Whenever any of this comes up I remember that physics professor's speech on first day of quantum mechanics that got viral:
“Nobody understands quantum mechanics. The people who came up with it don't understand it. I will do my best so that by the end of this course you don't understand it either, and so you can got out to the world and spread our ignorance.”
Quantum mechanics is illogical and stuff that happens makes no sense but can be recrcreated through experimentation....as long as you don't look at it.
Because it's part of reality, a foundational part of it even, it's logical basically by definition. If it wasn't, it would just mean our concept of logic is flawed.
Beyond that, we have perfectly logical and sensible descriptions for what is happening in quantum physics, the problem is just that we have more than one and don't know which is right.
I'd say we understand quantum mechanics better than most things.
We know more about the behaviour of an electron than we know about the oceans, the Earth, the sun, the weather, the stock market, the human body, prime numbers, and so on.
Do you mean "why" as in "why did X cause Y" or as in "why are things the way they are"?
In the former case, quantum mechanics is our most precise theory for coupling causes and effects, predicting the outcome of experiments to an incredible degree.
In the latter case, do we really have a grasp of that for anything? Why is the gravitational constant the value that it is? Why is pi the ratio of a circle's circumference and it's diameter? Mostly we ultimately have to say that it is so because we can observe that it is so. For quantum mechanics it is the same.
We understand the "how" better than most things. Quantum mechanics is extremely well-supported mathematically and experimentally. I think that's what they mean. The "why", an understanding of what a system that generated those results looks like at a macro level, basically no clue.
The consensus seems to be that the math works, don't try to figure out why.
It's not so much that there's no agreement, it's that the different understandings all give the same empirical results, so there's no way to decide on which understanding is "better".
Settling the argument is a matter of taste, not science. At least for now.
That is a somewhat narrow definition of "why", I'd say. But indeed, the transition from quantum mechanics to classical mechanics is unclear.
There are several interpretations of quantum mechanics, but they are empirically equivalent, so you can just pick your favourite and move on. That's not necessarily a big mystery. The math works, as you say, and that's the whole point of a physical theory.
There are also several interpretations of statistics. Does that mean we don't understand "why" a dice rolls results with a certain frequency?
Note that superconductivity and the quantum Hall effect are both macroscopic quantum effects, so we do know what a macroscopic quantum system looks like.
Oceans: We know the basic mechanics of currents, tides, chemistry, where all that water came from in the first place, and while there are a few known-unknowns it doesn't seem like a paradigm-shifting discovery is likely. They mystery is mostly because it's huge and we just can't look through it very well, and that there's too many physical inputs to track them all so models are abstractions by necessity.
The same goes for most of your list (I will not speak to prime numbers, I am an Earth Sciences guy and bad at higher math) in that we may not have a perfect map but we know the shape of it and where the probable gaps in understanding are. So the "why" is questions like "why do waves happen" or "why does the sun look yellow" or "why do we have embryonic 'gills'" and we have pretty good answers you can drill pretty deep into.
Pushing at the edges of physics is, I think, where the situation is flipped. We have very good models for the behavior of light but questions like "why is there a limit to the speed of information and why does light go that fast" and "why does it behave as a wave and also a mass-less particle" don't seem to have satisfying answers or even a means to be answered. Admittedly physics beyond its applications to organic chemistry is outside my education (again, math) but I try to keep up.
Whenever this picture comes up I remember that it's wrong - both electrons on it have the same spin, one is just rotated 180°, but it says +½ for one and -½ for the other, is like a part of the joke?
All electrons have spin 1/2, that's a property of it being an electron. They have a spin vector (the arrow shown) and whether it is in the same direction or opposite direction to the magnetic field it's in determines where it is plus or minus.
Now you might think "but what if it is not entirely aligned with the field, then it wouldn't be 1/2", which is true, on aggregate for large numbers of electrons, but if you ever look at a single electron its spin will either be "up" or "down" never any other orientation.
This is the kind of thing people are referring to when they say "no one understands QM", we know it is the case, we can measure it and predict it, but it makes no fucking sense.
I think where the sense starts to fall through is in remembering that it's not a ball though. It's a wave, and the spin only in one direction when interacting with something else, otherwise it's akin to three parts spinning clockwise, and one part spinning counter-clockwise. 🫠
I think the trick was to establish that disagreeing with the Copenhagen Interpretation makes you one of these idiots who can't comprehend Quantum Mechanics. Idiots like... Albert Einstein? Or... Erwin Schrödinger? You know, real morons.
