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-   -   Physics law evo video (from the Perimeter quantum time conference) (http://www.physicsforums.com/showthread.php?t=261903)

marcus Oct5-08 06:32 PM

Physics law evo video (from the Perimeter quantum time conference)
 
http://www.perimeterinstitute.ca/Eve...tum/Abstracts/

The week ending 2 October there was a conference on time and quantum theory at Perimeter.
Some who gave talks were
Lee Smolin
Roger Penrose
Neil Turok
Leonard Susskind
William Unruh
Rafael Sorkin
...
The link gives abstracts for the invited talks and for the contributed talks

Smolin's talk was particularly interesting. I've watched it several times and also downloaded the slides which are available PDF as well as being shown during the presentation. The video has a slide list with 7 pages of slides. I've tended to restart on page 4, because the first part of the talk develops gradually. Starting at the beginning of page 4 of the slides list, he goes fast. Here is the link. I click on "windows presentation" which is a double screen format, there are several options:
http://pirsa.org/08100049/

Smolin's talk was on the last day, the morning of 2 October. He talked a bit about his new book, that he is working on with Roberto Unger.

I learned stuff about physics law from this talk, it gave me a new perspective. Among other things he made the case for a natural history of physical law.

Fra Oct6-08 10:18 AM

Re: Physics law evo video (from the Perimeter quantum time conference)
 
Thanks for the link Marcus.

I listened to the mp3 version of the talk. It is generally inspiring as much of his talks/papers and I also thought some good questions from the audience appeared.

Quote:

Quote by marcus (Post 1902387)
I learned stuff about physics law from this talk, it gave me a new perspective. Among other things he made the case for a natural history of physical law.

Do you know of anyone else besides Smolin et all thatīs pondering an evolutionary perspective of the "laws" of physics in some related way?.

I share Smolin abstraction of evolving laws, but I did not quite see why this contradicted emergent time. Or rather, one guy in the audience raise the point that one should distinguish between problems of time, emergent or non-emergent but also the objevtivity vs subjectivity in time. I didnīt exactly see his suggestion here.

I suspect that a difference is also in how you treat othe bservers. I think the evolution of law, when combined with the evolution of observers, there is a kind of holographic relation between the observers and the rest of the universe. This is the part I donīt see smolins reasoning.

In the end questions also raised the point in objection to the notion of dynamical state spaces, that we could always picture a superspace which is fixed. I like smolins defense to this. It has to do with complexity and handling. If one adapts a holographic connection between an observer and itīs environment, then this puts a bound in the complexity of state space that can be represented by the observer. This also shows the assymetry in we looking into an atom, or we looking out into the external space. Itīs like inverted situation with respect to the boundary (between observer and the remainder of the universe)

Iīm starting to think that some yet not forumalated version of a holographic principle (where the boundary is the communication channel between observer and observed) is the missing element of reasoning to complement the evolutionary picture. It also supports the idea of dynamical state space, and also supports the idea mentioned in that talk about computability. One can not expect a finite sized computer to predict the universe. A kind of holographic principle also bounds the computer power.

I was currently reviewing some thinking of the holographic ideas and all of this things, in particular the evolutionary idea and the holographic have something in common.

/Fredrik

marcus Oct6-08 11:20 AM

Re: Physics law evo video (from the Perimeter quantum time conference)
 
Quote:

Quote by Fra (Post 1903269)
I listened to the mp3 version of the talk.

Did you also download the PDF version of the slides, to go along with listening to the talk?
There is quite a lot in the slides that he did not repeat in the talk. Because of time prssure he would often skip the middle part of a quotation (from, say, Peirce) and only read the first sentence and the last. And several times he skipped over 3 or 4 slides of interesting material just so as not to run out of time.

The page that has the MP3 link also has next to it a PDF link which if you click gives you the slides. There are 72 slides in the set so it takes a little while to download them all, but they allow a selective review of especially interesting parts of the talk.

I downloaded the slides even though I have been watching the video version, simply to have it handy for review. You may already have done this, but I mention the possibility just in case (or in case someone else wants to go that route.)

Just a few things from memory: I think it is a radical proposal to say that in full cosmology one cannot distinguish between eternal Laws on the one hand and Initial Conditions on the other hand. Only in studying some subsystem can this distinction be made, it is claimed. Then he argues that the universe as a whole cannot be governed by eternal laws---the assertion is meaningless or non-explanatory---the applicable laws must evolve with the universe, in time. He points to some surprising examples of this in quantum cosmology and particle physics. Then he argues that time may be fundamental in cosmology rather than emergent and relative. (there is no separate observer in cosmology, it is not a subsystem). Space may be emergent. He points to the interesting circumstance that approaches to quantum cosmology which assume an absolute time (but let space emerge) have been more successful, to date--which could be significant.

Fra Oct6-08 11:33 AM

Re: Physics law evo video (from the Perimeter quantum time conference)
 
Quote:

Quote by marcus (Post 1903329)
Did you also download the PDF version of the slides, to go along with listening to the talk?

Yes, I printed the 72p slides and browsed it while listening.

I've got the ischiatic nerve jammed in my leg today due to a damn trip last week and was home from work. The good side is that I got some more time to read :o) I didn't watch the video though because it's hard to sit in front of the PC.

/Fredrik

Fra Oct6-08 11:35 AM

Re: Physics law evo video (from the Perimeter quantum time conference)
 
Quote:

Quote by marcus (Post 1903329)
I think it is a radical proposal to say that in full cosmology one cannot distinguish between eternal Laws on the one hand and Initial Conditions on the other hand. Only in studying some subsystem can this distinction be made, it is claimed. Then he argues that the universe as a whole cannot be governed by eternal laws---the assertion is meaningless or non-explanatory---the applicable laws must evolve with the universe, in time.

This part makes perfect sense to me, and I think he is right.

/Fredrik

Fra Oct6-08 11:39 AM

Re: Physics law evo video (from the Perimeter quantum time conference)
 
Quote:

Quote by marcus (Post 1903329)
Then he argues that time may be fundamental in cosmology rather than emergent and relative. (there is no separate observer in cosmology, it is not a subsystem).

This statement in bold comes out as non-trivial to me. To me, there is always an observer, anything else makes no sense. But that's not the same as to suggest that the observers is outside the universe, or is classical. Only that there is non-trivial nonlinear feedback in between. So it's an "inside-observer", but an observer nontheless. Though of course there are many observers, not one.

/Fredrik


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