spin of massive neutrino at rest

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David Bernier - 18 Jul 2008 15:32 GMT

According to this Web page,
http://wwwlapp.in2p3.fr/neutrinos/ankes.html
"the neutrino seems to have a remarkable property: its spin
is always oriented in the direction opposite to its velocity."
[hypothesis of T.D. Lee et C.N. Yang, 1956].

John Bahcall wrote this about the solar neutrino puzzle:
http://nobelprize.org/nobel_prizes/physics/articles/bahcall/index.html

I believe neutrino oscillations imply by some general principle
that at least one of the three kinds of neutrino
has a non-zero mass.

Maybe the e-neutrino is massive. If so, maybe the spin
for a neutrino at rest would depend on what process created it.

I've only read a bit about dark matter. Could massive
neutrinos contribute to it? A neutrino only feels
the weak nuclear force. At high energies, weak
and EM-force are united. Does that disqualify
massive neutrinos as part of "dark matter"?

And would massive neutrinos take part in the
formation of new stars? If so, to what extent?

David Bernier

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Androcles - 18 Jul 2008 15:47 GMT

| According to this Web page,
| http://wwwlapp.in2p3.fr/neutrinos/ankes.html
[quoted text clipped - 14 lines]
| I've only read a bit about dark matter. Could massive
| neutrinos contribute to it?

Sure, if you believe it. Since you already believe neutrino oscillations
imply whatever it is you believe then they can do whatever want them to.

| A neutrino only feels
| the weak nuclear force.

The tooth fairy doesn't feel a thing.

| At high energies, weak
| and EM-force are united. Does that disqualify
| massive neutrinos as part of "dark matter"?

No, unless you believe it does.

| And would massive neutrinos take part in the
| formation of new stars?

Of course, if that's what you believe.

| If so, to what extent?

Oh, as far as the surface of the star I expect. Unless
you believe they go further, of course.

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Puppet_Sock - 18 Jul 2008 18:22 GMT

[ignorant dribblings about dark matter snipped]

Androcles would seem to be made of _dim_ matter.
Socks

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nuny@bid.nes - 19 Jul 2008 06:48 GMT

> According to this Web page,http://wwwlapp.in2p3.fr/neutrinos/ankes.html
> "the neutrino seems to have a remarkable property: its spin
[quoted text clipped - 9 lines]
> Maybe the e-neutrino is massive. If so, maybe the spin
> for a neutrino at rest would depend on what process created it.

Run through this a few times:

http://en.wikipedia.org/wiki/Neutrino

Yes, all 3 'known' flavors of neutrino are considered to be (just
barely) massive (sum the masses of one of each of the three flavors
and you get less than a third of an electron volt) and hence travel
(just barely) slower than light. Getting a neutrino to _be_ at rest
would be a good trick. How would you propose to relieve it of its
energy of motion? There seems to be a severe dearth of possible
physical mechanisms for them to shed energy through.

> I've only read a bit about dark matter. Could massive
> neutrinos contribute to it? A neutrino only feels
> the weak nuclear force. At high energies, weak
> and EM-force are united. Does that disqualify
> massive neutrinos as part of "dark matter"?

http://en.wikipedia.org/wiki/Dark_matter

Despite the fact that there can be such things as 'sterile'
neutrinos (that can't feel the weak force but can feel gravity), they
still move too fast to have allowed ordinary matter to clump into
galaxies. So, they're pretty much out as dark matter.

> And would massive neutrinos take part in the
> formation of new stars? If so, to what extent?

Where'd you get that idea?

Mark L. Fergerson

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Natural Science Forum / Physics / General Physics / July 2008

spin of massive neutrino at rest