A quantum experiment suggests there’s no such thing as objective reality

March 13, 2019 4:03 PM

Physicists have long suspected that quantum mechanics allows two observers to experience different, conflicting realities. Now they’ve performed the first experiment that proves it. They use these six entangled photons to create two alternate realities—one representing Wigner and one representing Wigner’s friend. Wigner’s friend measures the polarization of a photon and stores the result. Wigner then performs an interference measurement to determine if the measurement and the photon are in a superposition. The experiment produces an unambiguous result. It turns out that both realities can coexist even though they produce irreconcilable outcomes, just as Wigner predicted. That raises some fascinating questions that are forcing physicists to reconsider the nature of reality.
posted by GoblinHoney (63 comments total)

I'm so glad none of my research will ever force anyone to reconsider the nature of reality.
posted by ChuraChura at 4:17 PM on March 13, 2019 [19 favorites]

Wake me when this can be reproduced on a macro (non-quantum) scale.

I"m not saying it's not interesting, but I suspect that there's a lot we don't know about quantum behavior, and that could preclude this from happening at molecule level or larger.
posted by CheeseDigestsAll at 4:19 PM on March 13, 2019 [15 favorites]

>The next step is to go further: to construct experiments creating increasingly bizarre alternate realities that cannot be reconciled.

Sorry, is this the current American politics thread, or no?
posted by Sing Or Swim at 4:20 PM on March 13, 2019 [80 favorites]

We did some home brewing research that forced several people to reconsider the value of reality.

Can the Mefites who understand the physics of this, in a way I can't trust any media source to explain, come and provide me that service for free now?
posted by howfar at 4:21 PM on March 13, 2019 [6 favorites]

Yeah, but what about "Alternative Facts?"
posted by Chuffy at 4:21 PM on March 13, 2019 [4 favorites]

Previously, but focusing only on the thought experiment and not the physical experiment claimed in the FPP.
posted by Arson Lupine at 4:23 PM on March 13, 2019 [3 favorites]

The ultimate triumph of solipsism!
posted by Chrysostom at 4:23 PM on March 13, 2019 [3 favorites]

The ultimate triumph of solipsism!

Solipsism is the notion that there are no other minds but mine. It is not a synonym for philosophical idealism.

This , whatever its flaws as metaphysics may turn out to be, explicitly depends on the conflict between the experiences of two different minds.
posted by thelonius at 4:37 PM on March 13, 2019 [5 favorites]

It seems like it might be a much weirder and more interesting idea than that. Solipsism denies any communication between individuals, and hence any form of epistemological intersubjectivity, while this seems to hint at the idea of communication and epistemological intersubjectivity between irreconcilable realities. That's the sort of idea that's worth taking for a spin, while solipsism is just kinda dull. Although I have always wondered what solipsists' parties are like.
posted by howfar at 4:43 PM on March 13, 2019 [6 favorites]

Solipsism is the notion that there are no other minds but mine. It is not a synonym for philosophical idealism.

Pfff, exactly what I'd expect an imaginary person to say.
posted by Chrysostom at 4:45 PM on March 13, 2019 [29 favorites]

Man, between this and the time reversal experiment, I really wish this physicsmatt bat signal still worked.
posted by lazaruslong at 4:47 PM on March 13, 2019 [24 favorites]

I think it's dangerous to pose this in terms of the experience of minds. Physics is incapable of saying anything about minds. Physical observers aren't mental beings, they are frames of reference. "Observation" isn't perception, it is interaction. It would have been much better if the literature had chosen a less anthropomorphic term, like Detectors.

