Last time I started with wave-functions of quantum systems and the Schrödinger equation that describes them. The wave-like nature of quantum systems allows them to be merged (superposed) into combined quantum system so long as the coherence (the phase information) remains intact.
The big mystery of quantum wave-functions involves their apparent “collapse” when an interaction with (a “measurement” by) another system seemingly destroys their coherence and, thus, any superposed states. When this happens, the quantum behavior of the system is lost.
This time I’d like to explore what I think might be going on here.
Quantum physics is weird. How weird? “Too weird for words,” as we used to say, and there is a literal truth to words being inadequate in this case. There is no way to look at the quantum world that doesn’t break one’s mind a little. No one truly understands it (other than through the math). It’s like trying to see inside your own head.
Since we’re clueless we make up stories to fit the facts. Some stories advise that we just keep our heads down and do the math. (Which works very well but leaves us thirsty.) Other stories seek to quench that thirst, but every story seems to stumble somewhere.
One of quantum’s biggest and oldest stumbling blocks is wave-function collapse.
For the last two weeks I’ve written a number of posts contrasting physical systems with numeric systems.
(The latter are, of course, also physical, but see many previous posts for details on significant differences. Essentially, the latter involve largely arbitrary maps between real world magnitude values and internal numeric representations of those values.)
I’ve focused on the nature of causality in those two kinds of systems, but part of the program is about clearly distinguishing the two in response to views that conflate them.
Last week I read Quarantine (Greg Egan, 1992), a science fiction novel that explores one of the more vexing conundrums in basic physics: the measurement problem. Egan’s stories (novels and shorts) often explore some specific aspect of physics (sometimes by positing a counterfactual reality, as in the Orthogonal series).
In Quarantine, Egan posits that the human mind, due to a specific set of neural pathways, is the only thing in reality that collapses the wave-function, the only thing that truly measures anything. All matter, until observed by a mind, exists in quantum superposition.
Unfortunately, it’s difficult to explore how this ties into the plot without spoiling it, so I’ll have to tread lightly.
Too Weird For Words!
I started with the idea of physical determinism and what it implies about free will and the future. Then I touched on chaos theory, which is sometimes raised as a possible way around determinism (short answer: nope). In the first article I drew a distinction between “classical” mechanics and quantum mechanics because only at the quantum level is there any sign of randomness in reality.
It turns out that the quantum world is decidedly weird, and while we have math and models that seem to describe it extremely well, it can honestly be said that no one actually understands it. This time I’ll tell you about some of that weirdness and how it may (or may not) apply to the world as we know it.
The key question here is whether our brains make use of quantum effects.