When we look out into the universe, we can see a cosmic background of microwaves in all directions. It’s the thermal remnant of the big bang, but it also serves as a wall beyond which we cannot see. Until now.
Neutrinos From Outer Space!
Neutrinos are being detected from outer space, and that’s kind of a big deal.
Metamorphosis
We’ve long had indirect evidence that different types of neutrinos can oscillate into other types of neutrinos. We now have direct detection of this effect.
Inner Beauty
The Sun is incredibly bright, so how do we peer beyond its surface to its interior?
Imaginary Neutrinos
A new paper proposes that neutrinos may be tachyons. This is being presented in the press as a claim that neutrinos move faster than light, but that’s not the focus of the paper. Instead the paper argues that the electron neutrino could have an imaginary mass.
And the Number Shall Be Three
In earlier posts about dark matter, I’ve written about how neutrinos would seem to be a good candidate, but there simply aren’t enough of them to account for all of dark matter. As far as we can tell, there are three types (flavors) of neutrinos, and we know the upper limit of their mass from the distribution of galaxies in the universe. So the three known neutrino flavors can’t be the solution to dark matter.
Neutrino Rain
Yesterday I talked about the weirdness of neutrinos, specifically that there three types of neutrinos (known as flavors), and they can oscillate between different flavors due to the quantum fuzziness of their masses. If you go back and read that post, you’ll find its a pretty bizarre model that seems to assume a great deal just to solve what is known as the solar neutrino problem. So how could we possibly know that such a model is correct?
Mixing It Up
Neutrinos are perhaps the most enigmatic particles in the universe. They were first discovered in the 1950s as a product of radioactive decay, but they are also produced in nuclear fusion reactions. As a result, copious amounts of neutrinos are produced in the Sun through the pp-chain and CNO nuclear fusion processes in the core of our star. This makes the Sun a perfect candidate for doing neutrino astronomy. But when we first starting observing solar neutrinos in the 1960s, revealed mystery known as the solar neutrino problem. The solution to this problem wasn’t proven until the late 1990s, and it demonstrated that neutrinos are far more strange than we had imagined.
Common Core
Our Sun (like other stars) is powered by nuclear reactions within its core. Part of the way we know this is through the observation of solar neutrinos. When solar neutrinos were first observed, the levels observed were less than predicted by about a factor of three, which came to be known as the solar neutrino problem. Since then we’ve come to understand that neutrinos have mass, and can change between flavors (electron, muon, and tauon), which solves the solar neutrino problem. Our neutrino detectors are good enough that we can now produce neutrino images of the Sun, such as the image above, and the rates of neutrino emission are in good agreement with solar core models.
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