Which isn't to be construed as a defense of solipsism. The self can't be the only thing known to exist, because the self isn't a thing that exists.
posted by I-Write-Essays at 4:48 PM on March 13, 2019 [13 favorites]

I'm a bit perplexed by the the assertions that quantum effects only operate on the scale of atoms and molecules. Bose-Einstein condensates are quantum objects. Superfluid helium is a quantum object. Neutron stars are quantum objects. The nuclear process inside the sun is powered by a quantum effect.
posted by runcibleshaw at 5:05 PM on March 13, 2019 [12 favorites]

Reality: the lowest common denominator of perception
posted by Redhush at 6:25 PM on March 13, 2019 [6 favorites]

I have always wondered what solipsists' parties are like

As a former english graduate student, let me tell you that you are not missing much.
posted by mecran01 at 6:44 PM on March 13, 2019 [25 favorites]

words
posted by allium cepa at 6:44 PM on March 13, 2019 [2 favorites]

I really want there to be a gay physicists' organization called the Friends of Wigner.
posted by nebulawindphone at 6:59 PM on March 13, 2019 [1 favorite]

For reference, here's the paper. I'll have to look over it when I have some free time.
posted by Johnny Assay at 7:19 PM on March 13, 2019

(Is there a way to read this article without signing up for Technology Review?)
posted by lesser weasel at 7:36 PM on March 13, 2019

So, if the universe is such that two observers will receive different information about the photon (or entangled photons) how is that a contradiction? Wigner's test tells him the photon is in superposition, Wigner's friend observes that the photon has polarized. That is only a contradiction within the current physics paradigm.

Presumably, after study and further experimentation, we will develop a theory that explains the results. (That's still a pretty big deal, of course. Paradigm shifts (if this is what is called for) don't come along very often!)

I don't see why we ought to jump from the observation that this result (assuming the experiment can be replicated, etc.) is incompatible with out current theoretical framework to the claim that there is no objective reality.

Indeed the fact that we are measuring external states of affairs suggests that there is an objective reality or else what would be measuring?
posted by oddman at 7:40 PM on March 13, 2019 [3 favorites]

Relativity gives us a way to reconcile the differing reports of observers; we can say "A and B saw these events occur in different orders because of how they were moving relative to one another". If the reports in this quantum case differ in a consistent, predictable way (and I don't know if they do; someone who knows things, please speak up), perhaps a similar reconciliation could be effected.
posted by a snickering nuthatch at 7:44 PM on March 13, 2019

Now they’ve performed the first experiment that proves it.

they're obviously unaware of that time in 1982 that we dropped weapons grade LSD and climbed what's known as Unnecessary Ridge whilst dragging along a ghetto blaster pumping out a playlist that included mid-70s King Crimson, The Clash (Sandinista), various odd jazz things, Gong, some Penguin Cafe Orchestra, and Shostakovich ... or maybe it was Debussy. Somewhere, there's a cassette tape that knows for sure.

At least that's how I remember it. My friend Simon is pretty sure it was almost exclusively Brian Eno related.
posted by philip-random at 9:05 PM on March 13, 2019 [9 favorites]

Well if someone can just open the portal to the reality where HRC is president and the UK is not about to commit national suicide then I'll just be on my way.
posted by PenDevil at 2:00 AM on March 14, 2019 [3 favorites]

This makes sense. For the last 3 years, I've been living in Normal Reality, while a strange number of people are living in some Other Reality where Donald Trump is an intelligent, hardworking, physically-hale and honest businessman who is selflessly trying to improve the American government and make things better for working-class folk.

They're on the other side of some aggragate photon divide, I guess.
posted by Chronorin at 2:02 AM on March 14, 2019 [1 favorite]

This result is actually not incompatible with our current theoretical framework so much as it is incompatible with our intuition - the original thought experiment arose because it was a possible consequence of the current theoretical framework that seemed unintuitive. The interpretation that this implies there is no objective reality should not be taken to mean that there is nothing "out there" that we can understand, but rather that reality does not perhaps exist as a series of definite states that all observers can always eventually agree on.
posted by Nothing at 3:09 AM on March 14, 2019 [6 favorites]

I feel like anyone who has had an infuriating argument with a significant other about what one actually said or what actually happened groks this bit of physics on an intuitive level... Yes, yes, macro vs. micro, but also why don't you understand that the dishwasher doesn't always clean all the glasses and plates fully and why would you put them away like that?
posted by limeonaire at 5:08 AM on March 14, 2019 [5 favorites]

The idea that there is an abstract 'reality' that exists in some parallel realm, independent of our perceptions but interacting with them in some ill defined way, has always seemed odd and fanciful.
posted by signal at 6:22 AM on March 14, 2019 [4 favorites]

Well, it's not abstract is the trick
posted by thelonius at 6:29 AM on March 14, 2019 [2 favorites]

This result is actually not incompatible with our current theoretical framework so much as it is incompatible with our intuition

vice versa, s'il vous plaît.
posted by petebest at 6:56 AM on March 14, 2019

What is the sound of one reality confirming another?
posted by petebest at 7:01 AM on March 14, 2019 [3 favorites]

Physics is incapable of saying anything about minds.

