Archive for the ‘Particle Physics’ Category

zombie_front_imageThis Halloween I had a bit of a revelation. Between all the Sarah Palin costumes and dissertations on the physics of ghosts, I realized that the W and Z bosons are brain-eating zombies; a fact which helps to understand why physicists are trying so hard to find the Higgs boson. Let me explain.

First, what are the W and the Z (aside from annoyingly uncreative choices for names)? You’ve probably heard that there are 4 forces in nature: gravity, electromagnetism, the strong force, and weak force. Each of these forces is caused by exchanges of messenger particles. So what binds an electron to a proton — thus forming a hydrogen atom — is a constant stream of photons flying back and forth; hence, the photon is the messenger of the electromagnetic force. Similarly, gravity is transmitted by gravitons, and the strong force by gluons. The weak force is a bit odd. It has 3 messengers which are all slight different from each other: the Z, the W+ and the W-.


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The Nobel prize for physics has been announced. This year half of it goes to Makoto Kobayashi, Toshihide Maskawa and the other half to Yoichiro Nambu; all particle physicists.

As always, there is a lot of controversy with this choice. When I first heard the recipients my first thought, and I suspect almost every particle physicist had the same thought, was: “Why Kobayashi and Maskawa and not Cabibbo?” The Kobayashi-Maskawa paper was, in many ways, a generalization of earlier work by Nicola Cabibbo. For some entertaining wild speculation about politics and motivation, see the comments on this post by Thomasio Dorigo.

My take is that this is one of the exceedingly difficult situations created by the rule that the prize can only be shared by three recipients. Nambu clearly deserves a Nobel prize, and good arguments can be made for all of Cabibbo, Kobayashi and Maskawa. On the other hand, the committee can’t give the prize to particle physics (or to any other branch of physics) every year. So, something weird and controversial has to happen.

Now, instead of directly explaining what the prizes were for, I’m going to slide into an Amusing Anecdote.


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Happy birthday to me!

It’s my birthday today, and as a present to me the Large Hadron Collider will be turned on tomorrow. Thanks, International Community!

The History channel is joining in the celebration by broadcasting a special documentary on the LHC. David E. Kaplan, the host of the special, explains why you should watch it.

(While I’m on the subject, Clayton Brown and Monica Ross have made a documentary about particle accelerators. See their blog for more information, including the bit about the premier in Chicago on Sept. 19th.)

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Destroying The Earth

In the break room for the theory group at SLAC, I once found a folder titled “Scientific Eschatology”. Eschatology being the study of end times, this presumably was an attempt to understand what our current theories tell us about how we could go splat.

It’s always fun to think about the ways the world might end. Phil Plait has an entire book about it coming out soon. There are a lot of exciting possibilities. The sun might die, a nearby star might go supernova, nuclear war might break out, fiery horsemen might come riding out of the sky, the center of the Milky Way could turn into a quasar after colliding with Andromeda. (In that last case, we would all feel fine.) Of course, some of these are more likely than others.

On way that it should probably not end is for a scientific experiment to tear a hole in the fabric of spacetime. It is, therefore, a relief that the Large Hadron Collider, soon to turn on in Geneva Switzerland, will not produce this result, as some have claimed. The paper linked goes into some detail, but the bottom line is quite simple. The LHC collides two beams of protons. The Earth is constantly being bombarded by cosmic rays, which at high energy are mostly protons. The energy in the collisions of cosmic rays with The Earth (generally the upper atmosphere) are often as high as the energy of the LHC, occasionally much higher. A little math, and one finds that if the LHC was going to destroy our planet, it would have been destroyed many billions of years ago, just after it was formed.


What I find strange about this is not that people think we could destroy the world with science. Of the ways the world might end that I’ve heard of (where world is defined as “humans”), the most likely seems to be nuclear war. The surprising bit is that people think we could out-do nature itself in terms of the scale of destruction. There are places in the universe where collisions much, much, much more powerful than anything we will ever produce on Earth occur regularly. We’ve gotten pretty good at making particle accelerators – the LHC is an incredible accomplishment – but we still have nothing on, say, quasars.

I was reminded of this by the appearance of a new paper on the arxiv rebutting yet another claim that black holes would eat The Earth. The fun never stops.

Oh, and the folder titled “Scientific Eschatology”? It was empty.

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