Why Are We Not Constantly Bombarded by Neutrinos from the Stars?

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Discussion Overview

The discussion revolves around the question of why we are not constantly bombarded by neutrinos from stars, particularly in the context of the sun's neutrino production compared to other stars. Participants explore the implications of this question in relation to concepts like Olbers' paradox, the nature of neutrino detection, and the potential for neutrino telescopes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants note that while the sun produces a significant number of neutrinos, other stars also produce them, but the quantity detected from those stars is negligible compared to the sun.
  • There is a comparison made to Olbers' paradox, suggesting that the same reasoning applies to neutrinos as to why the night sky is not bright.
  • Participants discuss the concept of intensity and flux, indicating that the distance of stars affects the amount of neutrinos that reach Earth.
  • Questions are raised about the feasibility of building a "neutrino telescope" to detect neutrinos from other stars, with some mentioning existing neutrino detectors and their limitations in directionality.
  • Some participants mention that neutrinos change types randomly, which may affect detection rates.
  • There is a suggestion that the universe's finite age and size may limit the neutrinos that have had time to reach us.
  • One participant points out that while neutrinos are produced by stars, their weak interaction with matter makes them difficult to detect, even from the sun.
  • Discussions include references to specific neutrino detectors and their capabilities, such as the Super-Kamiokande and the IceCube Neutrino Observatory.
  • Some participants express confusion about the relationship between the light and neutrinos emitted by stars, questioning why both are not detected in similar quantities.
  • There is mention of the concept of "dark energy" and "dark matter" in relation to the universe's composition and the implications for star visibility.

Areas of Agreement / Disagreement

Participants generally agree that the sun is the primary source of detectable neutrinos, but multiple competing views exist regarding the implications of this observation, the nature of neutrino detection, and the relationship to Olbers' paradox. The discussion remains unresolved with respect to the broader implications of neutrino emissions from stars.

Contextual Notes

Limitations include the weak interaction of neutrinos with matter, the challenges in detecting neutrinos from distant stars, and the dependence on the definitions of terms like "flux" and "intensity." There are unresolved questions about the directional capabilities of existing neutrino detectors.

moe darklight
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If the sun produces so many neutrinos from fusion, then I would assume that so do all other fusion stars, yet why is it that our detectors detect only the number of neutrinos that would be expected to be produced from our sun? If neutrinos travel at nearly the speed of light and barely ever interact with anything, then shouldn't we be constantly bombarded by an endless number of them coming from the trillions of stars in the universe?
 
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I think this is basically the same question as in Olbers paradox - if there are so many stars out there, why is the sky not bright in the night ? you just ask the question for neutrinos instead of photons.

maybe we should call this one "moe darklights paradox" ?
 
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yes, it is basically the same question.

It is also related to intensity and flux. A star 5Ly away will radiate over the whole solid angle and only a tiny tiny tiny tiny fraction will reach earth, and only a tiny tiny tiny fraction will interact here. So the main component of neutrino flux here on Earth is our star the sun.
 
Neutrino telescope?

I can understand why our sun would be the largest source of neutrinos that we can "see", but all other stars should also produce neutrinos, but to us not in the quantity as from our sun.

This brings up a question I have. Since neutrinos are "particles", is it possible to build something like a "neutrino telescope"? With enough resolution, it might be possible to identify those sources with greater or lesser amounts of neutrino emission. Would this be another way to look at our universe? Does anyone know of anything being done along these lines? I'm aware of the various mines that have been converted into neutrino detectors, but to my knowledge, they're not particularly directional in nature, but I could be wrong.

Thanks.
 
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LongOne said:
I can understand why our sun would be the largest source of neutrinos that we can "see", but all other stars should also produce neutrinos, but to us not in the quantity as from our sun.

This brings up a question I have. Since neutrinos are "particles", is it possible to build something like a "neutrino telescope"? With enough resolution, it might be possible to identify those sources with greater or lesser amounts of neutrino emission. Would this be another way to look at our universe? Does anyone know of anything being done along these lines. I'm aware of the various mines that have been converted into neutrino detectors, but to my knowledge, they're not particularly directional in nature, but I could be wrong.

