Because you can

I was just having a conversation on Friday with someone about a bunch of Google employees who had ordered up a ridiculous amount of silly putty so they could do an experiment with dropping it from a great height. As someone educated in a faculty of engineering, this made tremendous sense to me: I’ve done my own experiments with various brands of superballs to determine the height at which they cease to bounce back and instead more-or-less turn to dust on impact1, and perhaps the less said about the “end of the week cafeteria jello drop” experiments the better.

But, those Googlers have nothing on the groups of mostly-German-but-hey-England-and-France-also-get-a-look-in researchers who recently performed the mother of all “drop it from a great height” experiments.

First of all, it turns out that ZARM has a 150m tower built expressly for researching dropping things. Right there we’re into awesome.

Second of all, though, is what they dropped. Their drop capsule was a Bose-Einstein condensate produced by cooling a gas of rubidium atoms to nine billionths of a degree above absolute zero. (Don’t worry, they aren’t going to splat it, at the bottom of the drop is an eight-meter-deep pile of polystyrene balls breaks the capsule’s fall.)

Now, they will tell you that there are very important and serious reasons for doing this, like these:

The experiment could lay the groundwork for BEC experiments in the weightless environment of space, where the quantum wave nature of the condensates might be used to create ultrasensitive matter interferometers, in much the same way that atoms are already used in such devices to probe minute physical effects. In the optical realm, interferometry usually relies on lasers; BECs are often compared to lasers in the way that they each represent a coherent collection of quantum objects—photons for lasers, atoms for BECs. Interferometers based on BECs could one day reach orbit to probe the intricacies of spacetime curvature predicted by general relativity and perhaps shed some light on the interface between quantum mechanics and gravity.

(That’s from the Scientific American quick writeup. Those with journal access can read the paper itself wherein reasons include “During the expansion over 1 second, the atoms form a giant coherent matter wave that is delocalized on a millimeter scale, which represents a promising source for matter-wave interferometry to test the universality of free fall with quantum matter.” Admit it, you wish you had a job that allowed you to say “a giant coherent matter waye” as part of your working routine.)

Those are all good and valid reasons for researching Bose-Einstein condensates in microgravity, but let’s admit it–the biggest reason to drop a ball of super-cooled rubidium down a forty story shaft is because you can.

  1. Hotels build on the “rooms around the perimeter of a large open atrium” plan are excellent for this–a quality superball dropped from the 8th floor can easily make it back up as high as the 5th floor.(back)

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Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Canada
This work by Chris McLaren is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Canada.