Pilot-wave theory “seems to me so natural and simple..."
December 14, 2014 6:26 AM   Subscribe

This idea that nature is inherently probabilistic — that particles have no hard properties, only likelihoods, until they are observed — is directly implied by the standard equations of quantum mechanics. But now a set of surprising experiments with fluids has revived old skepticism about that worldview. The bizarre results are fueling interest in an almost forgotten version of quantum mechanics, one that never gave up the idea of a single, concrete reality.

The experiments involve an oil droplet that bounces along the surface of a liquid. The droplet gently sloshes the liquid with every bounce. At the same time, ripples from past bounces affect its course. The droplet’s interaction with its own ripples, which form what’s known as a pilot wave, causes it to exhibit behaviors previously thought to be peculiar to elementary particles — including behaviors seen as evidence that these particles are spread through space like waves, without any specific location, until they are measured.

Particles at the quantum scale seem to do things that human-scale objects do not do. They can tunnel through barriers, spontaneously arise or annihilate, and occupy discrete energy levels. This new body of research reveals that oil droplets, when guided by pilot waves, also exhibit these quantum-like features.
posted by Elementary Penguin (103 comments total) 68 users marked this as a favorite
 
The territory is not the map. Light is light, a mapping to different kinds of observations is either a particle or a wave. "This idea that nature is inherently probabilistic " this thought is wrong in a subversive way, the longer phrase is something like - we can make excellent predictions about nature using probabilistic methods. So there certainly can be a new and slightly improved map, perhaps that is what the article should be about?
posted by sammyo at 6:40 AM on December 14, 2014 [9 favorites]


"This idea that nature is inherently probabilistic " this thought is wrong in a subversive way, the longer phrase is something like - we can make excellent predictions about nature using probabilistic methods

I'm no physicist, so I'm not going to opine on the rightness or wrongness of the claim; but I can say that there are plenty of physicists and plenty of quantum-physics inspired philosophers who have insisted categorically that what quantum physics reveals to us is a universe that is inherently probabilistic. That is, indeed, precisely what lies at the heart of Einstein's famous objection that "God does not play dice with the universe." So no, it's not just a claim that probabilistic methods make excellent predictions (though there are those who restrict themselves to that claim); there have also been claims that the map had to be probabilistic because the territory was as well.
posted by yoink at 6:45 AM on December 14, 2014 [16 favorites]


I don't understand any of this, so just tell me this: warp drive, transporters, and replicators?
posted by If only I had a penguin... at 6:49 AM on December 14, 2014 [12 favorites]


Physics noob here, but I thought one of the major issues with the Pilot Wave idea was that there was no medium for the wave (as the aether was disproved a long while back). But huh ? what do I know.
posted by parki at 6:54 AM on December 14, 2014


Yeah exactly I was going to ask just what a pilot wave is. The article defines it as "the droplet’s interaction with its own ripples," but what does that actually mean? How is it measured, and what would it mean to disrupt it by, say, observing it?

And the double slit experiments, as the article also mentions in a caption, have been done with single particles, which also seem to pass through both slits at once. What's the analogous situation for a pilot wave, and has that been demonstrated? Wouldn't a droplet have to travel through both slits at once?
posted by shivohum at 6:57 AM on December 14, 2014 [1 favorite]


I apologize for not being able to link to actual papers, which could probably answer some of these questions.
posted by Elementary Penguin at 6:59 AM on December 14, 2014 [1 favorite]


Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo.
posted by leotrotsky at 7:02 AM on December 14, 2014 [1 favorite]


one of the major issues with the Pilot Wave idea was that there was no medium for the wave

I noticed this in the article: "if space and time behave like a superfluid, or a fluid that experiences no dissipation at all" -- so I guess that's the proposed medium.
posted by shivohum at 7:13 AM on December 14, 2014 [1 favorite]


Here comes the aether again!
posted by Devonian at 7:17 AM on December 14, 2014 [6 favorites]


♫ Carryin' my waves like a tragedy ♫
posted by Songdog at 7:24 AM on December 14, 2014 [14 favorites]


paging physicsmatt....
posted by lalochezia at 7:31 AM on December 14, 2014 [8 favorites]


It's twenty years since I studied this stuff seriously (I still have Bohm's book, "Causality and Chance in Modern Physics" somewhere), but there's nothing woo about his pilot wave ideas. The main problem he has is that the Copenhagen interpretation is "good enough" to get on and get things done as a physicist & most working physicists are too busy getting on with doing science to worry too much about the phillosophical holes that may or may not underlie the theories they use every day. My understanding is that pilot wave based theories, which are non-local & so don't fall into the trap of violating Bell's inequality, make the same predictions that "standard" QM does, which makes them impossible to test.

(Also, electromagnetic waves don't require an aether, yet manage to wave themselves about the place perfectly happily - these are not aethiric theories.)
posted by pharm at 7:31 AM on December 14, 2014 [18 favorites]


I, in no way can speak to the validity of the theory, but it seems at least plausible and in doing some minor poking around I ran across this in Wikipedia regarding the 1952 Bohm paper:
According to physicist Max Dresden, when Bohm's theory was presented at the Institute for Advanced Study in Princeton, many of the objections were ad hominem, focusing on Bohm's sympathy with communists as exemplified by his refusal to give testimony to the House Un-American Activities Committee.
That coupled with a lot of stuff like "too-cheap" [not] realist "superfluous 'ideological superstructure'", "artificial metaphysics" instead of actually addressing the theory gives me slight pause to wonder if Pauli, Einstein, Heisenberg et al where falling into the classic trap of once having shaken stuff up themselves they where now defending orthodoxy and how things are done.

I'm not really defending Broglie–Bohm over the Copenhagen interpretation but it does seem it's worth careful examination with the possibility things may have been wrong in the past.
posted by edgeways at 7:50 AM on December 14, 2014 [4 favorites]


The particle in pilot wave theory only goes through one slit or the other, but the wave goes through both, which ends up jostling the particle around so it only ends up in interference bands.
posted by empath at 7:58 AM on December 14, 2014 [4 favorites]


Bohm's pilot wave approach is not inherently woo. It's neat that these experiments are providing a physical model for the approach but that does not really mean it's become more promising as a research avenue. Last I looked, the Bohm approach was an equivalent description of single particle quantum mechanics, but there isn't a unique extension to quantum field theory, and some of those extensions have problems. There are many, many completely equivalent ways to view QM (the relative state or many-world interpretation, the Copenhagen interpretation which is often more of a non-interpretation of shut up and calculate, the consistent histories interpretation, non-standard logics, objective state reduction, etc.)
posted by Schmucko at 7:58 AM on December 14, 2014 [1 favorite]


Quantum field theory, as I understand it is the fundamentals behind 'quantum theory' and if you think of things as fields and interactions with other fields and interactions propagating as waves with a frequency and and an amplitude - it seems fairly easy to visualize the pilot wave metaphor.
posted by sfts2 at 8:07 AM on December 14, 2014


Sounds like Eddy's in the space-time continuum again.
posted by quinndexter at 8:09 AM on December 14, 2014 [15 favorites]


Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo.

Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo-onderful mathematics.
posted by ennui.bz at 8:21 AM on December 14, 2014 [2 favorites]


I am amazed at the extent to which which "fashion" and "indoctrination" appear to have influenced the outcome of the debate so far. (If the article is to be believed.) Once again it becomes clear to me that science really is a human endeavor.
posted by vorpal bunny at 8:26 AM on December 14, 2014 [1 favorite]


Physics noob here, but I thought one of the major issues with the Pilot Wave idea was that there was no medium for the wave (as the aether was disproved a long while back). But huh ? what do I know.

I ain't know shit about shit, but even without an ethereal medium, particles have magnetism and gravity (right?), so maybe the waves are in those, kinda?

Gotta say, as a person who ain't know shit about shit, that magic teleporting particle theory has always seemed super ridiculous.
posted by Sys Rq at 8:34 AM on December 14, 2014



The particle in pilot wave theory only goes through one slit or the other, but the wave goes through both, which ends up jostling the particle around so it only ends up in interference bands.

but what is the wave and what is it going through?
posted by MisantropicPainforest at 8:39 AM on December 14, 2014


but what is the wave

An electromagnetic wave which needs to carrying medium.

and what is it going through?

The slits in the two-slit experiment.
posted by cthuljew at 8:52 AM on December 14, 2014 [1 favorite]


The wave is a quanta of energy travelling through spacetime.

The route is a groove carved or allowed by the electromagnetic and gravitational forces that govern the large scale cosmos. I posit that galaxies are locally held together by gravity which nobody disputes [much] but furthermore that galaxies become increasingly positively charged over time as more and more of their electron content is converted into "free" energy in the form of light. Galaxies expand and stretch the fabric of space on a massive scale and create enormous electromagnetic "grooves" and routes on a trans-galactic scale much like the field emitted by the Earth.

In 4D curved space light travels on a continuous path so long as gravity doesn't bend it back on itself into a death spiral as in the case of a black hole but we forget the role of magnetism in simple gravitational models. My theory is that galaxies are becoming increasingly "positive" and dark energy is simply the repulsive force of mega gigantic galaxies exerting electromagnetism in aggregate. There is no liquid ether medium but there are forces acting outward that stretch the invisible fabric of space time outward. The fabric isn't real matter or liquid, but the textural grooves we perceive are carved out by electromagnetic force like when you put a magnet under a piece of paper and drop iron filings on top.
posted by aydeejones at 8:55 AM on December 14, 2014 [2 favorites]


> Once again it becomes clear to me that science really is a human endeavor.

I don't think people chatting about science on Metafilter is really "doing science". And calling science a "human endeavor" is pretty vacuous - "a thing people do".

If you are implying, "Scientific truth depends primarily on fashion and indoctrination," then I'm going to have to disagree.

> Gotta say, as a person who ain't know shit about shit, that magic teleporting particle theory has always seemed super ridiculous.

People didn't just make these up to be clever! The observations that prompts these theories are also "super ridiculous" - and you could easily set up experiments in your own living room for not-so-much money that would show you particles teleporting and being in two places at once and all sorts of other ridiculous things.

And you're almost certainly sitting in a room filled with LEDs and microprocessors and other such contraptions whose basic construction is informed from start to finish by that same "super ridiculous" physics.

The nice thing about science is that you can look at all these observations yourself and come up with your own better theories - or at least understand why physicists felt forced to accept theories that are counter-intuitive.


My issue with what I understand of the pilot wave theory is that it doesn't seem to make any testable predictions. From what I've gathered, the argument is, "This physical system seems to have the same mathematics as quantum mechanics, and if so, they must have the same mechanism," and if I'm characterizing it correctly, my rebuttal would be, "Does not follow."

And my other issue is that this seems to be a local hidden variable theory - basically, a theory where there's some magic numbers "written down" that we cannot directly observe but actually account for the results. In this case, the "height of the pilot wave at each point" is the hidden variable. If you say, "Well, but your behavior at each point involves effects from the pilot wave at all other points, so it's non-local" aren't we back to non-locality and spooky action-at-a-distance?

Re-reading, I guess what I'm really saying is that I don't understand what the difference between this and standard quantum mechanics really is, other than a change of name.
posted by lupus_yonderboy at 8:56 AM on December 14, 2014 [13 favorites]


we forget the role of magnetism in simple gravitational models

I forgot to add, because the effect of magnetism on a light seems to be neglible or non-existent being that light carries no charge, but we know for a fact that the path of radiation is affected by massive magnetic fields when radiation comes crashing towards our atmosphere. The baryonic matter in the atmosphere itself does a handy job of colliding with radiation but there's a significant amount of "deflection" that goes on as you approach a heavily active electromagnetic body, but what we're more accustomed to observing is the emanation of light outward from such bodies.

What I'm saying is on the "woo line" but if any of it is novel, like supermassive black holes and Hawking radiation were decades ago, you read the novel parts here first...heh heh
posted by aydeejones at 9:00 AM on December 14, 2014


lupus_yonderboy: It's not a new theory in the sense that a theory is a mathematical characterization of data which explains previous results and makes new testable predictions. Just like the Copenhagen Interpretation, it's an interpretation of quantum mechanical theory. Copenhagen is essentially Bohr's assertion that, hey, we got our results, they're counter-intuitive, but they work, so let's not worry about it. However, what if there is actually a classical view you can take on the behavior of quantum particles that fits all the same math? Wouldn't that be a vastly preferable view of the world to one that essentially throws our hands up at a counter-intuitive result?
posted by cthuljew at 9:05 AM on December 14, 2014 [4 favorites]


Re-reading, I guess what I'm really saying is that I don't understand what the difference between this and standard quantum mechanics really is, other than a change of name.

