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Thread: Speed of light exceeded??

  1. #391
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    Just seen a report that the latest experiment
    shows neutrinos going at precisely light speed.
    Its the precisely bit I like. If that histogram
    they generate peaks at light speed then the
    normal error means there is still a chance they
    are a bit faster.


  2. #392
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    On a point of parsimony. This doesn't prove neutrinos don't travel faster than light. It simply invalidates the evidence that they do.

    Someone should really blow up Betelgeuse to settle this once and for all.

  3. #393
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    Cooked

    Quote Originally Posted by captain swoop View Post
    It wasn't someone turning the electric Can Opener on and off was it?
    Funny! We had one of those once at work. We would intermittently loose power to four adjoining cubicles at once. Circuit breaker would trip, nothing obvious going on in the cubicles. Finally, after paying for very good electrician, discovered it was a miswire to a lunchroom in another department 100 feet away. When they turned on the microwave, we were done!

    Regards, John M.

  4. #394
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    Quote Originally Posted by Glom View Post
    On a point of parsimony. This doesn't prove neutrinos don't travel faster than light. It simply invalidates the evidence that they do.

    Someone should really blow up Betelgeuse to settle this once and for all.
    My bold. That will not settle anything. The neutrinos will get here first, but that is because they will escape easily from the core and envelope at or near c, the speed of light in a vacuum. The other actions that eventually generate the light show of a supernova take a while longer to grind their way out of the star.

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    Quote Originally Posted by captain swoop View Post
    It wasn't someone turning the electric Can Opener on and off was it?
    That only works for magnetic monopoles.
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

  6. #396
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    Quote Originally Posted by Hornblower View Post
    My bold. That will not settle anything. The neutrinos will get here first, but that is because they will escape easily from the core and envelope at or near c, the speed of light in a vacuum. The other actions that eventually generate the light show of a supernova take a while longer to grind their way out of the star.
    Then we should dig a tunnel between the emitter and the detector so that photons and neutrinos can have a foot race.
    Et tu BAUT? Quantum mutatus ab illo.

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    Quote Originally Posted by Hornblower View Post
    The other actions that eventually generate the light show of a supernova take a while longer to grind their way out of the star.
    But can't we determine the amount of this time difference?
    If it takes 48 hours for the light show after the neutrino emission and we see a difference of 49 hours, then that would indicate FTL (or our estimate of the difference is wrong).

  8. #398
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    Quote Originally Posted by NEOWatcher View Post
    But can't we determine the amount of this time difference?
    If it takes 48 hours for the light show after the neutrino emission and we see a difference of 49 hours, then that would indicate FTL (or our estimate of the difference is wrong).
    Well, if we knew the exact timing of the collapse, the exact timing of the arrival of neutrinos, the exact timing of the arrival of the EM radiation, then yeah, we could do it. Problem is, a lot of that timing isn't all that well know or depends on distances or thicknesses of material that aren't all that well known. So most of what we have are nothing more than estimates. By the best estimates, the neutrinos of 1987A arrived about three hours before the EM radiation. That's matches estimates of how long it would take the EM radiation to break out of what was thought to be the progenitor of the supernova(since it was a core collapse and the EM had to work its way through the material of the star).

  9. #399
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    Quote Originally Posted by peteshimmon View Post
    Just seen a report that the latest experiment shows neutrinos going at precisely light speed. Its the precisely bit I like.
    I don't like it. As previously shown in this thread, if neutrinos have a mass, as many sensible people suppose, they should go very slightly slower than light speed. But at the level of precision of this experiment, the difference is not detectable. In fact the main point of the Gran Sasso experiment was not to measure their speed, that was merely a side issue. If we could measure some neutrinos going discernably slower than light speed, we would know their mass. For the moment it is other properties that lead us to believe they have a mass.

  10. #400
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    Quote Originally Posted by Ivan Viehoff View Post
    If we could measure some neutrinos going discernably slower than light speed, we would know their mass.
    Scientist A: Neutrinos should have mass, but we don't know how much.
    Scientist B: If we can measure how much slower than c they go, we should be able to figure it out.
    Scientist A: Great idea, let's set up an experiment.

