As someone who worked in neutrino physics for thirty years before retiring from research in 2000, I should be more excited than most by the report from CERN that neutrinos have been observed moving faster than light. And I am. The experiment looks very well done and the scientists involved are saying all the right things -- that their result is very preliminary and must be independently replicated before accepting it as scientific fact. If the observation is confirmed, it may be the most important discovery in science in the last 100 years.
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.
Nevertheless, the enormous attention currently being given to this result affords us the opportunity to delve into to implications of faster-than-light travel should it ever be observed, which are profound. To begin, it needs to be made crystal clear that despite what has been reported in the media, superluminal 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?
When you read, "Einstein proved that particles cannot go faster than the speed of light" you have to understand that this was not a consequence of the basic axioms of the theory of special relativity. To prove this he introduced an additional assumption now called the "principle of Einstein causality": cause must always precede effect. In that case, it then follows that we can't have superluminal motion.
Einstein causality certainly seems reasonable based on normal experience. Cause and effect are deeply embedded in our thinking, in both everyday life as well as virtually all of science. Causality is one of those commonsense notions, such as the world is flat, that hangs in there as a "self-evident truth" until some very bright person come along and says: "Maybe not."
A very bright Scottish philosopher named David Hume (d. 1776) said "Maybe not" when he pointed out over two hundred years ago that just because one event precedes another in our experience, we cannot conclude the first event necessarily was the cause of the second.
In modern chemistry and physics today, no distinction is made between cause and effect on the atomic and subatomic scales. Time is completely reversible. A carbon atom and oxygen molecule will combine to give carbon dioxide and energy. You can just as well have energy plus carbon dioxide give a carbon atom and oxygen molecule.
In 1948 Richard Feynman showed that, assuming our conventional direction of time an antielectron ("positron") going forward in time is indistinguishable from an electron going backward in time. Clearly when you reverse time, cause and effect are reversed. But it doesn't matter. The phenomena that are observed in submicroscopic chemistry and physics can be described either way.
Furthermore, many events on the quantum scale are described without even introducing cause and effect. For example, the theories that successfully describe atomic transitions and the decay of nuclei treat these phenomena as occurring spontaneously, without cause.
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.
the particle in question moved both faster than light and slower - contradicting Einstein.
I like the atheist push that says there is no causality so there is no God.- this fellow does love his atheist religion - a belief in something he can not prove, just as in all religions there is a belief in something you can not prove.
Einstein said that there could be particles traveling faster than light. Nothing can accelerate or decelerate though the speed of light but faster is OK as long as it came into being whilst faster than light. Neutrinos due not change speed so Einstein would have been OK with this.
Of course, I am NOT proposing this WAS the case. It is merely a thought experiment to consider and either examine or discard.
I was not aware that the detection of the shower of neutrinos associated with the burst of SN 1987A also could reflect some directionality back to the source of the observed detection. My major is not in physics/astrophysics (it was sociology.) I'm merely a well-read layman.
We have to move on....Al and his adherents had their day in the sun, and places on University Chairs.
Time to turn over a new century.
Newton's theory is still applicable today for most cases.
Einstein's theory will still be applicable in 200 years for most cases.
I have no need to throw out the baby with the bath water, thank you. I have no need to show disrespect for Mr. Einstein when he saw so much further than any other physicist of his day.
"The distance between the target focal point and the OPERA reference frame was precisely
measured in 2010 following a dedicated geodesy campaign. The coordinates of the origin of the
OPERA reference frame were measured by establishing GPS benchmarks at the two sides of the ~10 km long Gran Sasso highway tunnel and by transporting their positions with a terrestrial
traverse down to the OPERA detector".
It’s not like I am not disagreeing with global warming or evolution just that the speed of light is a universal constant and a speed limit. BTW I really appreciate you writing this article and having the patience to deal with crock pots like myself.
The difficulty will be showing how Mr. Einstein's theory in the non-quantum world might be wrong or insufficient. So far, in experiment after experiment, his theory has been substantially verified. It is when we find experimental results that reflect a possible problem with a theory that work can proceed in the development of a more accurate theory.
An interesting aside: we know that the General Theory of Relativity and the Theory of Quantum Dynamics are incompatible. Can it be that in the possible case of neutrons traveling faster than the speed of light, it is merely an example where quantum theory is trumping relativity? Physicists are clearly aware that since these two theories work very well in their own magisteria but that they are incompatible, there is a further underlying theory that will be a closer approximation to be developed sometime in the future.
Einstein did not say it all. He merely gave us a closer approximation than Newton.
Most people now think, thanks to social media coverage, that Einstein's theory is now finished, kaputt. That CERN are the winners and Einstein is the loser. And the velocity of information is increasing so fast that really nobody cares to offer a serious clarification- too much work, people will just intuitively "get it." That's what people said when Rome burned too.
Thank you for a very thought provoking article and for taking the time to respond to all your article's readers. You state and re-state: "The speed of light is constant by definition." For awhile I've wondered about whether C is really a "speed". Given a photon that leaves a star that is, say 1000 light years from an earth-bound observer, we can say that, from the photon's perspective, since it exists in a timeless state (t = 0), distance (d) would be: d = 1000 ly x t. In other words, distance = zero. So, again, from the photon's perspective, it has traveled no distance, no time has elapsed and therefore, it would follow that there's no real speed in the equation. Is this what "constant" means? Does it also imply that the concept of speed is only valid from a relativistic perspective? (Ugh! Sinking feeling that I just stated an obvious result from the Special Relativity equations...) But what does this say about our human perceptions of distance? Which of your books would you suggest, on this matter? Thanks.
CERN will repeat its findings and at least one study in 1999 data did not support it being a universal constant.(see blog.) I wish this author or any other physicist just for once would look at these facts. This is a game changer.
I liken this to a compass. It points to a magnetic north. Not to the true north. Except this is only more profound at greater distance. Say from here to the Magellanic Cloud. Also I gleemed the word mass from your paper. Neutinos are not influenced by magnetics, true? Light is, true? I'm not ready to throw Einstien out with the bath water. I therefore think before we glam on to this that much more dupilcation needs to be done and much more discussion.
While magnetism and gravity look somewhat similar, they are not in fact the same and different laws apply different results.
On the wild wild ignorant speculation zone, would it be possible that the neutrinos given the uncertainty principle were "skipping" very tiny distances in the trajectory? those distances added might account for the difference.