None of the leading interpretations of quantum theory are very convincing.
This much, I think I do understand: quantum theory works. The math is sound. Experiments match predictions (mostly). What's up in the air is what it all means (interpretation) and why the math works so well.
But the whole thing is so alien to our everyday perceptions that I doubt any interpretation would be convincing, at least to anyone who prides themselves on "common sense."
They ask us to believe, for example, that the world we experience is fundamentally divided from the subatomic realm it’s built from. Or that there is a wild proliferation of parallel universes, or that a mysterious process causes quantumness to spontaneously collapse.
Okay, no, they don't "ask us to believe." Religion peddlers ask us to believe. Politicians ask us to believe. Scientists do research and try to explain the results.
This unsatisfying state was a key element of Beyond Weird, my 2018 book on the meaning of quantum mechanics.
Yes, I'm okay with book plugs in here. Usually.
But after reading Decoherence and Quantum Darwinism, a book published in March 2025 by the physicist Wojciech Zurek, I’m excited by the possibility of an answer that does away with all those fanciful notions.
The title alone makes me skeptical.
See, Darwin was absolutely groundbreaking. Completely turned "common sense" on its head. His work laid the foundation for pretty much all of modern biology. But science has updated and refined pretty much every detail (from what I understand, anyway). But invoking Darwin is one of the things evolution deniers love to do to make science and those who follow it look bad. Consequently, every time I see "Darwinism" out of context, I cringe.
If you know something about quantum mechanics...
Which you don't. Neither do I.
...you can be forgiven for thinking that the big, strange deal is the quantum part: the idea that the world at the finest scales is grainy, that particles can only change their energy in abrupt quantum jumps by exchanging little packets of energy with fixed sizes.
"Strange" isn't just a type of quark; it's a matter of perspective. To the quantum world, our more deterministic, macroscopic existence is what's strange.
Ultimately, the arguments over quantum mechanics have much bigger stakes: what reality is.
And everyone's selling their own version of what reality is.
Quantum uncertainty, the physicist and philosopher Jeffrey Bub of the University of Maryland told me, “doesn’t simply represent ignorance about what is the case, [but] a new sort of ignorance about something that doesn’t yet have a truth value, something that simply isn’t one way or the other before we measure.”
We're conditioned to accept that everything is either true, or it's false. This is false. There are other possibilities: A statement can be neither true nor false. It can be both true and false. It can be obviously false and yet hold truths, like fiction writing. It can be non-determinable, as in quantum theory. And it can be paradoxical, like the famous "This sentence is false" and its equivalents. (There are probably other truth values, but those are the ones I thought of off the top of my limited mind.)
Which is to say that maybe the problem lies not in the quantum world, but in our limited minds.
But why should there be two distinct types of physics — classical and quantum — for big and small things? And where and how does one take over from the other?
Those are the main questions addressed in the article, so I'm quoting them.
The central element of Zurek’s approach is the phenomenon called quantum entanglement, another of the nonintuitive things that happen at quantum scales.
Again, though, I think it's a perspective thing. Entanglement seems weird to us (and there's a lot of misleading speculation about it out there, which one has to be wary of), but it's perfectly normal in the quantum realm.
The molecules in an apple are described by quantum mechanics, and photons of light bouncing off the surface molecules get entangled with them. Those photons carry information about the molecules to your eyes — say, about the redness of the apple’s skin, which stems from the quantum energy states of the molecules that constitute it.
This, for example. I'm not saying it's wrong—the author knows a hell of a lot more than I do—but I'm not saying it's right, either.
There's a lot more explanation at the link, by the way, and don't worry; there's no math involved.
Zurek’s theory of quantum Darwinism — which, again, uses nothing more than the standard equations of quantum mechanics applied to the interaction of the quantum system and its environment — makes predictions that are now being tested experimentally.
This, though... this is the important part. Maybe those experiments will support the theory. Maybe they'll falsify it. Maybe they'll leave it in an indeterminate state. But the important thing is that it's testable at all, which the highly popular (as in, fiction writers use it a lot) many-worlds interpretation isn't. At least not at our current level of understanding. Well, not "our" current level of understanding, which is pretty much limited to what celebrities are getting up to in their private lives, but scientists' current level of understanding.
This leads us to another revelation of decoherence theory, the one that persuades me that Zurek’s theory now tells a complete story. It predicts that all the imprints must be identical. Thus, quantum Darwinism insists that a unique classical world can and must emerge from quantum probabilities. This imposition of consensus obviates the rather mysterious and ad hoc process of collapse, in favor of something more rigorous.
I find myself wondering if this could also put to bed, finally, the question of "why is there something rather than nothing," which has always stuck in my craw like a sideways pretzel rod.
Now, if you didn't follow any of that, that's okay. I might blog about food again tomorrow, or rant about misinformation, or just tell jokes. But the article itself explains things rather well, I think.