And how do you suppose minds work, exactly?
posted by grumpybear69 at 7:01 AM on March 14, 2019 [2 favorites]

Yeah I'm also unsure what that is even supposed to mean. Our minds are physics and chemistry interacting, like basically everything else in the universe.
posted by GoblinHoney at 7:56 AM on March 14, 2019 [1 favorite]

> And how do you suppose minds work, exactly?

Clearly they are the consequence of physical law, but their study is not contained in the study of physics. Physics does not have words to describe minds, and it does not have laws about how they function. The same way that heat is an abstraction provided by thermodynamics to talk about the course-grained flow of energy through a system, we require other disciplines to talk about minds. From the point of view of physics, minds don't exist at all.
posted by I-Write-Essays at 7:56 AM on March 14, 2019 [5 favorites]

I take it to mean the distinction between “what these two people thought they saw” and “what these two people verifiably saw”. In the latter, mind isn’t relevant because appropriate instrumentation would report the same result as a human observer.
posted by ardgedee at 8:05 AM on March 14, 2019

Quantum mechanics doesn't have people, and it doesn't have seeing. It has particles, and it has linear operators. We anthropomorphize these things and talk about "observers" "seeing" things, but at the level of particle physics, there is no such thing as an eye to see with. There are only particles propagating through time. It's when we try to reason about physics using these anthropomorphic analogies to eyes and minds that we run into trouble, because those things don't actually exist. To get eyes and minds, you have to use a more course-grained theory than quantum mechanics provides.
posted by I-Write-Essays at 8:11 AM on March 14, 2019 [3 favorites]

As for how I actually think minds work, I imagine it's a lot like the way software works, but not in the way everyone usually makes that analogy.

Software can run on different computer architectures, and computer science doesn't care which, because the mode of computation is the same. On the other hand, programming languages designed to run on quantum computers are significantly different because the primitives of computation are different. Quantum logic is fundamentally different from classical logic.

I think minds are similar: the computational primitives implemented by our neurochemical brains don't yield classical logic either. Therefore, I think that naive comparisons to a computer get it wrong, but only because I think it's the wrong type of computer.

When studying computer science, it's not necessary to understand how the computer is engineered. Computer science doesn't concern itself with that. However, your programs will only run on a computer engineered to satisfy the assumptions you started with, so you better understand both.
posted by I-Write-Essays at 8:36 AM on March 14, 2019

Reality doesn't have particles and linear operators. We habitually try to reify those things and we speak of reality as being "made of" particles whose interactions are "governed by" operators, but in fact all of these things are mere artifacts of the lossy compression operation we rely on to construct our internal maps of the reality of which we are ourselves inseparable parts.

It's when we try to reason about our descriptions of reality as if they were reality that we run into trouble, because the things we each break our directly lived experience of reality down into while mapping it are not inherently shared across multiple minds; in order to agree about what it is we're seeing it is necessary though not sufficient to specify what it is we think we're seeing before we can communicate about it.

This experiment has not undone reality; that's not a thing that can in fact be done, because reality will be what it is and do what it does regardless of what any experimenter knows about it. But it might well force some people to clarify what they think they mean when they speak of objectivity.

What it has done is blown away the last shred of the illusion that there is some globally definitive map of reality of which the smaller map that any putatively objective observer would carry around in their own mind would necessarily be a proper subset.

It puts into stark relief the fact that each of us must make our own map and that there will be circumstances arising from differing access to information that can cause different people's maps not to share a completely reconcilable set of features even when all of them are constructed according to theoretical best practice. Mapping is an inherently lossy operation, and sometimes two of us will have no option but to lose different bits.

