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shoyer
adriand
I read somewhere that quantum mechanics is the most tested of all scientific theories. And it has been shown to be right, every time.
Hawking espoused this idea he called “model dependent realism”. The idea is that every human understanding of reality is model-dependent, that is, it is not “reality” that we truly understand (we can’t) but rather in every case we have some model of reality that is useful in particular situations. For instance, we know that Newtonian physics are not “real” but they are perfectly accurate in certain situations. So they are not “wrong” when they are used in those situations, in fact, they are right.
The author of the article writes, “While Einstein won a Nobel Prize for proving that light is composed of particles that we call photons, Schrödinger’s equation characterizes light and indeed everything else as wave-like radiation. Can light and matter be both particle and wave? Or neither? We don’t know.”
In model dependent realism, we can ignore this apparent contradiction. In some situations the model of light as a particle is the most useful, and in others, the model where it is a wave is the most useful. We have to accept that it is not “really” either of these models, but that no matter what we do, any model we come up with for it will still just be a model.
gus_massa
>> Can light and matter be both particle and wave? Or neither? We don’t know.
But we know! The answer is neither.
Light and matter are weird things that is impossible to describe with usual language, but they can be described very precisely with math language. The problem is that the equations are too complicated and difficult to use.
They have been tested thoroughly, for example in particle accelerators but in experiments with very few things moving around. It's very difficult to use them when the experiment gets bigger.
In some cases, you can make some approximations and get almost the same result if instead of the full correct equations you use the wave equation. It's just an approximation. Light and matter are never waves, but in some case they can be approximated as waves.
In other cases, you can make some approximations and get almost the same result if instead of the full correct equations you use the particle equation. It's just an approximation. Light and matter are never particles, but in some case they can be approximated as particles.
And in other weird cases, bot approximations get very inaccurate predictions.
colordrops
This very precise description is still just a model and will in all likelihood be improved or even replaced one day as well.
colordrops
Apparently Hawking coined this term in 2010. Robert Anton Wilson coined a similar term, "Model Agnosticism", all the way back in 1977 in his book Cosmic Trigger:
"The Copenhagen Interpretation is sometimes called "model agnosticism" and holds that any grid we use to organize our experience of the world is a model of the world and should not be confused with the world itself. Alfred Korzybski, the semanticist, tried to popularize this outside physics with the slogan, "The map is not the territory." Alan Watts, a talented exegete of Oriental philosophy, restated it more vividly as "The menu is not the meal."
tomthe
"All models are wrong, some are useful" describes it very well for me. It still amazes me, how late I really understood this and how many intelligent people not fully understand it.
jerrysievert
he expanded on that quite a bit in quantum psychology (1990), giving an expanded treatise on the software of the mind and how it maps our interpretation of reality.
quite a good read if you liked his previous works.
tluyben2
We are human and prefer elegance, so enough will continue to try to unify models anyway. I don’t buy that we cannot understand nature but this model dependent realism is fine as a practical way of working until we do understand it.
adriand
> I don’t buy that we cannot understand nature
I don’t think anyone is saying that, but in pondering this issue, I remembered how in Spanish there are two verbs for “to know”, “saber” and “conocer”. That latter verb is often explained in English as “to be familiar with”. The usage makes the point best: you can “conocer” a person but cannot “saber” them. That is, you can be acquainted with someone but you cannot truly “know” them, no matter how close you are to them.
Think about it: how well do you know yourself? You live in your own head and yet you are probably surprised by some of your own reactions, or dismayed by your actions, or fearful of certain emotions. If you do not fully understand yourself then what does understanding nature even mean? I cannot inhabit the mind of my wife, let alone inhabit a photon.
dorgo
> it is not “reality” that we truly understand (we can’t)
Yes, we can only describe with models what can be observed. But it is a bad excuse for ignoring contradictions in (or between) models.
DebtDeflation
>And it has been shown to be right, every time.
So has GR. Yet the two theories seem to be utterly incompatible.
raattgift
They aren't "utterly incompatible", they're largely compatible. For example, lasers work here on Earth, and between the Earth and its moon. Moreover, hydrogen maser clocks and cesium et al.'s hyperfine transitions are used in clocks which are sensitive to nearby mass concentrations, and altitude above the Earth.
There are whole textbooks written on the limit in which General Relativity and Quantum Mechanics work well together, with Birrell & Davies 1984 https://books.google.co.uk/books?id=SEnaUnrqzrUC being the most widely used by graduate students (and as a reference book for researchers).
Indeed, such textbooks go into where GR & QM make incompatible predictions, and almost all of those are in the limit of strong gravity, which in turn is almost certainly always deep within an event horizon, or isolated in the very very very early universe.
