Comments on: Is our universe natural?

By: CIPig on ID, prof’s tenure, and Cosmic Variance militancy « Dudesky

CIPig on ID, prof’s tenure, and Cosmic Variance militancy « Dudesky — Thu, 07 Jun 2007 18:57:14 +0000

[...] It’s interesting to see how Jo Anne acknowledges the extent of Prof Gonzalez’s science credentials: The department has denied tenure to Professor Guillermo Gonzalez. Prof Gonzalez, by all reports, is the author of nearly 70 peer-reviewed scientific papers, co-author of a major college-level astronomy textbook, his work led to the discovery of two new planets, and he has had his research featured in Science, Nature, and on the cover of Scientific American. Recently, he discovered what is known as the Galactic Habitable Zone, which essentially proposes that life forms when there is the right balance of unique conditions. A hypothesis not too different from our own discussions of the anthropic principle here in theoretical high energy physics! [...]

By: ‘Tis the Season for Tenure Flaps | Cosmic Variance

‘Tis the Season for Tenure Flaps | Cosmic Variance — Sun, 20 May 2007 08:00:36 +0000

[...] While we’re on the subject of tenure here at CV, there is yet another tenure flap happening in the physics department at Iowa State University. Which is my alma mater (always embarrassing to admit that, so I might as well get it out of the way early on). The department has denied tenure to Professor Guillermo Gonzalez. Prof Gonzalez, by all reports, is the author of nearly 70 peer-reviewed scientific papers, co-author of a major college-level astronomy textbook, his work led to the discovery of two new planets, and he has had his research featured in Science, Nature, and on the cover of Scientific American. Recently, he discovered what is known as the Galactic Habitable Zone, which essentially proposes that life forms when there is the right balance of unique conditions. A hypothesis not too different from our own discussions of the anthropic principle here in theoretical high energy physics… [...]

By: After Reading a Child’s Guide to Modern Physics | Cosmic Variance

After Reading a Child’s Guide to Modern Physics | Cosmic Variance — Wed, 01 Nov 2006 16:50:41 +0000

[...] Ol’ Wystan is right; we do have a better time than most of the universe. It would be no fun to constantly worry that “a lover’s kiss / Would either not be felt / Or break the loved one’s neck.” And in a sense, it’s surprising (one might almost say unnatural) that our local conditions allow for the build-up of the delicate complexity necessary to nurture passion and poetry among we creatures of median size. [...]

By: Rapped on the Head by Creationists | Cosmic Variance

Rapped on the Head by Creationists | Cosmic Variance — Tue, 08 Aug 2006 15:11:50 +0000

[...] I think this is a new category for my CV — “articles subjected to close reading by creationists.” (That, and pioneering the concept of the least bloggable unit.) Here is the first entry: my humble little essay for Nature entitled “Is Our Universe Natural?” has been lovingly dissected at “Creation-Evolution Headlines.” In which they claim that my paper “arms the intelligent design movement in the current fight over the definition of science.” Okay, now those are fighting words. [...]

By: The String Theory Backlash | Cosmic Variance

The String Theory Backlash | Cosmic Variance — Mon, 19 Jun 2006 18:02:07 +0000

[...] Of course, you do have to make the case that your personally favorite approach is a promising one, to the public and to colleagues in other specialties as well as to graduate students. This is not always a job that string theorists have done well. Some of them, I’ve heard rumors, can even occasionally be a mite arrogant. Let’s admit, this is something of an occupational hazard among academics; if universities fired all the arrogant people, the remaining faculty would be stuck teaching twenty courses a semester. And, while I think that an enormous landscape of stringy vacua might very well exist, I think that supporters of the idea have dramatically failed to take seriously the difficulty of actually calculating anything on that basis. Discussions about these crucial issues have all too often degenerated into sophomore-level philosophy-of-science debates, which haven’t done credit to either side. The truth is, we’re not doing science in a new way, it’s the same old way — trying to come up with the simplest possible consistent and coherent framework that explains the phenomena we observe. [...]

By: The View of the Universe from the Perimeter | Cosmic Variance

The View of the Universe from the Perimeter | Cosmic Variance — Thu, 08 Jun 2006 17:10:50 +0000

[...] It’s remarkable how polarizing the whole idea of the string-theory landscape and the anthropic principle really is. It’s not a simple split of string theorists vs. cosmologists vs. everyone else; there are string theorists who love the lanscape, as well as ones who hate it, and likewise for cosmologists or anyone else paying attention. I’ve been arguing that the landscape/multiverse might very well exist and is interesting to think about, but that it’s absolutely impossible right now (and might always be) to use it to calculate anything, or even to sensibly re-calibrate our notions of what is “natural.” I was happy to learn that Paul Steinhardt and Neil Turok are basically in agreement with this view, and are even writing a paper that attempts to make it crystal clear that the landscape does not correctly predict the cosmological constant ala Weinberg. In fact, if we’re allowed to take it seriously at all, it makes quite a strong and vividly different prediction altogether: the cosmological constant should be quite large (many times the matter density, although presumably not at the Planck scale), and we should live in a single lonely galaxy in an empty universe dominated by vacuum energy. Their paper is in preparation, and I hope to say more about it when it comes out. In the meantime, there is serious and hard work to be done to understand the generation and evolution of cosmological perturbations, so it hasn’t all devolved into a shouting match over whether talking about unobservable parts of the universe should count as science. [...]

By: LambchopofGod

LambchopofGod — Mon, 02 Jan 2006 04:13:12 +0000

I just noticed that Sean’s paper cites
http://arxiv.org/abs/hep-th/0503249

Any comment as to why that paper is relevant, Sean?

By: Bloggernacle Times » This Week In Science and Religion

Bloggernacle Times » This Week In Science and Religion — Tue, 20 Dec 2005 18:35:50 +0000

[...] Moving to non-Mormon blogs, the firestorm over superstring theory continues unabated. Some physicists really getting upset at how the Discovery Institute keeps trying to link Susskind’s thoughts on superstring theory with intelligent design. For a nice overview including links to a New Scientist interview, check out Not Even Wrong. Also up is a discussion of the same issues and the question of whether our universe is natural. It’s discussion that arose from the author’s Nature review. Lots of other links on this topic, but those two should get you started if you are interested. [...]

By: Count Iblis

Count Iblis — Mon, 19 Dec 2005 17:39:18 +0000

Sean,

in your paper hep-th/0410270 with Chen, you discuss a bit about unitary time evolution. This reminded me of this problem (I don’t work in this field so perhaps it is trivial):

If you start out with a region of some finite volume then presumably here are only a finite number of fundamental states available for that volume. If this region undergoes expansion and becomes larger, then shouldn’t there be less degrees of freedom available per unit volume if you demand unitary time evolution?

But if one thinks of the standard model as an effective low energy theory obtained by integrating out the fundamental degrees of freedom, then this means that the coupling constants would have to change according to a renormalization group transformation.

Or is this just an artefact of treating the expansion clasically? Is the density of states in the original space time for which the scalar field configurations are compatible with the expansion just the same as in the final space time?

By: Sean

Sean — Sat, 17 Dec 2005 17:07:20 +0000

The cosmic no-hair theorem, which roughly states that an expanding universe in the presence of a positive cosmological constant will generically approach empty de Sitter space, has by no means been rigorously proven in all interesting cases. Nevertheless, something like it is probably true, at least in an open universe. Jennifer Chen and I argue in favor of it in our first paper.