September 12, 2019

So, I’m waaaaaaay behind on The Last Emperox (it’s my own damn fault), and as a result I’m now clacking away furiously and also, as it happens, very happily employing my nanny software during the day until I get my writing quota done. What this means is that when I sign back on to Twitter and other social media, people are often asking me what I think about whatever the hot topic of the day is, which has happened while I was not at all paying attention.

The answer to this question at the moment is usually two-fold: One, I probably literally just heard about it right that second (because my nanny software blocks news sites as well as social media), so uhhhh, I probably don’t know; Two, it turns out that writing all day makes my brain tired, so what it wants to do after a full day of clacking away is look at pictures of cats more than try to generate informed, nuanced opinions on things. This will likely continue to be the case through the end of the writing of the book, which, remember, I am now behind on, because I suck.

This is a long way of saying that between now and the end of the writing of the book (which I hope to God will be done before I leave for a week to Australia at the end of the month), I’m declaring Hot Take Bankruptcy, meaning whatever it is you want me to opine about, I probably won’t, and even if I do, I can’t guarantee that the take will be anything more than “Ehhhhhh… ¯\_(ツ)_/¯?” I know this will be frustrating for many of you, who rely on me for your daily dose of hot, hot takes, especially online. But, well, ¯\_(ツ)_/¯? For now, I just don’t wanna.

Mind you, this doesn’t mean I won’t occasionally point to a news story of our president (or the UK’s prime minister) doing some dumbass thing or another, or things of that type. But that’s usually about me tweeting something that already conforms to and confirms an opinion that I already have rather than attempting to formulate a whole new opinion on something I’ll need to read up on and think about. One’s work and the other isn’t.

The good news is, one, you’ll get a book out of it, and two, when the book is (finally for God’s sake) done I’ll almost certainly be back with all the takes you can possibly stand, hot, cold, tepid and everywhere else on the heat spectrum. Plus, I will finally get around to doing a Reader Request Week here, which is super late this year. Promise!

But in the meantime, please don’t expect much in the way of hot takes from me, even if the issue is important to you (and even if you think I should really care about it). The outside world’s gonna have to go on without me for a bit. You go on ahead. I’ll catch up eventually.

I’ve been aware of the “Many Worlds” interpretation of physics for some time — longtime readers of mine know it’s intimately connected with space travel in my “Old Man’s War” series of novels. But in the real world, how does it connect to the actual physics we know and (profess to) understand? Actual physicist Sean Carroll knows, and in his new book, Something Deeply Hidden, he delves right into it.

SEAN CARROLL:

If there’s one thing the world doesn’t need, it’s another book on quantum mechanics. I mean, who hasn’t written one? In preparation for writing Something Deeply Hidden, I searched on Amazon for books with titles of the form “Quantum X,” and was rewarded with Quantum Eating, Quantum Touch, Quantum Leadership, and many more.

The existence of these books reflects the widespread conviction that quantum mechanics, however scientists might think about it, is fundamentally profound and deeply mysterious, so it could mean just about anything. You might expect to find a countervailing stream of books by sober-minded physicists and science writers, doggedly explaining that quantum mechanics isn’t really all that inexplicable after all. It’s science, not mysticism.

That’s not exactly what you find. Sure, there are valiant attempts to dispel the worst kinds of quantum woo. But even the most hardnosed quantum books seem to agree that the subject is unavoidably murky, something so bizarre and ill-understood that it’s not meant to be grasped by mere human beings. This or that quantum phenomenon is trotted out, accompanied by an implicit shaking of the head – “Can you believe it? This makes no sense at all!”

So my big idea for Something Deeply Hidden was: quantum mechanics is understandable.

To be clear, the challenge is not just that quantum mechanics is complicated or recondite, like general relativity or the standard model of particle physics. It’s that physicists themselves, who are supposed to be experts, don’t understand it, and in their more honest moments they admit it.

Quantum mechanics sits at the absolute heart of all of modern physics; it’s the deepest, most important idea that physicists have. But what we teach our students, as philosopher Tim Maudlin has put it, is a recipe, not a theory.

We can set up a quantum system, like an electron orbiting the nucleus of an atom. And we can measure something about it, like its position. The quantum recipe tells us the probability of getting any particular measurement outcome. And that recipe has been tested to enormous precision, and has come through with flying colors every time.

What we can’t actually tell you is what happens when you measure a quantum system. What counts as “measuring”? How quickly does it happen? Do you have to be conscious?

All of these questions are, in the standard textbook formulation, left entirely vague. The resulting recipe is good enough for government work, or for building incredibly complex technologies, but it falls well short of the clarity and rigor we would expect of a well-defined scientific theory.

Thus, in the words of Richard Feynman, “I think I can safely say that nobody understands quantum mechanics.”

At least, nobody thinks that other physicists understand quantum mechanics. Some of us, including myself, think we do understand the basics. The problem is that there is more than one honest, rigorous physical theory that reproduces the textbook quantum recipe in the appropriate regime. So we have multiple approaches, and have to decide which one is the best description of Nature; but that’s what scientists are always supposed to do.

So in the book I explain my favorite approach to quantum mechanics, the Many-Worlds formulation. It has a bad reputation, as it sounds a little science-fiction-y, or at least like you’re tacking on a bunch of extra stuff (entire universes worth) just to solve an irritating problem in quantum measurement. But the truth is the opposite: the theory is lean and mean, getting enormous mileage out of very few basic assumptions. The extra worlds are predicted by the theory, not tacked onto it.

One of the goals of Something Deeply Hidden is to make all that clear. But the broader, more important message is the one above: that quantum mechanics is understandable. Maybe my favorite understanding will turn out to be the right one, or maybe one of the various competitors. But they’re all ultimately intelligible, not ineffable.

It took me a while to come to this conclusion. I didn’t start out to be a rebel, fighting against the entrenched establishment of physicists who don’t want to face up to the quantum measurement problem. But the more I’ve worked in the field, and the more I’ve thought about it myself, the more irritating and embarrassing it is that we haven’t figure out quantum mechanics once and for all, and for the most part we haven’t even been trying. I’m hoping my book does its small part in changing that.

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Something Deeply Hidden: Amazon|Barnes & Noble|Indiebound|Powell’s

Read an excerpt. Visit the author’s site. Follow him on Twitter.

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