Is there a big bang inside of us all?

[Martin]

BTW check out this recent essay by Gerard 't Hooft

http://www.phys.uu.nl/~thooft/gthpub/QuantumGrav_06.pdf

 

He grapples with the issue of the indeterminacy of Quantum Mechanics.

How the collapse of the wavefunction is constantly (as you say it) injecting new decisions by nature or free will type stuff. "Initial conditions". I don't mean to be precise.

 

He wants a deeper level of reality in which there is simple determinism. He wants the indeterminacy of QM to be just a superficial illusory appearance that emerges from this deeper deterministic mechanics.

 

As we all know he is a Nobel theoretical physicist and one of a handful of the currently most influential in the world. Enormously respected guy. And he is very serious in this essay. He's been thinking about these things for some time and this is his latest and strongest statement on it.

 

It is written for fellow professionals so it is technical and you wont understand much of it, if you take a look. But you might as well look. It will give some taste, some idea, of deep controversy going on among physicists themselves.

 

You shouldn't have to rely entirely on popular books by Roger Penrose, or the commercial successes of Stephen Hawking from the 1980s. Try to get recent firsthand sources, post 2005 or at least post 2001.

[mooeypoo]

Also, McGarr, some of what you are suggesting (specifically about the multiple universes and the implications of such) sounds similar to some aspects of String Theory.

 

You should read about it. Wikipedia is a good starting point (though you should really go on to read better sources if you're interested in it).

[McGarr178]

Thanks for both for your interesting pointers. I read the essay on quantum gravity and it was very interesting. I don't pretend to have understood all the mathematics but I believe I understood the general thrust of it.

 

I like the idea of an underlying theory, with neither QM or general relativity in it's basic equations, both having an "emergent" nature. Also, the idea that the ultimate laws of nature are akin to cellular automaton.

 

It is cellular automaton that has influenced me most. I particluarly like the work of Stephen Wolfram.

 

What I am trying to do is to create a generalised analysis of the relation between the starting conditions and future of causal deterministic systems. I have read a lot of chaos theory, complexity theory and network theory.

 

I am particlary interested in how quickly a system descends into it's attractors. For the purposes of my analysis I define an attractor as any state that is part of a causal loop. That can be one of the preceding causes of itself. All non-attractor states descend into an attractor eventually.

 

I'm interested in the properties of systems that are resistant to this descent. The average amount of steps that each state is away from changing into an attractor. One such property is the existence of "late" starting conditions.

 

Another is the successive dampning and amplification of different parts of the starting conditions. This mechanism is used in the formation of our bodies when different genes are switched on and off.

 

I find it interesting that some physicists are saying that we are already in an attractor and that it can be analysed as a fractal.

 

http://www.newscientist.com/article/mg20127011.600-can-fractals-make-sense-of-the-quantum-world.html?full=true

 

Wouldn't that suggest that at some point in the future the conditions existing right at this moment will be reproduced?

[Martin]

Thanks for both for your interesting pointers. I read the essay on quantum gravity and it was very interesting. I don't pretend to have understood all the mathematics but I believe I understood the general thrust of it.

...

 

I'm glad you had a look at Gerard 't Hooft's essay. It is chapter two of this new book:

http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=9780521860451

 

This is an expensive (academic libraries market) book just published by Cambridge U. Press containing contributions by some 20 experts in the various approaches to defining quantum spacetime.

(Gen Rel teaches us that the gravitational field is really a field describing the geometry of space and time, i.e. that gravity = geometry, and so quantum gravity must be a quantum theory of the geometry of space and time and how it interacts with matter.)

 

The book's title is "Approaches to Quantum Gravity: Towards a New Understanding of Space, Time, and Matter"

I have highlighted the second part of the title because it is more clearly descriptive of the subject matter.

 

Free copies of some of the chapters are available online. (This is fortunate because as I say the book is quite expensive.)

 

You have read Chapter 2. In case you might be interested, here is Chapter 1:

http://arxiv.org/abs/gr-qc/0604045 (click on 'pdf' to get the full text)

Here are some addtional links:

The Nature of Time (first prize FQXi essay by Julian Barbour)

http://arxiv.org/abs/0903.3489

"Forget Time" (first prize FQXi essay by Carlo Rovelli)

http://arxiv.org/abs/0903.3832

Home page for the Foundational Questions Institute (long title: Foundational Questions in Physics and Cosmology, FQXi)

http://www.fqxi.org/

Edited April 5, 2009 by Martin

[McGarr178]

I read the links you gave me. The removal of time from physics seams like a mathematical sleight of hand to me.

