that some properties by their very nature must take determinate values or not exist at all

This is not a scientific principle. Science lives or dies only on the accuracy of its predictions - probabilistic or deterministic. Don't be confused by the fact that pre-quantum, pre-thermodynamics laws were deterministic - that was just a lucky fact, that persuaded people that all laws had to be the same.

As for the "some properties", quantum mechanics asserts (and experiments back it up) that there is no such thing as position, or momentum - that the combination of the two is the actual property that exists.

As for the different interpretations of quantum mechanics - they're all equivalent, or they differ in ways we can't measure yet. So none of them on their own say anything about how we should view reality. Only the predictions of quantum mechanics tell us about reality, not the models.

Actually, I don't think I agree with the thrust of this post. As long as you don't argue "this is weird, hence it is wrong", I think the if you find quantum mechanics strange you're more likely to prosper in the field that if you force your sense of normality to match quantum reality.

In the first case, you can easily discover a new physical law, find it weird, and cheerfully accept it. In the second case, a new law may be an assault on your feeling of reality, so you may be less willing to accept it - and if you did, you'd have to go through the whole process of updating your instincts again.

People can develop very good intuition about things they find strange, without having to find them any less strange.

Eliezer,

What is ironic about this posting is your indignation. Offhand it sounds like you are as guilty as those you criticize.

There is nothing weird about people finding a theory to be weird that does not correspond with their everyday surface perceptions, even when they are able to comprehend it intellectually. Also, and others have noted this more or less, there are a lot of different interpretations out there of what quantum physics "really means," and some are a lot weirder than others. Is it ontological that Schrodinger's Cat does not ei... (read more)

Wow, great post. Seriously.

In actuality, the biggest barrier to understanding modern physics is the math. The math models are what generate the "weirdness". Trying to use english to describe what the math models are telling us is what generates the "weirdness".

But if you suspend disbelief and go where the math takes you, useful things can be done, like nuclear power, solid state physics, etc.

This is one of the worst posts I've read here.

If you truly think "This person will never understand physics no matter how many books they read." then you are making great assumptions based on your personal prejudices.

If you don't find quantum physics weird (or at least understand why someone may), you don't have a grasp on current human intuition. Just because you recognize that quantum physics differs from everyday experience doesn't mean you can't understand quantum physics. It actually means you have a BETTER grasp on understanding human intuition, and has no bearing on whether you know (or have the capability of knowing) less or more about quantum physics.

Another way of looking at this is to realize that we are all pretty much hard wired to operate in a surface reality that more or less fits a Newtonian-Euclidean model of the world. We now know that this does not hold at high accelerations or at very large or very small scales in a lot of ways. So, these deviations, many of which have been clearly established beyong any doubt, seem weird to most people when they first hear of them, and may even still "feel weird" even after they have long come to intellectually comprehend and accept them.

Heck, e... (read more)

Are there data on how many physicists believe in astrology? I can understand how a few would, but I'd be astonished if the percentage weren't a lot lower than for Americans as a whole. Hey, there are PhD biologists who reject evolution--but not many.

If Richard Feynman can say:

What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school... It is my task to convince you not to turn away because you don't understand it. You see my physics students don't understand it. ... That is because I don't understand it. Nobody does.

then it may be strange to the point of being beyond understanding.

(Nobel Lecture, 1966, The Strange Theory of Light and Matter)

This is a great post. I just want to add: we might fail to understand physics and mass murderers for different reasons. When a terrorist slams a jet into a skyscraper, someone can say "I don't understand why that person did that? It's bizarre." But they seem to fail in understand because victims have a biased recall of transgressions (according to the work by Baumeister on the myth of pure evil). Perpetrators seem to actually have more accurate and complete understandings of transgressions. This is one of my favorite findings from social science.

In contrast, we seem to think physics is bizarre for different reasons.

Questions like "How are amplitudes converted to subjective probabilities?" are not automatically dictated by the theory

You might find this paper by David Deutsch interesting. Although, equation 14 bugs me, it seems to me |Psi_2> as defined doesn't necessarily exist.

as if it made sense to say of a particle that it has a position, but no particular position

That might or might not make sense (mathematicians have been tearing their hair out about non-computable numbers, see Chaitin's constant). But most quantum mechanists do not say that a particle has a position. In fact if you interpret Quantum mechanics in terms of "hidden variables" (there are underlying values for the objects, like spin and momentum, but we can't get at them) then you will generally come unstuck.

Can you explain to me the exact nature of th... (read more)

And so, like kudzu, the thread is taken over by the Great Quantum Debate... but Mitch, do you agree with the central point of the original post, that true facts cannot be "weird" or "bizarre" except insofar as we think like primates and not like reality? That we are always faced with a dilemma to eventually discard either the mistaken intuition or the mistaken fact?

