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afterburner
2006-Jul-18, 03:33 PM
I was just wondering...

How dense is the neutrino sea that we live in? (I've read a estimate of 1,000,000,000,000 neutrinos per cubic cm, but im not sure if thats correct)

Although neutrinos can pass through light years of lead withough "hitting" anything, they still interact through the weak force and, most importantly, through the gravitational force with other things...If we were to attempt to accelerate the ship to c, would the neutrinos have a sort of drag effect on the ship preventing it from reaching higher speeds? That is to say, if we were to somehow create a bubble of neutrino-free space around the ship("true vacuum" Edit: and shielded from EM radiation and small particles of matter), would the ship be able to accelerate to c faster...and perhaps beyond c?

How many neutrinos would hit a typical human body throughout the day? (I am aware that the majority of them go right through, but because there are uncomprehendable numbers of neutrinos going through me every hour, every day, I would think that some "hit" me) Would anyone have an estimate as to how many do hit me?

When a neutrino does hit something, what is the interaction like? Is it like a photon, where the photon gets absorbed(and there is no photon, until a new one gets re-released?) But as neutrinos only get produced in nuclear fusion, and my body does not have such processes, I doubt thats what happens (could be wrong). Is the neutrino forever(until i move) stuck in my body?(would that mean that that neutrino is from now on "still"?)...SO...If anyone knows, please share with me (and all readers)

Neutrinos get created through nuclear fusion..

Does that mean that ALL neutrinos in this universe were created that way, and now we live in a sea of them?

Since (im assuming) stars are the major sources of neutrino "production", is the general flow of neutrinos away from the stars?

How do neutrinos interact with each other?

How do neutrinos interact with photons?

Do neutrinos have a "shelf life"? Do they expire, or are the neutrinos from the early universe still around? If they are, would that mean that the universe is denser with neutrinos now, than it was yesterday, a billion years ago, and ten billion years ago?

If neutrinos get created through nuclear fusion...do we know exactly how they get created?

I think thats it for now :D

jlhredshift
2006-Jul-18, 06:03 PM
I'll add one more question-

Could they be heavy light (electromagnetic radiation)?

Squashed
2006-Jul-19, 01:19 AM
I was just wondering...

Do neutrinos have a "shelf life"?

I was reading a book which talked about half-lives of particles and, I believe, the proton lives the longest (which is quite a long time) and so I would say that even neutrinos have a half-life - whether it is shorter or longer than the proton's half-life, I do not know.

In other words, I think every particle has a half-life and if a neutrino is an actual particle then it too would have a half-life.

trinitree88
2006-Jul-19, 03:39 AM
Neutrinos are made when H fuses to He. Anti-neutrinoselectron-type are "made" in beta decay. When the C-14 in your body, and food supply decays...you emit them. So like the stars, you glow a little bit in neutrinos. So do nuclear submarines. The word neutrino is kind of thrown around a bit in the literature meaning either neutrino or antineutrino.

Neutrinos can participate in the universe via, as Afterburner comments..gravity, or the weak interaction. The weak interaction is mediated by force carriers...the W+, W-, or the Z0....formerly called the W0.

Picture decay of a free neutron. The neutron disintegrates, a proton, electron, and an electron-type antineutrino are produced. It's not that the electron and antineutrino "live" imprisoned in the neutron till it disintegrates...they are a product of the decay process.
In quarks, the neutron is two downs and an up. The proton is two ups and a down. So, in neutron decay, a down quark is converted to an up. This flavor (down-up) exchange occurs because of the weak current. A massive W- is produced by the down quark as it flips to an up. In short order, the W- decays into an electron and an electron-type antineutrino.
The antineutrino is birthed in the decay.

There are those who believe neutrinos may carry mass. Experiments have only so far delimited the upper bounds on what those possible masses may be no larger than....~.003 ev. These experiments are not inconsistent with massless neutrinos.
If neutrinos have mass, they must be subluminal..(or we throw out SR)(Einstein rolls in grave). Massless neutrinos travel at c from birth. E=hv works for them. E/c =hv/c also works for them. They have wavelengths, frequencies, but obey Fermi-Dirac statistics, because they have half-integer spins. That means they cannot pile up to an infinite number in an enclosed volume...(unlike photons which can because they have integral spins, and obey Bose-Einstein statistics which do allow that)
Massless neutrinos can interact via the three bosons,W+,W-, Z0. The Z interaction is universal...it acts on everything in the universe...no exception.
A neutrino can annihilate with an antineutrino of the same family...electron, muon ,or tau...and produce a photon, or a phonon (lattice vibration) of energy. Otherwise there is no expectation that there is a half-life of a neutrino.
The Proton decay experiment at the IMB showed that protons are stable to ~ 1031 years....as with neutrino masses, they may be indefinitely stable, but the data only says stable to this limit....so far.
I am quite pleased that a number of forum thinkers are converging on my delineation of the implications of a neutrino sea in every experiment ever done.
As the prompt neutrino burst from SN1987a only produced ~11 hits at the IMB, it's doubtful you'll see them in your vitreous humor during the year. I'll get the stats later.
To conserve lepton number, a neutrino may only disappear in another weak decay....they can however transfer energy and momentum in neutral currents (Z)...and continue on their merry way, redshifted.
They are not "heavy" photons. Photons are bosons. Neutrinos are fermions.
So far neutrino oscillations have only been determined where they have had substantial matter paths...MSW style.Pete.

