Are Neutrinos Faster Than Light?

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Discussion Overview

The discussion centers around the speed of neutrinos in relation to light, particularly in the context of their detection from supernova 1987A. Participants explore the implications of neutrinos arriving before light from the explosion and the mechanisms behind their escape from the supernova.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants note that neutrinos were detected three hours before light from the supernova, leading to questions about whether this indicates they travel faster than light.
  • Others argue that neutrinos do not exceed the speed of light, suggesting that they escape the supernova more quickly due to weaker interactions compared to photons.
  • There is a claim that photons react more strongly with matter, which delays their escape relative to neutrinos.
  • Participants discuss the nature of neutrinos, including the concepts of "right-handed" and "left-handed" neutrinos, with some expressing confusion over these terms.
  • One participant emphasizes that the diffusion time for photons and neutrinos depends on their interactions within the supernova environment.
  • There are corrections and challenges regarding the definitions and properties of helicity in relation to neutrinos and other particles.

Areas of Agreement / Disagreement

Participants express differing views on the implications of neutrinos arriving before light, with some asserting that this does not mean they travel faster than light, while others suggest that the timing of their escape is influenced by interaction dynamics. The discussion remains unresolved regarding the precise nature of neutrino behavior and the implications of their speed.

Contextual Notes

Participants reference the complexities of particle interactions and the definitions of helicity, indicating that there may be nuances and assumptions that are not fully explored in the discussion.

  • #31
Smells bad, and inconsistent with SN1987A…
There had been a delay of ~3h between the neutrinos and the gammas in SN1987A (it had been explained by astrophysical reasons, though). If one however interprets it as physical, takes the distance of the SN (168000 ly) and rescales it to the distance between CERN and Gran Sasso, one would expect at GS a delay of

Dt ~ 10000 s * (700e3/(168000*3e7*3e8)) ~ 5 ps

which is 1 millimeter… It is true that the SN neutrinos where in the MeV, but it looks strange that something dramatic happens between the MeV and the GeV…

Alessandro De Angelis

PS – People had claimed and then withdrawn, in the case of the SN1987A, a neutrino detection 1 day before – and also speculated about neutrinos being tachions; this would make however 50 ps, still not enough…
 
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  • #32
Do you mean this
http://arxiv.org/ftp/arxiv/papers/1109/1109.4897.pdf?
 
Last edited by a moderator:
  • #33
DrChinese
"The speed of light in a vacuum of course is equal to the speed of a neutrino in a vacuum."

Today in 2011, not all physicists think so (the above is article from Gran Sasso National Laboratory which just appeared in ArXiv.org).

This is a serious attempt to crash our fundamental basis. My impression, there is some experimental miss-interpretation, but how big team of good physicists in respectable Lab can make such conclusion, this is out of my mind.
 
  • #34
gvk said:
DrChinese
"The speed of light in a vacuum of course is equal to the speed of a neutrino in a vacuum."

Today in 2011, not all physicists think so (the above is article from Gran Sasso National Laboratory which just appeared in ArXiv.org).

Note the date on Dr. Chinese's post.

Please confine further discussion of the OPERA results to the existing thread:

https://www.physicsforums.com/showthread.php?t=532620
 

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