As to your quantum-question: as I understand it, the presences of particle species at particular locations are the dimensions of the configuration space, points within which... (read more)

Eliezer, If a theory seems bizarre to your intuitions, then either the theory is wrong or your intuitions need reshaping.

I'm leaning towards embracing your point more, but still two issues: 1) "need". If my intuition tell me something, but I know it's wrong, and I can deal with it without letting my intuition interfere, why do I need to reshape my intuition - shouldn't I just go with "don't trust my intuition"? 2) As a mathematician, I have good mathematical intuition. It helped me when I took a course on quantum mechanics and relativit... (read more)

There is an interesting critique of MWI here that I just finished reading. An fascinating topic to be sure. . .

Matthew C: My criticisms of Kent's criticisms of MWI (as formulated by Everett), in the paper you link to:

A Hilbert space has an inner product by definition, so mu is already an entity of the theory without needing any extra postulates.

In the example given, decoherence will result in the two terms of the RHS of (2) not being able to interfere with one another, which justifies considering them to be independent worlds, no intuition required.

Kent's talk about bases seems confused, the dimensionality of a basis is fixed by the dimensionality of the state spac... (read more)

I think it's unfortunate that this thread has veered off into debates about the inner workings of quantum theory and indignant defenses of what is and is not known in physics. Eliezer used quantum mechanics as an example to illustrate a larger point which has scarcely been mentioned here, a point which connects very clearly to the name of this blog -- Overcoming Bias, and yet everyone seems more interested in the metaphor than what it represents; they are mistaking the map for the terrain, as Eliezer might say =)

As I understand it, Eliezer is making a point about how short-sighted and self-centered it is to label a phenomena "weird". To call something weird is, in essence, identifying it as an outlier in our (woefully limited) data set of experiences. As Eliezer points out, this is a shortcoming of our model and not an inherent “eccentricity” in reality. Now I believe that being surprised is completely natural and in fact unavoidable, but what I believe Eliezer is really railing against is how fixated people can become with the “weirdness” of a universe which refuses to conform to our simple models and heuristics.

In cognitive psychology, there is a theory of cognitive gro... (read more)

You write: "There are no surprising facts, only models that are surprised by facts."

That's deterministic thinking. Surprising facts happen every once in awhile. Rarely, but occasionally.

But I agree with your general point. Surprise is an indication that you have a problem with your model, or that you have prior information that you have not included in your model.

but Mitch, do you agree with the central point of the original post, that true facts cannot be "weird" or "bizarre" except insofar as we think like primates and not like reality? That we are always faced with a dilemma to eventually discard either the mistaken intuition or the mistaken fact?

The reality is that possibilities are very large in number and actual knowledge is shockingly small. To genuinely "think like reality" might mean to maintain as constant and thorough an awareness as possible of every uncertainty in your exi... (read more)

Mitchell,

Have you heard of the Pondicherry interpretation of QM?

I had, but I had the wrong idea about it. At a glance, Mohrhoff's ontology appears to be as follows. There is a fundamental reality which is standard-issue Formless Infinite Oneness, and then there is a multiplicity of elementary physical facts ('observables' taking definite values) out of which everything physical is made. Every single one of those facts is utterly uncaused, both with respect to location in space and time, and the specific value taken. But quantum mechanics gives us the probabilities.

I do not, so far, see anything illuminating in what he ... (read more)

Mitchell,

What I find particularly interesting reading his papers is his emphasis that space and time are features of the macroscopic world, and don't go "all the way down".

They seem absolute and real to us because of our evolutionary psychology and especially the "space and time" orientation of the visual maps in our brains. He contrasts his view with interpretations which postulate an infinitely sliced spatial manifold which is fundamentally real, but cannot be measured at the finest scales. I'm assuming by that he is referring to MW... (read more)

interpretations which postulate an infinitely sliced spatial manifold which is fundamentally real

Strictly speaking, I suppose that is part of the interpretation, but it's a pretty mild part of the interpretation of QM, or at least QFT. Many people expect that this to stop being true in a unification with GR, but that's about physical law, not interpretation.

Wow...intellectual elitism turned sour and venomous. Your indignation is palpable and, frankly, quite off-putting. I'm not sure what the point of this post is....we should watch our syntax when we express awe?

Christopher,

Who else has the guts to talk to the audience like this? And hasn't your ratio of surprises gone down as you've learned more about the world?

The flagrant breaking of rule #12 in this post is one of the things that really makes it priceless. The other is just that it makes a valid point.

