Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids through a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold-shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
And painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed—you call
It wonderful; I call it crass.
“Cosmic Gall”, from Telephone Poles and Other Poems, John Updike, 1960.
Neutrinos, as Updike elegantly put it, are one of the most elusive particles in nature. They don’t only go through walls, planets, and humans; but also through the very instruments that are built to detect them, only occasionally leaving a trace behind them to evidence their pass.
That’s a lesson that everybody (even some of my fellow co-bloggers) working with this particle has learned the hard way. Detecting a neutrino always involves putting on its way a huge amount of matter to force a couple of them to “show up”, to reveal their existence. But why should we care about building such huge detectors if the neutrino is so indifferent to our efforts?
Well, the fact that its interaction with matter is so small makes it a perfect probe to observe the places where some of the most violent astrophysical phenomena in the universe are taking place. After its production, the neutrino will leave the place quietly, going through huge amounts of matter almost without being attenuated, bringing us the news, only if we have cared enough to put a detector in its way. As they have no electrical charge, they travel cosmological distances without being affected by magnetic fields so, at the time of their detection, they still point to their source. They also have huge decay times (if they decay at all) so they can travel for a long while without “breaking apart”. A neutrino is, in a sense, “our man in Havana.”
I’m tempted to say that neutrinos have such a weird personality because their father didn’t love them from the moment they were born, and called them just “a desperate remedy.” 🙂
Coming soon: the description of a full-fledged neutrino telescope. By the way, since the time that Updike wrote his poem it has been proved that neutrinos have a tiny but non-zero mass.