I believe the take-away was that we should be modeling space-time as a super-fluid... which is apparently a thing:

http://front.math.ucdavis.edu/0407.4433

http://www.nature.com/news/superfluid-spacetime-points-to-unification-of-physics-1.15437

http://phys.org/news/2014-04-liquid-spacetime-slippery-superfluid.html

I wish the journalist had gotten into this rather than getting sucked into the decades long debate over whether Bohmian mechanics is a legitimate scientific theory.
posted by ennui.bz at 9:11 AM on December 14, 2014 [1 favorite]


Lupus_yonderboy: the pilot wave is explicitly non-local, unless my memory has completely failed me.
posted by pharm at 9:13 AM on December 14, 2014 [2 favorites]


> However, what if there is actually a classical view you can take on the behavior of quantum particles that fits all the same math? Wouldn't that be a vastly preferable view of the world to one that essentially throws our hands up at a counter-intuitive result?

But I don't see that this view is any different or any more intuitive. The magic is still there, the results of the Bell test experiments are as valid as ever. The magic is simply sloughed off onto "the pilot wave" - it's still a non-local theory, it still has "spooky action-at-a-distance" but now "the pilot wave" is the medium that does all that instantaneous accounting for you.

On preview, the idea of spacetime as a "superfluid" seems fascinating, if beyond me (the math in the actual papers seems very hard). But that wouldn't fix the magic either - it'd just give it better mathematics. (The superfluid thing, from my super-limited-understanding, might well be a testable theory, which would make it a real, better theory in my book...)
posted by lupus_yonderboy at 9:16 AM on December 14, 2014 [2 favorites]


there have also been claims that the map had to be probabilistic because the territory was as well.

I need to flip a coin before deciding whether to classify claims like that as either tautologous or oxymoronic.
posted by flabdablet at 9:45 AM on December 14, 2014


that particles have no hard properties, only likelihoods, until they are observed — is directly implied by the standard equations of quantum mechanics. But now a set of surprising experiments with fluids has revived old skepticism about that worldview. The bizarre results are fueling interest in an almost forgotten version of quantum mechanics, one that never gave up the idea of a single, concrete reality.

So are we throwing out the Heisenberg out with the bathwater, then?
posted by hal_c_on at 9:50 AM on December 14, 2014


... So what we're saying is that Kirk should have captured Pilot whales instead of humpback whales?
posted by jefflowrey at 9:54 AM on December 14, 2014 [2 favorites]


It is very important for laypeople to understand that this is not a debate about the truth of quantum mechanics. QM has been richly proven in experiment, and its proof can be seen in the modern technology that surrounds us.

So far, this is a philosophical debate about how to "interpret" QM, not about experimental predictions. Pilot wave theory has not made any new predictions, at least no predictions that differ from the other interpretations of QM.




Disclaimer: I never studied Bohmian mechanics because, as the article says, it is a fairly neglected interpretation of quantum mechanics.
posted by Salvor Hardin at 10:02 AM on December 14, 2014 [3 favorites]


Bell's inequality says that, within the constraints of quantum mechanics, either realism or locality must be false. Realism here means that particles have defined properties prior to measurement, as opposed to many interpretations of QM, where a particle exists in a superposition of states that only collapses at the point of measurement. Locality means that particles can only interact in a direct, local manner, and thus two particles separated by a large distance cannot exchange information any faster than the speed of light. Realism and locality are both intuitive concepts that the macroscopic world appears to follow, but according to Bell's inequality, at least one of them does not hold on the quantum scale. There is a lot of disagreement about what exactly this means.

The pilot-wave theory keeps realism and does away with locality. A lot of physicists dislike this idea because hidden variables cannot be experimentally verified or accounted for within the rules of QM, and because nonlocality has the potential to allow for highly problematic phenomena, such as faster-than-light communication.

For what it's worth, Bell himself advocated for the de Broglie–Bohm theory, which is a precursor to the pilot -wave theory.
posted by dephlogisticated at 10:09 AM on December 14, 2014 [10 favorites]


I'm curious what the implications of pilot-wave theory are for quantum computing. My simple dilettante's understanding is that quantum computing requires a probabilistic model of quantum particles, in order for its first principles to hold. If a quantum particle always has one specific, deterministic state, as in the the droplet experiments, then it would not be superpositioned, and therefore a qbit would not hold multiple values at once.

Basically, I'm having trouble reconciling this with the argument that the deterministic and probabilistic models are different explanations for the same results. I can see how that's true for the slit experiment, where scientists are just observing a counter-intuitive behaviour. But when it comes to harnessing the counter-intuitive behaviour for specific ends, wouldn't the question of deterministic vs probabilistic have significant ramifications?

What am I missing here?
posted by Banknote of the year at 10:14 AM on December 14, 2014 [1 favorite]


lalochezia: "paging physicsmatt...."

♫ Paging physicsmatt for an explanation ♫
(FTFY)
posted by symbioid at 10:16 AM on December 14, 2014 [1 favorite]


Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo.--leotrotsky

You make that sound like crazy talk, but we use Soliton waves in long distance communications.

One of the reasons I like engineering over physics or mathematics is that usually there is no peer review, politics or drama--as long as it works. People can call it names all they want, but all it has to do is work and people will pay you for it.
posted by eye of newt at 10:18 AM on December 14, 2014 [5 favorites]


As I understand it, the pilot wave "explores" all possible alternative states, whereas the particle itself remains in only one state at any given moment. So in a quantum computer, the pilot waves of the qubits would pull the computational weight, ultimately steering the particles to the state representing the correct answer.
posted by dephlogisticated at 10:21 AM on December 14, 2014 [2 favorites]


Another noob here,

1. How are the first ripples (that lead to the formation of the pilot wave by interacting with the particle) set up? I think I understand the oil drop example. But, in there, the drop (particle) is able to interact with the wave because of the differences in the direction of travel, right? The drop moves along a more "bouncy" trajectory which gives time for the first wave to be set up and interact with the particle during its second bounce. Is this the same for light as well?