Ufonaut99
2006-Jul-19, 03:39 AM
I'll throw in a quick shot, although I'm sure more knowledgeable people will be along shortly....


If we were to attempt to accelerate the ship to c, would the neutrinos have a sort of drag effect on the ship preventing it from reaching higher speeds? That is to say, if we were to somehow create a bubble of neutrino-free space around the ship("true vacuum" Edit: and shielded from EM radiation and small particles of matter), would the ship be able to accelerate to c faster...and perhaps beyond c?
First off, not "beyond c". It's relativity that prevents us reaching c, and that has nothing to do with neutrinos.
Do neutrinos slow our acceleration? As you've mentioned, they can go through a planet without being affected - and hence, without affecting it - so they're REALLY not going to make any difference to a relatively tiny ship, no matter how fast it's going.


When a neutrino does hit something, what is the interaction like?
If a neutrino hits a neutron, it can produce a proton, and electron and a photon.If the neutron happens to be in the nucleus of an atom, this means the actual element changes. This is how the early neutrino-detectors worked - they had tanks of chlorine, and waited to see how much chlorine turned to argon.



But as neutrinos only get produced in nuclear fusion
Not quite true. Neutrinos can be produced in quite a few ways - eg. Are they produced in Fission as well? Also IIRC a neutron that's not part of an atomic nucleus has a half-life (of 14 minutes?) and decays into a proton,electron and neutrino.



But as neutrinos only get produced in nuclear fusion, and my body does not have such processes, I doubt thats what happens (could be wrong).
Don't forget, neutrinos (from the Sun and elsewhere) are streaming through your body just like they stream through the earth.


Is the neutrino forever(until i move) stuck in my body?(would that mean that that neutrino is from now on "still"?)...
No - when they hit, they have an immediate effect (and are "used up" in the process)


Since (im assuming) stars are the major sources of neutrino "production", is the general flow of neutrinos away from the stars?

I imagine so. However, I think the Big Bang created a lot as well.


How do neutrinos interact with each other?

They don't


How do neutrinos interact with photons?

They don't. Remember, Photons are the carriers of the Elecro-magnetic force, and neutrinos are electrically neutral.



Do neutrinos have a "shelf life"? Do they expire, or are the neutrinos from the early universe still around? If they are, would that mean that the universe is denser with neutrinos now, than it was yesterday, a billion years ago, and ten billion years ago?
I don't believe so. Remember that, for something to decay, it must have something to decay INTO. As far as we know, neutrinos are "elementary" particles, and there is noting lighter. They can't even decay into light (for the same Electro-magnetic reasons as above).
Is the universe denser with them now? I'd guess so.


Could they be heavy light (electromagnetic radiation)?
There's no such thing as "heavy light", since light (ie photons) by definition have zero rest-mass. If we found another particle that has mass, they wouldn't be photons.
Even so the answer's no, for the EM reasons above.

trinitree88
2006-Jul-19, 11:34 AM
[QUOTE=RobA] snippet




Not quite true. Neutrinos can be produced in quite a few ways - eg. Are they produced in Fission as well? Also IIRC a neutron that's not part of an atomic nucleus has a half-life (of 14 minutes?) and decays into a proton,electron and neutrino.

RobA . Not quite.....proton, electron, and electron-type antineutrino.


snippet:
No - when they hit, they have an immediate effect (and are "used up" in the process)


Neutrinos are not always "used up" when they hit....that's the virtue of the neutral currents, first seen at CERN in Gargamelle, the detector. A neutrino can slip unseen into a mass, interact delivering a forward scatter-only(massless neutrinos only)....the struck target receives energy and momentum...the neutrino leaves unseen, but redshifted, with less energy and momentum in it's budget.


