Give 'Til it Hurts

NASA Wants Your Urine

Yes, you read that right: NASA needs your urine.

The drive is to benefit NASA’s fledgling Orion Program, which aims to put astronauts back on the moon by 2020. The pee drive is to help engineers working on designing the new spaceship’s toilet.

I’ve got other NASA-related news, but I’m holding that in until tomorrow, even though I’m bursting to tell you.

Looking for Energy in all the Right Places

Bionic bra: Victoria’s circuit

An attempt to harness, as it were, the kinetic energy stored in the ones that bounce.

It turns out that the physics of breast motion has been studied closely for the last two decades by a gamut of researchers – most of them women.

Formally, perhaps.

Lawson explains that breasts move on three different axes: from side to side, front to back, and up and down. The most motion is generated on the vertical axis. Naturally, the bigger the breast, the more momentum it generates. “Let’s face it – if you’re a double-A marathoner, you’re probably not going to get that iPod up and running,” Lawson says. Measurements compiled by Lawson and her colleagues show that a D-cup in a low-support bra can travel as much as 35 inches (89cm) up and down (35 inches!) during exercise, while a B-cup in a high-support bra barely moves an inch.

Again, something that a motivated amateur scientist might have also observed.

via O, Teh Interwebz!

Photons Think

Because we can get them to concentrate. MIT opens new ‘window’ on solar energy

“Light is collected over a large area [like a window] and gathered, or concentrated, at the edges,” explains Marc A. Baldo, leader of the work and the Esther and Harold E. Edgerton Career Development Associate Professor of Electrical Engineering.

As a result, rather than covering a roof with expensive solar cells (the semiconductor devices that transform sunlight into electricity), the cells only need to be around the edges of a flat glass panel. In addition, the focused light increases the electrical power obtained from each solar cell “by a factor of over 40,” Baldo says.

The factor of 40 is in reference to the light collection, not solar cells themselves, i.e. you are collecting 40 times as much light as you’d get from the area of the edge of the sheet — there’s no comparison to what you’d get if the whole sheet were a solar cell. The action of the collector is much like my clipboard, except the dye is on the surface rather than inside the material. The advantages here would be in reducing the area of the solar cells needed, which are presumably much more expensive, and that some light would still be usable on the other side of the collector.

And Now For Something Slightly Different

The previous MOT video showed the atoms squirting out of the side when the trapping field was turned off. In this video things are more balanced, and you can see the atoms remaining in the beam overlap region, and fluorescing quite brightly. The trap is cycled on and off and you can see the trap “grab” the atoms and pull them back to the center; when the trapping field is left off it takes several seconds for the cloud to dim as atoms diffuse out, and that’s a qualitative sign that the atoms in the molasses are pretty cold. Probably tens of microKelvin.

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“Mr. Hands” is pointing out the trap axis at the beginning, as a cue to the person adjusting the trimming magnetic field. This kind of adjustment can be very laborious, as there are several parameters which need to be optimized, and they aren’t independent of each other. Beam alignment, magnetic field and beam intensity all need to be optimized, but all exert forces which can be offset by one of the the parameters, e.g. a slight imbalance in intensity can be offset by a small magnetic field, and the small amount of swirling of the atoms when the trap is turned off is likely an indication that this is the case.

However, at this level of adjustment, the atoms are the best indicators. An optical power meter or a magnetic field probe aren’t going to yield the precision necessary — they can only get you close. At this point you just have to wander around phase space, checking that you aren’t merely at a locally optimum signal. The true test comes when you can actually measure the temperature of the atoms, by imaging them in time-of-flight and seeing how much the cloud has expanded.

Finger on the Button

Kill Switches and Remote Control at Schneier.

Don’t be fooled by the scare stories of wireless devices on airplanes and in hospitals, or visions of a world where no one is yammering loudly on their cellphones in posh restaurants. This is really about media companies wanting to exert their control further over your electronics. They not only want to prevent you from surreptitiously recording movies and concerts, they want your new television to enforce good “manners” on your computer, and not allow it to record any programs. They want your iPod to politely refuse to copy music to a computer other than your own. They want to enforce their legislated definition of manners: to control what you do and when you do it, and to charge you repeatedly for the privilege whenever possible.
“Digital Manners Policies” is a marketing term. Let’s call this what it really is: Selective Device Jamming. It’s not polite, it’s dangerous. It won’t make anyone more secure — or more polite.

The Camera Adds Ten pounds

How many cameras are you wearing? (Chandler, to Monica)

candid camera, over at Cocktail Party Physics.

Richmond’s main hypothesis, however, was that the effect stems from the fact that the camera only has one “eye” (i.e., the lens), whereas human beings have two eyes, roughly 7 to 8 centimeters apart. The camera, it seems, lacks depth perception. The result is a kind of “flattening” effect that can make objects seem wider in photographs.

Shove Off

The other day Matt over at Built on Facts had an interesting post, “Pushing Things in Space.” And while it’s rocket science, it’s not really rocket science. It’s Newton’s Third Law in action (and reaction), which is first-semester physics.

There is a lovely scene where the titular robot [Wall-E] uses a fire extinguisher to propel himself through the vacuum of space. There’s no sense in critiquing the physics of a gentle animated film, but it gives us an opportunity to talk about the principal challenge of moving about in space – there’s nothing to push against. On earth you push against the ground with your feet while walking, or with your tires when driving. If you’re in an airplane, the propellers or jet engines pull in still air in front of the plane and push it out the back at high speed. Boats do the same thing with water. It’s just Newton’s laws in action.

Down in the comments, CCPhysicist, aka Dr. Pion, has the real content I want to dissect.

Your remark, “the principal challenge of moving about in space – there’s nothing to push against”, is false. The statement “If you want to push against something, you’ll have to bring it with you” is closer, but still conveys a false concept common in students.

Pushing on the ground does not make you move. It is the ground pushing on you that changes your motion.

I don’t think the statement is false. I think it’s easily misconstrued and is often found to be confusing from the perspective of a beginning student or a reporter. It reminds me of that famous quote that appeared in the New York Times years ago, critiquing Robert Goddard

That Professor Goddard with his ‘chair’ in Clark College and the countenancing of the Smithsonian Institution does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react–to say that would be absurd. Of course, he only seems to lack the knowledge ladled out daily in high schools.

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