New Hawking Landscape Paper & Mainstream String Theory Update"

[marcus]

this just posted, in case anyone's interested

http://arxiv.org/abs/hep-th/0602091BTW more along mainstream string lines there's also a new
paper by Robbert Dijkgraaf, Cumrun Vafa and Erik Verlinde.

http://arxiv.org/abs/hep-th/0602087

 

[selfAdjoint]

I am more and more of the opinion that instead of trying to evade or deal with the landscape people should be treating it as a symptom, and asking the question, of what deeper, unrecognized, facts about the universe is the landscape a necessary result?

Famously Lee Smolin has proposed an answer to that question: the deeper fact is the evolution of universes. He claims that his hypothesis is testable through astrophysical observations.

Now Hawking has proposed an answer of his own: the deeper fact is the no-boundary condition on the universe. He also claims his idea is testable through astrophysics. It remains to be seen whether the two proposals, alone or in combination, will tell the whole story.

Absent experimental data, cosmology and astrophysics are the only ways to gather objective data that may lead to a full answer to the question and permit a new research program that deals with the landscape from strength.

 

[Kea]

I am more and more of the opinion that instead of trying to evade or deal with the landscape people should be treating it as a symptom, and asking the question, of what deeper, unrecognized, facts about the universe is the landscape a necessary result?

Remember that the notion of evolving universes is only really deep if it is meant in the sense of a metaphysical investigation of laws, an idea that came to light in that Edge essay of Smolin's. A simple picture of a bag of universes (which is the way it is often described) is quite misleading, I think.

 

[selfAdjoint]

Remember that the notion of evolving universes is only really deep if it is meant in the sense of a metaphysical investigation of laws, an idea that came to light in that Edge essay of Smolin's. A simple picture of a bag of universes (which is the way it is often described) is quite misleading, I think.

I am all for depth, as my post indicated. If we can't escape metaphysics then we should face it. But I wonder if what you see as metaphysics really is?

 

[Kea]

But I wonder if what you see as metaphysics really is?

Ah! Exactly! Of course, if it becomes physics its not metaphysics, is it? But since it's the sort of stuff that people like to label as metaphysics, I thought it would be OK to use the word. Bad idea, I guess.

 

[Chronos]

I think both approaches have causality issues. CNS may be the lesser evil, but paradoxes appear to abound in both models. I dislike the path integral approach because, IMO, it treats the universe as a particle. The evidence favoring that assumption is sorely lacking, IMO.

 

[selfAdjoint]

I think both approaches have causality issues. CNS may be the lesser evil, but paradoxes appear to abound in both models. I dislike the path integral approach because, IMO, it treats the universe as a particle. The evidence favoring that assumption is sorely lacking, IMO.

(Warning: mixed metaphor ahead!)
There is absolutely no evidence for the nature of the universe at all. Testible theories that take us beyond saving the phenomena can be thought of as arrows pointing, perhaps vaguely or incorrectly, toward such an understanding. In the absence of evidence the brainstorming strategy is often thought valuable; don't put constrants on thinking too early, let a hundred flowers bloom. If Smolin's and Hawking's ideas are testable as their authors claim, then the false ones will be pruned soon enough.

 

[marcus]

I am all for depth, as my post indicated. If we can't escape metaphysics then we should face it. But I wonder if what you see as metaphysics really is?

a crucial and sometimes exciting philosophical issue, where to draw the line
since the thread started with a Hawking paper I will mention that old Hawking co-author George Ellis has some pertinent comments in his new essay

https://www.physicsforums.com/showthread.php?p=910888#post910888

I quoted some of Ellis here, in post #3. he rocks.