I thought up this question whilst sitting in the dark between taking photos a fe
ID: 1383609 • Letter: I
Question
I thought up this question whilst sitting in the dark between taking photos a few hundred feet underground in a slate mine. I'm aware that weakly interacting neutrinos can make through a few hundred feet of rock and these can be detected by equipment. I've also heard that cosmic rays have been detected by photographic sensors.
My question is if I am at a depth shallow enough for particles to reach me, would anything such as the particle itself or the decay products produce anything visible if they were to hit my retina?
How long would I have to wait?
Explanation / Answer
Neutrinos are very interesting particles. They almost don't interact with the rest of the universe at all. In fact, the neutrinos which come from the Sun, billions and billions of them are created in nuclear reactions in the Sun, they can travel the equivalent of 10 times the distance between the Earth and the Sun through water before they hit anything to make any kind of interaction at all. And not all of those interactions will actually produce a light which you'll be able to see.
So, just working on the number of interactions, that sounds incredibly unlikely, but there's also about 65 billion neutrinos going through every square centimetre of everything in the world all the time every second.
You can work out the relative ratios, how often they interact in a cubic centimetre (for this purpose, let's assume your eyes are very roughly about a cubic centimetre). In that liquid in your eye, it