Imagine a mathematical concept that approximates a particle across a spherical plane. Now imagine a force emitted from this sphere in a field. Okay, we're ready to talk about why this is wrong, too.
One of my favourite things is the one-paragraph short story "On Exactitude in Science":
On Exactitude in ScienceJorge Luis Borges, Collected Fictions, translated by Andrew Hurley.
" …In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast Map was Useless, and not without some Pitilessness was it, that they delivered it up to the Inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography."
I recall a Richard Feynman video where the interviewer asks him to explain how magnets work.
His answer amounts to "I can't explain that to you because if I gave you an accurate answer it would be too technical for it to make sense to you, and if I simplified it to the extent that you could understand, it would no longer be a meaningful answer."
His point was that we don't understand the interaction between fundamental forces enough to say, if we were to try and answer the question accurately enough.
So, in one sense ICP was right that we don't know how magnets work. But also they were wrong that scientists be lying. They shouldn't have been pissed.
I expect Feynman’s answer, if he had a whiteboard and unlimited time, would’ve been to dive into Maxwell’s equations.
With that in mind, his answer makes complete sense. Good luck explaining coupled PDEs to people who aren’t mathy in a few sentences without visual aid. The analogy to the gravitational force isn’t on point; there’s a lot more to be said about how magnets tie to into E&M more broadly, compared to gravity.
Though you’re absolutely right that once you get deep enough into any topic in physics that the answer to “why?” inevitably becomes “it just be like that”.
The analogy to the gravitational force isn’t on point; there’s a lot more to be said about how magnets tie to into E&M more broadly, compared to gravity.
Yeah, a proper answer would need to dive into how it relates to electricity for sure
To me, there's two ways you could interpret that, one is what are the effects of magnetism which we learn on high school physics, the other other is why does magnetism have those effects which is more something you'd learn in an undergraduate physics or chemistry degree.
I think OP's meme illustrates Feynman's point very well; there comes a stage where if the number of incorrect statements in your explanation outnumber the the correct ones, it's no longer a meaningful explanation.
I guess they are, there's for sure something to that, but at the same time these quantum or relativistic phenomena really can't be described accurately in simple words
It's certainly unintuitive, but that makes sense; our intuition is formed from our experiences, and we have no experience with the domains that relativity and Quantum mechanics apply to.
And yes you are correct, as it exists as a probability wave and has not finite size, it is not spinning. It does however have intrinsic angular momentum as seen in effects like Hydrogen Fine Structure, that behave exactly as though it were a ball spinning, with a set specific angular momentum. But don't worry, the confusion is alleviated when you learn that it very definitely isn't a ball spinning as it doesn't have a singular spin but rather a super position of possible spin states. You can think of it like, for example, three parts spinning clockwise and one part spinning counter-clockwise.
It usually around this point that I am reminded that the universe does not owe my puny monkey brain a lick of sense.
The memory required to track all these particles was insane, so we just made a wave of where they were most likely to be and picked a random spot when the exact location was needed. 🤷
i'm just kinda skeptical of suggesting we live in a computer simulation
tens of thousands of years ago, people looked up into the night sky or a raging tempest and projected human-like traits onto it.
Now instead of seeing an angry father figure in the stars, we're surrounded by computers so we look up (or down, in quantum cases), and see a desktop environment. It's... awful convenient.
Yeah, "spin" was a stupid thing to call it. We have a nice, hard definition of what "spin" is on a macro scale. Why take a complex property of matter that we don't have a name for, and give it the same name as a fairly common, easy-to-understand phenomenon? Extraordinarily smart people being idiots, honestly.
A ball, however tiny, has 3 dimensions, it has a surface that moves around a mathematical point at the center of the sphere.
A point of zero dimensions has no diameter nor perimeter, no surface with which to spin. Yet when influenced by a magnetic field, a point-like indivisible particle behaves as if it does spin.
As Chief Brody might say, we're gonna need a bigger math!
How about imaginary numbers and the complex plane?
Now add the Uncertainty Principle, just for shits 'n' giggles!
Probability space! Probability amplitudes and polarizations!
The way I understood it (probably wrong): imagine if a point like thing, but is actually a wave, hits something else. It will leave a trace on the detector curving in a certain direction. This is interpreted as angular momentum aka spin.
It's actually kind of liberating when you manage to do that.
