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Neutrino Bombshell

Neutrinos… nicknamed ghost particles because of their uncanny properties… are the most abundant particles in the Universe — around 100 trillion pass harmlessly through your body every second. They are created in many natural processes, including nuclear reactions in the Sun, explosions of stars and processes that generate radioactivity in Earth’s core. They are also made by particle accelerators and nuclear power plants.

But with no charge and a vanishingly small mass, they can be detected only indirectly, when they interact with another particle. Detectors are made from liquids that generate a suitable signal, such as a flash of light, during interactions, and electronics that convert the signal to an electrical pulse. Neutrino interactions are exceedingly rare, however, so the detectors have to be very large, and physicists very patient.

Alison Abbot – The singing neutrino Nobel laureate who nearly bombed Nevada, in Nature

I don’t know if it is more or less astonishing to remember that the average atom is something like 99.9999999999996% “empty” space, which means (given that neutrinos are a million times smaller than electrons, which are themselves a hundred million times smaller than atoms) there’s a lot of space for them to whizz through.

Foggy Bottom

By way of completeness, I should point out that atoms aren’t really empty space with electrons tidily orbiting a nucleus, but rather a buzzing electron cloud that effectively takes up all the space at once.

And yet… the neutrino rain still falls.

Footnote

The chances of any given neutrino interacting with a particle in your body is tiny – apparently one in a trillion trillion – so there’s only something like a one-in-four chance that a neutrino will interact with a particle in your body in your statistically-average lifetime.

Next time you’re in a crowded room see if you can work out who’s been hit.

I'd love to hear your thoughts and recommended resources...