Thanks.

The problem is, that neutrinos only interact VERY weakly with ordinary matter. Even from the sun we do not catch very much neutrinos in this detectors (though enough to have fun with them and verify our theories about how the sun is working). But as far as I know from normal stars there is currently no chance to catch any neutrinos. But in case of a supernova there are so much neutrionos emitted (I think the "neutrino luminosity" of a supernova is even bigger than the luminosity in the visible spectrum) that we can detect them. One of the early detectors just went operational just before SN1987 went KAWOOM, (or, more correctly, just before the light and the neutrinos from this explosion reached us), so the guys who built it were very happy about the many neutrinos they caught from this supernova.
 
LongOne said:
I can understand why our sun would be the largest source of neutrinos that we can "see", but all other stars should also produce neutrinos, but to us not in the quantity as from our sun.
Correct - but like Olbers paradox they should produce them in the same proportion as the light from the other stars compared to the sun. (that was really badly phrased!)

This brings up a question I have. Since neutrinos are "particles", is it possible to build something like a "neutrino telescope"?
The kamiokande detector is somewhat directional - using cerenkov radiation from the particles. The cl->ar detectos aren't
 
I thought the neutrinos change type at random
and that limited the detection rate
 
In reference to the Obler's Paradox type situation, I think the solution would be much the same as it is in reference to light. The universe is not infinite and therefore is not infinitely old, therefore light (or neutrinos) from all the stars has not had a chance to reach us.
 
  • #10
Nabeshin said:
In reference to the Obler's Paradox type situation, I think the solution would be much the same as it is in reference to light. The universe is not infinite and therefore is not infinitely old, therefore light (or neutrinos) from all the stars has not had a chance to reach us.

but for the light from stars which is reaching us? together with light,we should also find neutrinos?isn't?
 
  • #11
spidey said:
but for the light from stars which is reaching us? together with light,we should also find neutrinos?isn't?
'


Yes but the neutrinos interfear so incredible little, their cross section is of the order 10^-20 Barns! Photon has high cross section.
 
  • #12
  • #13
Thanks

astrorob said:
You may find this of interest;


A neutrino telescope planned for construction under the Mediterranean.

Yes, very interesting. Thank you.
 
  • #14
  • #15
neutrinos are extremely difficult to detect - they were thought of as massless particles but recent work suggests that neutrinos possesses a very small mass.

I don't understand the comparison made to the night sky being filled with light at night because of the number of stars.

Remember that's the point - if the universe was infinite then the night sky would be filled with light from the INFINITE number of stars out there. This is strong evidence that there are a finite number of stars out there and that the universe is almost entirely composed of non-baryionic material (about 70% dark energy and 25% dark matter.

As EInstein said "the universe is FINITE but UNBOUNDED"
 
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  • #16
malawi_glenn said:
'


Yes but the neutrinos interfear so incredible little, their cross section is of the order 10^-20 Barns! Photon has high cross section.

Is a "Barn" a standard unit of measurement?

Chuckle, thanks for a good laugh!
 
  • #18
Live and Learn, I always say. Thanks for letting me know that there really is a BARN in quantum mechanics. Now I'm getting an even better chuckle out of my ignorance!
 
  • #19
i thought that we were being constantly being bombarded by neutrinos,you should read the book SPACESHIP NEUTRINO (no it's not a picture book)
 
  • #20
rubecuber said:
i thought that we were being constantly being bombarded by neutrinos,you should read the book SPACESHIP NEUTRINO (no it's not a picture book)

I thought we were, also. Can you shed a few sentences from your reference?

Thanks.
 
  • #21
umm i don't have the book in front of me, i read it about a year ago, and my school library is closed. But it's in the first ten pages (near the beginning) just google neutrinos or wikipedia it.
rubecuber
 
  • #22
rubecuber said:
i thought that we were being constantly being bombarded by neutrinos,you should read the book SPACESHIP NEUTRINO (no it's not a picture book)

Yes, we are constantly constantly bombarded by them - but all (or nearly all) of them are coming from our sun. But Moe Darklights question was, why don't we receive more neutrinos from the stars, if there are so many stars out there.
 

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