It also forces us to take seriously the fundamental nature of quantum mechanics. QM is a theory that makes only probabilistic predictions. It cannot tell us what is or is not definitely there. All it can do is give us reliable predictions about the likelihood that a specified physical setup will yield a specified physical outcome. Anything that we tell ourselves is actually happening between setup and outcome is really nothing more than a complicated Just So story.
posted by flabdablet at 9:11 AM on March 14, 2019 [3 favorites]

because the self isn't a thing that exists.

so who's got the mild hangover this morning then?
posted by philip-random at 9:27 AM on March 14, 2019 [5 favorites]

I think using this result to justify relativism is fallacious reasoning though. Some philosophers would say that such an inference violates the criterion problem.

I usually say that the incoherence of relativism is apparent whenever someone argues that it is some grand meta-truth. Because a meta-truth is objective in form.
posted by polymodus at 1:03 PM on March 14, 2019 [2 favorites]

I think a closer guess to the truth, than "Oh no! Reality is inconsistent!" is that the universe at the smallest scales is made up of a bunch of probabilistic wavey things, that we describe in quantum mechanics by wave functions, that follow the rules of probabilistic wavy things that only end up looking like the world we see when you get enough of them interacting randomly together. So on a large scale we see things as having a position or a velocity, when really it's an approximation, a really, really good approximation to what a bunch of tiny little probabilistic wavey things do when enough of them are together interacting together with a lot of randomness.

So I'm guessing what this result essentially is, is that an "observation" does not actually magically collapse a wave function into a nice classical value, but is just another probabilistic interaction between probabilistic wavey things, which usually, in practice, means we've just made it interact with randomly enough other randomly interacting wavey things that it ends up acting classically, BUT if you're really, really, careful, like in this experiment, you can make it so that that's not quite the case and you turn out to be wrong if you assume an "observation" guarantees a classical result.

Remember, this, like Bell's inequality, are statements of probability. You can't do one trial and say "oh something absolutely impossible happened!" In fact in both cases, everything that does actually happen is quite self consistent, it's just that it what has to happen for physical laws to remain self-consistent on a quantum level is very unintuitive when you're used to how things behave in the large-scale classical world, especially when you compare it to what you think might have happened had you done things slightly differently.

Of course, the more brain-breaking question is "what does 'probabilistic wavy thing' even mean when even testing its value, drawing a card from the quantum deck so to speak, is also just an approximation of the interactions created by a bunch of probabilistic wavey things?"
posted by Zalzidrax at 4:23 PM on March 14, 2019 [2 favorites]

Man-it happened-just get over it. Yeah, it kinda happened again, sorta. We think, a good thing we do, but our thoughts don't hold water, we have to use our holey buckets for that. Oh wow! Did you see that-no. Spooky!
posted by Oyéah at 5:05 PM on March 14, 2019 [1 favorite]

I usually say that the incoherence of relativism is apparent whenever someone argues that it is some grand meta-truth. Because a meta-truth is objective in form.

I would never argue such a thing, because it seems to me that the only grand meta-truth applicable to reality is that it is in fact real; this is a tautology and therefore analytically true.

However, I'm perfectly happy with relativism as a fundamental basis of my own world view, and to argue for its usefulness as such, and to be amused by the discomfiture of absolutists every time something like this comes along and makes their position look that little bit less tenable.

It further seems to me that the fact that I can base what I consider to be a fully satisfactory world view on relativism while others apparently cannot bear to do so is actually a pretty good argument for it.

I think a closer guess to the truth, than "Oh no! Reality is inconsistent!" is that the universe at the smallest scales is made up of a bunch of probabilistic wavey things, that we describe in quantum mechanics by wave functions, that follow the rules of probabilistic wavy things that only end up looking like the world we see when you get enough of them interacting randomly together.

I prefer to think of the universe just being whatever it is and doing whatever it does, and the probabilistic wavey things as being features of the least lossy compression method we have yet devised for constructing workable maps of very very small parts of it.

It seems to me that the only way we can usefully predict the behaviour of those parts of the universe that interest us is to use conceptual maps that separate those parts out as map features. In order to perform such a mapping, we need some basis for distinguishing any given feature from the rest of the universe: a way to say, for any given feature labelled X, that this part of reality is X and that part is not X.