2. Was ether rejected prematurely? It is now, well accepted that gravity bends spacetime and influences the path/motion of particles. Does this spacetime not (for all practical purposes) fulfil the expected medium requirements?
posted by asra at 10:22 AM on December 14, 2014


I'm not actually disputing this whole pilot wave business but you have to admit that there's something inherently humorous about the statement:

Many of the fluid dynamicists ... have become convinced that there is a classical, fluid explanation of quantum mechanics.
posted by nicolas.bray at 10:24 AM on December 14, 2014 [6 favorites]


Quantum field theory is not just another phrase for quantum mechanics with the wave function as the probability field of a single particle. And pilot-wave theory may have problems being extended to quantum field theory. Quantum field theory enters in at a stage sometimes called "second quantization". It is the extension of quantum theory to talk statistically about many particles and their interactions. It involves the creation and annihilation of particles. When you start talking about multiple indistiguishable particles, you have to talk about what happens if you change their labeling: all probabilities have to stay the same, but that still allows the wave function to change algebraic sign. (If you exchange 2 particles twice, you have to get back to where you started, so you use both square roots of 1 to find what the "operator" of single exchange does, and the result is to multiply the wave function by either +1 or -1.) Those two possibilities are fermions (exchange changes sign of the wave function) and bosons (exchange does not change the sign of the wave function).
posted by Schmucko at 10:27 AM on December 14, 2014


Seeing the video brought back to me Clif High's notion of the entire universe resulting from a single pulse train happening at plank time scales. Wouldn't it be wild if this turned out to be true?
posted by MikeWarot at 10:47 AM on December 14, 2014


Now I know how my dog feels when I try to explain how the ball didn't really disappear I'm just hiding it. He believes me but he doesn't really get it.
posted by Bonzai at 10:50 AM on December 14, 2014 [15 favorites]


I am amazed at the extent to which which "fashion" and "indoctrination" appear to have influenced the outcome of the debate so far. (If the article is to be believed.) Once again it becomes clear to me that science really is a human endeavor.

Well, it's also not just human but also very trendy to go "haha, the establishment is wrong and while I have absolutely no idea what this is all about, this probably means that I'm smarter than all the smart people," especially on the Internet. Because nobody likes being stupid.
posted by effbot at 11:03 AM on December 14, 2014 [6 favorites]


Well, it's also not just human but also very trendy to go "haha, the establishment is wrong and while I have absolutely no idea what this is all about, this probably means that I'm smarter than all the smart people," especially on the Internet. Because nobody likes being stupid.

Quoted for truth. Also remembered for future use in similar situations.
posted by Alterscape at 11:10 AM on December 14, 2014


2. Was ether rejected prematurely? It is now, well accepted that gravity bends spacetime and influences the path/motion of particles. Does this spacetime not (for all practical purposes) fulfil the expected medium requirements?

The waves in QM are moving through space and time, but do not exist as waves in the medium of spacetime like gravity waves. Spacetime is described by relativity, the effects of which are completely negligible on quantum scales. Physicists have been trying to find a universal theory combining relativity and QM for a long time, with little success. The only place where relativity and QM are thought to be simultaneously relevant are black holes, which is one reason why theoretical physicists focus so heavily on them. Otherwise, relativity and QM are separate phenomena occurring on vastly different scales, with no obvious connection between them.

In QM, waves exist independently of any medium. The obvious question would be: well, then how are they waves? To which the only real answer is: that's just how the math works out. For whatever reason, wave equations accurately describe the behavior of particles on the quantum scale. Nobody knows why, and physicists have mostly stopped trying to explain it in non-mathematical terms.
posted by dephlogisticated at 11:12 AM on December 14, 2014 [1 favorite]


So does this say everything is happening all at once, including the responding ripples from what has already happened, and it influences what will happen? Where is the dark matter in all this, or is that a bigger phenomenon? I am a physics 0 but fascinated by wave motion and water.
posted by Oyéah at 11:15 AM on December 14, 2014



I am amazed at the extent to which which "fashion" and "indoctrination" appear to have influenced the outcome of the debate so far. (If the article is to be believed.) Once again it becomes clear to me that science really is a human endeavor.

Well, it's also not just human but also very trendy to go "haha, the establishment is wrong and while I have absolutely no idea what this is all about, this probably means that I'm smarter than all the smart people," especially on the Internet. Because nobody likes being stupid
.

Yeah... It's almost standard for new revolutionary ideas to displace old estabishment ones and then in turn get overthrown down the road after they become the established norm. The built in thing to science that makes it a bit better then say 'fashion' or many other human cycles is that the new ideas if accepted generally advance knowledge by being replicatable and improving our understanding. This is in no way saying scientists are less assholish, petty, hidebound, wrong, subject to fads or any other human failing you can name, but the results are better over time.
posted by edgeways at 11:20 AM on December 14, 2014


leotrotsky: Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo.

You're going to have to explain and defend that statement, because soliton theory is the basis for modern communications technology. And it's "theory" in a stronger, more provable sense than the theory of gravity - I can deduce it with only a massless paper and massless pencil.
posted by IAmBroom at 11:51 AM on December 14, 2014


empath: The particle in pilot wave theory only goes through one slit or the other, but the wave goes through both, which ends up jostling the particle around so it only ends up in interference bands.

Wow oh wow oh wow is that ever a succinct restatement of everything I got out of that article.

Bravo.

Ultimately, no matter what, "strings" don't exist, "branes" don't exist, "multiverses" don't exist, and even the real numbers don't exist. They're just mental constructs that allow us to describe what exists. But using the wrong constructs (1=3) leads to mistakes (contradictions with reality), so we search out constructs that work (particles emit photons in quantum light packets).
posted by IAmBroom at 12:01 PM on December 14, 2014 [1 favorite]


Thanks, dephlogisticated. That makes sense.
posted by Banknote of the year at 12:21 PM on December 14, 2014


OK someone must make a band called Aethiric Theories fronted by PhysicsMatt happen.
posted by digitalprimate at 12:27 PM on December 14, 2014


Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo.--leotrotsky

You make that sound like crazy talk, but we use Soliton waves in long distance communications.


The thing is that the effects they are looking at are certainly modeled by non-linear partial differential equations for the behavior of the fluid. If those nonlinear partial differential equations are "integrable" then this is actually "Soliton" theory.

Quantum field theory is not just another phrase for quantum mechanics with the wave function as the probability field of a single particle.

In principle though, you can define a "field theory" in terms of an action functional wrt a Hamiltonian, same as particle mechanics. The problem is that the phase space for a field will be infinite dimensional (well, really, one problem). So, formally QFT and QM arise from the same procedure of quantizing a classical mechanical system, but in practice quantizing a field theory runs into many technical problems that need to be solved in order for it to be non-pathological. Quantum theory starts with calculating the distribution of frequencies of the electromagnetic field in the "black body" problem. QM was largely developed as a toy theory so that you could think about the quantum parts without getting bogged down in those technical problems.

