So about a week ago, the 2015 Nobel Prize in Physics was awarded to Takaaki Kajita and Arthur McDonald for the discovery of neutrino oscillations which showed that neutrinos have mass. It turns out that this is a pretty big deal for particle physics (hence, why they won the Nobel Prize), and it also happens that I'm somewhat of a fan of neutrinos, so I thought I might write a bit about what these little guys are all about.
Neutrinos are actually pretty cool. They were first theoretically conceived in 1930 by Wolfgang Pauli - one of the most important pioneers of quantum physics. Originally they were a mathematical necessity, something of an adjustment particle so that something known as beta decay - a type of radioactive decay - would conserve energy and momentum. Physics requires that everything that occurs conserves energy, momentum and a handful of other things, and so the neutrino proved a convenient solution for the otherwise problematic beta decay.
Pauli, along with Enrico Fermi (who created the first nuclear reactor), jokingly nicknamed the particle a "neutrino", which in Italian means "little neutral one". The name stuck, and about two decades later in 1956 a bunch of other physicists published a paper confirming the first experimental evidence of the elusive particle...for which a Nobel Prize was awarded about 40 years later. Physics takes it sweet time with things.
Neutrinos are the second most abundant particle in the universe after photons, and every second trillions generated by the nuclear reactions in the sun pass through your body...and the Earth entirely. Neutrinos don't really do much however. This is because they're both neutral (no electric charge), and extremely tiny - one millionth the size of an electron (which is already really damn small).
How to Detect Italian Ghosts
So you might be wondering how do physicists even observe these tiny Italian buggers anyway. Well, it's rather simple - excavate a mountain, fill it up with water and wait a bit.
Okay, well it's a bit more complicated, but that's the gist of it. What happens is that very very occasionally, a neutrino will bump into an electron and cause a blue flash of light known as Cherenkov radiation, which is the optical equivalent of a sonic boom as the electron is travels faster than the speed of light in water. By observing these rare occurrences, physicists can experimentally observe neutrinos and do all sorts of fancy maths and physics,(occasionally winning a Nobel Prize for their fancy maths and physics).
Now this is all well and good, but physicists take this little Italian particle quite seriously. Mainly because it poses a bit of a problem with regards to the Standard Model of Particle Physics, which is our current theory of how the universe works. Now, the reason for why neutrinos are currently breaking physics is somewhat complicated, but thankfully I had a friend at RSI - Marti Oller Riera from Spain - who did a project on neutrinos!
How Italian Particles Break Physics
So Marti's paper - A computational approach to the optimum amount of shielding for background radiation on TeO2 bolometers - was all about the neutrinoless double beta decay and developing special bolometers which would aid in detecting it. Now, for those of you who may not know what the neutrinoless double beta decay is, it's a very rare type of radioactive decay that requires two produced neutrinos to annihilate themselves. Now, this is a big deal for particle physics and the standard model!
If this theorized type of decay is actually detected and confirmed, it would mean that the neutrino is its own antiparticle, it would be direct evidence of a popular theory in particle physics known as supersymmetry. Supersymmetry, in turn, is a big step forward for physics as it would help in unifying the theory of general relativity and quantum physics into a mesh theory of quantum gravity, giving us a better understanding of how the universe works. It would also be a step forward to understanding dark matter - the ever so elusive, spooky physics thing that every physics documentary on television ever makes a big fuss of.
But back to the whole Nobel Prize deal. So it turns out neutrinos can only be their own antiparticle if they have some mass (because quantum physics reasons). Well...it turns out they do!
So thanks to the Nobel Prize folks, Italians, a big mountains full of water, and of course Marti's new and improved tellurium bolometers , we might end up confirming without a doubt that neutrinos really are their own antiparticles. Of course, this would mean some other nifty physicists will have to get around to making a new theory of everything...which is somewhat troublesome. But hey, science is all about tearing down the old wallpaper and putting up a new, fancier one.