What QM does (and it's this, in my opinion, that makes it so non-intuitive to so many) is allow us to say that this part of reality is X and that part is not X to some specifiable and generally varying extent rather than as a hard and fast distinction. In QM we're allowed to superpose X and not-X and work with both at the same time.

QM says that some of the distinctions we wish to make in order to populate our maps simply cannot be made with certainty until more information has become available; we don't and can't know exactly what's going on between the launch of any given experiment and the measurement of its outcome because, at the smallest scales, the universe cannot be decomposed into repeatable or consistent patterns. The best we can ever do is work out everything that could possibly happen, assign a likelihood to each of those possibilities, and come up with an aggregate probability for any given predicted result.

Every part of reality is unique; no part of it is exactly the same as any other. In other words, no two parts of reality can be mapped exactly onto one another without choosing to ignore the distinction that allowed one to distinguish between those parts in the first place, and QM says that sometimes choices like that have got consequences. This electron is not that electron despite the fact that electrons qua electrons have all got identical properties.

What the linked research demonstrates is the existence of multiple maps that contain different features from each other and yet describe and predict the outcomes of a given experimental setup equally well. Which is, if one hews to a view that the universe is "made of" particles and fields, difficult to swallow because it raises the question of which particles and fields are really there. For those of us who prefer to think of particles and fields as map features rather than fundamental components of a limitlessly explorable territory, it's not the slightest bit disturbing.
posted by flabdablet at 5:57 AM on March 15, 2019 [1 favorite]

However, I'm perfectly happy with relativism as a fundamental basis of my own world view, and to argue for its usefulness as such, and to be amused by the discomfiture of absolutists every time something like this comes along and makes their position look that little bit less tenable.

You just told everyone:

It puts into stark relief the fact that each of us must make our own map

Relativists (of the type I meet just going about daily life, not the type who are well-versed in philosophy) are basically bullies because they insist on a thing and then lie by saying no, no, they only meant it applies to themselves. I don't know about absolutists, but when relativists talk to me, I feel the same language as being bullied.
posted by polymodus at 6:23 AM on March 15, 2019

I would never argue such a thing, because it seems to me that the only grand meta-truth applicable to reality is that it is in fact real; this is a tautology and therefore analytically true.

The statement reality is in fact real is not necessarily a tautology. Nor is analytic truth what matters. What matters is the performativity of relativists and thus the meta-truth that they insist on imposing, one that in my personal experience in practice is wielded as social propaganda.
posted by polymodus at 6:28 AM on March 15, 2019

None of this is an argument against relativism. The fact that some people are morally inconsistent has nothing to do with the question of what conditions for verifying or falsifying a statement/theory/web of knowledge etc. I've never observed the slightest correlation between people's epistemological and ontological position and their ethical consistency.
posted by howfar at 6:33 AM on March 15, 2019 [2 favorites]

It further seems to me that the fact that I can base what I consider to be a fully satisfactory world view on relativism while others apparently cannot bear to do so is actually a pretty good argument for it.

That is a terrible and immoral argument. If I base a fully satisfactory worldview on a harmful idea, and apparently other people cannot bear to do it, maybe that tells me the idea really is harmful.
posted by polymodus at 6:34 AM on March 15, 2019

That too is wrong. Relativism as regular people talk about it is always some moral position. The other person literally said that they based their worldview on relativism because it was satisfactory in leading a life.
posted by polymodus at 6:37 AM on March 15, 2019

The statement reality is in fact real is not necessarily a tautology.

I also think this statement in need of support. I think most people would agree that the word "reality" means something like "all the things that are real". "All the real things are real" seems like an obvious tautology to me. In what cases do you think that the argument above doesn't apply?
posted by howfar at 6:39 AM on March 15, 2019

Relativism as regular people talk about it is always some moral position.

Can you explain what this has to do with the moral worth of philosophical relativism?

