Should a neutrino be moving slightly slower than c?

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Discussion Overview

The discussion revolves around the speed of neutrinos in relation to the speed of light, particularly whether neutrinos should be expected to travel slightly slower than light due to their mass. The conversation touches on experimental results, theoretical implications, and the nuances of neutrino mass.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that neutrinos travel at the speed of light (c), referencing ICARUS results and suggesting that CERN's findings may be erroneous due to equipment issues.
  • Others mention the MSW effect, indicating that neutrinos have mass, but note the possibility that one mass eigenstate could be zero, which complicates the understanding of their speed.
  • There is a discussion about the implications of neutrinos from supernova SN1987A, which arrived with a slight delay compared to light, suggesting they travel extremely close to c.
  • One participant expresses skepticism about the measurability of any speed difference between neutrinos and light, citing technological limitations.
  • There is a side note questioning whether this topic should be merged with another existing thread on neutrinos.

Areas of Agreement / Disagreement

Participants express differing views on whether neutrinos should be expected to travel slower than light due to their mass. While some agree that any difference may be negligible, others highlight the complexities surrounding neutrino mass and speed, indicating that the discussion remains unresolved.

Contextual Notes

Participants mention the potential for measurement limitations and the implications of mass eigenstates on the speed of neutrinos, but do not resolve these issues or clarify the assumptions involved.

San K
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The ICARUS results evidence that neutrino moves at speed, not faster/slower, but same as c.
The CERN results seem to be wrong due to some error in the equipment.

http://arxiv.org/ftp/arxiv/papers/1203/1203.3433.pdf

aren't the neutrinos expected to travel slightly slower than c? (due to slight mass)

or is the mass (velocity) difference too small to be noticeable, by any experiment?

c = speed of light/photon

the photon has zero rest mass. i am assuming that the relativistic mass of the photon is less than that of neutrino.
 
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The MSW effect says that neutrinos have (some) mass...except there's the loop hole that 1 mass eigenstate of the neutrinos could be 0, so there's that. There are some upper bounds on neutrino masses, but they seem to be extremely extremely light.

Neutrinos from SN1987A showed that they basically kept their 3 hour head start on the photons over a distance of ~160k light years! This means they travel EXTREMELY close to the speed of light.

EDIT: I typo'd I should have said 1 mass eigenstate "COULD BE" 0. The MSW effect doesn't say that any of them has to be 0. It does say that not all of them can be 0, however.
 
You're right, they should. But as you say the difference may be incredibly small, especially if you consider that neutrinos from the 1987 supernova arrived at about the same time as light did (apart from the three hour difference which was due to other factors). So my guess is that the slight lag in speed for the neutrinos may be too small to measure with our current technology.

(BTW, shouldn't this question go into the other neutrino thread?)
 
lmoh said:
(BTW, shouldn't this question go into the other neutrino thread?)

Where it's already been answered in posts 750 and 751...
 

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