1 post from March 2008

In my research class, we had Prof. Lathrop come to speak for us today to demonstrate effective "talk" techniques in presenting research findings. I had previously seen him in the "Magnetic Storm" NOVA special, so I was pretty excited during his talk. He was admittedly, much calmer than the PBS documentary which hinted that we were all on the verge of getting cooked by solar radiation due to the steep decline/inevitable reversal in the earth's magnetic field. He was also much more detailed about the specs on the liquid-sodium dynamo models that the lab has been working on than NOVA was, so that was a bonus for me.

(A very basic overview of the topic if you can't be bothered to read his webpage or read the show's transcript:
 

• Earth's magnetic field is theorized to result not from a giant bar magnet (ahahaha) but rather from the dynamo theory -- electric currents from Earth's molten outer core is organized by the convection from the outer core and the Coriolis effect into N-S oriented magnetic "rolls" (fields). Moving conducting material across these "rolls" creates more electrical current, creating more magnetism, etc etc etc blah blah Faraday and Maxwell and Gauss are awesome dudes blah blah, resulting in a self-sustaining dynamo.
• The magnetic field covers the Earth (aka "magnetosphere") keeping lots of solar radiation away from us -- except a bit at the poles, where you get those lovely auroras.
• Earth's magnetic fields switches it up every 300,000 years or so. We know this because this switch shows up in volcanic layers, ancient pottery, In fact, we know that the magnetic North Pole drifts around a bit.
• We also know that the Earth's magnetic field has declined about 5% in the last century or so.
• It would be nice to predict how the fields are going to shift, so that we don't accidentally fry too many satellites and astronauts.)

I was really curious as to why the dynamo models required an outside field before it started up its own field. He said that at the scale that they're working on, it isn't possible. :sigh:

What's interesting is that every time he starts to examine the issue of magnetoturbulence*, his dynamo models result in something else, something just as interesting. He made a great statement saying that scientists should observe naively without hoping for "their" results, because explaining what results could be even more interesting in the end. In one of the experiments, the model produced inertial waves, which made the magnetic fields sound like this:

Isn't that lovely?

*which admittedly sounds less hysterical that "OMFG! THE EARTH IS SWITCHING IT UP! WE ARE PWNED BY RADIATION!"