I'm going to pop in a friendly reminder that many of us also have considerable knowledge of and training in these fields, and we may well have perspectives that are useful to you, even if you don't agree with them.
posted by howfar at 6:42 AM on March 15, 2019

Why it is, then, philosophically okay to go around telling people how important relativism should be to them? Doing that casually is not okay. So when you go around telling people that maps are this and that, and then extrapolate that to some sociological point, and then further down it gets to the point of talking about "absolutists" and their supposed "discomfiture" as if that was at all relevant in response to another commenter, I don't see how that is respectful philosophy. And so you have to ask where that behavior is coming from. It's one thing to have conviction about your worldview, it's another to conversational suck out the air in this way. It is white male philosophizing and I'm kind of over that.
posted by polymodus at 6:50 AM on March 15, 2019

Just a reminder that the reason this result occurs is because the quantum states involved started as pure states which are then manipulated in very delicate ways to get precise phase shifts while also being kept isolated from almost all of the outside world except for the other quantum states that the experimentalists wanted them to be entangled with.

In any day-to-day quantum system (i.e. damn near everything else in the Universe, including the quantum fields that make up the particles that compose your brain), no such isolation exists. As a result, thermal noise quickly decoheres pure states; scrambling phase angles. I strongly suspect that such noise, if it were allowed to be introduced into the system the experimentalists' constructed here, would very quickly bring the two "contradictory" views of the system's quantum superposition into agreement.

All of which is to say that this very interesting demonstration of quantum behavior has absolutely nothing to do with whether your macroscopic thermodynamically-interacting wetware system disagrees with other macroscopic thermodynamically-interacting wetware about the perception of macroscopic systems. Quantum field theory absolutely controls the processes that make your brain work; but the rules of quantum mechanics appear to tell us why large thermal systems such as ourselves do not notice such quantum effects (though there remain fascinating questions about how wavefunction collapse occurs, assuming that it does at all).

As a physicist, it can be very frustrating watching people taking pop-sci explanations of very interesting physics as the starting point to build a philosophy about how to live life. All that physics tells us is that the Universe is a staggeringly complex place, and humanity is a very small and very fragile part of it. What you do with that information is not something my field can tell you (though to me it suggests that "try not to be an asshole to the other fragile tiny bits of the Universe that you share this tiny world with." But that's just me).
posted by physicsmatt at 6:50 AM on March 15, 2019 [14 favorites]

I think most people would agree that the word "reality" means something like "all the things that are real".

I agree with that except for the part about breaking it up into things, which to my way of thinking is just a way to ruin a perfectly good tautology.

Quantum field theory absolutely controls the processes that make your brain work

I prefer the view that my brain just does whatever it does, but that quantum field theory is capable of providing exceedingly useful and accurate predictions about what any given piece of it is about to do if the inquiry is restricted to a small enough scale to make the predictive calculations feasible; and in particular that if I think I have some explanation for fine-scale brain processes that's not compatible with quantum field theory, or can provide more accurate predictions or better insights into structure than quantum field theory can, I'm almost certainly wrong.

In other words, I would be astonished to learn that there is anything going on in my brain at the scales to which quantum field theory is applicable that any other extant theory, physical or otherwise, could produce better predictions about. That said, I see no value in the view that any theory "controls the processes" going on in my brain, except to the extent that I might at some point be thinking about some such theory. Conforming to and controlling by are two quite different things, to my way of thinking.

I don't have the mathematical chops to grok quantum field theory in its fullness, but I've long suspected that what it amounts to is a codification of the consequences of the fact that the only constraint on reality is that of its own ongoing existence. It pleases me to believe that there are literally incalculable amounts of cancelling-out going on always and everywhere, and that what we inhabit is just exactly that insanely minuscule fraction of all that could be that actually manages to keep on being.
posted by flabdablet at 7:24 AM on March 15, 2019 [1 favorite]

when you go around telling people that maps are this and that, and then extrapolate that to some sociological point

If that's directed at me, could you point out the place where I'm alleged to have extrapolated the idea of inherently private conceptual maps to make a sociological point? Because I don't recall trying to do that, and I'm having trouble seeing where I'm supposed to have done it.
posted by flabdablet at 7:47 AM on March 15, 2019

From the internet:

Relativism is the belief that there's no absolute truth, only the truths that a particular individual or culture happen to believe.

