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A New Spin On Physical Phenomena
f00Dave writes "Researchers have discovered "a new physical phenomenon, electrostatic rotation, that, in the absence of friction, leads to spin". I'm a bit skeptical about the implied relationship between physical "spin" (as in rotation) and quantum "spin", however. Still, this is the sort of scientific advance that renews my faith in the system. Go nerds! =]"
Hey, isn't that where they stick a piece of buttered toast to the back of a cat and let it rip?
I never could get that working. My damn cat always ate the toast.. the fat bastard.
If there can be no friction, then there can be no output. What usefulness does a spinning object with no output provide, anyway?
Life is the leading cause of death in America.
Sounds pretty cool. Does the object ever reach a maximum velocity or does it just keep on going? Where is the energy coming from?
Checking out my form of escapism.
I'm more excited about the "absence of friction" part...
At last my dream of building a perpetual motion machine can be realized. Take that thermodynamics!
This gives me renewed hope for my latest project, a hyperdrive engine built of old Spaghetti-Os cans and dental floss.
Roving Web-Teleoperated Robot
I don't understand this submission:
I'm a bit skeptical about the implied relationship between physical "spin" (as in rotation) and quantum "spin", however. Still, this is the sort of scientific advance that renews my faith in the system.
What system are we talking about? Why does faith need to be renewed in it? What, have you lost faith in physics because it doesn't discover new laws every day?
Maybe that's the cool thing about scientific curiosity - the things you discover don't have to have commercial value in order to be discovered.
Consider this: when it was determined that a current flowing in a wire produces a magnetic field, or when Faraday discovered that moving a magnet near a wire or coil of wire can produce a voltage, I'm sure a lot of people said, "but seriously, what would this be used for?" And they probably said the same thing about countless other things that were discovered in situations where the effect was so small that they had no apparent use.
Of course now we look back and say, "what a dumb question! How could they now know these things could be useful?" And maybe 200 years from now somebody will look at this archived announcement on Slashdot and say the same.
Then again, maybe this will turn out to be a misinterpretation of the experimental observation. Time will tell...
[b.belong('us') for b in bases if b.owner() == 'you']
It's Magic!
Oh wait, no, it's due to the Earth's rotation!
Um, no, wait, it's due to a combination of the Earth's rotation and its orbit around the Sun.
Yeah! That's it!, Yeah, I got it! Woohoo!
Actually, Stephen Hawking is expected to say "it's the spooky force at close proximity."
Honestly, between you and me, I think this will turn out to be as real as cold fusion.
Here's the journal article from Applied Physics Letters
The Applied Physics Letters paper is just two pages long. There is no new physics here. Here's the skinny.
Sphere A is charged up; the two others, B and C, are at different distances from A. Each sphere is polarized in a non-uniform way (because each sphere has two hemispheres, one closer to the charged sphere and the other farther... just as tides form on Earth due to the moon).
The potential at the surfaces of B and C might be uniform but the charge distributions are not: they are dipole. Due to this dipole interaction (the more negativey charge hemisphere of one sphere wants to be closer to the more positively charged surface of the other sphere), Spheres B and C then tourqe to a different angle and will either a) stay there in the presence of some friction or b) oscillate back and forth in the absence of friction. Of course, there is always some element of friction due to the air and wire, but one can compensate by also oscillating the potential of A to make positive feedback, I imagine.
The press release was, in this physics grad student's opinion, horrible. Implications that this research has some impact on our understanding of electrostatics or (gasp) quantum mechanics is irresponsible. It's a cute trick, though, and I'll bet it will find applications in mico-,nano-tech and perhaps other research areas (e.g. experiments requiring precision angular measurements ).
Nanotech basically. They have basically discovered a way to use a distribution of electric charges on a configuration of three sphere to start one of the spheres rotating. This is different from current electric motors; they use magnetic fields to start things rotating. This kind of engine would use a lot less current to generate motion than conventional electromagnetic motors. This would be good for building little machines; it's really hard to make electromagnets at the subatomic scale, but metallic spheres? Much easier. And static charge? It's hard NOT to get something with static charge on it down at that scale.
Having said that, this is purely a proof-of-concept thingy. What they did was just say, "Look, we can use this simple setup to create rotation". It's like they stuck a magnet near another magnet dangling on a string ang made it rotate. That's a long way from an electromagnetic motor, but it is a first step...
Aprocryphal story related to me by my academic advisor:
William Gladstone, the Chancellor of the Exchequer, was invited to witness a demonstration of Faraday's electrical equipment. Gladstone asked, "This is quite interesting, Faraday, but of what practical worth is it?" Faraday replied, "One day, sir, you may tax it."
.f00Dave
I think this is an example of an overly-zealous press release from a university employee trying to make it sound more exciting than it is. The actual article (+ errata) by the researchers can be found atp rog=normal&id=APPLAB000080000015002800000001&idtyp e=cvips&gifs=yes
http://ojps.aip.org/getabs/servlet/GetabsServlet?
Sorry, if you aren't browsing from an institution that subscribes to Applied Physics Letters, you probably won't be able to download the article for free. But I'll be happy to paraphrase what I understood from the article:
This phenomenon was purely predictable from Coulomb's law and Gauss's laws of electrostatic attraction/repulsion. Many of you should have learned about these in freshman physics. The spheres were arranged in an assymetric pattern, so rotation isn't breaking any kind of symmetry. If you arranged their spherical balls in a mirror image pattern, the rotation will reverse. The authors aren't trying to say they measured some kind of new mystical force that hasn't already been understood for 100's of years but simply that there could be an engineering application that no one had thought of before.
I'm inclined to agree with the original poster's comment that this has nothing to do with quantum mechanical spin.
It sounds like they're saying the angular velocity will increase if the rotation is frictionless.
Yup, thats what they said.
Why won't this phenomenon cancel out at equilibrium amount of friction and keep the object spinning at constant angular momentum forever?
They didn't say it wouldn't. Presumably that is what would happen.
I[t] should also accelerate an object with a small amount of friction but at a slower rate than a frictionless object.
Yup. In their experiment the wire supporting the sphere was applying a counter-torque, it was just small enough that the new force was able to overcome it. By calculating the amount of torque generated by the wire after the number of revolutions made by the ball, they would have the static force generated.
In any case, we're talking about building a perpetual motion machine here and throwing the first law of thermodymics out the window.
Not likely. The kenetic energy of the rotation is probably balanced by a reduction in the net charge on the object. What they've got is basicly a really, really weak electric motor. A charged object in free fall would probably increase its angular momentum until it didn't have any charge left (then gravitational effects would probably eventually bleed all that energy back off again).
What I wonder is if its reversable, so rotation can be converted into a charge on the object.