Light shed on mysterious particle

[K.I.L.E.R]

http://news.bbc.co.uk/1/hi/sci/tech/4862112.stm

What does this mean for our future scientific development?

EDIT: I've done some reading. Does this finding mean that we're 1 step closer to a grand unifying theory?

 

[StefanS]

http://news.bbc.co.uk/1/hi/sci/tech/4862112.stm

What does this mean for our future scientific development?

EDIT: I've done some reading. Does this finding mean that we're 1 step closer to a grand unifying theory?

Actually it's been known for quite a while that the neutrinos have mass. They gave the Nobel prize for that discovers in 2002. So this is hardly any spectacular news.
Anyway, neutrions having mass a two-fold influence. On the one hand is eases the missing mass problem in astrophysics, on the other hand it has quite an influence on unifying theories. But it has the opposite effect: Neutrinos with mass compromise the original electroweak ttheory (unification of electromagnetic and weak interaction) and make the model more difficult.

 

[KimB]

On the one hand is eases the missing mass problem in astrophysics, on the other hand it has quite an influence on unifying theories.

Er, neutrino masses have nothing to do with the missing mass problem: they have to do with the solar neutrino deficiency problem. Specifically, we think we know something quite a lot, through terrestrial experiments, about how the nuclear reactions at the center of our sun work. We predict a rather large number of neutrinos emitted from the Sun. But when we went to detect them, we only found about one third that number coming from the Sun.

Once we went back and built a detector that could detect all three flavors of neutrinos (electron, muon, and tau), we found the expected amount. This finding requires that the neutrinos have mass.

But it has the opposite effect: Neutrinos with mass compromise the original electroweak ttheory (unification of electromagnetic and weak interaction) and make the model more difficult.

Well, the real problem isn't that it makes electroweak theory more difficult (and it really is only a tiny change, but one which is cumbersome in the math), but rather that it leaves us with the unanswered question as to why the neutrino masses are so small. This, quite possibly, will actually make it easier to find a good unified theory, because any good unified theory, we expect, would naturally predict small neutrino masses.

 

[IgnorancePersonified]

Some article was linking it to dark matter... Is that errounously linked to 'missing mass' or what? I will try find it as I read it late after a big weekend.

 

[StefanS]

Er, neutrino masses have nothing to do with the missing mass problem: they have to do with the solar neutrino deficiency problem. Specifically, we think we know something quite a lot, through terrestrial experiments, about how the nuclear reactions at the center of our sun work. We predict a rather large number of neutrinos emitted from the Sun. But when we went to detect them, we only found about one third that number coming from the Sun.

Once we went back and built a detector that could detect all three flavors of neutrinos (electron, muon, and tau), we found the expected amount. This finding requires that the neutrinos have mass.

Of course, it is of relevance to the solar neutrino problem. But I remember that some physicists speculated it could account for a share in dark matter. But I don't know the latest news in that field.

Well, the real problem isn't that it makes electroweak theory more difficult (and it really is only a tiny change, but one which is cumbersome in the math),

That's what I meant (cumbersome). But have mercy on me for I am not a native speaker

 

[arjan de lumens]

Of course, it is of relevance to the solar neutrino problem. But I remember that some physicists speculated it could account for a share in dark matter. But I don't know the latest news in that field.

While neutrinos are very much "dark" and as such obviously make up some of the total dark matter, they are not the main constituent (at most a few %, or else they would have prevented the formation of certain large-scale structures in the universe). One of the main phenomena that are associated with dark matter is the fact that many galaxies rotate much faster than what current theories + the amount of visible mass indicate, suggesting that there must be a large halo of dark matter within/around the galaxy to generate a gravitational field strong enough to support such rotation speeds. Neutrinos are much too "hot" (moving too fast) to be able to form such a halo - at >99% of the speed of light, no galaxy has a gravitational field remotely strong enough to prevent neutrinos from escaping.

 

[KimB]

Of course, it is of relevance to the solar neutrino problem. But I remember that some physicists speculated it could account for a share in dark matter. But I don't know the latest news in that field.

Ah, yes, that was ruled out some time ago. Basically, neutrinos are too hot to have played a role in structure formation in the early universe, which is now one requirement of dark matter.

 

[chavvdarrr]

While neutrinos are very much "dark" and as such obviously make up some of the total dark matter, they are not the main constituent (at most a few %, or else they would have prevented the formation of certain large-scale structures in the universe). One of the main phenomena that are associated with dark matter is the fact that many galaxies rotate much faster than what current theories + the amount of visible mass indicate, suggesting that there must be a large halo of dark matter within/around the galaxy to generate a gravitational field strong enough to support such rotation speeds. Neutrinos are much too "hot" (moving too fast) to be able to form such a halo - at >99% of the speed of light, no galaxy has a gravitational field remotely strong enough to prevent neutrinos from escaping.

yea, "dark" matter, "dark" energy, adding such crutches shows how bad is the situation right now .... physics is back in 19th century, everyone adds his own "constants" and "variables" and tries to explain what we see through usage of 2^(n-1)-dimension mathematics coupled with same old "axioms" ... and the unfortunate part - too many of those who try to rebuild the theory from the ground are nuts, and there are so many of them that its next to impossible to see the one that is right.

