5 ms·

Remember the faster-than-light neutrinos? Where they repeated the experiment multiple times with the same result? And nobody could find a plausible explanation

by hannob 11y ago

Remember the faster-than-light neutrinos? Where they repeated the experiment multiple times with the same result? And nobody could find a plausible explanation for an error? And then, some months later, they found it was just a bad cable. The sane rule of thumb on these kinds of experiments that seem to contradict basic physics is to assume it's just an error in the experiment or the data calculations. Even if they did it multiple times. If this gets replicated by multiple independent teams worldwide with different experiments - then we can talk about new physics. But it's important to understand how extremely unlikely that is. The best you can learn from these kind of stories is how hard it is to get science right and how subtle errors can be. Don't get me wrong: I'd love to see some star-trek-like science becoming real. But it certainly doesn't help to replace critical thinking with wishful thinking.

shin_lao 11y ago
Difference here is that the experiment has been done by two different teams from different countries using different protocols.
- makomk 11y ago
  If I recall correctly, the two teams got different results. Although they both found very small amounts of thrust that they couldn't explain, the actual amount of unexplained thrust was different by something like an order of magnitude.
- marcosdumay 11y ago
  And no team had a conclusive result.
Symmetry 11y ago
I'll agree that experimental error is the most likely explanation by far but I think there's still a noticeable chance that the explanation is some novel effect that doesn't actually violate conservation of momentum. If I were to give a break down on my expectations they'd probably be something like 90% Experimental error 9% Unexpected and novel consequence of current physics 1% New physics that doesn't actually violate momentum conservation ~0% Violation of conservation of momentum. But this has gone the point where even if it's experimental error I expect the mechanism will be at least somewhat interesting, as with the Italian speed of light experiment.
- mahranch 11y ago
  > ~0% Violation of conservation of momentum. I don't think the chance of violation of the conservation of momentum would be 0%. Unlikely? Yes. Highly unlikely? Most definitely, but not zero. Why? Because we don't yet have a "theory of everything". For all we know, (not saying this is the case, just a thought experiment/hypothetical) the string theorists have it right, and there are extra dimensions, or brane universes (a multiverse) and maybe this effect is in some way related to that (pulling/utilizing an energy from a higher 4th dimension). Granted, it goes against everything we currently know about physics, but so did a lot of things at one point. And that usually happens when we don't know enough about the area we're researching. And when it comes to quantum mechanics, we're only scratching the surface of what we know. There are plenty of things in quantum mechanics that are completely inexplicable. Things like the double slit experiment, quantum entanglement, quantum tunneling, etc.. We know those things occur, but very little or nothing at all as to the "how" and "why". They seem to defy known physics but there they are...
  - mikeash 11y ago
    That squiggly line in front of the zero means "approximately," so really you're in agreement. The chances are not exactly 0, but more like 0.0000001%.
  - Symmetry 11y ago
    It's certainly not impossible, which is why I put the "approximately" symbol in front of the zero. I would be very, very surprised if the TOE broke conservation of momentum but then again I found it very surprising that there's basically just one experiment that breaks reflective symmetry (I forget what it's Noether[1] equivalent conservation law is). [1]https://en.wikipedia.org/wiki/Noether%27s_theorem https://en.wikipedia.org/wiki/Noether%27s_theorem
    - mahranch 11y ago
      > which is why I put the "approximately" symbol in front of the zero. Ah, I missed that somehow... Haven't had my coffee.
JoeAltmaier 11y ago
Not a bad cable - wasn't it failing to account for relativistic effects in the GPS satellites used for time/location reference?
- mikeash 11y ago
  It was an improperly attached cable, and a bad clock. Relativistic effects on the GPS satellites was proposed as a potential explanation, but was not the final accepted cause.
- jasonwatkinspdx 11y ago
  No, it was one connector on one cable that had a fault that introduced latency in a rather unexpected way. The people doing this are much more sophisticated than "oops, forgot GR when doing GPS calcs."
deleted 11y ago
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by hannob 11y ago

shin_lao 11y ago

Difference here is that the experiment has been done by two different teams from different countries using different protocols.

makomk 11y ago
If I recall correctly, the two teams got different results. Although they both found very small amounts of thrust that they couldn't explain, the actual amount of unexplained thrust was different by something like an order of magnitude.
marcosdumay 11y ago
And no team had a conclusive result.

Symmetry 11y ago

I'll agree that experimental error is the most likely explanation by far but I think there's still a noticeable chance that the explanation is some novel effect that doesn't actually violate conservation of momentum. If I were to give a break down on my expectations they'd probably be something like 90% Experimental error 9% Unexpected and novel consequence of current physics 1% New physics that doesn't actually violate momentum conservation ~0% Violation of conservation of momentum. But this has gone the point where even if it's experimental error I expect the mechanism will be at least somewhat interesting, as with the Italian speed of light experiment.

mahranch 11y ago
> ~0% Violation of conservation of momentum. I don't think the chance of violation of the conservation of momentum would be 0%. Unlikely? Yes. Highly unlikely? Most definitely, but not zero. Why? Because we don't yet have a "theory of everything". For all we know, (not saying this is the case, just a thought experiment/hypothetical) the string theorists have it right, and there are extra dimensions, or brane universes (a multiverse) and maybe this effect is in some way related to that (pulling/utilizing an energy from a higher 4th dimension). Granted, it goes against everything we currently know about physics, but so did a lot of things at one point. And that usually happens when we don't know enough about the area we're researching. And when it comes to quantum mechanics, we're only scratching the surface of what we know. There are plenty of things in quantum mechanics that are completely inexplicable. Things like the double slit experiment, quantum entanglement, quantum tunneling, etc.. We know those things occur, but very little or nothing at all as to the "how" and "why". They seem to defy known physics but there they are...
- mikeash 11y ago
  That squiggly line in front of the zero means "approximately," so really you're in agreement. The chances are not exactly 0, but more like 0.0000001%.
- Symmetry 11y ago
  It's certainly not impossible, which is why I put the "approximately" symbol in front of the zero. I would be very, very surprised if the TOE broke conservation of momentum but then again I found it very surprising that there's basically just one experiment that breaks reflective symmetry (I forget what it's Noether[1] equivalent conservation law is). [1]https://en.wikipedia.org/wiki/Noether%27s_theorem https://en.wikipedia.org/wiki/Noether%27s_theorem
  - mahranch 11y ago
    > which is why I put the "approximately" symbol in front of the zero. Ah, I missed that somehow... Haven't had my coffee.

JoeAltmaier 11y ago

Not a bad cable - wasn't it failing to account for relativistic effects in the GPS satellites used for time/location reference?

mikeash 11y ago
It was an improperly attached cable, and a bad clock. Relativistic effects on the GPS satellites was proposed as a potential explanation, but was not the final accepted cause.
jasonwatkinspdx 11y ago
No, it was one connector on one cable that had a fault that introduced latency in a rather unexpected way. The people doing this are much more sophisticated than "oops, forgot GR when doing GPS calcs."

deleted 11y ago

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