Monthly Archives: January 2010

Don't Call Him a Prophet

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NASA’s Prophet Will Give You Nightmares

Professor Hansen has been driven into a strange situation, and produced a strange book. For one-third of a century now, this cantankerous scientist has been more accurate in his predictions about global warming than anyone else alive. He saw these disastrous changes coming long before others did, and the U.S. government has tried to censor or sack him for his prescience. Now he has written a whistle-blower’s account while still at the top: a story of how our political system is so wilfully, deliberately blind to environmental realities that we have no choice now but for American citizens to take direct physical action against the polluters. It’s hardly what you expect to hear from the upper echelons of NASA: not a call to the stars, but a call to the streets. Toss a thousand scientific papers into a blender along with All the President’s Men and Mahatma Gandhi, and you’ve got this riveting, disorienting book.

A Little Smack

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Laser Smackdown: The Most Amazing Use of a Laser?

Chad asks the question in general, but I am going to personalize it. I’ve had the opportunity to do some neat things with lasers, mostly related to laser cooling and trapping. I’ve trapped K-37, K-38(m), K-40, K-41, Rb-85, Rb-87, and Cs-133 (the first two of those being radioactive isotopes with half-lives of around one second) and in each case, made a slow atomic beam to send the atoms somewhere else so we could use them for whatever reason depending on the experiment. Making state-of-the-art atomic clocks? Pretty cool. I’ve made holograms, which are a not-too-shabby use.

But the neatest thing I ever did happened in grad school, while we were still building up to cooling and trapping. There was a science summer school in session, and our lab set up a demonstration: we took our home-built lasers and modulated the current being sent to them by tapping in to the output jack of a boombox. Then we sent the beam across the lab and onto a photodiode, and sent the AC output into another boombox. Music sent across the room on a beam of light! Essentially fiber-optic data transmission without the fiber, so we could show the students that blocking the beam stopped the music, and while this is standard (even boring) today and wasn’t really new even then, I thought it was the coolest thing I had ever done (to that point, anyway).

ML8 ML8

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(License Plate of a White VW Rabbit)

OK, I am a little embarrassed to be more than fashionably late to the blogohedron party, but this is the 50th anniversary of the laser, and the APS (and some partners) have launched the laserfest website, with lots of stimulating, coherent goodness. Also, Jennifer gives us the festival of lasers

Jennifer points out that

There are several different types of lasers. Solid-state lasers use crystals whose atoms are arranged in a solid matrix, such as ruby. CO2 lasers emit energy in the far-infrared and microwave regions of the spectrum. This type produces intense heat, and is capable of melting through objects. Dr. Evil coveted such a laser when he demanded “sharks with frickin’ laser beams” on their heads to torture Austin Powers to death – only to be foiled because sharks are an endangered species. Imagine his disappointment if, in addition to having to make do with cranky mutated sea bass, they were equipped not with CO2 lasers, but with conventional diode (semiconductor) lasers. These are the type used in pocket laser pointers and CD and DVD players. They are not even remotely lethal.

But beware. Semiconductors aren’t all wimpy — you can get fairly high power diode lasers, and amplifiers that will put out a respectable amount of power. Generally these amplifiers are tapered so the the output beam is larger than the input, so you don’t blow the device up, and the output facet is antireflection coated so that the gain is single-pass (it won’t lase very well on its own). A Watt (or several) of laser power may not be lethal, but it can burn you nicely if it’s focused down, and I have empirical data to back that up. It can also do retinal damage, and that can ruin your whole day.

Remember, kids: Do Not Look Into Laser with Remaining Eye

Pinch Me

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Levitating magnet brings space physics to fusion

The results, published this week in the journal Nature Physics, confirm the counter-intuitive prediction that inside the device’s magnetic chamber, random turbulence causes the plasma to become more densely concentrated — a crucial step to getting atoms to fuse together — instead of becoming more spread out, as usually happens with turbulence. This “turbulent pinching” of the plasma has been observed in the way plasmas in space interact with the Earth’s and Jupiter’s magnetic fields, but has never before been recreated in the laboratory.

I Yam What I Yam

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BREAKING: Popeye Admits To Spinach Use

“I wish I had never touched spinach,” Popeye said in a statement. “It was foolish and it was a mistake. I truly apologize. Looking back, I wish I had never sailed during the spinach era.”

Popeye also used broccoli, a person close to Popeye said, speaking on condition of anonymity because Popeye didn’t include that detail in his statement.

If the other allegations are true, this certainly explains the Tasmanian Devil’s ‘roid rage episodes.

The Outfielder Problem

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And by that I don’t mean Manny Ramirez.

How Does an Outfielder Know Where to Run for a Fly Ball?

To test three theories that might explain an outfielder’s ability to catch a fly ball, researcher Philip Fink, PhD, from Massey University in New Zealand and Patrick Foo, PhD, from the University of North Carolina at Ashville programmed Brown University’s virtual reality lab, the VENLab, to produce realistic balls and simulate catches. The team then lobbed virtual fly balls to a dozen experienced ball players.