Possibly more interesting than the failure to quantize gravity, is the failure to unify gravity and electromagnetism... which was the great project of the 19th century (it actually goes all the way back to Faraday) that Einstein died trying to solve.
posted by ennui.bz at 12:43 PM on December 14, 2014 [2 favorites]


The phrase "inherently probabilistic" has been troubling me.

Probability theory is the mathematics of incomplete information. Processes can be completely deterministic and still best described in terms of probability simply because we don't know enough. Consider drawing from a shuffled deck of cards: the order of the cards is physically fixed the moment we stop shuffling, but we describe the draws in terms of chance, and make predictions about them using probability theory, because we don't know what that fixed order is.

As such, to describe something as "probabilistic" is to say something not just about the thing itself, but about the thing's relationship to the person trying to predict it. And to say that a thing is inherently probabilistic can only mean that it's probabilistic for every possible observer -- that it's impossible in principle to predict it fully.

Which... may be the case for quantum phenomena? (The Uncertainty Principle comes to mind, but my knowledge of QM is meager and I don't want to overstate things.) But it sounds like pilot wave theory doesn't really affect whether that's the case or not. I guess the intuitive distinction is between "This thing is just plain random in itself" and "This thing is in theory mechanistic, but it is in principle impossible to know enough to predict it". But I don't think this distinction is philosophically coherent.
posted by baf at 12:49 PM on December 14, 2014 [4 favorites]


The waves in QM are moving through space and time, but do not exist as waves in the medium of spacetime like gravity waves.

This is really misleading. The wave function in QM (at least in the standard formulation) is a purely formal device. It's a solution of a complex partial differential equation, the Schrodinger equation, and so lives in a suitably nice infinite dimensional space, often a complex "Hilbert space". The wave function takes on complex values: it's in *no way* a physical wave traveling through any medium.

The relationship between the wave function and observations in space-time is strictly defined by a formal procedure, the infamous "collapse" of the wave function often written by something like :

< W|F|W* >

where W is the wave function, F is the property you are measuring, and the "bra-ket" represents an integral-functional of W which looks a lot like a Fourier transform.

But, basically, waves in QM *do not* travel through space-time. The wave-like properties follow from the fact that the Schrodinger equation has periodic solutions given certain boundary conditions.
posted by ennui.bz at 12:52 PM on December 14, 2014 [4 favorites]


Natural science does not simply describe and explain nature; it is a part of the interplay between nature and ourselves; it describes nature as exposed to our method of questioning. This was a possibility of which Descartes could not have thought, but it makes the sharp separation between the world and the I impossible.
- Werner Heisenberg, Physics and Philosophy: The Revolution in Modern Science, 1958

Which makes it, as Kurt Godel forced us to appreciate, rather silly to make any absolutist statements about how it all works. Fun, but silly fun.
posted by Twang at 1:07 PM on December 14, 2014 [2 favorites]


leotrotsky: Pilot wave sounds suspiciously similar to Soliton Theory, and that way lies woo.

You're going to have to explain and defend that statement, because soliton theory is the basis for modern communications technology. And it's "theory" in a stronger, more provable sense than the theory of gravity - I can deduce it with only a massless paper and massless pencil.


I'm sure it does; I'm not disputing that there's real science there. It's just that, in my experience, monomanical kooks are often drawn to solitons. The universe is a soliton, everything's a soliton, etc...
posted by leotrotsky at 1:17 PM on December 14, 2014


Natural science does not simply describe and explain nature; it is a part of the interplay between nature and ourselves; it describes nature as exposed to our method of questioning.

That's Kant.

To say that anything that is describable and explicable about nature necessarily involves a method of questioning, and therefore it's meaningless to even posit any "nature itself" beyond that: that's Hegel.

And in the end, Hegel may not have been so far from Descartes, for whom of course the accuracy of "our method of questioning" is ensured by God.

I'm with Kant.
posted by shivohum at 1:32 PM on December 14, 2014


I am reminded a bit of string theory, which was in vogue (in some circles) when I was studying physics in undergrad; it fixes a perceived problem with theory as it is broadly understood, but does so in a way that doesn't produce any testable/falsifiable hypotheses that differ from that theory. At least given the current limits of experimental apparatus.

That never struck me as especially interesting. If a theory doesn't produce falsifiable hypotheses, then it's ... well, the best thing you can say is that it's an interesting intellectual exercise that might someday come in handy.
posted by Kadin2048 at 1:33 PM on December 14, 2014 [2 favorites]


ltimately, no matter what, "strings" don't exist, "branes" don't exist, "multiverses" don't exist, and even the real numbers don't exist. They're just mental constructs that allow us to describe what exists.

This is pretty much transcendental idealism, and, if we can tow Koenigsberg some distance to Edinburgh or Athens, I'm in.
posted by thelonius at 1:36 PM on December 14, 2014 [1 favorite]


Pilot waves are the epicycles of quantum mechanics alas.
posted by fallingbadgers at 1:40 PM on December 14, 2014


Yup, yup, and yup. Just do an image search for "bohm trajectories" to see how "natural and simple" the pilot wave theory looks.

As a limited, but concrete counterexample to "no hidden variables," Bohm's theory was not woo. But as much as I enjoyed reading some of his later philosophically-oriented books, they do get pretty woo, or at the very least unnecessarily obscure.
posted by mubba at 1:55 PM on December 14, 2014


nature is inherently probabilistic

I see a sperm whale and a bowl of petunias that would like to disagr...

Oh, never mind.
posted by obiwanwasabi at 2:20 PM on December 14, 2014 [3 favorites]


I find the lack of physicsmatt in this thread disturbing.
posted by hippybear at 2:58 PM on December 14, 2014 [7 favorites]


Had a mental image of a 5D oil-droplet electron bouncing on its own 4D ripples around an atomic nucleus. Described it to my maths PhD wife and watched with glee as she covered her ears and screamed NOOOOO!

