This leads us to Winger's cat (see https://en.wikipedia.org/wiki/Wigner%27s_friend ). In the novel Timelike Infinity (great series btw), the Ultimate Observer is claimed to be the consciousness at the end of universe that collapses all entangled wave functions. Note the word "entangled" ... like a ball of yarn. The ultimate observer is a cat with a cosmic ball of yarn tracing back the histories of every particle.

Wave function collapse isn't caused by an observer, but rather "does the cat care about this?"