The rules of physics have a very clear purpose: to predict how and when some natural phenomenon occurs. So the question can be re-phrased as: why did we come up with the notion of a neutrino, what phenomenon did it explain?
We certainly didn't just happen to see one colliding with with something, we knew they have to exist far before the first one was ever detected.
Way to totally miss the point. I wasn't talking about the rules we create; I was talking about the actual rules in the physical world. These exist independent of us. They function, they don't predict.
The notion that those actual rules have some sort of purpose reeks of a medieval mindset, where the world is the creation of God and has His Purpose, which it is the function of natural philosophers to figure out.
> I was talking about the actual rules in the physical world. These exist independent of us. They function, they don't predict.
Nobody knows what those are though; mere humans have to get by with prediction.
In fact there's no airtight reason to think that you can even in principle make the leap from valid predictions to knowing what the actual physical rules really are. This is the whole "problem of induction" thing:
https://en.m.wikipedia.org/wiki/Problem_of_induction
No amount of observing the universe can ever conclusively prove that our ideas about how it really functions are true, because we're stuck inside it and can't directly inspect the clockwork, if there is any.
I find this sort of nihilism completely tedious. Yes, we can know there are neutrinos there. This physical reality is not identical with our theories about them.
Do you not recognize that "There is no purpose to neutrinos. Your question makes no sense." is itself tedious nihilism?
So you reinterpreted the OP's question in the most meaningless way you wanted to, and then declared "How does this question make any sense?".
Nice contribution to the discussion! /s
Yes, I interpreted "neutrinos" to mean "neutrinos", instead of something else.
How utterly terrible of me.