 

[KimB]

yea, "dark" matter, "dark" energy, adding such crutches shows how bad is the situation right now .... physics is back in 19th century, everyone adds his own "constants" and "variables" and tries to explain what we see through usage of 2^(n-1)-dimension mathematics coupled with same old "axioms" ... and the unfortunate part - too many of those who try to rebuild the theory from the ground are nuts, and there are so many of them that its next to impossible to see the one that is right.

No, not at all. We just don't yet have the data required to find out what the nature of these objects are. But we can currently say quite a lot about what these things are not, which is definitely a good thing. We aren't completely blind as to their nature.

Right now we really are at a the birth of a new branch of physics, precision cosmology. Ten years ago the nature of dark matter was largely unknown, and dark energy was just a dream cooked up by insane theorists. Since then we've performed a large number of very exciting experiments which have dramatically confirmed a number of rather stark theoretical predictions (mostly related to inflation), but require that there be some slowly-varying component to the energy density of the universe.

Until very recently, theory was very far ahead of experiment. Now the experiments have caught up, and it's time for the experiments to drive theory. This all makes it a very, very exciting time to be involved in cosmology. The questions the theorists want answered are very hard to answer, though, and thus require bigger, more expensive experiments. And most of all, time.

 

[chavvdarrr]

No, not at all. We just don't yet have the data required to find out what the nature of these objects are. But we can currently say quite a lot about what these things are not, which is definitely a good thing. We aren't completely blind as to their nature.

Right now we really are at a the birth of a new branch of physics, precision cosmology. Ten years ago the nature of dark matter was largely unknown, and dark energy was just a dream cooked up by insane theorists. Since then we've performed a large number of very exciting experiments which have dramatically confirmed a number of rather stark theoretical predictions (mostly related to inflation), but require that there be some slowly-varying component to the energy density of the universe.

Well, I'm biased - i was supposed to do my Mr of QE 10 years ago, but was soooo unsatisfied of the general route that dropped physics in exchange of computers (well that was one of the reasons).
So until a new Einstein comes I'll be sceptic
And according to few of my old classmates who work in places like CERN and the Chicago accelarator (its name went out my mind), many experiments always give same results : "we have nice fit with the thoery and we need more $$$ in order to go ahead" . Like the experiment for calculating gravity speed 1-2 years ago using gravity field of Jupiter... a friend of mine told me what the results will be BEFORE the experiment was made ! No, he wasn't working on that project
Such things hardly generate optimism in me

 

[KimB]

And according to few of my old classmates who work in places like CERN and the Chicago accelarator (its name went out my mind), many experiments always give same results : "we have nice fit with the thoery and we need more $$$ in order to go ahead" . Like the experiment for calculating gravity speed 1-2 years ago using gravity field of Jupiter... a friend of mine told me what the results will be BEFORE the experiment was made ! No, he wasn't working on that project

Well, we've expected for a very long time what the speed of gravity must be. Gravity waves propagating at the speed of light has been in Einstein's theory since the inception of GR. So of course your friend expected that result.

But there are some (including the resident GR expert here at Davis) who believe that the experiment you mention doesn't actually measure the speed of gravity, but rather just the speed of light.

Anyway, the really exciting thing about physics today is that we don't know what to expect. In both the fields of high energy physics and cosmology, we expect to be able to gain exciting new information out of upcoming experiments, but we really haven't nailed down much at all as to what that information should be. Different theories predict radically different behavior in upcoming experiments.

One really interesting and brand-new result came out of the 3rd-year WMAP data, which was just released a couple of weeks ago. The really exciting measurement is that they find, with the simplest models, a deviation of the scale factor from one by about 4 sigma (i.e. ruled out at the 99.9968% level).

The idea is that there were some primordial quantum mechanical perturbations in the very early universe that gave rise to all structure we see today. Different scales of perturbations would have been generated at different times: perterbations earlier-on would have expanded more, and would be responsible for the largest-scale structure. Our current universe, then, is highly dependent upon the amplitude of each of these perturbations. Since the universe had expanded many fold between the generation of the largest scale structure and the smallest, we don't expect the amplitudes of these perturbations to be completely independent of scale. The scale factor parameterizes this expectation, and if it differs from one, then we detect that different perturbation scales actually had different amplitudes.

So, the existence of this measured variation in amplitude based upon scale could give us a window into the possible models for inflation.