I'm sure this will come back to bite me during the divorce.
posted by Autumn Leaf at 5:01 PM on December 14, 2014 [3 favorites]


So is string theory still considered valuable to the extent that it at least contributed to new developments in theoretical mathematics? As I recall that was an aspect that string theorists specialists seemed to be excited about too.
posted by polymodus at 5:05 PM on December 14, 2014


Bell's inequality says that, within the constraints of quantum mechanics, either realism or locality must be false. Realism here means that particles have defined properties prior to measurement, as opposed to many interpretations of QM, where a particle exists in a superposition of states that only collapses at the point of measurement. Locality means that particles can only interact in a direct, local manner, and thus two particles separated by a large distance cannot exchange information any faster than the speed of light.

Anybody got a sound argument against both realism and locality being false?
posted by flabdablet at 7:33 PM on December 14, 2014


If the whole Boltzmann Brain thing is true, then realism and locality and everything else are just figments of your imagination. Or my imagination. Or somebody's imagination.
posted by Flunkie at 8:01 PM on December 14, 2014


> It is very important for laypeople to understand that this is not a debate about the truth of quantum mechanics. QM has been richly proven in experiment, and its proof can be seen in the modern technology that surrounds us.
...
So far, this is a philosophical debate about how to "interpret" QM, not about experimental predictions. Pilot wave theory has not made any new predictions, at least no predictions that differ from the other interpretations of QM.


Quoted for emphasis. Or, as Tony Leggett said in the article:
It may just be a matter of effort to recast the predictions of quantum mechanics in the pilot-wave language, said Anthony Leggett, a professor of physics at the University of Illinois, Urbana-Champaign, and a Nobel laureate. “Whether one thinks this is worth a lot of time and effort is a matter of personal taste,” he added. “Personally, I don’t.”
It should be noted that this isn't blind orthodoxy; Leggett doesn't believe QM to be a complete theory, specifically because of the measurement problem! He discusses the limits of QM in this exceptionally readable paper, which I recommend to everyone (some of it is quite mathematical, but there's plenty in there that is accessible to an intelligent layperson). However, he is very careful to distinguish between approaches to the measurement problem that are "verbal window dressing" and those that are experimentally testable, which is what this fails to do.

On preview, flabdablet: violation of the Leggett-Garg inequality (which can be thought of as a non-local analogue of Bell's) suggests that realism doesn't hold, regardless of locality. The violation has been experimentally observed.
posted by Westringia F. at 8:01 PM on December 14, 2014 [8 favorites]


It is too easy to dismiss science being a human enterprise as a truism. The point is that "Science" is sometimes put on a pedestal as some magic force. As was pointed out, it tends to be self-correcting in the long run, but when the usual human foibles like politics show up and may be a factor in a theory being considered or not, it becomes part of the discussion. That being said, the theory sounds interesting although rudimentary.
posted by blue shadows at 9:36 PM on December 14, 2014


Which makes it, as Kurt Godel forced us to appreciate, rather silly to make any absolutist statements about how it all works. Fun, but silly fun.
posted by Twang at 4:07 PM on December 14 [3 favorites +] [!]


This seems ridiculously and more importantly prematurely dismissive. Godel killed off logical positivism, to be sure, but there's a reasonable argument to be made that both of the primary interpretations of quantum mechanics have driven our species a little bit mad. Either all our striving is futile in the face of an existence defined primarily by statistical noise, or it's futile in the face of every conceivable outcome being equally meaningful and therefore utterly meaningless.

Post-modernism's assertion that it is nothing less than cultural adulthood has all the hallmarks of delusional hubris, and I think the soul of Einstein's assertion about God playing dice was that we should not throw out the essential aspirational heart of determinism: that there exists but one reality and it is our lot to shape it to be the best one we possibly can. Even if our decision in the matter is largely an illusion - or perhaps precisely because of that fact.
posted by Ryvar at 10:25 PM on December 14, 2014 [1 favorite]


In your world I posted this comment.

(Everett for the win!)
posted by Dumsnill at 10:52 PM on December 14, 2014 [1 favorite]


violation of the Leggett-Garg inequality (which can be thought of as a non-local analogue of Bell's) suggests that realism doesn't hold, regardless of locality.

Color me absolutely unsurprised. I would be very, very surprised to learn that particles described by QM turn out to have properties other than those predicted by QM; to my way of thinking, a particle is nothing more than a way to group a set of related attributes that identify some specific class of observable events, and the idea that it's actually a physical object anything at all like some kind of yoctoscopic billiard ball is implausible. If we can measure/observe an event, it's worth describing. If we can't, we ought to be cautious about taking seriously any of the Just So stories we construct about it.

I've often seen Bell's result presented as an either/or choice between the correctness of realism and that of locality; so what I'm really asking is whether the probable incorrectness of realism is evidence one way or the other for the correctness of locality.
posted by flabdablet at 3:23 AM on December 15, 2014


[A couple of comments deleted; please cut out the personal comments. ]
posted by taz (staff) at 6:26 AM on December 15, 2014 [1 favorite]


Pilot waves are reassuring nonetheless.
posted by Brian B. at 7:07 AM on December 15, 2014 [2 favorites]


If the whole Boltzmann Brain thing is true, then realism and locality and everything else are just figments of your imagination. Or my imagination. Or somebody's imagination.

A belief in Boltmann's brains is logically incoherent because its based on knowledge which you would not be able to trust, were it true.
posted by empath at 7:43 AM on December 15, 2014


A belief in Boltmann's brains is logically incoherent because its based on knowledge which you would not be able to trust, were it true.

Even if that were the case (what is your argument that it is?), that wouldn't make it logically incoherent, it would simply make it impossible to know that it were true.
posted by shivohum at 7:47 AM on December 15, 2014 [2 favorites]


Even if that were the case (what is your argument that it is?), that wouldn't make it logically incoherent, it would simply make it impossible to know that it were true.

A belief in boltzmann's brains is a belief that you are a brain that spontaneously popped into existence and your memories and so on are mere illusions and that you spin apart in a moment. Which is to say that you know absolutely nothing about the world, including all the laws of entropy and so on that caused you to hold a belief that you're likely to be a boltzmann brain to begin with.
posted by empath at 7:51 AM on December 15, 2014


On the upside, it matters not a whit if you're wrong.
posted by flabdablet at 9:27 AM on December 15, 2014 [1 favorite]


that you're likely to be a boltzmann brain to begin with.

Ah, so you're interested in likelihood -- a different issue than the logical coherence of the concept itself. You're saying that if we are Boltzmann brains, that tends to undermine our justifications for believing our beliefs to be true, and thus our belief that we are Boltzmann brains.

