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2. Neutrino interference. Is this a thing? Pretty sure it's not a thing.It's an interesting question. I think that the answer is yes.
Assuming there are no experimental physicist nearby...
Trying to use a grating grid or mirrors with neutrinos is impossible, so you must try something else.
You must pick another particle that has charge and that decays to neutrinos, like in the article.
Yo must use a https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experime... to make two rays, the idea is that each particle is "split" in the two rays. (The correct formulation is more complicated and use a lot of algebra. The incorrect formulation say that each particle is split. Just bear with me and assume the particles can be split.)
If you miss align the two rays, perhaps with a magnetic field, you can get an interference pattern when the two parts of the particle colide when the ray colide (again, the algebra makes sense in spite the English version is weird).
But you can make the collision far away to ensure the particles have decayed and in the site of the collision they are neutrinos instead of the original particle. After the decay, the "two half" of the neutrinos are coherent and can produce an interference pattern.
So if you design everything very carefully, I think it's possible at least in theory.
I really don't expect that is humanly possible to build that experiment, but there are some ingenious people out there.
[What about aligning a supernova and two nearby black holes that act as gravitational lens. I'm not sure it works, but is sounds too cool not to try.]