Well, it's a belief, so best taking on as a hypothesis, as opposed to some kind of verifiable theory. I suppose it may be true. I also suppose it may not be true. That is, who the f*** knows what constitutes absolute truth, and how could you prove it or disprove it anyway? It's not just beyond our comprehension. It's beyond our ability to comprehend beginning to comprehend comprehending. Or as physicsmatt just put it:

All that physics tells us is that the Universe is a staggeringly complex place, and humanity is a very small and very fragile part of it. What you do with that information is not something my field can tell you

Back to that internet info:

If you believe in relativism, then you think different people can have different views about what's moral and immoral.

I may not believe in relativism, but I definitely believe this.
posted by philip-random at 8:00 AM on March 15, 2019

omg it worked! welcome back plz never leave us again
posted by lazaruslong at 1:03 PM on March 15, 2019 [2 favorites]

Guys, it's okay to say you don't understand quantum mechanics and leave it at that. I don't understand why QM always leads to unrelated discussions of weird philosophical stuff.
posted by runcibleshaw at 7:53 AM on March 16, 2019 [1 favorite]

I think because those of us who don't know the math (and I am very in this category) have only ever heard it discussed in terms of weird philosophical stuff.

It's only fairly recently that I learned there was a specific way of dealing with things mathematically that set quantum mechanics apart from earlier kinds of physics — and I still don't really understand what it is. For my whole life, any time a teacher (even a science teacher, even at a fancy college!) or a journalist (even a science journalist! even in a publication that assumed pretty high science literacy!) has talked to me about quantum mechanics, it's been in terms of woo-woo bad-Sci-Fi-style philosophical paradoxes.

So like, one dumb joke aside I've been sitting this conversation out, because it's recently been pointed out to me that there's a bunch of math here that I don't know and that I sound like a dingus when I ignore it. But if it wasn't for that one friend mercifully setting me straight, yeah, no, I'd be following the lead of every teacher and every nonspecialist writer I've ever seen discuss this stuff.
posted by nebulawindphone at 11:39 AM on March 16, 2019

Rereading my last comment and I should clarify. QM does bring up some real weird philosophical stuff by its very nature. The results of QM are counterintuitive to our normal experience of reality. I just don't understand how we get to morals from the outcome of experiments being countierintuitive.

And I do understand some of the (basic) math of QM (though it's been a while), but I would never claim to know what it means for the nature of reality. Though I do like multiple worlds because you get some fun sci-fi stories.
posted by runcibleshaw at 3:16 PM on March 16, 2019

Which parts of quantum mechanics as a physical theory (rather than as an excuse to pontificate about philosophy) are you most confused by? I will self-promote one of my essays on the nature of quantum field theory here, though I realize that for some reason, discussing quantum field theory tends to cause fewer brain-exploding moments than quantum mechanics does. Or, at least, it causes different brain explosions.
posted by physicsmatt at 5:33 PM on March 17, 2019 [2 favorites]

I think you're old enough to know the truth about quantum mechanics.
posted by signal at 7:14 PM on March 17, 2019 [4 favorites]

Hah! I'm in a grad-level seminar on Cognitive Neruoscience and Machine Intelligence / AI and one of my colleagues is preparing his presentation and research paper on quantum computing. Immediately sent him that comic, only to get a reply reminding me that he already mentioned he's reading Scott Aaronson's book to prep for the assignment. That comic is great.
posted by lazaruslong at 12:54 PM on March 18, 2019

Some short reactions from physicists and philosophers

Suppose, in other words, one were dead-set on maintaining that the physical world is local in the face of all the experimental evidence that it isn’t. How might that be done?

It seems rather desperate but I suppose one might go so far as denying the very existence of any objective physical reality at all. Or, as I sometimes put it, “Nothing really exists, but thank God it is local”. But as should be obvious, this accomplishes nothing. If there is no objective physical world then there is no subject matter for physics, and no resources to account for the outcomes of experiments.

posted by vibratory manner of working at 1:34 PM on March 21, 2019 [3 favorites]

Best comment ever:

Thank you for attending this session of “a person transparently promotes their own preferred interpretation of quantum mechanics in the comment section, because most everyone in the original post was doing the same thing”.

posted by flabdablet at 8:19 PM on March 21, 2019 [2 favorites]