In a few days I’m heading to East Africa for a couple-week long trip, planning to be in Uganda on November 3 for the (short) total solar eclipse that day. This will be followed by a few days in London, then back here with regular programming resuming around November 11. While away I’ll shut off the commenting system, since I’m hoping to not have internet access during most of the trip.
Here’s some short items that might be of interest:
- For the latest from CERN about SUSY, see this overview from ATLAS. The bottom line is quite simple: zilch, in every channel examined. Limits on a gluino mass are about 1.2 TeV, and there seems little prospect of much change until 2015, when results at 13 TeV start to come in. A naive extrapolation says that ultimately the LHC should be able to set limits on gluino masses of up to 2 TeV. Pre-LHC, the limits were about 300 GeV (from the Tevatron). I don’t know anyone who is optimistic that it will turn out that the 62.5% energy jump in 2015 will find something when the 400% energy jump didn’t (and the theoretical arguments for SUSY implied that it should have already been seen at the Tevatron).
- Steven Weinberg has an article about the current state of cosmology and particle physics, entitled Physics: What We Do and Don’t Know. About string theory he has this to say:
String theory is attractive because it incorporates gravitation, it contains no infinities, and its structure is tightly constrained by conditions of mathematical consistency, so apparently there is just one string theory. Unfortunately, although we do not yet know the exact underlying equations of string theory, there are reasons to believe that whatever these equations are, they have a vast number of solutions. I have been a fan of string theory, but it is disappointing that no one so far has succeeded in finding a solution that corresponds to the world we observe.
The main reason for disappointment about string theory is not that a solution corresponding to the SM hasn’t been found, but that the theory predicts nothing at all. All indications are that the dead end that string theory has hit is not that (if one could actually figure out what the theory is…) of no SM solution, but that of so many solutions that you can get anything you want. Unfortunately Weinberg seems to be of the “if a fundamental theory predicts nothing, that’s too bad, but maybe how the world works” camp, rather than the more standard “if a fundamental theory predicts nothing, it’s a bad fundamental theory” camp. He goes on to argue that we may have to just give up on fundamental physics and be content with this theory that predicts nothing:
Such crude anthropic explanations are not what we have hoped for in physics, but they may have to content us. Physical science has historically progressed not only by finding precise explanations of natural phenomena, but also by discovering what sorts of things can be precisely explained. These may be fewer than we had thought.
Back in 1977, in the wake of the great advances of the Standard Model, Weinberg famously made the statement that:
The more the universe seems comprehensible, the more it also seems pointless.
Presumably the universe is still pointless, but now the argument seems to be that it’s also incomprehensible.
- Unlike Weinberg, Frank Wilczek hasn’t been a fan of string theory. From a recent interview:
3. Is String Theory a dead end? Is there news coming, regarding scientific advances, or experimental confirmations?
Many very smart people continue to work on string theory, and I expect that they’ll continue to do interesting work, in mathematics if nothing else. Whether they’d be more productive doing something else, is another question. It is unfortunate that in the early days people got carried away, and promised much more than the theory
could reasonably be expected to deliver.
and about anthropics:
It is the scope of anthropic reasoning that’s debatable. I hope we can avoid appealing to it very much in fundamental physics, but time will tell.
- According to the Stony Brook newspaper though, based on information from Michael Douglas, all is well with string theory:
String theory has done quite well so far in explaining all of the forces of the universe. The theory has matured, and so have the mathematical equations it has produced. An equation describing the universe is considered successful if it is symmetrical. What that means is if the equation is taken apart and its components rearranged, it should still produce the same conclusion. If the rearrangement of an equation does not yield the same result, it is deemed unstable and not a good descriptor of the universe or its forces.
The equations that have stood up to the test of symmetry have predicted the existence of particles that help bridge the gap between general relativity and quantum field theory. For example, string theory predicts a particle called the graviton, thought to be a closed loop string that is responsible for the gravitational force…
Gravity is weak.
String theory not only predicts the particle that constitutes gravity, it also helps describe why it is so weak…
Currently, the ability to test the predictions from string theory is very limited and some have said that this roadblock is impossible to overcome.
Douglas thinks otherwise.
The next phase of this theory will likely take a lot of hard work and fresh ideas. String theory has made enormous strides in the relatively short amount of time that it has been around, and it is thought by many to be the most promising of the so-called “theories of everything.”
In a few more years, who knows what exciting advances could be in store?
The article doesn’t mention Douglas’s decision to stop working on string theory and go to work for a hedge fund.
- The Financial Times has its own take on the current state of fundamental physics research, with an article on The new physics.
- Also at the Financial Times is a good survey of Physicists and the financial markets, describing various current activities of physicists now working in the financial industry.
- Harvard University Press has just released a new book by Steve Nadis and S.-T. Yau, a history of the Harvard math department entitled A History in Sum: 150 Years of Mathematics at Harvard. It concentrates on the period 1825-1975, and I enjoyed it quite a bit. It ends right about the time I arrived there as a student, so covered history that I never had known much about.
Harvard’s role as a mathematics research institution began with Benjamin Peirce, who taught there from 1831-1880. It only started to become a world-class institution around 1900, with young faculty who had gone to Germany for their training. The book covers a fairly long list of great 20th-century Harvard mathematicians (including George David Birkhoff, Morse, Whitney, MacLane, Ahlfors, Gleason, Mackey, Zariski, Brauer and Bott), and makes a serious attempt to explain some of the mathematical ideas they developed. As a result, a large part of the book is not just history, but actual exposition at a popular level of a wide range of mathematics, together with quotes from many other prominent mathematicians about the significance of the ideas.
If you’re interested at all in the history of mathematics, this book is well-worth finding a copy of.
- David Appell has an article about the SSC, the major disaster for US HEP research. Next year should see a book on the topic by Michael Riordan, Tunnel Visions: The Rise and Fall of the Superconducting Super Collider.
- The Simons Foundation Quanta magazine continues to put out many high quality stories about science, with one of the latest an article by Natalie Wolchover about experiments searching for neutrinoless double beta decay, which would indicate a Majorana neutrino mass term.
- The SETI institute has a series of SETI Talks, available on YouTube, with the latest featuring Joe Polchinski on Black Holes and Firewalls.
- The Boston area Joint Math Colloquium this week with have Edward Frenkel speaking on The Langlands Program and Quantum Physics. Afterwards you can go up to Harvard Square and get him to sign a copy of his new book.
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