 

A periodic event can not be substituted for time and remove it because the word periodic iplies it.

 

I can describe all cubes by their width, length and volume but does that mean I have removed height from the world of cubes?

 

Am I missing something? It is very complicated. I have tried my best but like I said it seams like sophistry.

[mooeypoo]

I read the links you gave me. The removal of time from physics seams like a mathematical sleight of hand to me.

 

A periodic event can not be substituted for time and remove it because the word periodic iplies it.

 

I can describe all cubes by their width, length and volume but does that mean I have removed height from the world of cubes?

 

Am I missing something? It is very complicated. I have tried my best but like I said it seams like sophistry.

 

What do you mean the "removal of time" from physics?

Last I checked, time was still part of physics... can you show which of the links you took this from? Either I'm missing something, or you might've misunderstood.

[McGarr178]

http://arxiv.org/abs/0903.3832

[mooeypoo]

Interesting. Martin, can you shed light on this? I've never heard about this before, I always thought time was an integral part of physics (the notion of space-time, etc).. I'm going to need to read more than an abstract about this, and hope that Martin still follows the thread and can help us shed light on the matter

[swansont]

There's a whole thread dedicated to Rovelli's paper

 

IIRC he's advocating getting rid of time in a treatment of quantum gravity, not in all of physics. And by parameterizing it.

[Martin]

I read the links you gave me. The removal of time from physics seams like a mathematical sleight of hand to me.

...

Am I missing something? It is very complicated. I have tried my best but like I said it seams like sophistry.

 

Hello again McGarr,

I was wondering where you went. Glad to see you back. Your thread has a lot of other content besides just about time. You could fairly object to hijacking if we got into a discussion focused on just time on your thread.

 

Hi Moo and Swansont,

Maybe I will start a fresh thread about time. It shouldn't be primarily based on the FQXi essay---as Swansont points out, we already had a Yuri thread about that. Maybe we can take a different starting point.

 

Like chapter 1 of a new book that just came out talks about the successive weakening of the idea of time that started in 1905 and has continued in several steps.

EDIT:

McGarr,

I went and started a thread about the progressive weakening of the time concept.

I think I understand where you are coming from---or might be coming from---when you say "sleight of hand" and "sophistry". Heh heh.

Basically McGarr, I welcome and enjoy your presence because you actually read stuff, struggle through and get as much as you can (and skip the rest, just like i do, I guess). And your blog shows that you are highly articulate. And seriously interested in science from a kind of original point of view.

So it doesn't bother me if you decide that Rovelli's attempts to understand time amount to "sophistry".

I don't feel I need to argue or persuade in this regard, everybody has to see by their own light.

 

However, in case you or anyone wants to ask or comment here's the link:

http://www.scienceforums.net/forum/showthread.php?p=484180#post484180

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Merged post follows:

Consecutive posts merged

McGarr,

 

getting back towards your main topic (if I understand your drift) you were drawing inspiration from a pop-sci journalism piece in the Telegraph about some 2007 and 2008 speculation by Hawking (with Hertog and Hartle).

 

The corresponding scientific papers are available free on arxiv, in case you want to glance at the source. (As a rule better not to rely entirely on a journalistic paraphrase.)

 

The general topic is "quantum cosmology" so here is a list of recent keyword "qc" papers ranked by citation count to give a glimpse of the research context.

http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2006&FORMAT=www&SEQUENCE=citecount%28d%29

 

The two papers by H, H, & H are numbers 39 and 43 on the list.

One is a brief 4 page thing and one is a longer more detailed 43 page account.

 

The Hawking approach to quantum cosmology attracted interest in the 1980s and 1990s and has now to a large extent been superseded by newer ones as the field evolves. He used to refer to it as a "path integral" or "sum over histories" approach. In that type the geometry of the universe does not develop according to a definite trajectory but follows a weighted sum of all possible trajectories that get from state then to state now. The current lead versions of quantum geometry/gravity are of the same (path integral/sum over histories) general type but differ significantly in detail. Younger people now. Hawking has retired and his recent papers are not much cited.

Edited April 11, 2009 by Martin
Consecutive posts merged.