Alternate View

THE CHINK IN EINSTEIN'S ARMOR

Up until September of 2011, April would have been the perfect month to write an April Fool’s Day column about faster-than-light neutrinos, or faster-than-light anything for that matter. But faster-than-light particles are now serious scientific business.
You readers know as well as I do that, despite the rampant use of FTL drives supported by plausible-sounding, double-talk science in even hard science fiction, it has been assumed to be an immutable fact of life, armored by Einstein, that nothing can go faster than light. To seriously suggest otherwise has always been greeted with hoots of derision from physicists and educated laymen, if the claim was even noted at all. Granted, a host of FTL effects are in the domain of acceptable science, things involving the subtleties of phase vs. group velocity, Cerenkov radiation, and quantum entanglement. But what I’m talking about is what every SF reader is thinking: FTL as in a bullet, or a spaceship, or a human getting from point A to point B in less time than it would take a beam of light, in vacuum, to make the trip.
Since I’m writing this in October, and the news broke just a few weeks ago, I have no idea what the story will look like when you read this. A survey of the blogosphere finds some people saying, essentially: “Einstein said it can’t be done, not without infinite energy to do it. And even then, you’d go back in time and mess up the space-time continuum and wreck causality. Everyone knows that!” Others are a bit more optimistic and nuanced in their responses, and with good reason. It was the guys at CERN who up and measured the FTL neutrinos, not some mad scientist in his basement.
And they did it well enough to have stymied the usual heckling and derision, at least for the time being.
The paper is called “Measurement of the neutrino velocity with the OPERA detector in the CNGS beam,” and it has over 150 coauthors. “OPERA” stands for “Oscillation Project with Emulsion-tRacking Apparatus.” The actual purpose of the experiment was to produce an assortment of neutrinos and watch for them to oscillate from one flavor into another (muon neutrinos into tau neutrinos). However, the nature of the experiment was such that the set-up was perfect for measuring the velocity of the neutrinos as well.
And when they did that, as carefully as they absolutely could, they found that the neutrinos were moving faster than light.
If you think about it, and if the result turns out to be right, the OPERA experiment is the model “archetypical science fiction serendipitous huge breakthrough.” Prior to this, the Manhattan Project was the paradigm for decades; a team of the best and brightest scientists is brought together in a crash program for the sole purpose of developing the atomic bomb. But in that case, those involved were fairly confident that what they sought could, in fact, be built. I used this trope in my own Dykstra’s War when a team was assembled to reverse-engineer an alien FTL drive.
OPERA is just a bit different. In this case, a team of scientists put together an experiment to further explore the domain of known science. They used the biggest accelerator on the planet and the highest technology available to probe the secrets of the neutrino. But along the way, one of the things they found was entirely unexpected and would, if verified, shake the very foundations of physics in a way not seen since the days of Michelson and Morley (which very much sounds like the teaser for a hard SF novel).
I strongly urge each of you to read the original paper, which is available here: <http:// arxiv.org/ftp/arxiv/papers/1109/1109.4897. pdf> For a particle physics paper, it is remarkably accessible even to the layman, and the typical Analog reader shouldn’t have much trouble understanding it, even if a few technical terms and abbreviations remain mysterious.
Very briefly, this is how the experiment was performed. Near-light-velocity protons from the accelerator at CERN were directed into “a 2-meter-long graphite neutrino production target.” This produced charged mesons, which “decay in flight into neutrinos in a 1,000-meter-long vacuum tunnel.” The neutrinos then flew through the Earth for about 730 kilometers to the OPERA detector and the arrival time was noted. The experimenters didn’t follow individual neutrinos, of course. Rather, they noted the arrival time of a brief burst of neutrinos.
Bear in mind that this was not some kind of drag race between photons and neutrinos, where they raced side by side and the neutrinos won. It was more like a time trial for the neutrinos. As with any such trial, be it top fuel dragsters or subnuclear particles, accurate timing relies on knowing precisely where the starting point is as well as the finish line. You also need to know very precisely when the timing started and exactly when it ended.
For the OPERA experiment, the starting point and time were easy to determine; the starting point is the target and the time is that instant when the proton beam slammed into it. That time is known to within a fraction of a nanosecond. The position of the target is known to within a few centimeters. The team took great pains to ensure that the position of the detector is known just as precisely, as well as the arrival time of the neutrinos. Given this data, all that needed to be done was to subtract the start time from the end time and shazam—they showed the neutrinos arrived about 20 nanoseconds faster than a photon of light would have.
