What is the role of an observer in "consciousness causes collapse"? [duplicate]

Question

If a "conscious observer" is part of a theory of physics (e.g. some versions of QM, cosmology), then how (according to what theories) did the universe evolve before the existence of conscious life forms ?

If we take a particularly narrow view of requiring human observers then this would have to account for almost the whole history of the universe, and even a most speculative view would surely have to allow the first generation of stars to form and explode before life could evolve.

Logic suggests that if we have to have theories that deal with the universe "pre-life" then they should probably also work "post-life"

Answer 1

You have delved into the area of philosophy as much as physics. Is a conscious observer a mature human? What about a baby human? What about an ant? A worm, a single cell amoeba?. The answer to your question is that no one agrees on an answer. Perhaps the most widely accepted is the Copenhagen interpretation which posits that an "observer" or a "measurement" is merely a physical process. One of the founders of the Copenhagen interpretation, Werner Heisenberg, wrote:

Of course the introduction of the observer must not be misunderstood to imply that some kind of subjective features are to be brought into the description of nature. The observer has, rather, only the function of registering decisions, i.e., processes in space and time, and it does not matter whether the observer is an apparatus or a human being; but the registration, i.e., the transition from the "possible" to the "actual," is absolutely necessary here and cannot be omitted from the interpretation of quantum theory.

So don't try to count the number of angles dancing on a pinhead. Just accept that some sort of measurement device is required under this general observer idea.

Answer 2

If a "conscious observer" is part of a theory of physics (e.g. some versions of QM, cosmology), then how (according to what theories) did the universe evolve before the existence of conscious life forms ?

You have just narrowed down one of the biggest problems with any interpretation of quantum mechanics that concludes that conscious observers are responsible for the collapse of the wavefunction. Because of this kind of issues (what was before? what is consciousness?) is why these interpretations are excluded by the vast majority of the physics community. Any elaboration on how even these interpretations work is far off topic for Phyiscs SE, as it would just be philosophy, sophistry and speculation, hardly based on testable predictions or math.