Gray Area: Eliezer, why are you concerned with untestable questions?

Questions you can easily test experimentally are hard for Science to get wrong.

There are numerous questions that are hard to test experimentally right this minute but are extremely important because of their future consequences. I bet you can think of one or two.

I chose quantum physics as my point of departure because the case is mathematically clear-cut.

Incidentally, it looks to me like you should be able to test macroscopic decoherence. Eventually. You just need nanotechnological precision, very low temperatures, and perhaps a clear area of interstellar (intergalactic?) space.