Over at Puffho, Victor Stenger ponders the evidence for faster-than-light neutrinos in a nice piece called “No cause to dispute Einstein.” Many of us know Victor as an eloquent atheist/physicist, but he also informs us us that he worked for thirty years on neutrinos. Clearly, he’s eminently qualified to pronounce on the CERN experiments suggesting that those particles can move faster than light.
Stenger makes two points. First, like many physicists he’s wary of the results, mainly because they’re contradicted by earlier data on supernovas:
However, a big fly in the ointment is the supernova in the Large Magellanic Cloud, which sits just outside our galaxy 168,000 light-years from Earth. It was first seen by the naked eye on February 24, 1987. Three hours before the visible light reached Earth, a handful of neutrinos were detected in three independent underground detectors. If the CERN result is correct, they should have arrived in 1982. So, if I were a wagering man, I would bet the effect will go away because of some systematic error no one has yet been able to think of.
However, if particles can move faster than light, then there’s an astounding conclusion: effects can precede causes.
. . . superluminal [faster-than-light] motion in no way contradicts Einstein’s theory of special relativity published in 1905. Einstein’s equations fully allow for particles to travel faster than light — provided they never travel slower. Physicists have speculated about such objects for years. They are called tachyons. Many searches have been conducted, with no significant signals until now.
Einstein showed that it was impossible to accelerate a particle moving less than the speed of light (in a vacuum) to the speed of light or higher. Similarly, a tachyon cannot be decelerated to or below the speed of light. Only massless particles, such as photons, travel at exactly the speed of light.
However, there is a problem with tachyons. They imply that cause and effect are interchangeable. Consider the famous duel between Aaron Burr and Alexander Hamilton on July 11, 1804. An observer moving by at less than the speed of light with respect to the participants would have seen the bullet from Burr’s gun enter Hamilton’s lower abdomen. However, another observer moving faster than light would have seen the bullet emerge from Hamilton’s abdomen and enter Burr’s gun. Did Burr kill Hamilton or did Hamilton kill Burr? [jac note: I don’t understand the last sentence since in no frame of reference did Burr die. But the point is clear.]
Stenger says—and I did not know this—that the principle that causes must precede effects was an add-on that Einstein made to his theory of special relativity; it was not a consequence of his theory itself. And if particles can move faster than light, then our whole notion of cause and effect is inverted. This complete reversibility of time, and hence of cause and effect, is inherent in the Feynman diagrams of particle-particle interactions.
As a card-carrying New Atheist, and author of several good books on atheism, Stenger can’t resist using this possibility to get a little dig in at the faithful:
So, if confirmed, the reported result from CERN or any future observation of superluminal motion will not lead to the overthrow of Einstein’s theory of relativity. Its significance will be to overthrow the distinction between cause and effect. At the worst, Einstein might be faulted for taking causality a little too seriously.
Finally, you might want to ponder what effect the demise of causality would have on the notion of God as the ultimate cause of all there is.
Over at the Guardian’s science section, Alom Shaha points out why the “Faster than light story highlights the difference between science and religion.” It’s all about doubt, replication, and hesitancy, of course:
But the recent fuss over the possible existence of faster-than-light neutrinos illustrates precisely how different science and religion are when it comes to questions of “belief” or “knowledge”. . .
One of the things that appeals to me about science is that, unlike religion, science is not dogmatic. It does not say: “This is the way things are, and it can be no other way.” Instead it says something like: “Based on the evidence we have so far, this is how things probably are; if clear and solid evidence is discovered that shows this is not how things are, then we will need to change our minds.”
Science can seem rather weak in comparison to the certainties religion offers. But it is this very “weakness”, this refusal to issue absolute statements of truth, that allows science to progress, and to come up with increasingly better ways of explaining the world.
It’s the usual stuff, but the public can’t hear this too often. Religion not only offers no certainties, but offers no knowledge, either.