Many recent theoretical physics ideas allow for the possibility that our universe is part of a multiverse - a set of distinct alternate universes. Both particle physics and cosmology, for various reasons, have found this notion

String theory, for example, can (in some interpretations) view our universe as being confined onto a 3-dimensional brane, which allows for other multi-dimensional branes. (In string theory, the total universe has 9 or 10 dimensions, not counting the time dimension, so there's a lot of room for various types of branes ... and therefore various types of universes.)

In the vast majority of these theories, the different universes can't interact. The theories often predict that in the early universe, at the moment of the big bang (or shortly thereafter) minor quantum fluctuations in the fabric of the universe itself expanded rapidly during the period of inflation, resulting in large regions which ended up with different physical laws as they cooled down. (This process of eternal inflation, of which Linde is one of the primary founders, is described in great detail by his colleague Alex Vilenkin in his book Many Worlds in One: The Search for Other Universes.)

Still, it's fun for scientists to speculate on these sorts of things. Andrei Linde and Vitaly Vanchurin at California's Stanford University have done just that. By making some basic calculations, making assumptions about the quantum properties of the early universe at the moment of the big bang, they were able to consider how that universe would have expanded through the process of inflation - where small variations in the early universe expanded rapidly. Each of these regions would have eventually settled into regions which ended up with their own sets of physical laws as it cooled down.

Anyway, their result is the "humungus" number 10¹⁰¹⁰⁷. However, they did point out that the human brain can't really comprehend more than 10¹⁰⁶ pieces of information, so realistically that's the most universes that could be distinguished by a human being, even in principle. (In practice, that's still a heck of a lot of information to process.)

Their original paper, How many universes are in the multiverse?, is available on arXiv.org.

No, it's not the great pumpkin, Charlie Brown. Physicists are kept up by questions about the very nature of space, time, and reality itself ... and New Scientist has broken these concerns down into the "Seven questions that keep physicists up at night." These questions come out of a panel discussion among physicists speaking at the "Quantum to Cosmos" festival, which took place at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, last week. Videos from the festival are available on the website.

Comedy Central's resident faux-pundit, Stephen Colbert, interviewed rock star particle physicist (and People magazine's sexiest physicist) Brian Cox on the October 28 episode of The Colbert Report. Cox was there to promote his new book (co-written with Jeff Forshaw), Why Does E=mc²: And Why Should We Care?

Colbert led into the interview by discussing the recent analysis that concluded the Large Hadron Collider (LHC) is failing because of influences from the future which prevent the Higgs boson from manifesting. In the days since I first posted about this analysis, I have thought about it more and come up with a counter-analysis.

The argument proposed is that there is some sort of inherent property that revealing a Higgs boson is "abhorent to the universe." For this reason, influences from the future cause the LHC to fail, to avoid the generation of a Higgs boson.

However, the LHC is only going to cause collisions of about 14 TeV energy ranges, and collisions of this sort (and higher energy levels) happen between particles in nature regularly. Influences from the future don't prevent stars from exploding or streams of high energy particles from colliding with the upper atmosphere. If these collisions result in Higgs bosons, it seems like they'd have be continually thwarted throughout the universe.

The analysis does have one way of being salvaged, however, and it's a far more economical solution. If the Higgs boson is "abhorent to nature," then maybe these sorts of collisions just don't generate it. In this scenario, there's no need to explain some sort of ad hoc influence from the future to prevent the Higgs from being discovered ... there would just need to be some element to the structure of the universe that makes the Higgs directly inaccessible at these energy levels.

Brian Cox rightfully calls these "sabotage from the future" results "bollocks," although he does say that this is more amusing bollocks than the stuff about the black holes devouring the earth (which is a "steaming pile of bollocks").

What he focuses his discussion on is the nature of space and time within the universe. His new book explains Einstein's theory of relativity, which is the foundation upon which all modern physics is built ... because it defines the environment (i.e. spacetime) in which all other science takes place. (Food science is, apparently, not science according to Cox, which tells me that he hasn't seen the Food Network program Good Eats.)

The show is available for free viewing on The Colbert Report website or on Hulu.com. It's the October 28 episode. You can skip directly to the second part, which contains the LHC discussion, or the third part which shows the interview with Cox.

Michael Green has been appointed as the Cambridge University Lucasian professor of mathematics, a position once held by Sir Isaac Newton and previously held by Stephen Hawking. Hawking resigned from the university at the end of the 2008-2009 academic year because of a university policy that requires resignation at age 67 (see "Hawking to Step Down from Professorship").  Hawking will, among other things, be working some at Canada's Perimeter Institute, where he has accepted a Distinguished Research Chair position. (The Institute recently named a new building after Hawking.)

So on to his successor, Michael Green, who assumes the professorship on November 1. He has some big shoes to fill - not only has the position been held by Newton & Hawking, but also by Charles Babbage and Nobel-winner Paul Dirac (known as the British Einstein) - but he's created some big footprints himself, as one of the major innovators in the early days of string theory. Together with John Schwarz, Green helped to show that string theory had the ability to cancel many anomalies which had almost doomed the theory, leading to the "first superstring revolution" in the early 1980s.

While Green is certainly worthy of accolades, I've got to confess that I'm a bit startled that he's been appointed to this role. Green is 63, which means that he'll only be able to hold the position for 4 years before retiring himself. Hawking, alternately, was appointed when he was 37, so was able to hold the position for 30 years. Because of the high profile of the position with Hawking leaving, Cambridge University was no doubt under pressure to give it to someone with extensive achievements, and Green is an excellent choice in this regard.

However, I wonder if this isn't partly a sign that there just not that many younger British innovators of mathematical physics to choose from. Hawking was awarded the post in 1979 for work done in the 1960's and early 1970s. Thirty years later, his replacement is largely being recognized for groundbreaking work performed in the early 1980s. What younger British physicist could be appointed the position for groundbreaking work performed in the late 1990s and early 2000s? In four years, when Green is forced to retire, what worthy successor will replace him? What young up-and-comer will have the gravitas needed for this post?

Honestly, I can't think of many, and with a new emphasis on only funding research that provides explicit economic benefit, it's unclear that the British government will foster more theoretical physics innovators in the future. Do you have any suggestions? Leave them here.