Semi-classical gravity (SCG) works well as an "effective field theory", and simply marries a classical curved spacetime (General-Relativity style) with a relativistic quantum field theory (standard-model-of-particle-physics style). In particular, with minor caveats, on the cusp of strong gravity SCG is successful enough in the astrophysical study of stellar remnants that it is reasonably believed to be good everywhere outside black hole horizons and after the very early universe. https://en.wikipedia.org/wiki/Semiclassical_gravity -- one of the caveats is noted there, namely given a sizeable mass (> kilograms) brought into a superposition of space, it is not clear at all what SCG predicts a cavendish apparatus or other gravimeter will point to. This is a possible incompatibility of SCG's two more-fundamental theories in the weak gravitational field, low-energy matter, and low-speeds-compared-to-c limit, and is a puzzle that hopefully will be informed by clear experimental data some day.
Since we can't get information back from inside a black hole horizon; can't see anything in the very very early universe (electromagnetism hadn't "frozen out" of the GUT yet for instance); direct detectors of very early universe gravitational radiation are implausibly hard engineering tasks; and a bowling ball sized mass will be extremely hard to keep in a coherent state for reasonably long periods of time; these are really academic problems rather than practical ones.
japanuspus
As a former quantum physicist who has just decided to go back into quantum computing, this was my take as well: Introductory quantum physics courses may still include wave-function collapse and all that nonsense, but I have not met many physicists who use this as a mental model.
To be a bit more specific as to how _decoherence_ solves this, one way to see it is that classicality (i.e. observables having specific values) is an emergent property in the limit of near-infinite degrees of freedom in the same way that e.g. thermodynamic properties (temperature etc.) are emergent properties of classical systems in the limit of near-infinite degrees of freedom.
Putting it on the edge, claiming that quantum theory is at a dead end is like claiming statistical physics is at a dead end.
One of my personal favorites for how to formalize this is the work on "pointer states" by Wojciech H. Zurek. There is a freely available Physics Today articls [0], and you can find surveys of further work e.g. in the introduction of [1].
[0]: https://arxiv.org/abs/quant-ph/0306072 Zurek, Decoherence and the transition from quantum to classical -- REVISITED [1]: https://arxiv.org/abs/1508.04101 Brasil, Understanding the Pointer States
konschubert
Okay, cool, I’m 100% with you.
But could we then please stop teaching the collapse nonsense to first year students?
The logical inconsistencies of the collapse interpretation are an insult to their intellect.
orbifold
The collapse just stands for the unknowable details of the interaction with the environment during measurement, a good quantum physics course will explain that and include experiments that make that clear. For instance the Stern-Gerlach experiment illustrates this well.
luc4sdreyer
> in the limit of near-infinite degrees of freedom.
Can you explain or express this in a simpler way? Is it almost like saying macroscopic?
pdonis
> namely that the measurment problem is solved by decoherence
I think "solved" is too strong. The Wallace paper you reference, for example, does not claim that decoherence solves the measurement problem. His claim is only the more modest one that understanding decoherence helps to clarify what the measurement problem actually is.
ravi-delia
I'd love if decoherence was now the dominant perspective, and I at least am largely convinced barring some huge revolution, but it would surprise me very much. In terms of my acquaintances (largely the department of my university) team "I don't care, does it matter?" takes top spot followed by equal parts collapse and decoherence. Oh, and some Bohmian people but I don't know them as well, as interesting as it would be if they were right.
l33tman
Decoherence theory is really somewhat orthogonal to the measurement problem. Decoherence explains how the "collapse" happens gradually if you have a non-perfectly isolated system by seeping entanglement. But at some point you still need to activate the stipulation that you as an observer is drawn into the entanglement and at that point whatever's left of the wavefunction "collapses".
In essence the Copenhagen interpretation is still correct as a simplification that can still be OK in most cases. This is reflected by the fact that practising solid state physicists have successfully used this 20's style of QM for 100 years now.
michaelwilson
How can you be a "former quantum physicist"? Did you somehow unlearn everything that made you a quantum physicist?
Maybe you meant to say "formerly paid to be a quantum physicist"? :-)
analog31
I can't speak for the parent, but I have a physics degree from 30 years ago. Since then my career has diverged from academic physics to the point where it would take some effort to re-learn even my graduate level QM coursework, much less familiarize with current research topics. So I could see where the "former" status comes from.
SinParadise
>How can you be a "former quantum physicist"?
By disentangling himself with quantum physics. He was a quantum physicist, so I assume he knows how to do it.
shoyer
I guess "quantum physicist" can mean either an academic credential or a job title. In my case, I have the former but no longer the later. I finished my PhD nine years ago and no longer work in the field.
ISL
I disagree strongly with the author's pull-quote that "We know nothing more than Bohr, Einstein, Schrödinger, and Heisenberg."
There has been roughly a century worth of experiments since the quantum theory came into being. Those experiments have scythed through myriad attempts to explain the mechanism by which quantum theory apparently describes reality.
