----- Original Message ----- 
From: "Alberto Monteiro" <[EMAIL PROTECTED]>
To: "Killer Bs Discussion" <[email protected]>
Sent: Wednesday, November 09, 2005 11:13 AM
Subject: Re: What Does 'Almost Nothing' Weigh?



> Was it dismissed the hypothesis that neutrinos had an
> "imaginary" mass [i.e., they were tachions]?

IIRC, the only reason anyone thought that neutrinos travel faster than
light is that supernova neutrinos have been observed a very short time
before the light from the supernova.  There are a couple of obvious
problems with this.  If they go faster than light, then it is by very
little, since the timing difference is only a few hours for intergalactic
distances (millions of light years).  Second, the timing difference is
close to the same for different distances...which would not be true if the
timing difference is due to speed.  Third, tachions are not suppose to
interact with normal matter...any interaction would be problematic...and
not just with a simple virtual Z or W.

A more obvious explanation was that the neutrino flux originated slightly
before the light flux.  That does make sense, since the star that is about
to go supernova is, essentially, transparent to neutrinos, but not to other
elements.  For example, IIRC, it would take years after the sun stopped
neutrino production for it to stop shining...the supernova process is much
faster, but not really instantaneous. My memory is that the physics of this
has been worked out to general satisfaction.

Dan M.


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