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Faster-Than-Light Particle Results To Be Re-Tested
surewouldoutlaw writes "After the astonishing news from CERN that the OPERA experiment had detected neutrinos traveling faster than light speed, challenging Einstein's theory of special relativity, there has been some skepticism over the results. Now Fermilab, near Chicago, has announced it will attempt to replicate the experimental results within four to six months."
How could we see it coming, if it's traveling faster than light?
You deduced its pending arrival by virtue of it having arrived.
The barkeep says 'We don't serve faster-than-light particles in here'. A neutrino walks into a bar.
Confirmation of the results of an experiment by an independent party is standard practice in the scientific community. Without it, the findings wouldn't even be considered completely valid! Nothing to see here...
They already did the experiment, and actually found similar results but did not claim any significance. Of course they are going to repeat this, once they finish kicking themselves.
The process is working.
The scientists at CERN asked for peer review and checking of their methodology. This announcement means that at least on paper the method was near-perfect for Fermilab to be committing resources in the near future to prove/disprove it.
I see what you [are going to do] there.
They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance. - Terry Pratchett
Having neutrinos fly at 'true c' rather than a lower 'apparent c' isn't a good solution, because it doesn't take in account neutrino bursts from supernova 1987A. The neutrinos from that supernova were detected only four hours before the light from it. That's explainable with what we know about internal stellar processes. But if the neutrinos were flying FTL then they should have arrived four years earlier.
The most likely explanation for the CERN results (apart from experimental error) is that neutrinos are tachyonic -- they have imaginary mass, and naturally fly faster than light. The higher their energy, the closer to lightspeed they travel.
That's not a trivial situation. To use a technical term, it breaks relativity into itty bitty pieces. We will have to change a lot of theories around. But it's unlikely that the value of c is going to change.
Genocide Man -- Life is funny. Death is funnier. Mass murder can be hilarious.
OPERA has just found that either neutrinos travel 0.03% faster than photons we've measured, or their equipment has an unknown systematic error. Assuming there's no equipment error, I would find it more palatable to assume that light around Earth travels a bit below c and that neutrinos travel closer to c. What we think of as vacuum could really be a medium with refractive index 1.0003, perhaps due to a uniform background of weakly-interacting particles (maybe even dark matter) that affect photons but not neutrinos.
I have a physics undergrad degree; if there's someone here with better qualifications, would you care to weigh in on the idea that c could be 0.03% faster than the speed of light we measure on Earth?
Expected time to finish is 1 hour and 60 minutes.
There once was a lady named Bright,
Who could travel faster than light.
She left one day
In a relative way
And came back the previous night.
So, either you already saw it coming, or you didn't :-)
Now, to understand it better, read All You Zombies by Robert Heinlein (pdf of complete story). Considered by many to be the greatest time travel short story ever.
The theory of Relativity still holds true, what this experiment (if it's accurate) changes is our idea of matter and causality: if neutrinos have imaginary mass, they are allowed to traver faster than light, as tachyons; and causality may have to be revised, from a onward moving arrow to a regular dimension, in which the future can influence the past.
http://www.gizmodo.com.au/2011/09/nikola-tesla-predicted-faster-than-light-particles-in-1932/
If they succeed in recreating the measurements, doesn't it just mean that c was set at too low a value, and that the true speed to light in a vacuum is slightly faster than originally thought?
c is not a fundamental value, its a function of the permeability and permittivity of either empty space or some dielectric (something like inside a piece of coaxial cable, etc). Or rephrased, you are arguing the impedance of free space is wrong, and generations of antenna and RF engineers would disagree with you. Also c shows up in energy mass equivalance e=mc2 and all that which seems quite accurate. And in time dilation experiments it seems to work quite well. Astrophysics "stuff" thats far away seems to confirm that neutrinos do not exceed light speed in vacuum; this test involved blasting thru rock instead of vacuum so that is no huge problem; theres a long history of shoving light thru materials results in weird behavior. Given how many decimal places that kind of stuff has been verified, more than this result which was only 6 sigma or whatever, I'm thinking fundamental constant fine tuning is awful unlikely.
