Monthly Archives: February 2009

A Glimpse Inside the Ivory Tower

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Guest Column: Letting Scientists Off the Leash

Where does the money come from to pay for our science? Mostly from the federal government — your tax dollars at work — and non-profit foundations. Income from grants written by professors is the single largest contribution to the Stanford University budget (the second largest is endowment income, and student tuition is a distant third). Stanford has an enormous endowment ($17 billion before the market crash) but applies it in a heavily leveraged manner — in other words, they tend to use it to prime the pump and not to support ongoing research programs.

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Air = Gravity

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Air equals gravity in movies (again)

No WAY. Air = gravity. No air = no gravity. How clearer could it be? This also happened in the movie Wall-E and I posted about it then. Basically, many people think that if there is no air there is no gravity. It sort of makes sense – if you are in space, there is no air and no gravity. Except that there IS gravity in orbit. And what about the moon? There is no air there, but clearly there is gravity.

Insignificant Next to the Power of the Pants

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Top 278 Star Wars Lines Improved By Replacing A Word With “Pants”

I find your lack of pants disturbing.
Chewie and me got into a lot of pants more heavily guarded than this.
You came in those pants? You’re braver than I thought.
Governer Tarkin. I should have expected to find you holding Vader’s pants.
Tell that to Jabba. If you’re lucky he might only take your pants.

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Follow the Bouncing Atom

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Bouncing atoms take a measure of gravity

Pretty cool. The experiment uses a technique used in interferometry, where a laser standing wave induces an absorption-emission cycle of an atom, so it receives a momentum “kick” of twice the photon momentum (one kick for absorption, and once for emission), effectively making a diffraction grating out of light if they were moving through the standing wave, and uses this to bounce the falling atoms.

If the colour of the laser light and the frequency of pulses are set correctly, the atoms will be set bouncing and the acceleration due to gravity can be deduced from the experimental parameters and Planck’s constant. The team managed to sustain this bouncing for about 100 cycles, which they say is the equivalent of dropping the atoms about 2 cm in a standard experiment.

ArXiv link

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Come in Here, Dear Boy, Have a Cigar

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By the way, which one’s Pink?

The Factual One ponders The physics of… Pink Floyd?

What’s more interesting is the fact that the refractive index is generally not a constant. Within the same material it can be different for different wavelengths. Usually – but not quite always – higher frequency light experiences a higher refractive index. It gets bent harder. It’s not obvious at the level of classes I teach why this should be so. Since the details aren’t really the key issue, the main thing to remember whether it’s high frequency or high wavelength that gets bent most strongly. It can be difficult to remember, until I remind the class about this:

[cue Dark Side of the Moon album cover]

More discussion at The Quantum Pontiff