Scientists Levitate Mice for NASA 237
sterlingda writes to tell us that scientists have built a mouse-levitating superconducting magnet, working on behalf of NASA to study variable levels of gravity. The group hopes to ascertain what physiological impacts prolonged exposure to microgravity might have. "Repeated levitation tests showed the mice, even when not sedated, could quickly acclimate to levitation inside the cage. After three or four hours, the mice acted normally, including eating and drinking. The strong magnetic fields did not seem to have any negative impacts on the mice in the short term, and past studies have shown that rats did not suffer from adverse effects after 10 weeks of strong, non-levitating magnetic fields."
Been done before... (Score:5, Informative)
For those who like pics... (Score:3, Informative)
Looks more like a cheese shredder than a large, scientifically purposed apparatus.
Re:Been done before... (Score:4, Informative)
From TFA:
Other researchers have made live frogs and grasshoppers float in mid-air before, but such research with mice, being closer biologically to humans, could help in studies to counteract bone loss due to reduced gravity over long spans of time, as might be expected in deep space missions or on the surfaces of other planets.
Re:no side effects?! (Score:5, Informative)
Re:B-b-b-but, EM radiation! (Score:4, Informative)
Cell phones operate at different frequencies and different power levels than the apparatus used in this experiment, so the lack of adverse effects on the mice does not really say anything about the effects of a cell phone on mice (or humans).
Re:Sounds fun! (Score:1, Informative)
It took 16 Tesla to float a frog, so it would take about 150kT to levitate a human. The strongest field created by man was 2.8kT, but was a single pulse and created with explosives. The strongest continuous field was 45T so good luck waiting for the scale-up.
http://en.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_field) [wikipedia.org]
That said, I'd wait to see the long term physiological effects on the mice. It's possible that any cellular damage would scale up as well...
Re:Sounds fun! (Score:4, Informative)
That isn't how it works. The same fieild intensity that levitates a mouse would levitate a person. However, the volume throughout which the field is of constant intensity would have to be scaled up and the energy stored in the field is proportional to volume so your number may not be too far off if seen as a measure of the size and cost of the magnet.
Re:Seriously, Slashdot? (Score:4, Informative)
This is actually a discussion site, not a news site. We come here for the discourse and the surprisingly effective moderation system.
Re:B-b-b-but, EM radiation! (Score:3, Informative)
The field in this experiment isn't EM radiation at all. It's just a (really big) magnet. There is no time varying component (it has no frequency) so it does not have an electric component (look up Maxwell's equations). This has as much to do with EM radiation as a cup of water on your desk has to do with the waves on the ocean.
That said, if you move a wire through it, you'll generate one hell of an electic field, but only while the strength of the magnetic field through the wire is changing.
Re:bipolar mice? (Score:5, Informative)
For that matter, why does anyone think it's normal for humans to eat cow secretions?
Ah; now that's a more interesting one. Once upon a time it wasn't normal [bbc.co.uk] however, (almost certainly, unless you are a freak or are Chinese) you and your genetically dominant have been taking advantage of a recent gene mutation [scientificamerican.com] to make that normal.
Re:Been done before... (Score:1, Informative)
Read more carefully. It said experiments with rats in strong, but non-levitating magnetic fields showed no adverse effects (over some time span).
Re:I've done similar experiments before... (Score:3, Informative)
Not sure about the squirrels, but others have great success putting Linux on dead badgers [strangehorizons.com]. That may be cross-compilable to squirrels, but you'd definitely need the memory stick version, just from space concerns.
Re:bipolar mice? (Score:4, Informative)
I have kept mice as pets and while they will eat cheese they prefer nuts,fruits and breads.
Re:bipolar mice? (Score:5, Informative)
That's begging the question. By definition, whatever humans do as a species is ipso facto *normal*. What is considered normal will change over time though.
Re:bipolar mice? (Score:3, Informative)
Re:Sounds fun! (Score:5, Informative)
With 16T, you can levitate an object of any size so long as it predominantly consists of water. It's not like a 1g frog will float, but a 2g frog will fall in the same magnetic field. The reason why the things floated are small is because its easier to make small magnetic fields. If you have a current going around a loop, and you double the radius of that loop, your peak magnetic field drops by a factor of 4. You do not need 150kT to levitate a human. You just need a magnet that is physically larger with the same field strength and geometry.
One more thing. It's not just the magnitude of the magnetic field that controls whether something will levitate or not. The key is that the magnetic field gets weaker as you move up. Wikipedia [wikipedia.org] tells me that levitation power is proportional to B*dB/dZ. (the magnitude of the field times how quickly it diminishes as you move upward) That is to say, if you had a 150kT magnetic field, and it was constant everywhere, you wouldn't float in it.
How this works (Score:5, Informative)
Regarding gradients: The gradients used in MRI vary in *position*. Yes in time, as well, but only because they are pulsed. We can ignore ramping issues to first order. Since the field varies as a function of position, when you move around, indeed the flux is changing which can induce currents in looped conductors so as to oppose the change. This is called induction. Many people, my self included, notice a strange sensation when first entering an MRI magnet. This is because the field is only homogeneous over a relatively small volume, outside of which there are once again field gradients (these are different than the intentional field gradients used to obtain an MRI image). It is probably not axons but something in the ear that is picking this up, I am not sure. Also, field strength has *nothing* to do with this effect. It's how fast the field changes as a function of position, i.e. the gradient, combined with the velocity of the pickup object.
Regarding repulsion: Water is diamagnetic. That means that the little spins (i.e. electrons) orbiting the atoms of a water molecule tend to align *against* the applied field direction. These spins will experience a repulsive force, hence the levitation.
Re:bipolar mice? (Score:2, Informative)
"rotten" is an emotionally loaded term, but fundamentally cheese is a cultured food.
No culturing necessary: milk proteins precipitate at low pH, and that's all you need to make cheese. A little proteolysis with papain, chymosin, etc, will change the character a little, as will pressing and culturing, but all you really need to do is precipitate the proteins. It's easy [chow.com]