What Does Quantum Mechanics Suggest About Our Perceptions of Reality?

Quantum mechanics suggests that we perceive at most a tiny sliver of reality. Of course we already
knew that! We knew that the visible spectrum is only a small part of the spectrum of electromagnetic radiation. We knew that the universe is much, much larger than our ancestors believed.  And we already knew that we are made of things that are too small for our eyes to see. So how is it news that we only perceive a tiny sliver of reality?

It’s news because quantum mechanics says that the part of reality that we do not perceive is radically different than the part of the world that we do perceive. The difference is so profound that we still don’t fully understand how to talk about quantum reality. There doesn’t seem to be any direct analogy between quantum reality and the reality we perceive with our senses.

Before I explain the gap between our perceptions and reality, I want to state that I completely disagree with the idea that quantum mechanics forces us to accept an idealist view of reality. Idealism says that the physical universe is made out of our perceptions – in other words, out of spiritual reality.  Several early interpreters of quantum mechanics thought that it supported this idealistic understanding of reality. Why would they have thought this? The reason, quite simply, is that they didn’t know how to cope with the issue of quantum indeterminacy.

Quantum indeterminacy is the unavoidable fact that not all quantities can simultaneously have determinate values.  For example, if an electron has a location, then it simply has no speed – it is neither at rest, nor is it moving slowly, nor is it moving quickly.  There simply is no fact of the matter about its state of motion.  Similarly, if an electron is in a definite state of motion, then it’s not in any particular place – not here, nor there, nor anywhere.

Let’s be completely clear about what we’re saying here.  We are not just saying that if you know the position of the electron, then you don’t know whether or not it’s moving.  We’re saying that if the electron has some position, then it does not have any state of motion.  What could this possibly mean?  Nobody is quite sure.

But the story gets more interesting.  Whenever a conscious observer tries to determine the position of the electron, she will always finds that it does indeed have a position.  Similarly, whenever a conscious observer tries to determine the state of motion of an electron, she will always find that it does indeed have some particular state of motion.  If these facts weren’t true, then we wouldn’t be able to test the predictions of quantum mechanics! So how are we to reconcile the fact that sometimes the electron doesn’t have a position with the fact that, whenever we look, it does have a position?

Some quantum pioneers, such as Heisenberg and Wigner, thought that the act of “looking” caused the electron to take on a definite state of motion, or a definite position.  And then it wasn’t much of a further leap for them to suggest that, before anybody looks, there wasn’t any electron.  If that were the case, then physical reality is brought into existence by our acts of perception.

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What Does Quantum Mechanics Suggest About Our Perceptions of Reality? | BQO