From Physics

And The World is Still Here

Huge, and fantastic, news: The LHC has had COLLISIONS.

Geneva, 23 Nov (THAINDIAN NEWS) Today the LHC circulated two beams simultaneously for the first time, allowing the operators to test the synchronization of the beams and giving the experiments their first chance to look for proton-proton collisions. With just one bunch of particles circulating in each direction, the beams can be made to cross in up to two places in the ring. From early in the afternoon, the beams were made to cross at points 1 and 5, home to the ATLAS and CMS detectors, both of which were on the lookout for collisions. Later, beams crossed at points 2 and 8, ALICE and LHCb

I wish to also point out that no black hole was created that swallowed us up and the earth did not just explode, in other words the LHC did not kill us. YAY!

100 Year Old Aftershocks?

Great now we get to be freaked out not only by recent earthquakes, but also by earthquakes from 100s of years ago. Thanks a lot science.

Large earthquakes are often followed by aftershocks, the result of changes in the surrounding crust brought about by the initial shock. Aftershocks are most common immediately after the main quake. As time passes and the fault recovers, they become increasingly rare. This pattern of decay in seismic activity is described by Omori’s Law but Stein and Liu found that the pace of the decay is a matter of location.

At the boundaries between tectonic plates, any changes wreaked by a big quake are completely overwhelmed by the movements of the plates themselves. At around a centimetre per year, they are regular geological Ferraris. They  soon “reload” the fault, dampen the aftershocks, and return the status quo within 10 years. In the middle of continents, faults move at less than a millimetre every year. In this slow lane, things can take a century or more to return to normal after a big quake, and aftershocks stick around for that duration.

Stein and Liu’s study could help scientists to more accurately predict the risk of future earthquakes, especially in unexpected areas. If they’re right, then it would be positively misleading to base such assessments on small quakes that could sometimes be aftershocks of historical events. In the longer term, Stein and Liu predict that such approaches will “overestimate the hazard in some places and lead to surprises elsewhere”. The disastrous earthquake that hit China’s Sichuan province in May 2008 highlights the catastrophic impact that unexpected mid-continent quakes can have. (Not Rocket Science)

And I Thought All Physicists Worked on the LHC

Chad Orzel has an illuminating article up up on his blog Uncertain Principles talking about the misconception the media has that all physicists do high energy particle physics and then talks about the things that keep low energy experimenters up at night(spoiler: it does not involve blowing up the solar system or accidentally creating black holes that will swallow our planet). From the Article:

Taking Data: I’ve done my share of late-night data acquisition, mostly for a combination of the second and third reasons above. In grad school, the main experiment I worked on took data on 45-minute cycles, which needed to be paired up, so the time for a single useful data set was an hour and a half. That involved a lot of late nights at NIST.

Planning Experiments: The one time I vividly recall being kept up at night by a physics problem, I was trying to do calculations in my head to determine whether I ought to completely and radically revise a grant proposal to do a different sort of experiment than what I had planned. This was a week or so before the deadline, and it had occurred to me that I could use my proposed apparatus to do a slightly different sort of experiment than that described in the many pages worth of proposal that I had already written.

I spent a couple of hours lying in bed, trying to do calculations in my head to determine whether I could reach the temperatures and sensitivities required to make the measurements needed. This didn’t actually get anywhere– I ended up having to call a couple of other people on the phone, before deciding that it wasn’t a sure enough thing to justify the hasty re-writing– but it definitely did keep me up at night.

So there’s a list of physics-related things that have literally kept me up at night. You’ll notice that none of them involve particle physics, quantum gravity, or multiple universes– while the Big Questions are interesting, they’re generally too abstract to keep me engaged at the level necessary to keep me up late. If you suggest a way to answer one of those questions with a low-energy AMO physics experiment, I’ll happily lose sleep trying to make it work, but absent some tangible connection to empirical reality, I’m just not interested enough to stay up past my bedtime.

I suggest going and checking out the rest of the post if you really want to know what keeps regular physicists up at night.