Only in Quantum Physics: Spinning While Standing Still

NY Times ^ | September 21, 2004 | KENNETH CHANG

[PatrickHenry]

Science list Ping! This is an elite subset of the Evolution list.
See the list's description in my freeper homepage. Then FReepmail me to be added or dropped.

[GSlob]

"...scientists believe this will lead to such inventions as 'super beer', or beverages that can be drunk faster than their hotter counterparts..."
Trouble is that as long as "super beer" keeps its zero viscosity, nobody would be able to hold it, but would start leaking it immediately, without any time to go to the john. What a bummer.

[farmfriend]

bttt

[NewJerseyJoe]

> Only in Quantum Physics: Spinning While Standing Still

Not true! Not only in quantum physics -- cBS has been spinning and standing still for the last week and a half.

[GOPJ]

Thanks for the ping.

[Alamo-Girl]

Thanks for the ping!

[Virginia-American]

I saw pictures of this years ago:

(Nonusperfluid) liquid He4 was spun on a turntable. When it was cooled to a superfluid, very thin vortices appeared, running from top to bottom. 6 or so, more-or-less evenly spaced, marching around the container.

The explanation was that He4 has spin 0 and is therefore incapable of rotation; in the superfluid state, the mass of He4 acts as though it were a single atom, incapable of rotation (IIRC, the superfluid's momentum is zero, so the location of the individual atoms is indeterminate by the Uncertaintity Principle). The vortices are hollow, so in a sense nothing is rotating, yet angular momentum is conserved.

Google search turned up Feynman's Theory of the Superfluid Bose-Einstein Condensate which says among many other things

Paradox of rotating buckets of superfluid.

Rotate an ordinary liquid uniformly in a bucket. The shape of the free liquid surface is parabolic from the gravity and the centrifugal force with curvature omega^2/2g, where omega is the rotational rate and g is the acceleration of gravity. The two-fluid model predicted a different reult that would depend on temperature since only the normal component should have any viscosity like the ordinary liquid. In fact, the rotating bucket of superfluid has the same parabolic profile for the free surface as does the ordinary liquid! Why is the zero viscosity superfluid also rotating? Feynman suggested a uniform distribution of quantized vortex lines parallel to the axis of rotation of the bucket like the magnetic field inside a long straight coil. The number density of lines was 2m omega/h per unit area of the free surface. The mean spacing between the lines was b = (h/m omega)^1/2 -- a fraction of a milimeter in real experiments. ...

[LogicWings]

"Nothing here makes sense," he admitted.

I think the attempt at observation distorts the observation. We don't really know what is going on here. It is too far removed from our realm to fully understand.

As an aside, since I don't have time to keep up with this stuff.

What is, "Bttt?"

[PatrickHenry]

As an aside, since I don't have time to keep up with this stuff. What is, "Bttt?"

Bump to the top. (Interstellar internet nerdspeak.)

[RightWingAtheist]

Art Bell is about as trustworthy as Algore when it comes to sound science. This has zero, zilch, nada to do with anit-gravity, and merely confirms experimentally what has already been known theoretically.

[Pete'sWife]

I've done that.

Then I quit drinking.

[TIGHTEN]

The guy Art Bell was interviewing discussed his experiments. He, not Bell, claimed a possible avenue to anti-gravity using this method.

And yes, of course I know there's goofy people on Bell's show, so what? That doesn't mean the guy wasn't correct. In fact, he was correct as this "official" experiment showed...the ring "appeared to lose mass." That's the same conclusion Bell's guest made.

I was merely pointing out that this experiment was not original.

[Calvin Locke]

Spinning while standing still...

I read that Hawkings book a few years back. He had a chapter on spinning particles. Like one that had a 1/2 spin - it had
to spin twice to see it once. Or that's the best I can remember.

[RightWingAtheist]

It appears to lose mass but it doesn't actually do so. It all has to do with the fact that at very low temperature, matter acts funny, in ways we're not accustomed to at "normal" temperatures. Einsteins's good ole'E=M*C(squared) tells us that you can't get rid of mass without expending or releasing a LOT of energy, so that's clearly not what's happening here. The most likely explanation-and I'm no scientist either, but I am following from the article, and there are plenty of scientists here who will correct me if I make a serious misstep-is that as the helium slows down, its atoms spread out like a Bose-Einstein condensate, filling the empty spaces which normally exist between them. The helium doesn't lose mass, but instead has it more widely distributed. Imagine holding two rubber balls, one in each hand, which are made of the exact same amount of material, but one of them is solid, and small enough to rest in the middle of your palm, while the other one is hollow, and so large that you can barely cup your fingers around it. The larger ball will also seem to be lighter than the larger one, even though it weighs exactly the same, because its mass will be more spread out. That's probably what is happening to the helium in this experiment.

[RightWingAtheist]

Ping on #34; let me know if I've said anything foolish.

[Physicist]

as the helium slows down, its atoms spread out like a Bose-Einstein condensate, filling the empty spaces which normally exist between them. The helium doesn't lose mass, but instead has it more widely distributed.

Virginia-American was on the right track in his post. There is no mass loss, and distribution has nothing to do with it. What happens, unless I am mistaken, is that 15% of the solid goes into a spin-0 Bose-Einstein condensate. This part of the mass can have no angular momentum other than zero. (Aside: I wonder how this would appear under the Lense-Thirring effect?) When the researchers attempt to impart angular momentum to the solid as a whole, this percentage of the solid is "tone deaf" to the imparted rotation. As a result, the moment of inertia changes discontinuously. It's like the condensed 15% isn't even there, as far as rotation is concerned.

What TIGHTEN was referring to was probably the apochryphal "Podkletnov effect" (Google it up). No serious scientist has been able to reproduce Podkletnov's claims.

[RightWingAtheist]

Thanks

[RightWingAtheist]

BTW, my turn to correct you. The article said 1.5% instead of 15% :-) Once we figure out the whys and hows of this 1.5%, I wonder if we'll be to put a greater percentage of an equal amount of helium used in this experiment into this state, and see what interesting effects turn up.

[RightWingAtheist]

I think this page here will help explain things. You have to scroll down a bit to read the discussion of helium superfluidity, but it's worth it for the lay reader to slowly make your way through, to grasp an understanding of the theory behind the experiments. Yes, understanding superfludity is helping us to explain gravity, according to this article, but it is not leading us to antigravity.

The diagram above is from the article, and simply illustrates the phenomenon in the demonstration which V-A was talking about. The actual superfluid gyroscope the schema is supposed to represent, however, was one centimeter square in size, and rested on a single silicone chip.

[TIGHTEN]

Physicist, you are correct. The "Podkletnov effect" was the discussion I heard. So I was very wrong on all counts, including an essential detail I didn't recall; the experiments were conducted with an electromagnetic field as a catalyst for producing the supposed "gravity shield."

RWA, thanks for the link, I will check it out tonight...whether I understand any of it is another story:) I've only read one book on quantum physics, Shroedingers Cat.