UC Riverside Researchers' Discovery Of Electrostatic Spin Topples Century-old Theory

RIVERSIDE, Calif. -- April 2, 2003 -- In a discovery that is likely to impact fields as diverse as atomic physics, chemistry and nanotechnology, researchers have identified a new physical phenomenon, electrostatic rotation, that, in the absence of friction, leads to spin. Because the electric force is one of the fundamental forces of nature, this leap forward in understanding may help reveal how the smallest building blocks in nature react to form solids, liquids and gases that constitute the material world around us.

Scientists Anders Wistrom and Armik Khachatourian of University of California, Riverside first observed the electrostatic rotation in static experiments that consisted of three metal spheres suspended by thin metal wires, and published their observations in Applied Physics Letters. When a DC voltage was applied to the spheres they began to rotate until the stiffness of the suspending wires prevented further rotation. The observed electrostatic rotation was not expected and could not be explained by available theory.

Wistrom and Khachatourian designed the study with concepts they had developed earlier. "Experimental and theoretical work from our laboratory suggested that the cumulative effect of electric charges would be an asymmetric force if the charges sitting on the surface of spheres were asymmetrically distributed," said Wistrom. "In the experiments, we could control the charge distribution by controlling the relative position of the three spheres."

Yet, for more than 200 years, researchers have known only about the push and pull of electric forces between objects with like or unlike charges. Since as early as 1854, when Thomson, later to become Lord Kelvin, theorized about an electric potential surrounding charged objects, scientists have concentrated on understanding how electric and magnetic phenomena are related.

"While Thomson's hypothesis of electric potential has brought enormous benefits when it comes to modern electromagnetic technologies, we now realize that his definition of electric potential was not exact," said Wistrom. "The effects are particularly noticeable when the spheres are very close to one another." (Electric potential is the ratio of the work done by an external force in moving a charge from one point to another divided by the magnitude of the charge.)

Indeed, the general applicability of Thomson's theory has not been tested experimentally or theoretically until now. In the Journal of Mathematical Physics, Wistrom and Khachatourian recently published the breakthrough that provides the theoretical underpinnings for electrostatic rotation. "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.

He added, "This is curiosity driven research that starts with a simple question and ultimately leads to findings that will likely have impacts across many fields of science and engineering. Because electrostatic rotation without friction leads to spin, we can only speculate how this discovery will provide new approaches to aid the investigation of fundamental properties of matter."

Spin is used in quantum mechanics to explain phenomena at the nuclear, atomic, and molecular domains for which there is no concrete physical picture. "So the discovery of electrostatic rotation and the identification of electrostatic spin as a natural phenomenon opens up an entirely new field of inquiry with the potential for significant advances," Wistrom said.

Editor's Note: The original news release can be found here.

Note: This story has been adapted from a news release issued for journalists and other members of the public. If you wish to quote any part of this story, please credit University Of California - Riverside as the original source. You may also wish to include the following link in any citation:

http://www.sciencedaily.com/releases/2003/04/030403072949.htm

I'm just saying that from the article, it appears to me as though these two "geniuses" have re-discovered the Right Hand rule.

Apply direct current [DC]. Get magnetic field effect.

Now, can I have my grant money for this "breakthrough"?!

Well, the operative words are "appear" and "to me". You're talking about a Lorentz force as observed with an electric current running along a wire, which produces a magnetic effect. They're talking about a Coulomb force as observed in a charged piece of amber--it has an electric charge, but since there is no movement of this charge, there no magnetic effect. The right-hand rule applies to the former, not to the latter.

As I said, the wording was not completely straightforward but that it supported my rather than your interpretation. I said that the right-hand rule pertained to the effect produced by an electrical current

Ampère showed that two parallel wires carrying electric currents attract and repel each other like magnets. If the currents flow in the same direction, the wires attract each other; if they flow in opposite directions, the wires repel each other. From this experiment, Ampère was able to express the right-hand rule for the direction of the force on a current in a magnetic field. He also established experimentally and quantitatively the laws of magnetic force between electric currents.

and that in this particular case the DC voltage was applied to produce an electrostatic field not to maintain an electric current. I read the actual paper and found that my interpretation of the slightly ambiguous sentence in question was, indeed, the correct one:

In all experiments, the surface-to-surface separation distance between spheres exceeded that for sparking in dry air by at least one order of magnitude. Surface-to-surface separation distances were typically larger than 5 mm. Also, the experiments were conducted in isolation from the surroundings by carefully insulating all fasteners and connectors, by utilizing a large open space, or by installing the experimental assembly in a Faraday box. Hence, current flow was negligible. We have found that our experimental model offers a particularly powerful approach to investigating electrostatic phenomena, and we have previously used similar setups to successfully calibrate the electrostatic force.1,2 The absence of electrical current and magnetic materials, natural or induced, leads us to conclude that the experimental assembly was electrostatic.
--Appl. Phys. Lett. 80, 2800 (2002), pp.2800-2801.

Here's more of the paper:

The spheres are stationary in both configurations, held in place by a combination of electrostatic, gravitational, and tension forces. Evidence for moment of force is based on experimental observations after 10, 20, and 200 h after voltage is applied to the center sphere at which times the spheres were deemed to be in static equilibrium. The experimental evidence for an electrostatic moment of force was as follows: 1. translational movement is not observed, 2. rotation about the vertical axis of the sphere proceeds until standstill where the induced moment of force is offset by the restoring torque of the suspending wire ~only after the external power supply is disconnected does the sphere return to its starting position, 3.the direction of the rotation remains invariant between replicate experiments, and 4. the magnitude of the net angular displacement increases with the length of the suspending wire.

We propose that rotation is the result of the continuum of static charges residing on the surface of the metal spheres. Theoretical evidence for rotation about the geometrical center of each sphere is obtained from the classical definition of the static moment of force, which, in the spirit of Cavendish and Coulomb, is determined from an action-at-a-distance perspective.

The correspondence between the theoretical prediction and the experimental observations lends considerable support to the notion that the rotation is an electrostatic entity. It is important to note that the direction of the rotation is explicit in the equation for moment of force. Rotation is either up or down, taken perpendicular to a plane passing through the sphere centers.

We have demonstrated a Coulomb motor where the moment of force is induced by an assembly of three spherical conductors held at constant potential. The rotation of the spheres about the axis perpendicular to the plane passing through the center of the spheres is shown to be a natural consequence of the electrostatic force. We find that when the charged spheres are stationary the only degree of motion that remains is rotation. Hence, the electrostatic coupling between the three charged spheres is converted to a net rotation beyond the observation that the rotation is likely to be general. The Coulomb motor appears to be feasible in systems ranging in size from molecular to macroscopic, and would be a useful device in situations that require angular motion.

Ok, just a little background: I am a senior physics major at Hillsdale College, and have been working on this exact problem for my senior thesis. Results have been mildly conclusive, however, a few things worth mentioning:

The paper which this article refers to contains very few details which are sketchy at best. It contains precious little data about the magnitude of the rotation observed or the factors which determine it. While this does not prove them wrong by any means, this should invoke extreme skepticism already. Hence one of the reasons I have chosen this for my thesis.

Now, I have not completed analysis of my data yet. However, I have come to one very important conclusion: The orientation of a sphere effects the amount of rotation. I do NOT mean that the orientation of a sphere -with regard to the other two- influences the rotation. If you remove one of the spheres and then proceed to reattatch it to the same position in space but rotated from its initial orientation (Say, 1/4 a turn or so), the amount of rotation of that sphere is effected.

What does this mean? If I had more time to work on this, I'd love to dig deeper into it, but the most obvious conclusion is that the rotation is not fundamental to a perfect sphere, but rather is due to small imperfections on real spheres. You cannot make a sphere which is perfectly smooth. There is always some error, however small. With large voltages being applied (in my case, 3-12 kV... in their's, I believe it went as high as 20 kV, although I am not positive), even small surface imperfections could cause small forces. Given that the magnitude of rotation is very small (About 1/16 of a full rotation, at most. On the order of 1/400 of a rotation at least. Given the hair-thin Tungsten wire used, this is a tiny force), this seems quite plausible.

However... I should really be working on writing my thesis instead of talking about it... so... away I go!

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