Physicists can choose between interpretations of quantum mechanics according to "taste" precisely because there are no observable ways to differentiate between them. As soon as those ways become available to us, "taste" will give way to experimental tests.
There is still ample room for cleverness. Experimentalists are pushing forward where we can, but another observation like Bell's might be sufficient to allow, pardon the pun, a quantum leap.
geijoenr
For some time already we are in an "epicyclean phase" of physics, trapped by the extraordinary predictive success of Quantum Electrodynamics and still using mathematical methods devised in the 19th century (variational calculus). This has lead us to the current situation, with extremely complicated theories at the limit of human understanding that bear no new results. It will take a modern day Copernicus to come up with a new view of physics, that will result in simpler, more productive models, to take us out of the local maximum we are in.
cogman10
That makes the assumption that there exists a simpler view of physics that will result in more productivity.
IMO, some of the smartest people that have ever lived, live right now. Mainly because we have more humans alive than ever before. The amount of brain power working to find these simpler models is breath taking, yet we aren't seeing the elegant simple solutions fall out like we once did. I don't think that's a problem with the ingenuity, I think that's a problem with the problem.
dav_Oz
If the brain power is focused in the "wrong" direction or all the smart people are constantly looking under the same set of "street lamps" it doesn't matter how many there are. Unconventional thinking is hard you can't force it solely with numbers arguably quite to the contrary: a large agglomeration of scientists can systematically enforce a proportionally larger conformity pressure.
It is a hard balance to strike because on the one hand you want to be constantly challenged by your fellow scientists but on the other hand also just take the foolish liberty to fully develop your (most likely flawed) intuition.
So even if I'm highly sceptical of Wolfram he gets my full respect and also Hugh Everett [0] who wrote a letter to Einstein as a 12-year old with Einstein answering: Dear Hugh: There is no such thing like an irresistible force and immovable body. But there seems to be a very stubborn boy who has forced his way victoriously through strange difficulties created by himself for this purpose. Sincerely yours, A. Einstein And later in life courageously confronted Nils Bohr with the [...] idea that the universe is describable, in theory, by an objectively existing universal wave function (which does not "collapse") i.e. Many-Worlds-Interpretation.
ravi-delia
I think it's easy to underestimate the extent to which the greatest minds have also turned to every weird permutation you could think of. Personally I figure we'll probably find some deeper theory just since the Standard Model still has its issues and gravity isn't rolled in yet, but there's every reason to think that this problem is hard, not just untried. Much of the most interesting work in the last century has been ruling things out.
There are lots of nifty ideas that are explored until insurmountable holes are found in them. The two main nonstandard lines of thought that have had any real progress are decoherence, which I'd call a success, and string theory, which I'll avoid rating because I have string-theorist friends but am not a liar. There are plenty of others, and maybe one will bear fruit, but honestly when the next big break comes it'll probably be really obvious.
allisdust
Good point. I guess all the great minds of this time see occupied with how to maximise ad clicks.
nwallin
Copernicus' model had the planets orbiting the same in circles at uniform speed. This does not match reality, so Copernicus just chucked in some epicycles to correct the error. Copernicus's model had all the complexity of epicycles, but he hard coded the first epicycle into the system by having the planets orbit the Sun instead of the Earth.
We wouldn't need a Copernicus to solve this problem, we would need a Copernicus, then a Kepler, (ellipses & non-uniform speed) then a Newton, (gravity causes ellipses and non-uniform speed) and then an Einstein. (gravity is warping of space-time)
If quantum field theory is as wrong as Ptolemy's geocentric model was, we're hopeless. Because QFT very well predicts the observations; our observations have no ellipses in them that invalidate circular orbits, our observations have no anomalous Mercury precession that invalidates Newtonian gravity, no speed of light being consistent in all directions to invalidate luminiferous aether. To say that we simply need a smarter theoretical physicist is simply wrong -- our current theories do not contradict the things we are able to observe.
We know that general relativity and quantum mechanics do not play nice at small scales and high local gravity. But we cannot observe this conflict. And that's nothing to go on.
We would need an observation which shows that general relativity or QFT is wrong about something before we could conceivably make foundational progress on making new or different theories. And every few months there's a new article about "Einstein is proven right again" or "LHC experiment shows all readings are nominal".
spookthesunset
So what is dark matter?
This thing that keeps galaxies bound that we cannot see but can only observe the effects… I think the hunt for it will push us into new territory.
That being said, as you say there has been nothing yet found that violates GR/QFT.
nwallin
The leading candidate for dark matter is that it's a soup of particles that interact gravitationally, but not via the electromagnic or strong nuclear force. If we're very, very lucky, it might interact via the weak nuclear force, which means there exists a slim theoretically possibility that we might be able to observe it interacting via the weak nuclear force. That being said, even if it does interact via the weak nuclear force, there's nothing to say it doesn't interact in a way which gives us the power to differentiate it from, say, neutrinos. And if it doesn't interact via the weak nuclear force, then we cannot every make any characterizations of it ever, not even with arbitrarily advanced technology.
