The hypothetical field with one element (known as Fun) now has its own blog, ceci n’est pas un corps. Among the many things of interest, there’s a link to a video of Alain Connes explaining his recent paper with Consani and Marcolli on the subject. This is part of a project at the Journal of Number Theory to get authors to produce video introductions to their papers.
Over at the n-category Cafe, there’s a discussion of Alan Weinstein’s new paper on The Volume of a Differentiable Stack. A stack is a sort of replacement of a quotient space, of a sort that allows one to keep track of the fact that different points may correspond to different stabilizers. One would like to naturally assign as many properties of spaces as possible to stacks, and one interesting question is how to count sizes, for instance how to define volumes. If everything is finite, it turns out the thing to do is to count points by dividing by the size of the stabilizer, but something much more subtle is required in the differentiable case, where the sets involved are all infinite.
The last year has seen a flurry of activity on hep-th that goes under the name of the “M2 mini-revolution”, or maybe AdS4/CFT3. I’d been waiting for some expository accounts of this to appear to read more about it, and there’s a new one here. It includes graphs that show a total of 157 papers on the topic with 223 authors. Things didn’t really get started until this past spring, with the number of papers peaking at 40/month in July, with 53 new authors joining the game that month. Since then, the trend is downwards, with 21 paper in September. Thomas Klose does a good job of surveying the subject and what has been learned about it. The only applications mentioned are in the last line of the last page, which refers to possible future uses in condensed matter physics.
The 2009 fiscal year has started already, with no federal budget in the US. The idea now seems to be to wait until it’s half over next March or so, then have the new administration put together a 2009 budget and a 2010 budget simultaneously. In the meantime, a continuing resolution has been passed, under which money can be spent at the level of the 2008 budget. This is pretty bad news for US HEP, since the relevant 2008 level was one involving serious budget cuts. The effect of these was mitigated by a later supplemental appropriation, and that can evidently be used to keep the Fermilab budget at a level such that layoffs can be avoided (see discussion from Oddone here). But it remains completely unclear what will happen to the lab a few short months from now.
This past weekend the Skeptics Society at Caltech cosponsored with the Templeton Foundation a conference on Origins: the BIG Questions. The afternoon session was devoted to discussing God, the morning featured physicists promoting anthropics. An account of the talks is here, including this about Lenny Susskind’s talk
The conference began with a real bang – the Big one of course, and a lesson on what preceded that singularity as best understood today by physicists. Susskind condensed his Stanford undergraduate cosmology course into a beautiful one-hour primer on the universal constants (Planck’s, gravitational constant, speed of light…) that support life. It turns out that life can only evolve and survive in a narrow window of values for these constants, a fact that Christians have recently embraced as proof of an intelligent designer. But Susskind explained how quantum mechanics support the existence of a multiverse that regularly spawns new universes with different sets of constants, making it inevitable that our comfy universe should appear. (I asked him whether a future day Dr. Strangelove could create the conditions that spawn a new universe in our own – he said no, but without a compelling explanation.)
and this about Sean Carroll’s:
Caltech physicist Sean Carroll delivered a great talk on time’s arrow – how time fits into the universe and how it cannot exist without fluctuations in entropy. He explained how the physical constants give our universe just the right amount of clumpiness so that time can flow, and he presented an alternative theory – consistent with quantum mechanics – on how universes can bear “babies” with differing constants.
After Carroll, Caltech biologist Christoff Koch explained how:
consciousness may in fact entail a new force not yet discovered by physicists.
Update: Sean has a posting about the “Origins” conference, mainly devoted to explaining what was wrong with the presentation of a crackpot who was speaking as part of the religion segment.