On A Universe From Nothing

Chalnoth

Sean Carroll chimes in on the idea of a Universe from Nothing, and I get a feeling that many people who browse this forum would enjoy a read through it:

http://blogs.discovermagazine.com/co...-from-nothing/

Here's a quote:
As a rule, I tend to agree rather forcefully with most things that Sean Carroll has to say, so I highly recommend a read of the whole post if this kind of topic interests you.

Mark M

Chalnoth, thanks for posting, great article. I really should put more effort into keeping up with Cosmic Variance.

sahmgeek

Thanks Chalnoth. I really enjoyed reading that as well. Just read the Atlantic and Scientific American pieces on Friday. Carroll provides a nice summary and, of course, I very much appreciate his handling of the goals of the philosophy of science at the end.

skydivephil

Another great post. Is there a better blog than Cosmic Variance on cosmology? If so I havent found it .

RUTA

A colleague and co-author on several of my papers is a philosopher of physics. As a physicist, it sometimes requires extensive discussion with him for me to understand a point he is trying to make -- philosophers are not constrained by the tacit assumptions I have adopted unwittingly over years of studying physics. Recently, we have been engaged in a protracted discussion on precisely the topic of this link. I suspect this will clear up the confusion between us and vindicate my view for once! Thanks very much for posting it, Chalnoth

marcus

Yes thanks for posting the link. I read Sean's post a day or so ago and liked it very much. Good idea to pass it on!
http://blogs.discovermagazine.com/co...-from-nothing/
Peter Woit also has a blog post on the squabble over nothing in which he links to Sean's post, among others, and which has a variety of viewpoints represented in the comment:
http://www.math.columbia.edu/~woit/wordpress/?p=4623

Chronos

I still have a disconnect with the 'universe from nothing' via quantum fluctuation hypothesis - what 'fluctuated'?

Chalnoth

Well, I think, as Sean points out, it isn't that there was literally nothing, but rather that there was a quantum mechanical state which we might be considered to be effectively nothing (e.g. no matter fields with non-zero values).

Naty1

Chalnoth: thanks for the post!!....

I had asked about the Hawking Hartle no boundary proposal not too long ago here....

http://www.physicsforums.com/showthr...41#post3892541
without much response....

and Sean Carroll summed up two alternative viewpoints very conveniently....

sahmgeek

Again, thanks for an interesting link.

I don't have time now to read all the comments, but Bravo Lee Smolin!

Darken-Sol

symmetry=nothing?

Chalnoth

What are you talking about?

marcus

I'm glad you found some of the comments interesting! Here is the direct link to the first comment by Lee Smolin:
http://www.math.columbia.edu/~woit/w...comment-109957

(Peter Woit's response: http://www.math.columbia.edu/~woit/w...comment-109963 )

And Smolin's reply:
http://www.math.columbia.edu/~woit/w...comment-109987

sahmgeek

Marcus,
I was going to ask, but found my answer here. Thanks to your past self!
http://www.physicsforums.com/showthr...der+His+Legacy

Darken-Sol

i was reading about spontaneous symmetry breaking. i just figured that the nothing everything came from was that symmetry. a complete lack of discrimination perhaps. i have a few questions about absolute potential and nothingness, but i want to study more on the subject first.

marcus

Sahmgeek, glad you found that!

Darken-Sol, I sort of know what you mean. I wouldn't bring in the word "nothing" quite yet, I would just focus mentally on the idea of total homogeneity. It is a very speculative idea so one can't push it too far or be too precise, but it's intriguing.

Now we have many electrons and they are all different because different things have happened to them and caused them to be here or there and do this or that.

But suppose all the electrons were the same, with no ability to distinguish between them!
The electron "field" would just be one bland homegeneous field. No more "many" because no more differences.

Maybe when a prior universe collapsed and rebounded to make this one, there came a time when everything was the same.

Suppose "here" was exactly the same as "there". Perfect and complete symmetry. Then there would not even be any proper space.

Suppose at very high very high energy density, electrons are the same as quarks. All distinctions between particles go away. All particles are the same particle.

So in reaching a state of maximum density the universe becomes very boring. Totally symmetric and homogeneous. Reality has been put thru the blender. then the rebound starts.

The energy density begins to ease off and symmetries start breaking spontaneously all over the place, in every facet of reality. "This" becomes distinguishable from "that" in a vast catastrophic cracking apart....
=========================

It is not take seriously, just an innocent exercise of imagination. Real theory must keep in step with observation and experimental tests. But I think I can get some idea of what you were talking about.
I just will not equate that idea of total symmetry with "nothing" because that tempts people to get into a futile discussion about words. There might be some subterranean connection, but it is not worth the risk of getting trapped in discussion on a merely verbal level.

awktrc

I just wanted to let you know that, in my opinion, you are the best poster here. You always succinctly point out the problems and inconsistencies in some of these (out-there) theories, hypotheses or conjectures.

Thank you. You are the main reason that I continue to read this Forum.