If that's true we're hosed. There would be no insights, no way to theory ourselves out of it. Only nerds wailing futilely about dark matter on the internet. And sadness. And we wouldn't know it's because all our theories are correct, but we don't have the complete picture of the extra-Standard Model dark matter particles, or if it's because some variation of MOND is true, (although it's extremely unlikely to be a MOND variation) or if we're as wrong as epicycles vs curved fabric of spacetime.
lacker
It will take a modern day Copernicus
We might already have a modern day Copernicus. Could be string theory, could be something else. The problem is that we don't really have any experimental data that can't be explained by the Standard Model. What we really need is a modern day Galileo that can perform some sort of observations, like finding Jupiter's moons, that don't fit in with the existing conventional physics.
bricemo
27% of the universe is totally unknown (dark matter) and another 68% is totally unknown (dark energy), leaving only 5% of our universe that is explained by the standard model.
Feels very epicycle-ish and ripe for a major shift.
Iwan-Zotow
they are both called dark for a reason
not very observable
JumpCrisscross
> we don't really have any experimental data that can't be explained by the Standard Model
What was the evidence Copernicus saw that epicycles didn't explain? (Honest question.)
dr_dshiv
Nothing. His model actually fit the data worse than epicycles. He just thought it was a more sensible approach that matched the Pythagorean opinion.
It wasn’t until Kepler that a geocentric model involving ellipses actually was more predictive.
Might be worth returning to the Pythagorean interpretation (which Bohr discussed): All is number. The world is made of math, not stuff.
ricksunny
Could the would-be modern-day Copernicii be being stymied by modern-day academic funding structures and grant review committees?
Qem
I also have this impression. I think the current system lacks intellectual diversity. Lots of people pursuing the same few popular lines of inquiry, because if they get away from the herd, they have a hard time joining a big research group, getting funds and getting more people to read and cite their papers.
pgalvin
Only an undergraduate in Physics, but rest assured that there are many smart minds currently in search of this! Building bigger particle colliders is not the only solution, and there are a lot of interesting things being done with e.g. neutrino physics that may bear fruit in contradicting the standard model.
floxy
Hmm, a new kind of science.
vba616
Due to the mixed reviews, I haven't bothered to read
https://en.wikipedia.org/wiki/A_New_Kind_of_Science
https://en.wikipedia.org/wiki/Chaos:_Making_a_New_ScienceOneLeggedCat
I read this humongous damn thing around 2004. It's not worth it.
aeternum
Wolfram has a proposal, by that very name.
Hasn't yet made useful predictions though.
beaconstudios
Are more modern information-theoretic and dynamical models not used for quantum mechanics? They're both relatively recent and extremely innovative mathematical models.
Granted, I'm not mathematically fluent enough to know if they represent a deviation from variational calculus!
PartiallyTyped
There is constructor theory
ravi-delia
They are, and you see them used sometimes (my friend is actually using something like that in her thesis), but for the Grand Theory type stuff it seems like this blog is talking about they aren't as useful. They reduce to the same math as before, and on a fundamental enough level the shortcuts they let you take just aren't useful.
analog31
In my view the problem with interpreting physics theory precedes the quantum era. Nobody really knew what classical gravity or magnetism consisted of. The idea of the planets acting on one another instantaneously without contact in a vacuum was absurd on the face of it. Einstein was disturbed by this.
The history of QM that I learned in school a long time ago, is that a few physicists endorsed adopting a purely mathematical formalism with no preferred interpretation in order to be free of preconceptions that might prevent them from making progress. They were still free to debate interpretation, but considered it to be separate from the problem of forming an experimentally testable theory.
But in terms of finding a philosophically satisfactory interpretation, we don't know what to look for. No science has ever attempted to dig deeper than the level of analogies that are easy to grasp. And it seems reasonable that the interpretation should depend on the science. Otherwise we risk embracing an interpretation that becomes a barrier to progress, or that is overturned by new experimental evidence.
I think the biggest problem with fundamental physics today, is that it's hard. As in, hard enough that it's not yielding answers at the rate that it was 100 years ago, and we don't know when it will: 10 years, 100, 1000? The big problem -- reconciling quantum mechanics and gravity -- won't be solved until we solve it. A theory that solves this problem will require one of those two things to be "wrong" in some sense, in which case its interpretation will have to be revised.
dfdz
The quotes from scientists at the end of the article nicely summarize my opinion on this article:
> Deutsch, too, seemed impatient with my dissatisfaction over our understanding of the nature of reality. “Someone might equally well say: We may know what dogs look like and how they behave, but we don’t know what a dog ‘actually is’,”
jleyank
From the point of view of chemistry, QM “works”. It provides results that can be tested experimentally and predictions that can be validated. There are issues with computability but that’s more engineering than science. Determining structure, spectra and other physical properties is quite helpful.
