First time I disagree with Ethan:

If you want to know what reality is, it’s this: what we can observe, measure, and predict about nature under every combination we can dream of setting up.

Nope. I mean, I do appreciate what he says and the fact that experiments are at the heart of physics. But K.I.S.S. principle or Occam Razor here is needed.

First of all, it is true that we do the experiments, but physical experiments must be valid without the “we” factor.

The phrases “We observe” or “You can observe” are misleading. Observing, in physics means interaction.

So, if you think to “trick” quantum particles with experiments, it seems that they “cheat”. But, if you remove the “we” factor and substitute “observe” with “cause an interaction” the double slit experiments shows a different “reality”:

Make photons (or other particles) interact with the beam going through the double slit, and their quantum property as single particles stop to be observable. It doesn’t matter if or when you look at the results…

Quantum are the rules of reality, but when interactions occur most of the “bizarre” properties of quantum world are no longer observable. The more particles you have in a system, and the more the system acts in a deterministic way.