Wednesday, July 20, 2005

he's dead, Jim

James 'beam me up, Scotty' Doohan died today, although I seem to recall that he turns up again sometime in the future... but that may be in some other time-line or parallel universe, I'm not sure.

I just read that the Milwaukee School of Engineering granted Doohan an honorary degree because his role as Chief Engineer of the Starship Enterprise inspired many students to study engineering. I can't say that he was what inspired me, but he was responsible for harshing my mellow when I was studying semiconductor physics.

I was learning about the band gap, the electrical potential difference between an atom's valence band (basically 'bound electrons') and its conduction band (basically 'free electrons'). When particle-ish things like photons or electrons strike a material with enough energy they make an electron jump across the band gap, but if they don't have enough energy to cause a jump they just pass right through the material. This is why semiconductors work - bias them with enough energy and the electrons pop up into the conduction zone, and the semiconductor acts like a conductor.

Metals, on the other hand, don't behave like this. They've either got a negative band gap (all the levels sort of fuzzed together) or open spots in the valence band, which at reasonable energy levels means they effectively have zero band gap. This means they pretty much always catch particles that hit them. And that means no transparent aluminum.



Blogger Writermama said...

I remember the day, years ago, my good friend Robin left for the Star Trek convention in downtown Salt Lake. She was all dressed up, and James Doohan, the guest star there, ended up giving her a kiss on the right cheek. (She still remembers which cheek.) He also told her he believes there is "other life out there." Maybe he is visiting "them" now.
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