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This link recently saved by orzelc on September 02, 2012
This link recently saved by orzelc on May 11, 2012
This is a repost and update of a six year old post in which I listed what I think are the most interesting and pressing open problems in theoretical physics, or at least the area that I work in, quantum gravity. I thought it might be worthwhile to revisit. This list doesn't even pretend to be objective - it omits entire areas of theoretical physics - it is mainly a reflection of my personal interests; a summary of puzzles I find promising to spend brain time on.
This link recently saved by orzelc on April 25, 2012
Is supersymmetry, as a symmetry that might explain some of the puzzling aspects of particle physics at the energy scales accessible to the Large Hadron Collider [LHC], ruled out yet? If the only thing you’re interested in is the answer to precisely that question, let me not waste your time: the answer is “not yet”. But a more interesting answer is that many simple variants of supersymmetry are either ruled out or near death.
This link recently saved by orzelc on March 30, 2012
The search for ways to unify and understand physical phenomena goes back to Kaluza and Klein, who in the 1920s tried to combine electromagnetism with gravity by adding a fourth spatial dimension to the usual three (plus time). More recent theoretical work has suggested that a theory of everything may need 11 spacetime dimensions. Boada et al. are suggesting an experimental strategy for investigating how matter behaves in extra dimensions. Their idea is to encode a fourth spatial dimension in an internal degree of freedom offered by atoms trapped in an optical lattice, and do it in such a way as to exactly reproduce the physics described by a 4D Hamiltonian. The authors show two ways of observing such effects: one is to look for single-particle effects, such as rates of decay of excited states as a function of dimensionality; another is to search for many-body effects such as insulator-to-superfluid transitions that depend on the number of dimensions.
This link recently saved by orzelc on March 23, 2012
We published a paper recently. We also posted the code used to generate the results. The day after the paper came out, somebody found an error. A potentially very serious error. I went through a lot of fear and panic, and then I thanked the person who found it and my students and I worked on the problem. The error was a rather embarrassing one, a mistake that we really shouldn’t have made. The buck stops with me, and what it boils down to is that I had not gone line-by-line through code that somebody else wrote. I had checked some of the code, but as the project got bigger and the students displayed more competence, I stopped checking line-by-line and started focusing on output.
This link recently saved by orzelc on July 14, 2011
In fact, the field of quantum gravity was born in 1916, even before physicists had properly explained the other fundamental forces, electromagnetism and the nuclear forces. Twenty years later, a young Russian physicist by the name of Matvei Bronstein realized that gravity would be the hardest force of all to quantize. But before he could do something about that, he was swept up in Stalin’s Great Terror and executed at the age of 30.
This link recently saved by orzelc on March 09, 2011
"One of my first blog posts on US LHC was titled “My Workbench,” following the style of the regular column in Seed magazine. This semester our group finally moved to a new building, so I wanted give a snapshot of my research environment. So, without further ado, here’s my annotated office.
Before going into details… yes, it’s an office. I don’t have a lab, I don’t wear a lab coat, I don’t even wear closed-toed shoes. (When indoors I’m usually shuffling around in comfy Birkenstocks.) This is partly because I’m a theorist and my experimental colleagues wouldn’t let my clumsy hands anywhere near lab equipment—but actually most experimentalists have very similar offices where they do much their analysis work (Christine’s rappelling onto the ALICE detector notwithstanding!)."
This link recently saved by orzelc on December 17, 2010
"Let me end this post with a request: I want all of my readers to visit the YouCut page, and propose that quantum computing and theoretical computer science research be completely eliminated. Here’s my own CAREER Award; go ahead and cite it by number as a particularly egregious example of government waste.
See, I’m hungry for the honor (not to mention the free publicity) of seeing my own favorite research topics attacked on the floor of the House. As we all know, it’s child’s play to make fun of theoretical computer science: its abstruseness, its obvious irrelevance to national goals—however infinitesimal the cost is compared to (say) corn subsidies or defense contracts for stuff the military doesn’t want, however gargantuan the payoffs have been in the past. So what are Eric Cantor and Adrian Smith waiting for? I dare them to do it!"