Neutrinos can interact with photons via the neutral current(Z0)...which is universal, and couples to all the particles in the SU(5) symmetry, including the force carriers, photon,gluon, weakon, graviton


:eek: :shifty: Pete

afterburner
2006-Jul-19, 03:17 PM
Hmm...
So humans are no good as neutrino detectors?
There is no way a human can detect fluctuations in the neutrino sea without the aid of technology? (even though our own bodies produce neutrinos)

Do all objects have an effect on the neutrino sea? (eg. does a rock in my back yard affect the neutrino sea in any way. That is to say, if that rock wasnt there, would the neutrino sea be any different in that area?)

I read that there are three types of neutrinos...are the proportions of the different types roughly the same?

What is the wavelength and frequency of a neutrino?

Thanks

trinitree88
2006-Jul-20, 12:43 AM
Hmm...
So humans are no good as neutrino detectors?
There is no way a human can detect fluctuations in the neutrino sea without the aid of technology? (even though our own bodies produce neutrinos)

Do all objects have an effect on the neutrino sea? (eg. does a rock in my back yard affect the neutrino sea in any way. That is to say, if that rock wasnt there, would the neutrino sea be any different in that area?)

I read that there are three types of neutrinos...are the proportions of the different types roughly the same?

What is the wavelength and frequency of a neutrino?

Thanks
Afterburner. Should we be proximate to a prompt neutrino burst from a supernova...your body would not only detect it....it might catapult you out of your lawn chair, while dozing in the sunshine and catching them beneficial rays.
As to the rock, yes there is a "shadow" in the sea for every massive object....and Yes the sea would be different.
The relative proportions of the three families are at present a little fuzzy at the low energy limit.Patience.
E=hv E/c = hv/c gives neutrino energy and momentum. c=v(Lambda)...works...for neutrinos and photons. Ciao. Pete:shifty:

Ufonaut99
2006-Jul-20, 02:27 AM
Thanks for the corrections, Pete. I certainly never expected the interaction with photons via Z0.


I read that there are three types of neutrinos.
This comes from the Standard Model. All matter comes in three "families", so :
1) Up Quark, Down Quark, Electron, ElectronNeutrino
2) Strange Quark, Charm Quark, Muon, MuonNeutrino
3) Top Quark, Bottom Quark, Tau, TauNeutrino

Each member of each family has similar attributes to equivalent members of the other families, but the masses increase (eg. the Muon has charge of -1 like the electron, but a greater mass).

In addition to all that, each of these is also mirrored with Antimatter (eg. Anti-Up Quark, etc) - so you could say that really there's 6 different types of neutrinos.


Quote:

How do neutrinos interact with each other?
They don't


Thinking about it, was I right with this answer? How would we know?

afterburner
2006-Jul-20, 02:43 AM
....it might catapult you out of your lawn chair, while dozing in the sunshine and catching them beneficial rays.

I really should put up some kind of a fence in my back yard...

trinitree88
2006-Jul-20, 11:54 PM
Thanks for the corrections, Pete. I certainly never expected the interaction with photons via Z0.


This comes from the Standard Model. All matter comes in three "families", so :
1) Up Quark, Down Quark, Electron, ElectronNeutrino
2) Strange Quark, Charm Quark, Muon, MuonNeutrino
3) Top Quark, Bottom Quark, Tau, TauNeutrino

Each member of each family has similar attributes to equivalent members of the other families, but the masses increase (eg. the Muon has charge of -1 like the electron, but a greater mass).

In addition to all that, each of these is also mirrored with Antimatter (eg. Anti-Up Quark, etc) - so you could say that really there's 6 different types of neutrinos.



Thinking about it, was I right with this answer? How would we know?

RobA. I believe you are correct there.
I'm out on a limb here...but don't mind it at all. "The Key to the Universe"...circa 1979-80 by Nigel Calder, a popular British science writer. "The force carriers feel the force themselves..."...when Calder writes it, he's referring to the gluons feeling the color force, but it also applies to the weak force...so if neutrinos emit Z's and Z's are carriers they can interact with each other...both Z's and gravitons are universal acting on all the particles in the SU(5) symmetry...including themselves....and in the case where the low energy Z qualifies as a graviton...it does double duty.
The muon-type neutrino has been experimentally confirmed, AFAIK the limited tau "beams" has been a roadblock of sorts, but the success of the muon confirmation led many to surmise that the tau physics is real too.
I have a few interesting experimental concepts, but need to tread carefully on territory involving proprietary information, so I'll leave a few questions, pending... Pete

trinitree88
2006-Jul-20, 11:58 PM
I really should put up some kind of a fence in my back yard...

Lol. :D Hey, we sell Canadian hemlocks at the garden center....I have three fences already to do this month on Cape Ann...:D Pete.:shifty: