I no longer recall who pointed me to this current.com post titled “Scientists Make Radio Waves Travel Faster Than Light “– somebody on Facebook, I think. As it would be a pretty neat trick to make light move faster than light, I took a look. The opening is fairly standard semi-gibberish:

Scientist John Singleton insists that Albert Einstein wouldn’t be mad at him, even though at first blush Singleton appears to have twisted the famous physicist’s theories about light into a pretzel.

Most people think Einstein said that nothing can travel faster than the speed of light, but that’s not really the case, Singleton said.

Einstein predicted that particles and information can’t travel faster than the speed of light — but phenomenon like radio waves? That’s a different story, said Singleton, a Los Alamos National Laboratory Fellow.

Singleton has created a gadget that abuses radio waves so severely that they finally give in and travel faster than light.

This is fairly clearly the result of somebody not understanding the explanation they were given. What was really puzzling about the article, though, comes very near the end:

If Einstein were still alive, he probably wouldn’t be all that surprised by the discovery, Perez said, even if it does seem on the surface to conflict with some of his theories.

That might not immediately seem odd, but this is actually the first mention of anybody named Perez. There’s no earlier reference giving his first name or institutional affiliation. That’s pretty unusual for what is otherwise a fairly professional-sounding article.

This happens because the post is incompetently copied from this article from a Santa Fe paper– whoever appropriated it for current.com dropped a couple of paragraphs, including the one identifying Singleton’s co-author, Mario Perez, also of Los Alamos National Laboratory.

This isn’t quite plagiarism– the Santa Few New Mexican article is linked from the top of the original page– but it’s pretty sleazy. And also makes the original not-all-that-clear article even more confusing by dropping a bunch of material.

What’s really going on, here? I can’t find any recent press releases in my RSS feeds, but the thing they’re talking about appears to be related to this prerprint about pulsars, in which a John Singleton and Mario Perez of LANL, along with a number of other people, discuss the radiation emitted by rapidly rotating neutron stars. They specifically talk about the Crab Nebula pulsar, which appears to emit a narrow beam of radio waves that sweeps around like the beam from a lighthouse, producing regular pulses of light every time the beam sweeps over the Earth.

What’s superluminal about this? Well, their argument is that this sort of rotating beam has to be generated by a loop of current in the source, and given the rate of rotation and the size of a neutron star, this means that there must be a current in the magnetosphere of the star that is going around at an effective speed greater than the speed of light.

The bulk of the paper is highly technical discussion what sort of radiation you get from such a source, but the key claim is in the introduction:

Unless there is no plasma outside the light cylinder, therefore, the macroscopic distiribution of the emitting current in the magnetosphere of a pulsar should have a superluminally rotating pattern in r > c/ω (where r is the radial distance from the axis of rotation and c is the speed of light in vacuo). Such a source is not inconsistent with special relativity. The superluminally moving pattern is created by the coordinated motion of aggregates of subluminally moving particles [3]. It has been experimentally verified, on the other hand, that such moving charged patterns act as sources of radiation in precisely the same way as any other moving sources of electromagnetic fields [4,5,6,7].

(The references to experimental verification are all to things I can’t access– some old Russian journals and some IEEE stuff.)

What you have is a collection of charged particles– electrons and protons, presumably– in the outer part of the star, with a disturbance in the distribution that moves faster than the speed of light. The individual particles don’t move faster than the speed of light (and the light they emit moves, by definition, at exactly the speed of light), but the pattern does. And that faster-than-light moving pattern itself generates light, that takes the form of a tight, powerful beam of radio waves sweeping around in a circle. Which is what we observe.

There is a hint of the correct explanation in the original newspaper article:

And other effects have also shown the possibility of phenomenon traveling faster than light, but Singleton’s experiment has taken that to a new level, Singleton said.

“If you take a laser and shine it on the moon and swing it rather gently, for example, the spot on the moon travels faster than the speed of light,” Singleton said. “If an effect can do that, it makes you wonder if you can do things with light to get the equivalent of a sonic boom.”

That’s what the faster-than-light radio waves — more scientifically known as superluminal transmissions — do. They’re the light version of a sonic boom, he said.

The laser-on-the-moon thing is one of the standard examples in talking about superluminal motion. The key feature of it– which Singleton probably mentioned, but it got left out of the article– is that there is no physical thing involved in the motion that moves faster than the speed of light. The spot on the surface of the moon moves faster than the speed of light, but that’s not a thing, it’s just a point in a pattern of light. The individual photons making up the pattern all move at exactly the speed of light, and follow straight lines (ok, geodesic curves) from the laser to the moon.

What they’re talking about in the paper, and presumably what they’ve done in the lab, is the result of a pattern in a distribution of charged particles moving faster than light. Which does some cool things, but does not involve any physical object moving at speeds greater than the speed of light in a vacuum. Careful analysis will undoubtedly show that there is no way to use this pattern to transmit information at superluminal speeds, either.

The combination of a confused article and incompetent semi-plagiarism makes the current.com article sound like they’re claiming something completely crazy. They’re not. They’re just the victim of bad writing and worse copying.

Comments

  1. #1 Uncle Al
    July 1, 2009

    The obvious superluminal event is collapse of quantum entanglement into an observable. It is better than superluminal! It is instantaneous across arbitrarily large distances and through arbitrarily large volumes. The exculpatory footnote is that it cannot convey information.

    No cat, no cradle.

  2. #2 Eric Lund
    July 1, 2009

    On the surface, the result isn’t new to me. There is no physical objection to a phase velocity greater than c, and in fact you do find such phase velocities near wave cutoffs in plasma. The moving laser spot on the moon, and presumably also the wave structures emitted by the pulsar, would also be phase velocities. I’ve heard via colloquium about similar superluminal phase fronts coming from galactic jets.

    The abstract of the Ardavan et al. manuscript (Singleton is the last author; I don’t know whether astrophysicists follow the custom of putting the authority figure last, as some non-physics fields do) makes one brief mention of superluminal sources, but that doesn’t seem to be a result of the paper–they seem to take it as given that you can have superluminal phase fronts. I’m not sure how you get the current loop itself to move superluminally–maybe by a “crack the whip” effect–but that is not a necessary condition for having the phase fronts in the beams move superluminally.

  3. #3 Bill Watt
    July 1, 2009

    Howdy,

    I added a link from the comments section on the Current article to your response.

    Thanks!

    Bill

  4. #4 Bill Watt
    July 1, 2009

    Howdy,

    I added a link from the comments section on the Current article to your response.

    Thanks!

    Bill