Most of physics can be explained using billiard balls on a pool table. Quantum mechanics is a game of pool where the 8 ball can turn itself into a 3 ball and a 5 ball, which go their separate ways, for no apparent reason. Or where a 1 ball can appear out of thin air, so long as it’s accompanied by a -1 ball, and then vanish—again for no apparent reason. Sometimes a ball in one of the pockets can pop back out, and sometimes two balls that should have collided will pass right through each other.
In Search of Schrödinger’s Cat by John Gribbin attempts to explain the quantum world to us humans living in the “real” world. The book begins by making it clear that common sense does not apply to quantum reality. Atoms and photons and various fermions and bosons follow their own secret rules, and we humans have to accept that strange things do happen without ever knowing why.
By approaching quantum mechanics from a historical point of view, Gribbin shows how one discovery led to another, increasing the amount of evidence for “quantum weirdness” even as scientists worked harder and harder to prove subatomic particles made logical sense until finally they threw up their hands and gave up. Some of the very people who created quantum mechanics, such as Erwin Schrödinger himself, were the most incredulous about it.
The book was published in the 1980’s, and since then we have built larger and larger particle accelerators, and there have been new developments in quantum science. But the essential mysteries are still mysteries, and In Search of Schrödinger’s Cat is a good introduction to the subject. Equations are kept to a minimum, but there are a few. Some prior familiarity with time travel and alternate universes as presented in science fiction would help as well.