U think that the univers is realy expanding? think again

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In summary, the conversation discussed the expansion of the universe and the role of neutrinos in it. It was mentioned that scientists are still trying to determine if neutrinos have mass and how that would affect the expansion. However, it was pointed out that this discovery would not have a significant impact on the expansion. The conversation also touched on the possibility of a fourth generation neutrino and its role in correcting density profiles in a cold dark matter model. The reliability of information on Wikipedia was also brought up. Overall, the conversation highlighted the ongoing research and debates surrounding the expansion of the universe and the role of neutrinos in it.
  • #1
darkness_limits
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u think that the universe is really expanding?? think again

well i readed recently in a physics magazine that the scientist are trying to find if the neutrino has any mass , if it is true then the universe will be contracting and not expanding and the big bang theorie is false.. what is the relation ?
 
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  • #2
Er... you are about 10 years too late. We ALREADY know the neutrinos have mass! The neutrino oscillation experiments have been going on for the past 10 years, at least. This has no effect on the universe expansion as of yet. In fact, the whole reason for the "dark energy" scenario is due to the more recent observation that the universe seems to be expanding at an even faster rate than expected!

Zz.
 
  • #3
Even worse, the neutrino 'mass' is far too insignificant to affect the 'big picture' of expansion. It is not a viable candidate to explain 'dark matter' or assert it's place as the 'missing mass' in a Lamda universe.
 
  • #4
Chronos said:
Even worse, the neutrino 'mass' is far too insignificant to affect the 'big picture' of expansion. It is not a viable candidate to explain 'dark matter' or assert it's place as the 'missing mass' in a Lamda universe.
This is correct. I would like to emphasize that the mass of the known neutrinos is too insignificant. However, the existence of a heavy fourth generation neutrino has been recently postulated in order to correct the too cuspy density profiles of a pure cold dark matter model. See for example: Constraining Warm Dark Matter candidates including sterile neutrinos and light gravitinos with WMAP and the Lyman-alpha forest.
 
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  • #5
hellfire said:
This is correct. I would like to emphasize that the mass of the known neutrinos is too insignificant. However, the existence of a heavy fourth generation neutrino has been recently postulated in order to correct the too cuspy density profiles of a pure cold dark matter model. See for example: Constraining Warm Dark Matter candidates including sterile neutrinos and light gravitinos with WMAP and the Lyman-alpha forest.

Er.. are you sure? I thought the recent http://physicsworld.com/cws/article/news/27569 kinda dashed that hope?

Zz.
 
  • #6
You might be right. I was relying on the wikipedia article about MiniBooNe that claims that there are indications pointing towards the existence of the sterile neutrino and that this information is more recent than the april paper also mentioned there (and that I assume to be the source for the physicsworld article you have linked). However, I've checked now the MiniBooNe web and I was not able to find any more recent information. It seams that the wikipedia article is not very accurate.
 
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  • #7
hellfire said:
It seams that the wikipedia article is not very accurate.

That goes without saying.

Trust Wikipedia at your own risk.

Zz.
 
  • #8
The quality of articles on Wiki vary wildely, and daily. It is an unreliable source, IMO.
 
  • #9
ZapperZ said:
Er.. are you sure? I thought the recent http://physicsworld.com/cws/article/news/27569 kinda dashed that hope?

Zz.

Not really. The LSND signal that MiniBooNE was trying to reproduce is in the wrong region of the sterile neutrino parameter space to account for warm dark matter.
 
  • #10
But even LSND has backed down from its own findings when it couldn't find it again, no? Or am I thinking of another experiment here?

Zz.
 
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  • #11
ZapperZ said:
But even LSND has backed down from its own findings when it couldn't find it again, no? Or am I thinking of another experiment here?

Zz.

My point was that MiniBooNE does not rule out the full parameter space for sterile neutrinos. The big news back in April was that it had found nothing where the hint of a signal reported by LSND had been. This is in a region of the parameter space quite remote from any sort of dark matter candidate.
 

1. Is the universe really expanding?

Yes, scientific evidence strongly suggests that the universe is expanding. This was first discovered by astronomer Edwin Hubble in the 1920s and has been confirmed by numerous studies since then.

2. How do we know that the universe is expanding?

Scientists use a variety of methods to measure the expansion of the universe, including observing the redshift of light from distant galaxies, studying the cosmic microwave background radiation, and measuring the distances between galaxies.

3. What is causing the expansion of the universe?

The leading theory is that the expansion of the universe is driven by dark energy, a mysterious force that makes up about 68% of the total energy in the universe. This force is thought to be responsible for pushing galaxies away from each other at an accelerating rate.

4. Has the universe always been expanding?

No, the expansion of the universe is thought to have started with the Big Bang, which occurred approximately 13.8 billion years ago. Prior to this event, the universe was extremely dense and hot, and has been expanding ever since.

5. Will the universe continue to expand forever?

It is currently believed that the expansion of the universe will continue indefinitely, unless there is a significant change in the amount of dark energy or other unforeseen factors. However, the rate of expansion may change over time and is still being studied by scientists.

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