In summary, either its wrong (which seems unlikely given all the verification they did) or its new physics. Simply tuning up the known constants is just not gonna work.
To fit other, higher precision experiments, its gotta boil down to something like the logical inverse of the light refraction law, where light slows down in certain materials (like, say, glass) resulting in refraction and timing issues (like pulse dispersion in optical fiber). The analogy is maybe neutrinos "speed up" when rammed thru solid rock due to some strange property of rocks, or floating about in a rock-produced gravity well, or something like that.
I can totally see how previous subatomic experiments would miss the neutrino effect; after all its hard to shove gammas or plain ole light quanta thru a couple zillion KM of solid rock... Its too technologically hard to do, until trying out the neutrinos...
A good example of how F-ing around in the lab doing blue sky stuff simply because you can, is the primary source of interesting ideas.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
It's not so simple. We've measured the speed of light to great precision. We know what that speed is, and we know photons are massless, so we know with very high confidence what the speed of massless particles is. If neutrinos travel faster than light, then this is very surprising and points to something new and interesting. I'm avoiding referring to 'c' because it would be ambiguous: in traditional relativity, the constant speed of light is equal to the maximum possible speed, which is also in essence the ratio between space-like and time-like variables in the theory (the slope of light-cones and all that). It's a constant that reappears over and over again, and marvelously it's precisely equal to the speed of light. It can't be as simple as just "we were wrong, c is a bit higher than we thought" because it would immediately mean that "c" isn't as universal as we thought: the symmetry of the universe must be somehow different so that photons and neutrinos (and probably other particles) follow slightly different rules.
But if this result is indeed true, and neutrinos travel faster than light, then this is truly amazing and could mean different things. One possibility is that different particles actually have different 'speed limits' (and different causal cones), so there is c_light, c_neutrinos, etc. There are many other possibilities (extra dimensions, breaking of Lorentz invariance, imaginary mass, closed timelike curves, etc.). All of them amount to a substantial rethinking to some aspect of physics. This is definitely exciting, since it could be telling us something very new! And it won't be as simple as just adjusting a constant a bit. (If we tweak the value of "c" in our equations even just a bit, all kinds of well-tested observations, in everything from cosmology to the functioning of transistors, would come out wrong...).
Lastly, it's worth keeping in mind that it's probably a subtle experimental error (very subtle!). This is still useful, because it will teach us something new about experiment design and possibly even teach us something about particle physics. For instance, the timing calculation is based on certain models of the packet of neutrinos that are generated. But, it could be that the packet that arrives at the end is slightly different than the one sent out at the beginning, thus altering the way one should compute the flight time. This could point to some interesting, previously unknown, ways in which neutrinos are generated, or interact with matter, or interact with each other. In any case it will be interesting.
c isn't just the speed of light. It's a constant that appears in all kinds of equations: sometimes as the speed of light, sometimes as the permeability of vacuum (Maxwell equations, etc.), sometimes as the ratio between matter and energy (E=mc^2), sometimes as the fundamental ratio between space-like and time-like quantities (relativity, etc.), and so on. It's quite amazing that this same constant comes out with the same value in all these different ways. (And, again, we can measure this constant in totally different experiments and come up with the same value.) This points to a fundamental symmetry in our universe, a realization which gave rise to relativity, quantum physics, and so on.
In short, you shouldn't think of it as merely being the speed that light (or any other particle) travels. It's a fundamental value that is deeply entrenched in just about every branch of physics you can think of. It so happens that it's also the speed that photons travel at. (That's, no accident, of course.) Changing the value of c even slightly would propagate through all of our physics equations, and would lead to totally different predictions for a host of results. (More specifically, we would start getting the wrong predictions for many things!)
So the explanation for this new result must be something rather more subtle than just adjusting c.
But I have wondered what physics would say would happen if the object were an ideal incompressible solid strong enough to withstand the amount of force required to overcome its inertia.
I'm guessing it would say that there's no such thing as an incompressible solid. Atoms don't touch each other. You can always move atoms a bit closer to each other if you push them hard enough.
(and you'd have to push very hard indeed to move an object as heavy as a stick that's a light-year long...)
No sig today...