Recently, I came across a believer who offered a unique argument for the existence of God. He had been reading about the beam splitter experiments that confirm quantum entanglement. Specifically, he had read about the delayed-choice quantum eraser, where they don’t “observe” the system until some time after the experiment, and the nature of the pattern on the detector (whether it’s an interference pattern or a solid pattern) changes, and future events appear to shape the past.
He argued that since the wavefunction can’t collapse — and quantum events can’t be determined — until after they are observed, then the universe couldn’t exist until there were observers. Since it obviously did exist, that means there must have been a Great Observer — God — long before there were conscious beings.
While interesting, this argument fails for two reasons. First, there’s nothing inherently special about observation. When you observe a system, even a quantum system, you are physically interacting with it, and it’s the physical interaction that changes the quantum state, ie, causes the wavefunction to collapse (Cf. environmental decoherence). Second, the wavefunction is holistic. It exists through all space and all time, so it already “knows” (if you’ll excuse the anthropomorphism) that the system will be “observed” at a later time. It doesn’t matter whether you do it tomorrow or a million years from now.
What do I mean that all of time exists? All of time exists now? If you ask that question, you’re still stuck in an intuitive way of thinking about time. All of time doesn’t exist now any more than all of space exists here. All of space exists, and all of time exists. That’s it. If you move in relation to a distant object, you move into its past or future time slices — into past or future “nows” for that distant object. They all exist concurrently. It’s a weird way of looking at the universe, but the universe behaves in weird ways. Our evolved psychological intuitions are adapted to the meso-scale environment that our ancestors had to negotiate for thousands of years. Saying that the universe is weird is really more a statement about us than the universe.
So while it was a good try, it was based on a lack of understanding of the underlying physics. But at least he was trying to learn something, and I appreciate his effort.