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! =]"

Comments

Re:Sponataneous Spinning?

[k3v0]

the site says it spins until the tension of the thin metal wire gets too high

Why only frictionless?

[Jason1729]

It sounds like they're saying the angular velocity will increase if the rotation is frictionless. Why won't this phenomenon cancel out at equilibrium amount of friction and keep the object spinning at constant angular momentum forever? I should also accelerate an object with a small amount of friction but at a slower rate than a frictionless object.

In any case, we're talking about building a perpetual motion machine here and throwing the first law of thermodymics out the window. This makes the cold fusion claims sound pretty tame. At least they said where they were getting their energy, here it seems to come from nowhere.

Jasom
ProfQuotes

Re:Why only frictionless?

[Anonymous Coward]

From the article:
"When a DC voltage was applied to the spheres..."

There's an external power source. This is NOT a "perpetual motion" machine.

Exactly

[Anonymous Coward]

The article even says:

"It is very satisfying to learn that electrostatic rotation can be predicted by the simple laws of voltage and force that date back at least 200 years," Wistrom said.

So there's no discovery here. No new physics. The article goes as long way to imply there's some kind of mysterious new physics involved.

How many other scientists get to show their balls online?

Re:Sponataneous Spinning?

[gunnk]

According to the article the answers are:

a) it spins until the tension in the wire counters the rotational force, and

b) the energy comes from the DC voltage they applied to the setup.

the real article

[awaspaas]

Here's the journal article from Applied Physics Letters

Re:the real article

[zCyl]

Or here if you don't like pdf's.

The article shows much more clearly than the pop news release that the rotation has nothing to do with quantum spin, and is entirely a classical electrostatic phenomenon. I will try to translate the article briefly:

Essentially, when you apply a charge to the first of the three metal spheres, the charges all repel each other and go to the outside of the first sphere. This exerts a repulsive force against the like charges on the other two spheres, causing an imbalance as more charges are pushed to the far side of the spheres (from the first one) than are on the close side of the spheres. Then, because the second and third spheres have an imbalanced charge distribution, they also exert forces on each other which further displace the charges.

The displaced charges result in a potential which isn't perfectly balanced like two spheres would be, and the resulting calculation shows an interaction proportional to 1/(r^6), where r is the separation distance, which yields a rotation.

Re: quantum vs classical spin

[TeknoHog]

There's a good reason why the quantum spin was named spin in the first place: A charged particle with spin exhibits a magnetic moment, and so does a rotating charged sphere. However, electron spin is quantized differently from rotation, so we know it's not really rotation.

Re:i dont get it

[Anonymous Coward]

Relevant detail is available at http://www.engr.ucr.edu/~wistrom/

APS article

[imkonen]

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 at
http://ojps.aip.org/getabs/servlet/GetabsServlet?p rog=normal&id=APPLAB000080000015002800000001&idtyp e=cvips&gifs=yes
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.

Re:ObSimpsons

[unicron]

Yeah, we all raced to get that one in. Bastard. My only is to provide the entire scene:

That night, in bed...

Marge: I'm worried about the kids, Homey. Lisa's becoming very obsessive. This morning I caught her trying to dissect her own raincoat.
Homer: [scoffs] I know. And this perpetual motion machine she made today is a joke! It just keeps going faster and faster.
Marge: And Bart isn't doing very well either. He needs boundaries and structure. There's something about flying a kite at night that's so unwholesome. [looks out window]
Bart: [creepy voice] Hello, Mother dear.
Marge: [closing the curtains] That's it: we have to get them back to school.
Homer: I'm with you, Marge. Lisa! Get in here. [Lisa walks in, chuckling nervously]In this house, we obey the laws of thermodynamics!
-- The last straw, "The PTA Disbands"

look at it from this "angle"

[EEgopher]

I see hidden importance in the exact placement of the spheres, the angles and distances at which they are separated, which are not explained in the article. What I see happening is the spheres being positioned in such a way that the Coulomb forces act primarily (entirely?) in a tangential fasion on the two free-floating spheres, resulting in net rotation instead of net axial displacement. Could be merely a trigonometric stunt rather than new electrostatic observations.