    [Later]

    Scientist A: We've got the speed results!
    Scientist B:
    Scientist A: Yeah, we may want to try that again.

    BTW: Will "we" be able to measure the speed difference of light and neutrinos from the Supernova just discovered in M95?
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

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    Quote Originally Posted by Extravoice View Post
    BTW: Will "we" be able to measure the speed difference of light and neutrinos from the Supernova just discovered in M95?
    In theory yes but in practice no. The reason is that we only managed to detect 24 neutrinos from SN1987a using three different detectors. The main reason we where able to corrolate them with SN1987a was that the SN was observed visually and that the observed time lag was supported by supernova models. M95 is about 225 times further away which means that statistically we should only detect about 1/50000 as many neutrinos as from SN1987a. I don't know how much better (or worse) current neutrino detectors are but they are not that much better than they where in 1987. I'd be surprised if we detected even one neutrino and even then it would most certainly be lost in the noise.

  12. #402
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    Yes that is the other possiblity of the
    histogram spread, the speed being just
    less than light. But the peak is not
    centered on some line, it is between
    error bars of the speed due to the error
    in the measured distance. So we don't know
    where we are

  13. #403
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    Quote Originally Posted by Extravoice View Post

    Scientist A: Neutrinos should have mass, ...
    Scientist B: "I didn't know neutrinos were Catholic".

    BTW: Will "we" be able to measure the speed difference of light and neutrinos from the Supernova just discovered in M95?
    I'm waiting for the gravitational waves detectors to start ringing so we can argue about the speed of Gravitational waves.

    BTW; several spectra have just been completed and it appears to confirm a type II supernova (as suspected):
    http://www.cbat.eps.harvard.edu/iau/...CBET003054.txt

    Doppler shifted hydrogen alpha lines show the ejecta velocity to be ~ 5% the velocity of light.

    Gsquare
    Last edited by Gsquare; 2012-Mar-21 at 03:52 AM.

  14. #404
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    Quote Originally Posted by peteshimmon View Post
    So we don't know
    where we are
    I know I'm right here... so I know I can't be all there.

    G^2

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    Quote Originally Posted by Gsquare View Post
    I know I'm right here... so I know I can't be all there.

    G^2
    You are not where ever you were then...and apparently you will not know now; at least not within 40 ns.

    Sheesh! I thought that was way too much to be an experimental error - it is not like they were using one detector with old D-cell batteries.

    The full explanation, complete with both the distribution and window cut-offs and all that tough timing stuff will be most helpful.

    I ran into a timing calibration problem that may have been quite similar once: There was a bad coupling in a wave guide that returned a strong pulse a few usec before the first expected echo. Since we used spacing between the first two expected pulses to verify the scope sampling rate, our scope timing was off ~20%. (This wouldn't happen with most modern scopes, since the set-up parameters are parsed with the data.)

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    The dog, the dog, he's at it again!

  17. #407
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    Quote Originally Posted by NEOWatcher View Post
    But can't we determine the amount of this time difference?
    If it takes 48 hours for the light show after the neutrino emission and we see a difference of 49 hours, then that would indicate FTL (or our estimate of the difference is wrong).
    How would we know it takes 48 hours?
    As above, so below

  18. #408
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    Quote Originally Posted by Glom View Post
    Someone should really blow up Betelgeuse to settle this once and for all.
    I nominate you, then. We can give you an old Space Shuttle. You can beam back to us the difference in seconds between the emission of neutrinos and photons, just prior to being blown to plasma, and then we can measure the difference on earth!
    As above, so below

  19. #409
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    Quote Originally Posted by Jens View Post
    How would we know it takes 48 hours?
    That's why I was asking, I just figured that ther might be some kind of star formation theory and its math that could predict it.

  20. #410
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    Quote Originally Posted by Gsquare View Post
    I know I'm right here... so I know I can't be all there.