There are ways around even this likelihood / justification issue, though. For example, given that one is a Boltzmann brain with vast and seemingly coherent networks of memory, scientific concepts, and so on -- perhaps the truth is lower-organization than a lie. Perhaps, given a complex set of memories and concepts, the highest entropy such network is the one that is actually reflective of reality. Perhaps it would take far more order to generate an imaginary such network than to simply generate a network that was more or less borrowed from reality.

So perhaps then we do have justification for believing our beliefs, even if we were a Boltzmann brain. It is far more likely that our memories and beliefs hew at least roughly to reality than that they do not.
posted by shivohum at 9:41 AM on December 15, 2014


Perhaps, given a complex set of memories and concepts, the highest entropy such network is the one that is actually reflective of reality.

No, the whole point of the concept is that it it is not. If the math behind boltzmann brains is correct, it is almost unfathomably more likely that a random accumulation of particles would put itself in the exact state that your brain is in right now, than that the entire universe exists, but if the math behind it is correct, then you're probably a boltzmann brain, which means that anything you think you know about the math is illusory. This is a total derail, though.
posted by empath at 9:49 AM on December 15, 2014


than that the entire universe exists

Who says it has to exist now in the state in which we remember it? The memories and beliefs that fill a B-brain may be of some lower-entropy state and place of the universe that existed long ago, but "borrowing" from a cognitive network that matches true reality at some point in space-time may be require far less order than something completely imaginary, and if so, the mathematics and physics generated from the perceptions of that state may still be timelessly correct.
posted by shivohum at 10:09 AM on December 15, 2014


I don't think you understand what a b-brain is, frankly. The 'rest of the universe' in a b-brain universe is an endless, unchanging, indistinguishable sea of particles at maximum entropy. There is nothing else out there. There's no past or future because the past is indistinguishable from the future in such a universe. Concepts like 'long ago' don't make sense. The whole point of the concept is that for any sort of ordered universe to exist that is beyond the b-brain, it has to be lower entropy (and thus more unlikely) than just the brain itself.

The b-brain concept was really an argument against the idea that our universe came about because of a random fluctuation in such a maximum entropy universe, since it's far, far more likely for a single brain to fluctuate into existence than an entire universe.
posted by empath at 10:22 AM on December 15, 2014


since it's far, far more likely for a single brain to fluctuate into existence than an entire universe.

Yes, but it is likely (indeed, almost inevitable) that at some points even in a high entropy sea of particles, fluctuations WOULD bring universes into existence. It may be unlikely that any particular brain -- say, any of ours -- is currently in such a universe; it may be far more likely it's a B-brain. But my point is that if it were a B-brain filled with memories and concepts, it would be higher-entropy for those memories and concepts to correspond to one of the universes that previously fluctuated into existence. And if it did, then most B-brains are ghostly memories of someone who once lived in a fluctuation.

And the science and math known by that someone then might well be valid.
posted by shivohum at 10:44 AM on December 15, 2014


But my point is that if it were a B-brain filled with memories and concepts, it would be higher-entropy for those memories and concepts to correspond to one of the universes that previously fluctuated into existence.

This is just a cute supposition though, and doesn't actually make any sense. You're totally right that if there were some process by which that was true, then there's justification in both trusting our knowledge AND accepting a physical theory that makes boltzman brains likely.

There is no such process by which this is true, however, so we have to choose one of "trust our knowledge" and "boltzman brains are more likely than our observed universe".
posted by vibratory manner of working at 11:20 AM on December 15, 2014 [1 favorite]


Very cool experiment. However, it is a difference without a distinction. Claiming that the trajectory is "deterministic" doesn't make it deterministic. One can firmly believe that it is predetermined, but the conundrum is that to predict its exact trajectory requires knowing the initial conditions exactly. Now, at first glance, that may seem like a technical problem, but not one that theoretically erases determinism. But note this: most real values are irrational. And to know an irrational number requires knowing it to an infinite number of decimal places, without any shorthand representation that suffices. Further, to know whether the value is rational or irrational requires measurement to an infinite number of digits. To say the initial starting position is 2½ doesn't allow one to predict the trajectory because the computation of the value in the predictive equation requires an infinite degree of precision. So for theoretical reasons, the trajectory is still not deterministic and we're stuck with a probabilistic universe. Which, to me, is the more exciting universe to inhabit.
posted by Mental Wimp at 11:40 AM on December 15, 2014


There is no such process by which this is true, however

Well, to swing things back around to the topic of the post -- what if spacetime were a superfluid such that (from the article) 'an interaction between two particles in [it] sets them on paths that stay correlated forever because the interaction permanently affects [its] contours... "As the particles move along, they feel the wave field generated by them in the past and all other particles in the past," Bush explained.'

Any universes that fluctuate into existence, then, would have set ripples going in the wave field such that any spontaneous B-brains are far more likely to be related to those ripples than not.

That actually makes a lot of sense. If a universe fluctuates into existence, evolves humans, and then disappears, how likely is it that something as incredibly specific as a human B-brain fluctuates into existence and isn't related somehow to the remnants of that universe?
posted by shivohum at 11:40 AM on December 15, 2014


If the whole Boltzmann Brain thing is true, then realism and locality and everything else are just figments of your imagination. Or my imagination. Or somebody's imagination.

Clearly a figment of our collective, nonexistent imagination.
posted by Mental Wimp at 11:43 AM on December 15, 2014 [1 favorite]


That actually makes a lot of sense. If a universe fluctuates into existence, evolves humans, and then disappears, how likely is it that something as incredibly specific as a human B-brain fluctuates into existence and isn't related somehow to the remnants of that universe?

It's far more likely that such a universe never happened, than it is that a brain fluctuated into existence all by its lonesome. And I know you'll say that given an infinite amount of time and space, such a universe has to have existed. Indeed, an infinite number of them. And an infinite number which are nothing like them, and an infinite number which are kind of like that, but a little different, and no matter how many of these universes happened, how many times, there are many, many, many, many more by many orders of magnitude, boltzmann brains which have nothing to do with any of them.

