of 39 (232971)
08-13-2005 12:02 PM
Reply to: Message 6 by cavediver
08-13-2005 7:30 AM


Just what is it you're looking for in those caves?

Nice thing about being an astronomer is that you can keep on doing it as long as you like. I had a job I loved but one that we have to retire from at age 60. (A mixed blessing.)

Thanks for the thoughts on Barbour. I keep reading that linked article and trying to get my head around his ideas. I imagine some day someone like Barbour or cavediver is going to have something go click and they will see something that everyone will have missed, and physics will head off in a totally new direction. :)


Everybody is entitled to my opinion. :)
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randman 
Suspended Member (Idle past 2510 days)
Posts: 6367
Joined: 05-26-2005


Message 8 of 39 (233575)
08-16-2005 12:57 AM
Reply to: Message 1 by GDR
08-10-2005 3:42 PM


great thread
I noticed this awhile back, but not sure if I have the educational level to comment correctly on the particulars. I do think the issue of time is one that needs to be resolved and is largely unresolved.

However, the concept of both time and space being removed, or considered somewhat derivative or illusory is probably correct, as the one physicist noted, and as GR indicates via length contraction and time dilation.

One concept has sort of interested me in it being related, which is the concept that from the photon's perspective, time is non-existent and so too is space due to length contraction eliminating all distance (via the comments on the other thread), and to me this is a profound concept because it suggests everything can be thought of as an immaterial singularity occupying neither space nor time!

www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=2&t=206&m=91 -->www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=2&t=206&m=91">http://www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=2&t=206&m=91

Keep in mind any theoritical measurement from any vantage point in the universe should be as accurate as another and so the measurement of space and time as not existing, from the photon's perspective, seems to me just as accurate, even if baffling, than measuring from earth-space and time.

This message has been edited by randman, 08-16-2005 01:04 AM

This message has been edited by randman, 08-16-2005 01:07 AM


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NosyNed
Member
Posts: 8802
From: Canada
Joined: 04-04-2003


Message 9 of 39 (233577)
08-16-2005 1:14 AM
Reply to: Message 1 by GDR
08-10-2005 3:42 PM


Greene on time
In "The Fabric of the Cosmos", Brian Greene talks about all of time as existing just as the other dimensions of space time are all 'there' even if we aren't at some of the points in it.

As I read what he says; we preceive that time is a moving instant of existing presence but, like a lot of other things, this preception is wrong: all of time exists both past and future.

However, that doesn't suggest that we can touch any of it but the fleeing present and the future as it comes along. (Well, not yet anyway)


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randman 
Suspended Member (Idle past 2510 days)
Posts: 6367
Joined: 05-26-2005


Message 10 of 39 (233580)
08-16-2005 1:19 AM
Reply to: Message 1 by GDR
08-10-2005 3:42 PM


wonderful link
Looking at the following comment, I cannot but think of how it parallels theology and imo, an intelligent view of God's perspective, which is of course the right one.

In Barbour's universe, every moment of every individual's life— birth, death, and everything in between— exists forever. "Each instant we live," Barbour says, "is, in essence, eternal." That means each and every one of us is immortal. Like the perpetually unmoving lovers in Keats's "Ode on a Grecian Urn," we are "for ever panting, and for ever young." We are also for ever aged and decrepit, on our deathbeds, in the dentist's chair, at Thanksgivings with our in-laws, and reading these words.

http://www.discover.com/issues/dec-00/cover/

This is something I have thought and articulated for awhile, but from a theological perspective, namely that from God's perspective or we can say, from the most correct and scientific view of reality (if Barbour is right), the entire history is ever now, and still exists.

I have used this to talk of how God can still save every man that has gone to damnation because he is still alive before that, and able to be "elected" unto salvation.

Now, before a mod slams me for getting off-topic, I am just illustrating how it seems this idea that physics has stumbled on existed in theology before that.

In terms of the science, I cannot comment on the math behind it. I do think time dilation and length contractio support the concept, but then again, that would support the concept of both time and space merely being an artifact of our perspective, and not something that holds up from other perspectives, physical perspectives mind you, within the universe.

But I am fairly new to a lot of physics.

Maybe someone in that field can comment more?

This message has been edited by randman, 08-16-2005 01:19 AM


This message is a reply to:
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GDR
Member
Posts: 4365
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.8


Message 11 of 39 (233582)
08-16-2005 1:37 AM
Reply to: Message 10 by randman
08-16-2005 1:19 AM


Re: wonderful link
Hi randman

The link is the same link that I used in the OP. :) (Great minds think alike.)

