No Championship for MIT This Year

Well, MIT finally lost a football game yesterday in the second round of the D-III tournament. They end up at 9-0 in the regular season and 10-1 overall. This is still much better than probably anyone really expected them to do this year.

Science and Interstellar

Salon has a brief excerpt from Kip Thorne’s book The Science of Interstellar, in which the author/physicist attempts to explain some of the scientific concepts used in the film. I still haven’t seen Interstellar, but I’ve heard mixed things from other physicists and astrophysicists (mostly that the visuals are cool but the plot is lacking and fairly nonsensical).

The excerpt isn’t bad but I think it’s probably a bit too high-level for most readers since all the material explaining many of the concepts is hopefully in the book but left out of the Salon piece.

It seems that the science behind the crazy things like wormholes and black holes in the film are based on the idea that our universe is a four-dimensional space embedded into a larger space. Think of this as a higher dimensional analog of creatures living on the surface of a ball. To those creatures, the universe (a sphere) is three dimensions, but we know that it is four (one of those is time in both cases). This idea shows up quite a bit in modern theoretical physics and in some sense is the basis of string theory and M-theory, a generalization of string theory. In both cases more than four dimensions are required to get sensible physics out of the theory, so these extra dimensions can be both small (compactified) – leading only to quantum effects – or large, where the particles and fields of the Standard Model are somehow confined only to our four dimensional space. In some theories, you can let gravity operate in all dimensions, which can explain why gravity is so much weaker than the other forces: it operates in more dimensions, diluting its apparent strength. This last points appears to be an important part of the physics of the movie.

A few things on terminology:

  1. The bulk: The greater dimensional space that the universe is embedded into. Gravity can travel throughout the bulk, so objects in other universes can have effects on ours through gravity.
  2. Branes: Higher dimensional objects. A particle is 0 dimensions, a string is 1, and a brane is an arbitrary number (up to the number of dimensions in the bulk). Our universe can be seen as a 4-dimensional (3 space + 1 time) brane embedded in the bulk.
  3. AdS: Anti-de Sitter space. This is the name for the spacetime with a uniform negative curvature. In the film, we are not creatures living on a sphere (which is the analog for de Sitter space), but rather creatures living on an infinitely large saddle or potato chip. In reality, as far as we can tell, space is flat, so any curvature would have to be incredibly small.
  4. Tidal forces: Non-uniform forces on different parts of an object. For example, the force of gravity on Earth from the moon is slightly stronger on the side of Earth nearest the moon, so fluids such as water are being pulled to the near side of Earth (instead of everything being pulled together by the same amount), creating tides.
  5. Action: The time integral of a Lagrangian or integral over space and time of a Lagrangian density. In field theories, the Lagrangian density is a function of fields and field derivatives that contains all the physics of the system. The system evolves in such a way that extremizes (maximizes or minimizes) the action, so the evolution of the system can be understood by applying calculus of variations to the action. Part of what theoretical physicists do is to come up with Lagrangians (either for fundamental theories or for effective theories applying only under certain conditions) that describe either novel or poorly understood physical systems in order to understand their properties. These are often designed to fix problems with our current incomplete theories. For example, the Higgs boson comes out of a Higgs field added to the Standard Model Lagrangian in order to fix some problems with unitarity and gauge invariance that are introduced when massive vector bosons (the W and Z) are added to the theory.

CU Wins NCAA Cross Country Championship

Over the weekend, the Colorado men’s cross country team won the NCAA Division I championship for the second straight year. The race was a 10k course in Terre Haute, Indiana. The Colorado team ended up with 65 points although the top two runners were both from Oregon, with the best finishing with a time of 30:19. Stanford came in second with 98 points. The northeastern region sent an all-Ivy set of individual qualifiers with two from Columbia and one each from Harvard and Yale. The Colorado women’s team also did quite well, ending up at #7 out of 31 qualifying teams. For some reason, the women’s course is only 6k instead of using the same 10k as in the men’s race.

New T2K CCQE Neutrino Cross Section Result

T2K released a preprint today measuring the charged-current quasielastic scattering cross section of muon neutrinos on carbon using the ND280 off-axis near detector. The measurement reports the total cross section, the double-differential cross section using muon kinematic variables (muon momentum and angle with respect to the beam direction), and also reports a fit to the axial mass parameter of a theoretical model. There is good agreement between the measured flux-averaged cross section and the expectation from theory, and agreement between the measured and expected differential cross sections are also mostly good. The axial mass extraction is also reasonably consistent with expectations, so overall, everything seems to fit pretty well to expectations from the NEUT Monte Carlo generator and also from previous measurements.

Problems at ESPN Over Evolution?

So former Red Sox pitcher/failed wannabe videogame mogul Curt Schilling has apparently been spewing a bunch of ignorant nonsense over Twitter in recent days, mostly involving attacking evolution. Schilling is currently one of ESPN’s many famous former players on the payroll to provide on air commentary once in a while. One of the networks actual commentators and journalists, Keith Law, responded with a series of tweets answering some of Schilling’s inane questions that supposedly should stump supporters of evolution. As a result, the Lawhas been ordered off Twitter for a few days. ESPN has been quite evasive over the official reason for this (they say that it’s not about his opinions), but the timing suggests that the suspension is for embarrassing Schilling in public. Unlike Schilling, Law is employed to provide actual content, so we would hope that the network would give him the benefit of the doubt over this. He kept his tweets much more factual and respectful than Schilling’s.