[sown]

What does this mean? If there was a supernova eons ago in another galaxy and I'm the only human who had been hit by a cosmic ray, does that mean it didn't exist or happen until ... ?

Does measurement have to include an agent? Could measurement mean interaction with other atoms?

[photonic29]

>Does measurement have to include an agent? Could measurement mean interaction with other atoms?

Indeed it can. Roughly put, if information about the state left the undetermined system, a measurement has been made. One of the most frustrating interpretations of literature such as this is the idea that there is something spooky, special, and reality-making about a conscious mind. Lots to think about there philosophically, but the physics happens at lower levels of abstraction.

[matt_kantor]

The trouble with questions like yours is that we're the ones asking them. The results of an unobserved measurement cannot be known, so there's no way to completely remove agency from our experiments.

Personally, I think the simpler and less egocentric view is that all measurements produce wavefunction collapse, even when there's nobody looking.

See https://en.wikipedia.org/wiki/Von_Neumann–Wigner_interpretat... and https://en.wikipedia.org/wiki/Measurement_problem if you want to read more.