But the boltzmann universes and brains posit a starting state (a sea of particles at maximum entropy) which we have no real reason to believe ever existed, I don't think, and neither has much to do with quantum mechanics, in any event, and more to do with statistical mechanics.
posted by empath at 11:54 AM on December 15, 2014


The Most Embarrassing Graph in Modern Physics

A poll of only 33 individuals, but it's interesting to note how much disagreement remains among the experts. And not a single advocate for de Broglie-Bohm.
posted by dephlogisticated at 2:52 PM on December 15, 2014


These comments sound awesome if you read them in Dr Sheldon Cooper's voice.
posted by obiwanwasabi at 3:37 PM on December 15, 2014 [2 favorites]


The Most Embarrassing Graph in Modern Physics

There are some better (IMO) arguments about why this poll should not be so embarrassing in in this post and comments at John Preskill's blog.

I don't get this statement in particular by Carroll:
We won’t know whether supersymmetry is real without performing very costly experiments. For quantum mechanics, by contrast, all we really have to do (most people believe) is think about it in the right way.
If it has nothing to do with experiment, then how is it physics, and not just a popularity contest about what feels more intuitive (or at most a matter of mathematical convenience like different conventions for signs or units)? How would we ever agree which interpretation is right, unless one of them leads to new physics?
posted by mubba at 5:32 PM on December 15, 2014 [1 favorite]


I think he's mostly talking about the development of new theories to explain the experiments we already have.
posted by empath at 5:52 PM on December 15, 2014


And an infinite number which are nothing like them, and an infinite number which are kind of like that, but a little different, and no matter how many of these universes happened, how many times, there are many, many, many, many more by many orders of magnitude, boltzmann brains which have nothing to do with any of them.

Except that not just any old configuration of atoms can actually function as a brain. A functioning brain implies an expected environment (even if it not currently in that environment), from which it takes and processes input from particular kinds of sense organs, where it sends out decisions to act to particular kinds of limbs, etc. It's not even possible for a B-brain to function without being related to an expected universe.

Now if, at any given point in time, there is an infinite amount of time prior, and thus an infinite number of universes prior, then presumably every possible expected environment where brains might evolve has to have existed.

And if that's true, then in some subset of those infinitely varied universes, in fact, the precise B-brain in existence must have existed in its real form.

So the B-brain is actually guaranteed not only to be related to prior universes, but to have existed in its exact configuration before.
posted by shivohum at 6:39 PM on December 15, 2014


Hmm, Carroll says several times that he's talking about "interpretation." Another quote from just above that: "There are a variety of experimental probes, all of which confirm the theory to spectacular precision. And yet — we don’t understand it. Embarrassing. To all of us, as a field (not excepting myself)."

So he's not talking about developing new theories that make different predictions; he's talking about "understanding" the theory and spectacularly accurate predictions we have. Which seems like asking for the exact same QM in a form that's more intuitively understandable according to someone's judgment.

It's kind of like someone in 1875 complaining that no one really understands the theory of electromagnetism, because even though the theory works so well at predicting induction, radio waves, etc., the properties of the luminiferous ether are so counterintuitive! (How can a substance only support transverse vibrations with immense frequency in any direction, but none at all longitudinally??) Of course, a few years later Michelson and Morley, Thompson, and others came along and experiment got ahead of theory, but when theory caught up with relativity and QM, shit just got weirder and less intuitive.

Both blog posts have lots of good comments about how the foundations of QM can be tied to actual new physics. I don't think it's at all a waste of time to investigate the foundations, but as plenty of commenters there said, the poll itself has nothing to do with physics.
posted by mubba at 7:08 PM on December 15, 2014


Svihohum: You really need to read about what you're talking about. The whole point of a b-brain is that there is no body attached to it. And no past, and no future. It's just a temporary collection of particles in the configuration of a brain which will disappate in moments. It's the minimal configuration necessary to produce something which in the moment is experiencing all the sensations that you are right now.

You might believe that's absurd, and indeed it is. The point of the thought experiment was that as absurd as that is, it's far more likely to have occurred than that this entire universe was a random fluctuation in a sea of particles that were in thermal equilibrium. It was just a counter argument to a certain theory about the origin of the universe.
posted by empath at 7:08 PM on December 15, 2014 [1 favorite]


You really need to read about what you're talking about.

And you really need to realize that comprehending the full implications of a concept requires more than rote regurgitation of the way the concept's been understood.

It's the minimal configuration necessary to produce something which in the moment is experiencing all the sensations that you are right now.

And I argued that even such a minimal configuration would have to have originated in design from a particular expected environment which would necessarily have existed. Anyway, I think this discussion has been played out.
posted by shivohum at 8:06 PM on December 15, 2014


Oh yeah. Forgot about this. (wiki) So, yeah, QM is describing real things, not just probabilities.
posted by cthuljew at 2:07 AM on December 16, 2014 [1 favorite]




Previously regarding pilot-wave theory. physicsmatt made a few comments there.
posted by Golden Eternity at 6:49 PM on December 17, 2014


thelonius: ltimately, no matter what, "strings" don't exist, "branes" don't exist, "multiverses" don't exist, and even the real numbers don't exist. They're just mental constructs that allow us to describe what exists.

This is pretty much transcendental idealism, and, if we can tow Koenigsberg some distance to Edinburgh or Athens, I'm in.
No - I'm not suggesting protons don't exist, but the proton as a hard ball (Rutherford model) doesn't, nor does the "fuzzy cloud of probability" that is pictured in so many physics textbooks, vainly attempting to make the idea visual for students about to hit some of the most revolutionary concepts of their lives.

I'm simply distinguishing between effective thought models (Rutherford, Dual-Wave-Particle Nature, elastic sheet with heavy planets distorting space-time) and real-world events.

If anything, I'm closer to Funes the Memorious than Transcendentalism. Or rather, science is Funes. The word is not the thing, no matter how tightly we define the word to more precisely box in the thing. No amount of words are the thing. No thought about the thing is the thing. What the universe is, and what we understand about what it is, are (IMO) eternally non-intersecting.
posted by IAmBroom at 9:58 AM on December 18, 2014 [1 favorite]


Except insofar as that there are regions of the thing - us - where those very things do intersect, by virtue of one of them being implemented on the hardware of the other.
posted by flabdablet at 10:29 AM on December 18, 2014


I'm simply distinguishing between effective thought models (Rutherford, Dual-Wave-Particle Nature, elastic sheet with heavy planets distorting space-time) and real-world events.

Just have to quote G.E.P. Box, once more: "...all models are wrong, but some are useful."

These real-world events you speak of, you have a more useful model?
posted by Mental Wimp at 12:48 PM on December 18, 2014 [1 favorite]


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