It's not true, but if you pretend it is, it allows you to do all kinds of math. Follow the rules as if the spin were real and there were real momentum and it allows you to predict things that you can test. It's almost like looking at a really good magic trick, where you know that what you seem to be seeing isn't possible, but the magician is manipulating things so that your brain can anticipate what's coming next.
Whenever any of this comes up I remember that physics professor's speech on first day of quantum mechanics that got viral:
“Nobody understands quantum mechanics. The people who came up with it don't understand it. I will do my best so that by the end of this course you don't understand it either, and so you can got out to the world and spread our ignorance.”
Or something to that effect.
I'm so good at not understanding stuff. My time has come.
Quantum mechanics is illogical and stuff that happens makes no sense but can be recrcreated through experimentation....as long as you don't look at it.
The end
Quantum mechanics is extremely logical - we understand the math extremely well, and the math describes reality better than any other theory.
It is, however, not intuitive.
I was just being cheeky
It's perfectly logical, what happens makes sense, we just don't know key facts about what is actually happening.
How can you know that
Because it's part of reality, a foundational part of it even, it's logical basically by definition. If it wasn't, it would just mean our concept of logic is flawed.
Beyond that, we have perfectly logical and sensible descriptions for what is happening in quantum physics, the problem is just that we have more than one and don't know which is right.
What definition of "logical" are you using here?
Coherent and coming from sound reasoning
I'd say we understand quantum mechanics better than most things.
We know more about the behaviour of an electron than we know about the oceans, the Earth, the sun, the weather, the stock market, the human body, prime numbers, and so on.
We generally have a grasp of "why" for that stuff though, even if the whole picture is currently hidden or too complex.
Do you mean "why" as in "why did X cause Y" or as in "why are things the way they are"?
In the former case, quantum mechanics is our most precise theory for coupling causes and effects, predicting the outcome of experiments to an incredible degree.
In the latter case, do we really have a grasp of that for anything? Why is the gravitational constant the value that it is? Why is pi the ratio of a circle's circumference and it's diameter? Mostly we ultimately have to say that it is so because we can observe that it is so. For quantum mechanics it is the same.
Or do you mean "why" in some other way?
We understand the "how" better than most things. Quantum mechanics is extremely well-supported mathematically and experimentally. I think that's what they mean. The "why", an understanding of what a system that generated those results looks like at a macro level, basically no clue.
The consensus seems to be that the math works, don't try to figure out why.
It's not so much that there's no agreement, it's that the different understandings all give the same empirical results, so there's no way to decide on which understanding is "better".
Settling the argument is a matter of taste, not science. At least for now.
That is a somewhat narrow definition of "why", I'd say. But indeed, the transition from quantum mechanics to classical mechanics is unclear.
There are several interpretations of quantum mechanics, but they are empirically equivalent, so you can just pick your favourite and move on. That's not necessarily a big mystery. The math works, as you say, and that's the whole point of a physical theory.
There are also several interpretations of statistics. Does that mean we don't understand "why" a dice rolls results with a certain frequency?
Note that superconductivity and the quantum Hall effect are both macroscopic quantum effects, so we do know what a macroscopic quantum system looks like.
Oceans: We know the basic mechanics of currents, tides, chemistry, where all that water came from in the first place, and while there are a few known-unknowns it doesn't seem like a paradigm-shifting discovery is likely. They mystery is mostly because it's huge and we just can't look through it very well, and that there's too many physical inputs to track them all so models are abstractions by necessity.
The same goes for most of your list (I will not speak to prime numbers, I am an Earth Sciences guy and bad at higher math) in that we may not have a perfect map but we know the shape of it and where the probable gaps in understanding are. So the "why" is questions like "why do waves happen" or "why does the sun look yellow" or "why do we have embryonic 'gills'" and we have pretty good answers you can drill pretty deep into.
Pushing at the edges of physics is, I think, where the situation is flipped. We have very good models for the behavior of light but questions like "why is there a limit to the speed of information and why does light go that fast" and "why does it behave as a wave and also a mass-less particle" don't seem to have satisfying answers or even a means to be answered. Admittedly physics beyond its applications to organic chemistry is outside my education (again, math) but I try to keep up.
Whenever this picture comes up I remember that it's wrong - both electrons on it have the same spin, one is just rotated 180°, but it says +½ for one and -½ for the other, is like a part of the joke?
All electrons have spin 1/2, that's a property of it being an electron. They have a spin vector (the arrow shown) and whether it is in the same direction or opposite direction to the magnetic field it's in determines where it is plus or minus.
