we know that simply observing an experiment can change the outcome. We don't know why that is either, AFAIK
We most certainly *do* know why observation affects an experiment. It's the Heisenberg uncertainty principle in action - if you make a measurement of the state of a system, that variable is known to some degree of precision. Its conjugate variable is thus made uncertain to a degree prescribed by the uncertainty principle. This has nothing to do with consciousness or a living observer.
A simple double-slit experiment works because of the uncertainty in the position of the particle. The wavefunction interferes with itself as it comes out of both slits and affects the possible positions it can be observed at on the detector. If you measure whether the particle passes through one of the slits, it's position is no longer uncertain, the wavefunction changes, and the experiment reflects that. This is well-understood quantum mechanics, although the popular press likes to pretend we don't know anything about it. And yes, IAAP (I am a physicist).