Barbour's whole concept has huge implications for both science and theology. It is impossible to really get our heads around. Time does seem to be a real enigma in that our perceotion of it certainly changes as we age and I imagine we have all had those experiences where time seems to stop during an accident.

I think it does also indicate however, that science really has come up against a bit if a wall and that it is going to take another Einstein, (Maybe it's Barbour), to go off in some new direction that everyone else has missed.

I'm working my way through Greene's book for the second time in hopes that I retain more this time around. :)


Everybody is entitled to my opinion. :)
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randman 
Suspended Member (Idle past 2510 days)
Posts: 6367
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Message 12 of 39 (233586)
08-16-2005 1:44 AM
Reply to: Message 11 by GDR
08-16-2005 1:37 AM


Re: wonderful link
Well, I like that comment on great minds......

I think from a theological perspective, the idea is not too difficult to grasp. Just imagine the creation like a movie, except God is present both at all points in the movie, and has the DVD on his computer and tinkers away sometimes (and maybe even others try to break in to do the same), but He keeps it under His control.

So from God's perspective, it is all in the present, and He can change the movie at anytime.

But it's very interesting to think physics and math is at the level of stating the same thing!

Thanks for posting this stuff, by the way.

This message has been edited by randman, 08-16-2005 01:45 AM


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GDR
Member
Posts: 4365
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 1.8


Message 13 of 39 (233592)
08-16-2005 2:08 AM
Reply to: Message 12 by randman
08-16-2005 1:44 AM


Some kinda hard drive
But where is all the data from all these eternal universes stored? I gather that each of Barbour's nows are a planck time. There's been more than a few planck times pass into history since the BB. :)

I agree that the notion that photons or anything else that moves at light speed is fascinating. Cavediver, who seems to know more about this stuff than the rest of us put together seems to have it figured out mathematically and isn't too impressed. Still, it seems to me that the fact that we have particles that take billions of light years to get to us and yet from their perspective got here in zero time over zero distance is enough to at least get one's attention.

I'm not sure how light, or gravity for that matter fits into Barbour's universes. It seems to me, that as anything that travels at light speed is effectively outside of time, then light would be able to move freely from one universe to the next under Barbour's scenario.

Well I am severely out of my depth here but it sure is a fascinating topic. There is a young girl in our church that just about to start university with the goal of being a research physicist. She has scholarships coming out here ears and has already completed several university courses while still in high school. She just loves the stuff. If she can stick with it I think that she is going into this field at a an incredible time.


Everybody is entitled to my opinion. :)
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Replies to this message:
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randman 
Suspended Member (Idle past 2510 days)
Posts: 6367
Joined: 05-26-2005


Message 14 of 39 (233594)
08-16-2005 2:21 AM
Reply to: Message 13 by GDR
08-16-2005 2:08 AM


Re: Some kinda hard drive
Yep, it's very interesting and probably will take us on a technological evolutionary leap. Hope we don't blow it.

But where is all the data from all these eternal universes stored?

I think he's saying the data just isn't stored but the whole thing is still there all the time.

Still, it seems to me that the fact that we have particles that take billions of light years to get to us and yet from their perspective got here in zero time over zero distance is enough to at least get one's attention.

No kidding. May make sense in math, but it doesn't lessen the paradigm altering nature of it.

It seems to me, that as anything that travels at light speed is effectively outside of time, then light would be able to move freely from one universe to the next under Barbour's scenario.

That's a pretty interesting concept, and one I suspect he contains within his idea.

Thanks again for bringing this stuff to the fore. I may have to take some time to try to digest his book if not too technical, and maybe even quit posting so much.


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JustinC
Member (Idle past 2455 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 15 of 39 (233700)
08-16-2005 2:17 PM
Reply to: Message 13 by GDR
08-16-2005 2:08 AM


Re: Some kinda hard drive
quote:
Well I am severely out of my depth here but it sure is a fascinating topic. There is a young girl in our church that just about to start university with the goal of being a research physicist. She has scholarships coming out here ears and has already completed several university courses while still in high school. She just loves the stuff. If she can stick with it I think that she is going into this field at a an incredible time.


GDR, if you don't mind me asking, how old are you and why don't you consider getting involved in physics? You seem fascinated enough by it.
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