What was the cliche? All theories are wrong, some theories are useful. It needs to be rephrased from vector codes into massively parallel codes but people can work with that.
jiggawatts
To me, this always felt like programmers excusing abhorrent code with "but it works".
Quantum theory isn't. It's not a single, cohesive, consistent theory.[1] There is no recipe you can apply, it's just a bunch of guessworks and heuristics that happen to produce the numerically correct equations if you keep trying long enough. This isn't secret or some sort of external criticism, you'll find this front-and-centre in the foreword of many a QM text!
Schrödinger famously arrived at his equation basically through numerical methods. He just tried things until it "fit" the desired output.
Now, there's nothing wrong with this, per-se. It's a perfectly viable approach for getting going, for getting something and using it as a starting point. But it isn't the endpoint, because approaches like this often have virtually no explanatory power.
A similar example is collecting insects, categorising them, giving them Latin names, and putting them up for display in a museum. You can learn a lot, amass enormous amounts of information, but without a theory of genetics and natural selection you will always be blind to the underlying truth of it all.
QM is just like bug collecting. We're collecting numerical equations that work, but we have essentially no clear understanding why. We've built a tree of life, and nobody has had the lightbulb moment that explains why it's a tree.
[1] There was a paper published a few years back where a bunch of working quantum physicists were asked some simple multiple-choice questions about the fundamentals of the theory. There was no consensus opinion on anything! PS: You'll get similar results if you ask priests of a random Christian sects about the basics of religion. Conversely, you will get nearly zero disagreement if asking Chemists about the basics of their science.
chii
> because approaches like this often have virtually no explanatory power.
the famous feynman have produced a response to this train of thought - usually from the laymen - where they demand an "explanatory theory". The answer is usually "don't know"; why gravity work the way it does? - don't know, but we can calculate orbits to great precision; why does photons or electrons travel the way it does? - don't know, but we can make very precise predictions via Quantum Electrodynamics theory.
The laymen demands an explanatory theory, because there's an underlying assumption they don't even verbalize - that such an explanatory theory can be understood _without the maths_, that the principles of the laws of physics operate on basic, understandable lego pieces. What is somewhat unconceivable is that the explanation _is_ the maths. To whit, we don't even have an explanation for the idea of inertia! We just observe it, and measure it (as mass). There's no explanatory theory.
jfengel
You could say that the "explanation" of inertia is that which preserves the symmetry of space translations under Noether's theorem. But that doesn't tell a physicist any more than they already knew, and it tells a layman even less.
jiggawatts
"don't know" -- that doesn't mean we can't know, it just means we don't currently have an explanation. If you had asked similar fundamental questions about the "why" of beetle species a few centuries ago, even the most prolific beetle collector in the world would have answered "don't know".
"The laymen demands an explanatory theory" -- and so do scientists! Why do you assume scientists are somehow "above" explanations, and are content in ignorance?
"explanation _is_ the maths." -- People had good rules of thumb for evolution (such as dog breeding practices), and Gregor Mendel could have come up with his mathematical rules for selection before Darwin published his explanatory theory of natural selection. That doesn't mean that it's worthless to try to aim for an explanatory theory of QM instead of a purely numerical / observational one.
somenameforme
Confounding variables are a strong argument against this. Give me two sets of data that have no causal relationship, and it's very possible (if not likely) I will be able to demonstrate not only a causal relationship but also observational predictability through the existence of confounding variables. Let me use ML models and this becomes trivial.
Do school names determine how good a school will be? Of course not. However, schools have names which tend to be reused: cultural icons, scientists, etc.. And schools in low performing areas are going to have a different distribution of chosen names than schools in high performing areas. So you can create a model that will not only demonstrate this but also offer legitimate observational predictability that a school's name will, on average, determine how well it will do.
The only way you could really refute this hypothesis is by understanding the true confounding variable, or by running some huge scale multiple decades long experiment where you changed the names of new schools and measured the performance difference. That experiment is clearly not really practicable, so all you're left with is understanding.
And this is really where the risk is. If we ever begin to build upon something that is unsound then it risks everything from that point onward being also invalid. At best everything collapses and you realize you must have made a mistake. At worse, you simply end up adding endless epicycles until at some point everything starts to completely stall out muddled in its own invalid fundamentals and irreconcilable complexity.
BeFlatXIII
I'm trying to remember which textbook or professor was the one who said that "shut up and calculate" was the Feynman interpretation of QM.
kayamon
Feynman must have driven his wife mad.
"Honey did you take the garbage out?"
