A “no math” (but seven-part) guide to modern quantum mechanics (arstechnica.com)

This was quite a fun read... One question I have is, in that short clip of the stripes produced by phthalocyanine, why are the slits closer together at the top than at the bottom?

Is this because it, moreso than a single neutron, is heavy, and so those slits being closer together is caused by gravity interference?

I wonder if there is a guide specifically explaining the mathematics of quantum mechanics & M-theory, for us mathematicians with free time.