Posts Tagged 'relativity'

Don’t bet on the failure of relativity

Yes, I've used this xkcd comic before. So sue me. [Credit: Randall Munroe. Click for the original.]

Yes, I’ve used this xkcd comic before. So sue me. [Credit: Randall Munroe. Click for the original.]

One of the unfortunate side effects of being a professional science writer is that people send me their big ideas about how to solve major problems in physics. These are usually very poorly constructed; many don’t have any equations at all, and therefore have no way to make predictions that can be compared with experiment or observation. A few are a little more sophisticated and show at least a little background knowledge in physics. Even these, though, usually start from a fundamental misunderstanding of a standard theory (usually relativity or quantum mechanics).

These ideas don’t need debunking for a number of reasons. They’re sent privately to me, or if they’re published, it’s self-published in a book, printed in a fringey journal, or posted on the anything-goes preprint site Vixra. (I won’t say no good ideas are ever posted at Vixra, but it’s a pretty good guess that if something is on that site, it’s wrong.) They aren’t peer-reviewed, and wouldn’t pass muster with any professional physicist.

However, sometimes these ideas get into the public regime, and there’s where the problems start. The most recent of these is a paper by University of Georgia molecular geneticist Edward T. Kipreos, published in the generally reputable journal PLOS ONE; the university also sent out a press release. I don’t have time to spent tearing the whole paper apart (I have deadlines to meet), but suffice to say that this paper isn’t fundamentally different than the deluge of “theories” I get on a weekly basis. (And yes: what follows does not constitute a thorough debunking.)

Kipreos starts off with a rather controversial assertion: the special theory of relativity, which governs physics at high energies and motion close to the speed of light, is wrong. He replaces it with another idea, that any two simultaneous events are simultaneous in every frame of reference. From that idea, he claims he can make the accelerated expansion of the Universe, which we call “dark energy”, simply go away.

As you can tell, this isn’t a modest proposal at all, but (to use the unkind phrasing usually attributed to unkind physicist Wolfgang Pauli) it isn’t even wrong. His modification to the laws of physics are too large, with implications he avoids by not dealing with them. Instead, he focuses on a few small aspects of relativity: the loss of simultaneity between moving frames of reference and the time-dilation effect measured by two observers moving rapidly with respect to each other. These are connected phenomena, but they are both consequences of the larger theory, which is not only well-tested in its own right, but the foundation of the two best-tested theories we have: general relativity and quantum electrodynamics.

Special relativity, developed by Einstein from earlier work by the likes of Henrik Lorentz and Henri Poincaré, is based on two principles: 1) the basic laws of physics hold good in every reference frame moving at a constant velocity and 2) the speed of light in a vacuum will have the same value, no matter how fast the measurer is traveling. Since speed is ratio of a distance to an interval of time, to keep the speed of light the same relative to every frame of reference, different observers will measure different lengths or time intervals, depending on how fast they are moving with respect to each other. That also means that two events that appear to happen simultaneously to one observer may not appear to be simultaneous to another observer moving at a different velocity. Neither measurement is wrong — absolute simultaneity is simply something that isn’t compatible with the laws of physics. The loss of simultaneity is a natural consequence of relativity, and (to oversimplify just a little) is a natural consequence of the speed of light being the same in every reference frame.

Kipreos’ model, by contrast, starts by restoring absolute simultaneity; he then picks a handful of experiments to argue that they are compatible with this idea. In his scheme, each “gravitational center” (say the center of Earth) constitutes a preferred reference frame, and measurements are performed relative to that frame. Most of this is argued not in the mathematical language of physics research, but in long prose paragraphs. I’m not versed in the cell biology literature, but I suspect it would be difficult to publish a paper making its arguments qualitatively like that in any scientific field. But we don’t need long equations or empirical arguments to see that the model is still wrong.

First, one of the main examples Kipreos uses is GPS satellite timing differences between Earth and orbit. This is due both to a small special relativistic time-dilation effect (since the satellites are moving faster than the Earth rotates) and a gravitational effect from general relativity: clocks run more slowly under the influence of gravity. Kipreos ignores that entirely. Similarly, he assumes the non-gravitational relativistic Doppler effect equation describes the measured redshift of galaxies in cosmology, but that’s decidedly a general relativistic effect. If you assume the redshift of a galaxy is due to actual motion, you’d find that distant galaxies appear to be moving faster than the speed of light relative to us. You need general relativity (or a theory very much like it) to understand spacetime expansion, but Kipreos hand-waves that entire issue away. And I haven’t even gotten into his discussion of type Ia supernovas.

Various physicists have considered how to test whether there might be preferred reference frames in violation of relativity; there are very stringent limits on that possibility, both within special and general relativity. Kipreos’ theory isn’t a minor alteration to a well-tested theory, but a huge modification that would likely contradict a wide variety of experimental results.

PLOS ONE is a peer-reviewed journal, but in this case the peer review process failed. As a journal, PLOS takes pride in publishing some papers that are a little speculative in the interests of engaging researchers in post-publication discussion. This paper doesn’t fall into that category: it’s the kind of thing that a sophisticated undergraduate student of physics could see is completely wrong. There is no value in publishing such a thing. I don’t know who peer-reviewed it (and don’t need to), but I find it hard to believe any physicist read and approved of it.

I’m sure Kipreos is a good geneticist, but there’s a reason for that: he paid his dues, spent his time in the classroom and lab, and learned how his field works. Any major discoveries he could make within molecular genetics would arise out of his understanding of that field. If anyone wants to understand cosmology, their first step should be to take the time to learn how it works, rather than metaphorically jumping to the last chapter of the book without reading everything that comes before it. That way leads to problems and annoying emails and ranty blog posts.

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