"When you say garbage, have you considered if garbage can even really exist?"spekcular
Come on. We have plenty of good heuristics for why things are the way they are. Quantum theory is no more a bunch of "guessworks and heuristic" than Newtonian mechanics.
Also, physicists disagreeing on interpretational issues related to quantum foundations is not the same thing as disagreeing about the fundamentals of the theory.
mhh__
The things that Schrodinger tried are still valid physics, just for different systems. He didn't know that, but now we do, this has little bearing on modern physics.
Also chemists have the luxury of agreeing because the fundamentals of their work (not the day to day act of doing chemistry) gets to assume the presence of physics i.e. it's stampkeeping (depending on who you ask).
jleyank
Not quite stamp collecting, although botany or anatomy head in that direction. Call chemistry “just applied physics” as engineering is “just applied science”.
ravi-delia
If you asked chemists questions as "fundamental" as the ones posed to quantum physicists, they'd be exactly as lost because they'd be exactly the same questions. Shockingly, when you have a level of abstraction beneath you you get to have pure empirics, trusting that the foundations add up to get the right answer. If every field of knowledge that relies on empirical evidence rather than a grand unifying theory was stamp collecting, QM would be one of very few that wasn't.
kayamon
To use the bug collecting analogy, I like the idea that by capturing and describing these particles perhaps we've killed them in the process.
jiggawatts
The analogy I like to use is that high-energy particle physics is like trying to learn a game like chess or baseball by analysing the statistics of past games.
That's literally what goes on at CERN. They run effectively trillions of experiments, collect millions of them (after some filter), and then they draw histograms.
Unless you know nothing about mathematics, you know that histograms are inherently statistical beasts. It's meaningless to talk about the histograms of one experiment.
Could you learn to play, say, tennis by drawing histograms of player movements? Ball bounce locations? No? Why not!? It's tons and tons of data! Accurate, scientific data!
Quantum physicists would argue that only statistics exists. I like to point to the fact that one hydrogen atom can exist, and it can have on electron. Or zero electrons. In nice countable, integral quantities. You can place a single gold atom on a crystal lattice with an AFM or even draw cute pictures with them: https://cen.acs.org/analytical-chemistry/imaging/30-years-mo...
Just because some people think only collecting bugs is what biology is all about, doesn't mean that there isn't more to it...
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hujun
sounds like how ML/neuron network works today, computer comes up a super complex math equation that no human could understand to fit the data fed
ximile
I find it kinda hilarious that you all seen to be discussing some sort of cutting edge or controversial idea called "quantum theory" or "quantum physics", when I have to assume you're taking about century old theories of quantum mechanical systems like ones that continue to help design the electronics that you read this piece of shit article on.
rndphs
Well yeah, there is still unresolved issue(s) with at the very least the interpretation of quantum theory, if not the math. Before decoherence things were even worse, and that was much less than a century ago. The fact that physicists still haven't reached a consensus on what the theory means is very intriguing to many people. Although it's true that people probably underestimate just how much this territory has been trodden. The current quantum computing hype likely plays a role in it seeming "cutting edge". It may just be flavour of the month.
dzdt
One avenue for progress that the author overlooks is distinguising between quantum mechanics interpretations where wave function collapse is considered part of the theory vs. where wave function collapse is considered to be a useful approximation.
I expect as we see quantum computers increase in scale it will become more apparent and accepted that there is no such thing as "collapse": that is just the approximation for a large system including the observer becoming entangled with a smaller quantum system under consideration.
I think even the disillusioned author here would have to take that as progress.
drujensen
As former amateur physicist, who read a couple books over the years :)
To me it's quite simple. We haven't detected what is causing the waves that the particle of light is riding on. The particle of light is like a surf board, riding a wave and will always hit the shore in the interference pattern. Einstein and Bohr were both right.
What has been the wrong assumption over the years is that the light is generating the waves. It seems obvious to me that something else outside of the light (that we haven't detected yet) is generating the waves.
My amateur physicist guess is the waves are generated by the clock cycles of the computer simulation we are in. All computers require a clock to function. Why would our universe be any different?
zuminator
Not saying you're wrong in the slightest, but why would our universe be like a computer? When our understanding of the universe was very primitive we thought everything was alive (animism). Then a little more technology and we thought the universe was like an orrery or a clock (mechanism)[0]. Then a little more and we think it was like a computer (turingism?) Occasionally you'll hear it's like a hologram, a simulation (what's it simulating?), a graph [1], or some other faddish concept.
We just like to make metaphors to put this thing in a box that we can't understand. But perhaps at its most fundamental level it will defy comprehension or even definition.
[0] In the philosophical sense; https://en.wikipedia.org/wiki/Mechanism_(philosophy)
[1] https://syncedreview.com/2020/04/17/stephen-wolfram-the-path...