I agree with James Somers. Best post on this blog I've read so far. Best short writing that I've read in a while anywhere, Eliezer.

I see the point of the post, but it's too harsh. Naive physics (like folk etymology) is important, a facet of the human mind worth studying and paying attention to. It should be overcome, but it can't be replaced by some higher form of intuition. No one can force themselves (him/herself?) to intuit quantum physics. Naive physics can and should be superseded by real physics, but our original intuitions remain intact. The two forms of understanding can live side by side, each with its proper function. Reminded me of a recent piece by Chomsky. Excerpt:

De

I see the point of the post, but it's too harsh. Naive physics (like folk etymology) is important, a feature of the human mind deserving of study. It is indeed the case that some beliefs arising from intuition should be overcome, but they can't be replaced by some higher form of intuition (no one can force himself to intuit quantum physics). Naive physics can and should be superseded by real physics, but our original intuitions remain intact. The two forms of understanding can live side by side, each with its proper function. See this recent piece by Chomsky, about (among other things) how we've been forced to believe in apparent "absurdities" since Newton.

This post makes a valuable point, but the point is weakened by too much hyperbole -- or rather by hyberbole that seems like a plausible non-hyperbolic statement that the writer might actually believe.

Whenever I hear someone describe quantum physics as "weird" - whenever I hear someone bewailing the mysterious effects of observation on the observed, or the bizarre existence of nonlocal correlations, or the incredible impossibility of knowing position and momentum at the same time - then I think to myself: This person will never understand physics... (read more)

Don't confuse scientific models with truth or reality.

Quantum mechanics, relativity, Newtonian and Aristotilian dynamics are all models that, in certain situations, do a good job of predicting reality. Light is not a probabilistic model any more than it is a particle or a wave. It is light and every way we currently have of understanding is an inperfect model -- even if we don't understand just how it's imperfect yet. If the history of science has taught us anything, it's that.

I think the real issue here is not that it is unacceptable to perceive real phenomena as weird or bizarre, but that it is unacceptable to think that something real ought not be so (based on some model of reality) and continue without updating the model or understanding why the weirdness or bizarreness leaks in.

To pick on C.S. Lewis and the religious in particular, Lewis conflates many times the Laws of Nature with the 'Laws' of Morality. Laws of nature cannot be broken; those of morality most definitely can be and are. And perhaps as another facet of the n... (read more)

Sometimes people use words like "bizarre", "incredible", "unbelievable", "unexpected", "strange", "anomalous", or "weird" to mean "counterintuitive". Is that really all that different from noticing that you're confused but not yet deciding whether your model is at fault or your perception of the new information is? When you hear about something that seems like it's at odds with everything you've ever observed, saying that it's "unexpected" at the very least is truthful, isn't it? Whether or not you intend to investigate further and integrate it (or not) into your map is another matter.

“That’s weird” is a colloquialism for “I notice that I am confused.” Saying so is an important intermediate step towards understanding... or so I’ve heard. Once you understand, then weirdness is a non-issue -- you are no longer confused.

Yes, quantum mechanics is weird. It violates my intuitions, and the intuitions of (nearly?) every human. No, we can't rewrite our intuitions, and knowing quantum mechanics is weird is important because if it wasn't weird we might think we didn't have to shut up and integrate. I won't simply accept that reality is weird just because a scientific theory like quantum mechanics implies it is. Especially since there is such a good chance of quantum mechanics being wrong -- since it clashes with General Relativity. I can't say that the successor to quantum-GR wi... (read more)

Well, speaking your own language, the reality is supposedly not "weird", but nothing prevents a good map of reality to be still weird. There were a lot of moments in development of science when the current, working picture looked weird, until a deeper understanding came. Take, say the expression of quantum basics given by people who failed to "shut up" http://lesswrong.com/lw/q5/quantum_nonrealism/ or just how it was at sufficiently young state. It was the physics of that time (not a reality) and as we agree now it is weird.

So what do... (read more)

"What many people refer to as common sense is nothing more than a collection of prejudices accumulated before the age of eighteen." -- Einstein (first quote I ever memorized, at age nine)

Actual physical reality is "out there" somewhere, and quantum mechanics is a map we use to find our way around parts of it. Often in physics two maps can be identical in their predictions, but differ substantially in the presentation. Hilbert-space quantum mechanics gives us a presentation of complex amplitudes in configuration space. Phase space quantum mechanics is mathematically equivalent, but the presentation is in terms of (possibly negative) probability fields in "real" x,y,z,px,py,pz,t phase space.

Quantum mechanics does indeed model some real measu... (read more)

Surprise exists in the map, not in the territory.

Surprise exists in the territory because the territory contains the map.