Now you might think "but what if it is not entirely aligned with the field, then it wouldn't be 1/2", which is true, on aggregate for large numbers of electrons, but if you ever look at a single electron its spin will either be "up" or "down" never any other orientation.
This is the kind of thing people are referring to when they say "no one understands QM", we know it is the case, we can measure it and predict it, but it makes no fucking sense.
That makes sence though, thanks for clearing that up
I think where the sense starts to fall through is in remembering that it's not a ball though. It's a wave, and the spin only in one direction when interacting with something else, otherwise it's akin to three parts spinning clockwise, and one part spinning counter-clockwise. 🫠
Ah much better, thank you
The Many Worlds Interpretation must be rejected because it makes sense and we've already agreed that Quantum Mechanics is not supposed to make sense.
Well put. I will never understand how Bohr managed to persuade so many scientists to commit themselves to not making sense.
I think the trick was to establish that disagreeing with the Copenhagen Interpretation makes you one of these idiots who can't comprehend Quantum Mechanics. Idiots like... Albert Einstein? Or... Erwin Schrödinger? You know, real morons.
Imagine a mathematical concept that approximates a particle across a spherical plane. Now imagine a force emitted from this sphere in a field. Okay, we're ready to talk about why this is wrong, too.
There's no analogy for any of this that doesn't have some flaw.
All analogies have flaws. If they didn't, they wouldn't be an analogy, they would be describing the very thing itself.
One of my favourite things is the one-paragraph short story "On Exactitude in Science":
Source: https://www.sccs.swarthmore.edu/users/08/bblonder/phys120/docs/borges.pdf
Imagine trying to maintain a map of any size complexity physically! Yet another underrated way digitize technology has been a paradigm change
Something something map territory
That's like your opinion, nerd
You lost me at 'spherical plane'
A hollow sphere.
You could picture this as a spherical cow of uniform density if you prefer.
A circle?
A big, red bouncy ball.
Cow.
Definitely a cow.
No, cows are spherical.
I recall a Richard Feynman video where the interviewer asks him to explain how magnets work.
His answer amounts to "I can't explain that to you because if I gave you an accurate answer it would be too technical for it to make sense to you, and if I simplified it to the extent that you could understand, it would no longer be a meaningful answer."
All of the most-impactful minds in science were mocked by their contemporaries.
Think about it.
His point was that we don't understand the interaction between fundamental forces enough to say, if we were to try and answer the question accurately enough.
So, in one sense ICP was right that we don't know how magnets work. But also they were wrong that scientists be lying. They shouldn't have been pissed.
That interview answer always seemed like a cop-out to me. You could make a comparison to gravity to explain how magnetism "just is".
I expect Feynman’s answer, if he had a whiteboard and unlimited time, would’ve been to dive into Maxwell’s equations.
With that in mind, his answer makes complete sense. Good luck explaining coupled PDEs to people who aren’t mathy in a few sentences without visual aid. The analogy to the gravitational force isn’t on point; there’s a lot more to be said about how magnets tie to into E&M more broadly, compared to gravity.
Though you’re absolutely right that once you get deep enough into any topic in physics that the answer to “why?” inevitably becomes “it just be like that”.
Yeah, a proper answer would need to dive into how it relates to electricity for sure
https://xkcd.com/1489
Title-Text: "Of these four forces, there's one we don't really understand." "Is it the weak force or the strong--" "It's gravity."
Here's the video.
It's been a while since I watched it, so judge for yourself.
To me, there's two ways you could interpret that, one is what are the effects of magnetism which we learn on high school physics, the other other is why does magnetism have those effects which is more something you'd learn in an undergraduate physics or chemistry degree.
The answer to why they have those effects would grant you a Nobel prize.
I think OP's meme illustrates Feynman's point very well; there comes a stage where if the number of incorrect statements in your explanation outnumber the the correct ones, it's no longer a meaningful explanation.
A lot of Feynman quotes are ultimately just witty cop-outs IMO.
I guess they are, there's for sure something to that, but at the same time these quantum or relativistic phenomena really can't be described accurately in simple words
It's certainly unintuitive, but that makes sense; our intuition is formed from our experiences, and we have no experience with the domains that relativity and Quantum mechanics apply to.
Uuuh I have to remember that one
Sounds like a class with an attribute called spin.
It does however also have repercussions that are inline with it being a sphere that is spinning.
Didn't it say it wasn't spinning?
Also I love your handle.
Thank you!