Dylan16807
What's the difference between a clock and a computer? And there's no difference between computer and computer simulation.
Being a hologram is something I see as a significantly different type of comment. That's about how a sphere of space is mathematically equivalent to a flat 2d shell using equivalent but warped physics. It doesn't change anything about the nature of the universe except sort of the number of dimensions. And it's orthogonal to those ideas.
I'm not sure how to categorize the graph thing but it's not widespread at all.
Zamicol
> why would our universe be like a computer?
Because information is fundamental.
Computers just so happen to be our best tools in the information domain.
po
> The particle of light is like a surf board, riding a wave and will always hit the shore in the interference pattern.
This is exactly Bohm's Pilot Wave theory that the article talks about. It has been debunked to some extent but I believe the debunking is still somewhat controversial for proponents. There are neat macro-level simulations of it called "Walking Droplets" if you search for them.
BatteryMountain
But then every point in space has it's own clock, so you'd have gazzilions of tiny clocks instead of one big global clock that tickets for the entire universe/reality.
Or perhaphs if we do have one big global clock, your distance from it warps/distorts other parts of the reality at each point in space? Maybe there is a limit to how far this heartbeat travels (edge of the universe)?
You can also then ask, at what speed or clock cycle is reality "rendering" and is it the same speed everywhere? It would seem each point renders itself and there would be no big global processor doing the rendering.
Then finally if you really want to dig deep, ask why is it being rendered to begin with. Might need some psychedelics for this one instead of math.
What if there are no clocks nor any points, what if matter is just a condensate of frequencies/sound/harmonics - that is, there is a "great piano player" and the "sound" it emits is the universe, just a side effect. If it stops playing, the universe disappears/collapses into nothingness.
note: A point here referring to a point in a massive 3d grid of points.
goldorak
That's why time slows down near heavy objects, there is more calculus to be done and don't want to drop frames.
CorrectHorseBat
>All computers require a clock to function. Why would our universe be any different?
Clocks are not required at all, even for digital computers. They only make designing computers a lot simpler.
Zamicol
Clockless computers don't have a global clock but they still have components that "tick".
Dylan16807
Depending on the design, no more than abacus has components that "tick". And I'd never say an abacus requires a clock to function.
If even a single bit gets hung up in a straightforward clockless design, everything else waits for it.
None of that is really visible to something inside the computer, though. The OP is describing calculation steps, not clock cycles.
mrjangles
I come to HN to learn new things in fields I know little about, like tech and computers, I always find the comments to be authoritative and interesting.
However, whenever I read the comments on any subject I happen to know something about, like physics, they are always completely nonsense from people who clearly have absolutely not even the smallest amount of experience in the area they are talking about. The worst part is, all these comments sound extremely authoritative, if I didn't know any better I would have believed they were experts.
This makes me very worried about the Gell-Mann Amnesia affect. I'm very worried that all the comments I've been reading on here about tech and computer topics are also just from larpers who are pretending to be experts but actually don't know anything.
bee_rider
I think the discussion of computer stuff here is much better than the physics discussion. It is a website about startups after all.
I only know a tiny bit of modern physics, and in a sort of backdoor fashion through electrical engineering, and even I can spot the occasional "this guy learned quantum physics via Star Trek" post.
raphlinus
The Gell-Mann Amnesia effect is real here. The difference is that, for many computer and computer-adjacent topics, the principals will often chime in. That gets you a level of authoritativeness that's hard to match. Even within computer topics, though, you see authoritative-sounding comments that are just wrong. That happens like clockwork in any thread having to do with undefined behavior, for example.
I also know a little about Covid (having a minor in molecular and cell biology, and obsessively consuming resources like TWiV for a while), and the median amateur virologist comment here is just a howler. Occasionally you'll have people who really know what they're talking about comment, but it usually gets drowned out.
The key, then, as always, is to read everything critically. Then there's some real insight to be gained here.
xtracto
I feel the same when reading comments about medicine. I'm absolutely ignorant of that field, but I cringe at the authoritative sounding comments often found in HN.
x86_64Ubuntu
From what I've seen on HN, things about tech implementations and software libraries are generally rock-solid. But if you venture into something else, such as QM, the humanities or god-forbid politics, that's when it becomes a nightmare mix of pseudo-intellectualism.
That isn't to say that there aren't voices from experts in those fields that contribute to the discussion, but they are usually drowned out with "The sample size it too small" with an n=20000 or "they aren't letting different ideas into [insert scientific field here]" as they've mentioned further up in this thread.
0x1062
name and shame, so those of us non-experts can spot the bad comments.
dang
Please correct wrong information without shaming others. We're trying to avoid the online callout/shaming culture here.
https://hn.algolia.com/?sort=byDate&type=comment&dateRange=a...
sam_goody
dang, you read every comment on every thread?
And you stay polite and interactive?!