Of course, even if without derision, most scientists the world over assume there is some kind of systemic error involved in the measurements. Even the scientists from CERN are skeptical that the neutrinos are really moving faster than light, even though that’s what they measured, and even though they’ve so far failed to find where it is that the experiment might have gone wrong.
I also am skeptical that this measurement will stand, even though I’m in the camp that actually expects FTL phenomena like this to eventually start showing up in experiments. The Global Positioning System, which is what was used for accurate positioning and timing, is a complicated and finely tuned instrument. Using it to determine both exact locations and clock synchronization requires incredible attention to the subtleties of the GPS itself. Regardless of whether or not the FTL finding survives scrutiny, reexamining it will ensure that any subtle wrinkles still remaining in the proper use of the GPS will be ironed out.
But suppose the results do stand up to review and we’re forced to conclude that the neutrinos did, in fact, arrive faster than light. Then the question becomes whether or not neutrinos are actual tachyons, or if they got some sort of FTL “boost,” or jumped through hyperspace or something like that. Classical tachyons have been written about in the pages of this magazine for over forty years, both in fact and fiction. They are particles that have imaginary mass and always travel faster than light. The hyperspace idea is simple enough—somehow during the impact the neutrinos jumped through a higher dimension and moved FTL prior to reentering our space and resuming travel at just under c. This would get them to the target early, but they wouldn’t be actual tachyons.
Since I favor an aether-consistent hypothesis, I’m partial to the boost idea. Recast in modern language, I think this idea may carry some weight among conventional physicists now that we know the “quark-gluon plasma” is actually a quark-gluon superfluid. I think that, upon impact, the spacetime superfluid itself deforms. The little bit of spacetime that the neutrinos are emerging from is expanding and moving with respect to the rest frame. It’s something akin to “micro-inflation”—a short period of FTL expansion that rapidly diminishes.
Consider a prosaic analog of this effect.
The speed of sound in dry air (at 20 degrees Celsius) is about 343 meters per second. Suppose a firecracker is set off a mile away and you have some apparatus that starts timing at the flash and stops when the bang arrives. You can easily measure the speed of sound this way and get close to the expectation value. However, if you try this again from farther away with a nuclear explosion as the sound source, the sound will consistently arrive sooner than expected. What also is strange is that, if you are say 15 miles away from the explosion, and your associate is 20 miles away with a similar setup, and you compare notes to calculate the speed of sound over that five additional miles, you will find it was the expected value.
How does this work?
With anything as violent as a nuclear explosion, you must bear in mind that the bang you’re timing started out from a hypersonic blast front. The source is initially moving far faster than sound and it takes a while before the sound wave decouples from the blast wave. So if you start timing the instant you see the light from the explosion, you will find that the sound is arriving sooner than you calculated it should. By the time the sound wave is 15 miles out, it’s moving at the normal speed. In short, the sound wave gets an initial high-speed kick in the butt.
The implications of this are clear. Put another OPERA detector twice as far away, and if the neutrinos show up 20 nanoseconds early at both of them, then we know they’re not tachyons.

Some scientists have complained that the FTL result was made public too soon. I find this position to be both timid and foolish. CERN has the biggest and best accelerator facility on Earth, staffed with some of the best physicists in the world. They have already done all they can to find some kind of mistake, yet still they measured neutrinos moving faster than light. If it turns out that there is a mistake and their measurement is invalid, we will find out sooner by letting everyone in the world mull it over, rather than by having the guys who’ve already looked it all over look it all over again. If the finding holds up, then the sooner everyone knows about it the sooner we can start rewriting the textbooks.
Over ten years ago I predicted in an Alternate View (“Five Predictions for Century 21,” July/August 2000) that “(f)aster-than-light travel will not only be recognized as possible, but recognized as feasible and within reach of twenty-first-century science.” Since there is no limit to the speed at which “aether can move through aether” I expected that sooner or later this fact would begin to show up in our experiments, whether we were looking for it or not. It’s too early to know if the OPERA experiment is the first of these. It may be, it may not. But I sincerely hope we’ve finally found that chink in Einstein’s armor.
One big enough to drive a starship through.