And yes you are correct, as it exists as a probability wave and has not finite size, it is not spinning. It does however have intrinsic angular momentum as seen in effects like Hydrogen Fine Structure, that behave exactly as though it were a ball spinning, with a set specific angular momentum. But don't worry, the confusion is alleviated when you learn that it very definitely isn't a ball spinning as it doesn't have a singular spin but rather a super position of possible spin states. You can think of it like, for example, three parts spinning clockwise and one part spinning counter-clockwise.
It usually around this point that I am reminded that the universe does not owe my puny monkey brain a lick of sense.
I read an article that was arguing that the universe could be unknowable to our brains. That was real depressing
More like its so small the idea of spin doesn't really mean anything.
The universe is a digital simulation confirmed
there's lots of physics that cannot be described in algorithmic terms, and (as best I misunderstand it) quantum is the most that
QM is entirely algorithmic, it just operates on values that are of type "Probability Distribution"
sure, if you say so
Are you implying that's wrong or you just don't know
i'm just kinda skeptical of suggesting we live in a computer simulation
tens of thousands of years ago, people looked up into the night sky or a raging tempest and projected human-like traits onto it.
Now instead of seeing an angry father figure in the stars, we're surrounded by computers so we look up (or down, in quantum cases), and see a desktop environment. It's... awful convenient.
I wasn't suggesting that, I just meant that a theory can be algorithmic while working with probability distributions rather than deterministic values.
https://xkcd.com/895/
There was great episode on PBS space time about it.
https://www.youtube.com/watch?v=pWlk1gLkF2Y
In short it doesn't rotate, it just has magnetic field that behaves as if the source was spinning charge
The electron is rotating in the sense that it resists a tilting force.
https://www.youtube.com/watch?v=PdN1mweN2ds
Disclaimer: My knowledge of physics ends at the high school level.
Apparently there is an experiment where they get an object suspended in water to rotate when being bombarded by electrons with the same spin.
Although my physics knowledge is probably less than the average highschool level.
I studied (a single course...) at university level and I think you understood at least as much as I did.
Right-hand rule bitches!
Imagine a woman in hot pants with thighs like a Robert Crumb dream woman.
I don't know if it helps with this problem though.
NoU Imagine a cactus eating a deer.
That's a challenging wank.
(RIP Sean Lock)
Yeah, "spin" was a stupid thing to call it. We have a nice, hard definition of what "spin" is on a macro scale. Why take a complex property of matter that we don't have a name for, and give it the same name as a fairly common, easy-to-understand phenomenon? Extraordinarily smart people being idiots, honestly.
imagines a static cube
Ahhh....
Well... Technically they oscillate at a certain frequency.
It's only half spinning too.
A ball, however tiny, has 3 dimensions, it has a surface that moves around a mathematical point at the center of the sphere.
A point of zero dimensions has no diameter nor perimeter, no surface with which to spin. Yet when influenced by a magnetic field, a point-like indivisible particle behaves as if it does spin.
As Chief Brody might say, we're gonna need a bigger math!
How about imaginary numbers and the complex plane?
Now add the Uncertainty Principle, just for shits 'n' giggles!
Probability space! Probability amplitudes and polarizations!
The way I understood it (probably wrong): imagine if a point like thing, but is actually a wave, hits something else. It will leave a trace on the detector curving in a certain direction. This is interpreted as angular momentum aka spin.
There are also things like Hydrogen Fine Structure , that behaves as though it is a ball that actually spins. 🤷
You must be thinking of the Stern-Gerlach experiment.
Ah yes the spin
The trick is to accept it without thinking about it
It's actually kind of liberating when you manage to do that.
It's not true, but if you pretend it is, it allows you to do all kinds of math. Follow the rules as if the spin were real and there were real momentum and it allows you to predict things that you can test. It's almost like looking at a really good magic trick, where you know that what you seem to be seeing isn't possible, but the magician is manipulating things so that your brain can anticipate what's coming next.
Shut up and calculate!
Is more like a feeling
electrons be vibin
The middle finger is for B field. The thumb is reserved for force. The index finger is for current. 🎵
Lozenge's Thumb Rule
I am imagining a glorious unibrow
I've always understood it more like a cake that's moist, but it's not a cake and it's not moist.
And if you're lucky it doesn't exist at all.
How about:
"Imagine you have ADHD, but you're forced to sit in place."
Would that work?
No.
I think it's like the magnetic charge of the thing?
Particle spin and charge are different properties
Nope, distinct property. I don't think there's any good analogy really (that I've heard).