Are you sure you are human?
lenocinor
I think the thing that honestly puzzles me is: before physicists learned physics, did their entire desire to be in the field spring from “shut up and calculate”? Or was there a time in their lives (especially when they were young) where they thought (or felt) a desire to get into physics to understand the underlying mechanisms that drive the universe? I feel like, at least for some people, the second thing must have been true. So, given that most quantum physicists seem uninterested in interpretations, where did this desire go? Did it disappear? Did the field get them to stop caring? Did it feel silly to them at some point? Did it feel hopeless? Or something else? I genuinely want to know.
cevi
The interpretations don't tell you anything that the calculations didn't tell you already (if an interpretation of quantum mechanics ever predicts something different from what quantum mechanics predicts, then it can be ruled out empirically by performing the appropriate experiment). Interpretations which don't give you a faster way to get to the results of those calculations just waste your time and get in the way of understanding. Theoretical computer science indicates that there is no significantly faster way to get the results of many of those calculations - no matter how elegant the interpretation feels, at best you have to do the same amount of work to get the same answers about what will actually happen in reality, and at worst you end up computing a million irrelevant details about things the interpretation invented which have no real-world consequence.
Someone who is genuinely interested in understanding the way the world works ends up asking questions about what goes into the calculations - what's the Lagrangian, how many degrees of freedom (i.e. quantum fields) are there, what symmetries or constraints are satisfied by the laws of physics, how can we set up the math to avoid pathological situations where the results of our computations are infinite, and so on. Philosophically motivated interpretations of quantum mechanics shed exactly zero light on these questions.
Well.. there is a caveat. If quantum mechanics was somehow incorrect - that is, if unitary evolution of a state vector in a Hilbert space didn't actually describe reality at all - then all of the above would be wrong. But in that case, every single interpretation of quantum mechanics would be wrong as well. Quantum computers would just flat out not work.
lenocinor
Thanks for taking the time to respond. I can see the perspective (at least currently) of “the interpretations don’t add any meaningful information” being the reason not to be interested.
lambdatronics
There are a broad range of motivations. In my case:
- I wanted to work on nuclear fusion energy, for the future of humanity.
- I was told that if I had a PhD in physics, I could do just about anything - it's a way of keeping options open.
- I liked tinkering in the lab & learning new mind-expanding concepts in textbooks.
- I viewed it as a test of my intelligence. (Turns out, it's more about perseverance.)
I know at least one string theorist, and they seem to be motivated primarily by liking to mess around with abstruse mathematics. Some others seem to enjoy the 'nerd cred.' I think the ones whose sole motivation is 'getting to the bottom of the universe' probably burn out early, b/c there's so little of that to be had right now. (I've heard from several people who got their PhDs in particle physics who went on to do data science/programming, saying that the field is depressing and that's why they didn't pursue it further.) As for me, I found the 'shut-up-and-calculate' attitude a major turn-off to studying quantum physics. (Plasma physics uses little or no QM, so that worked out for me.)
lenocinor
I never thought about all these other motivations. Thanks for responding with them! And it sounds like there may be at some physicists like I was describing that get burnt out or discouraged too.
scythe
>Another alternative is to suppose there are hidden factors that we can’t quite access. David Bohm influentially suggested that a particle is accompanied by a “pilot wave” that guides its trajectory through the double-slit experiment and creates the interference pattern. Most physicists will tell you that this kind of “hidden variable” interpretation of quantum theory has been ruled out by a combination of experimental results and mathematical proofs.
This isn't the problem with Bohmian mechanics at all. Bohmian mechanics "solves" the EPR experiment by letting hidden variables jump around across spacelike separations. This cannot be disproven by Bell tests.
The problem with Bohmian mechanics (which I have always heard called "Bohmian mechanics", and not "pilot-wave theory") is that it isn't truly relativistic; it doesn't happen in Minkowski space and nobody has to my knowledge extended it to Minkowski space in a way that is widely considered acceptable. If the author likes Bohm's approach so much, he should learn about the ongoing developments:
http://en.wikipedia.org/wiki/de_Broglie-Bohm_theory#Relativi...
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As former quantum physicist, I find it little troubling to read "quantum theory has reached a dead end" in specific reference to the interpretation of quantum mechanics. Most quantum physicists could not care less about how quantum mechanics is interpreted when it makes highly accurate quantitative predictions, and there are still plenty of interesting open problems for quantum theory (e.g., related to the practical design of algorithms and hardware for quantum computers).
This article also misses what is likely the leading interpretation of quantum mechanics by actual quantum physicists, namely that the measurment problem is solved by decoherence (the quantitative theory of how classical states emerge from quantum states):
https://en.wikipedia.org/wiki/Measurement_problem#The_role_o...
https://royalsocietypublishing.org/doi/10.1098/rsta.2011.049...