Velocity of a Neutrino

[aViolentBee]

Can anyone tell me the velocity of a neutrino please? I couldn't find it anywhere...

[Strange]

It depends how much energy it has. But because of their low mass, most neutrinos move at pretty close to the speed of light.

[aViolentBee]

So would I be wrong if I said 1.08×10⁹ km/h?

[Strange]

No.

 

More here: http://en.wikipedia.org/wiki/Measurements_of_neutrino_speed

 

It looks like the speed of neutrinos is, so far, indistinguishable from the speed of light.

Edited November 9, 2014 by Strange

[DimaMazin]

So would I be wrong if I said 1.08×10⁹ km/h?

Yes. Neutrino has mass therefore has only relative velocity( velocity of light isn't relative). We can detect only neutrino with high energy therefore you would be right only relative to a neutrino which we can detect.

[aViolentBee]

Thanks for the replies guys. I'm a dummy in physics/maths but I find it interesting!

[michel123456]

Yes. Neutrino has mass therefore has only relative velocity( velocity of light isn't relative). We can detect only neutrino with high energy therefore you would be right only relative to a neutrino which we can detect.

That doesn't make much sense.

If all velocities under SOL are relative, if a velocity very very close to SOL is relative, then SOL is relative too.

Only that this relativeness is the same for all observers.

 

[elfmotat]

That doesn't make much sense.

If all velocities under SOL are relative, if a velocity very very close to SOL is relative, then SOL is relative too.

Only that this relativeness is the same for all observers.

 

 

Oh no, what are you on about? Neutrinos are massive particles. That means they don't move at c, and they have rest frames. Nothing moving at the speed of light has a rest frame.

[michel123456]

My comment was related to DimaMazin's statement that:

Neutrino has mass therefore has only relative velocity( velocity of light isn't relative)

the first part is understandable: "Neutrino has mass therefore has only relative velocity". Agree,

 

I question the second part: "velocity of light isn't relative"

Edited November 9, 2014 by michel123456

[elfmotat]

My comment was related to DimaMazin's statement that:

the first part is understandable: "Neutrino has mass therefore has only relative velocity". Agree,

 

I question the second part: "velocity of light isn't relative"

 

It depends on what you mean by "relative." If you mean "frame-dependent," then it is not relative. If you mean "measured relative to some other object," then it is relative. This is all just semantics.

[swansont]

I question the second part: "velocity of light isn't relative"

 

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Moderator Note

The invariance of c is a standard part of relativity, and is not part of this discussion. Please take it up elsewhere, if you wish to discuss it further.

 

 

edit: followup post moved to http://www.scienceforums.net/topic/86473-physics-terminology-split-from-velocity-of-a-neutrino/

Please take it up elsewhere = please start a new thread

 

Regardless of specifics, it's off-topic for this thread

 

 

[ajb]

Also remember that it was thought for many years that neutrinos were massless and so travel at the speed of light. Thanks to the phenomena of neutrino oscillations, that is they can change flavour strawberry to chocolate electron, mu or tau, we know they have a mass. This oscillation process requires a mass and has no formulation in the original set up of the standard model of particle physics. The standard model today includes these oscillations.

[michel123456]

I am not questionning invariance of C.

 

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If the neutrino has mass, its velocity is relative and thus a neutrino should not have a velocity. It would be like asking "what is the velocity of Swansont" ans someone to shout "MOVING IN WHICH REFERENCE FRAME!?!?"

[swansont]

 

If the neutrino has mass, its velocity is relative and thus a neutrino should not have a velocity. It would be like asking "what is the velocity of Swansont" ans someone to shout "MOVING IN WHICH REFERENCE FRAME!?!?"

 

!

Moderator Note

"The neutrino should not have a velocity" is a nonsensical statement. It's also not really tied to the OP, since one could substitute any massive object into the discussion. Thus it is off-topic. PLEASE stop hijacking the thread to discuss the particulars of relative vs invariant, or whatever your commentary or question is, if it's not tied to the topic of the OP.

[DimaMazin]

Theoretically neutrino can have any velocity (which is less than velocity of light in vacuum) in any reference frame.

[MigL]

Just my opinion...

Neutrinos are produced in fairly energetic processes, so their initial speed is very high ( close to c ).

They interact rather weakly, so they don't really lose that initial speed.

Your chances of finding one at rest beside you is, therefore, virtually nil.

 

Neutrinos started a race with photons from the Magellanic Clouds. They were produced by the same event, a super nova, yet because the photons interact with the plasma surrounding the super nova and were slowed down by these interactions, they arrived here after the sub-luminal neutrinos.

[DimaMazin]

 

Your chances of finding one at rest beside you is, therefore, virtually nil.

 

 

What are your chances of finding one at rest if 10¹⁰ neutrinos at rest are beside you?

[Strange]

What are your chances of finding one at rest if 10¹⁰ neutrinos at rest are beside you?

 

Zero. We can only detect neutrinos with high enough energy to interact with atoms.

[DimaMazin]

 

Zero. We can only detect neutrinos with high enough energy to interact with atoms.

Does our inability to detect neutrino at 0.99c that they don't exist at the speed relative to us?

Edited November 12, 2014 by DimaMazin

[swansont]

Does our inability to detect neutrino at 0.99c that they don't exist at the speed relative to us?

 

There's no mechanism to create them at, or bring them to, rest with respect to us.

[DimaMazin]

 

There's no mechanism to create them at, or bring them to, rest with respect to us.

I mean that we are humanity. Theoretically that will be possible in future when 'redshift' of neutrinos from an escaping far galaxy will reduce speed of neutrino to 0.99c. And our spacecraft will accelerate to 0.99c in the same direction of motion of the neutrino.

Even now maybe such neutrinos exist from invisible galaxy or escaping another universe.

[swansont]

I mean that we are humanity. Theoretically that will be possible in future when 'redshift' of neutrinos from an escaping far galaxy will reduce speed of neutrino to 0.99c. And our spacecraft will accelerate to 0.99c in the same direction of motion of the neutrino.

Even now maybe such neutrinos exist from invisible galaxy or escaping another universe.

 

How would a neutrino that's at rest with respect to us but far away ever get to us?

[DimaMazin]

 

How would a neutrino that's at rest with respect to us but far away ever get to us?

Neutrino can be at rest with respect to us when gets to us after accelerations.For example when a universe is escaping from us and is radiating neutrinos to us, and we are escaping from the universe with acceleration.

[swansont]

Neutrino can be at rest with respect to us when gets to us after accelerations.For example when a universe is escaping from us and is radiating neutrinos to us, and we are escaping from the universe with acceleration.

 

"A universe escaping from us" (or vice-versa) makes no sense. There is only one universe with which we interact.

 

Any large-scale effect, e.g. expansion, would happen for the neutrinos as well as us. Aside from that, how would you accelerate a neutrino?

[Strange]

Neutrino can be at rest with respect to us when gets to us after accelerations.For example when a universe is escaping from us and is radiating neutrinos to us, and we are escaping from the universe with acceleration.

 

I'm not sure what you are trying to say, here. However, there is thought to be a "cosmic neutrino background" equivalent of the cosmic microwave background (CMB). This would consist of neutrinos released 380,000 years before the CMB and hence would be at an even lower temperature. If we were able to detect these low energy neutrinos, they would give us a lot of information about the early universe. But it seems unlikely they can ever be detected.