    G^2
    And as it happens, I'm wearing a T-shirt that says, "We're all here because we're not all there."

    No neutrinos were harmed in making of this post.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  21. #411
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    Quote Originally Posted by Trebuchet View Post
    And as it happens, I'm wearing a T-shirt that says, "We're all here because we're not all there."

    No neutrinos were harmed in making of this post.
    I knew I shoulda copyrighted it when I had the chance.

    - "Driver carries no money, he's married." -

    --This entire post made with recycled electrons.--

    ..

  22. #412
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    The head of an experiment that appeared to show subatomic particles travelling faster than the speed of light has resigned from his post.

    Prof Antonio Ereditato oversaw results that appeared to challenge Einstein's theory that nothing could travel faster than the speed of light.
    BBC

  23. #413
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    I certainly hope it is for reasons other than the topic of this thread.
    Last edited by Extravoice; 2012-Mar-30 at 06:49 PM. Reason: improved clarity
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

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    Italian physicist behind 'faster-than-light' test resigns
    An Italian physicist at the head of a team that made a cautious but hugely controversial claim that neutrinos may travel faster than the speed of light resigned on Friday following calls for his dismissal.

    Antonio Ereditato submitted his resignation before a vote on a motion by some members of his OPERA team that he be removed after tests this month contradicted the claim that the universe's speed limit had been broken.

    A headline in Corriere della Sera called Ereditato "the physicist of flop."
    Adios Antonio .. RIP !

    Regards

  25. #415
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    It appears that the reason for the no confidence vote was members of the team felt the announcement wasn't careful enough with the language of the announcement. Failing to make sure the press was aware that the results were preliminary.
    Details here

  26. #416
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    Quote Originally Posted by Extravoice View Post
    I certainly hope it is for reasons other than the topic of this thread.
    As do I, if not it would be following an example of science at its best with science at its worst.

  27. #417
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    What was Ereditato's role there? Was he leading all of the
    neutrino observations? If so, a vote of "no confidence" and
    consequent resignation for not making clear to media what
    was in fact overabundantly clear (that the neutrino speed
    measurements were not completely certain) strikes me as
    massive overkill. They must have not liked the guy, and
    were looking for an excuse. Awfully flimsy excuse, I'd say.

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  28. #418
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    The lesson to be learned here, is about the importance of precision in Science communications.

    Handling the press is a matter for considerable communications and leadership skills. Being a Science Professor doesn't automatically qualify one as a being a guru in handling the press.

    The recent BAUT Faq thread here, for me, is about this very aspect of what we do here at BAUT. These fora are good training ground for understanding just how our messages land in the minds of readers, (with almost instantaneous feedback).

    The 'Golden Age of Astronomy', in which we presently find ourselves, imposes the crucial need to develop effective communications skills, when talking about complex science matters, and the scientific process. I wonder if Ereditato has had extensive experience in playing under the public scientific announcement spotlight ? (It would seem he certainly has now).

    Accountability for one's words, is where the forum rules and moderation play a role.
    Assuming responsibility for one's words however, seems to be entirely up to the individual.

    Regards

  29. #419
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    That seems very sad. Media coverage of the matter blew it out of proportion, but it seemed like Ereditato had done a pretty good job of making it clear that it was an unexpected result, that they knew it was probably the result of a mistake in the measurement somewhere, but that they had been unable to find that mistake and were making the preliminary results public in the hope that someone else would be able to determine where the problem was.
    Conserve energy. Commute with the Hamiltonian.

  30. #420
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    Quote Originally Posted by Grey View Post
    That seems very sad. Media coverage of the matter blew it out of proportion, but it seemed like Ereditato had done a pretty good job of making it clear that it was an unexpected result, that they knew it was probably the result of a mistake in the measurement somewhere, but that they had been unable to find that mistake and were making the preliminary results public in the hope that someone else would be able to determine where the problem was.
    That was my impression also. They wanted the physics community to look over their data and methods to see if there were any errors. I'm not sure what else Ereditato could have done. Unless this is also related to some unknown political splits within the group, that isn't related to the test results.

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