Another confusing "stuff transmitted faster than light" claim pops up

[mmcirvin]

I thought the name Gunter Nimtz sounded familiar. Something like this makes the rounds every couple of years or so, and sometimes the same people are involved.

The Ars Technica writeup is good except that the phrase "the evanescent field has no energy in it" should read "has no power in it". Of course it has energy; it's just not going anywhere (until the other prism shows up, as the article explains further down).

As the sci.physics FAQ explained many years ago, the question of whether something or other can in some sense go faster than light is a tricky and subtle one, and confused claims to have violated relativity on this score abound. They're generally divided into three categories: those in which the researchers are themselves confused, those in which the PR office that wrote the press release is confused, and those in which the journalists writing the newspaper or magazine article are confused. This one seems to be in the first category. It makes absolutely no sense to say you've violated special relativity via some process that is explainable with standard classical electrodynamics or QED, since they're explicitly compatible with special relativity.

Comments

Ah, the old group velocity trick.

[notr.livejournal.com]

Of Schottky tunneling, he points out that "the particle barrier penetration time has not yet been determined due to parasitic time consuming electronic interaction effects in a semiconductor." What he omits is that those parasitic effects account precisely for the electron's delay in reaching the barrier in the first place that permits the tunneling to appear instantaneous.

As silly as the FTL claim is, this is still an incredibly cool large-scale demonstration of the existence of virtual particles--as long as the audience is already convinced of the existence of photons, of course. Now we just need a microwave-range demonstration of the photoelectric effect to couple it with, though at large quantum numbers that starts to be complicated by multi-photon absorption.

[mmcirvin.livejournal.com]

To complicate matters, virtual particles, it's true, are perfectly capable of going faster than light--but this is neither a violation of special relativity nor a means of transmitting information. And for virtual photons, to some extent it's a gauge-dependent statement, which opens up a whole other can of ontological worms.