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Wow, I feel like this article was written for me. I too just recently stumbled upon the significance of Planck's work while reading David Bohm's "Quantum Theory

Wow, I feel like this article was written for me. I too just recently stumbled upon the significance of Planck's work while reading David Bohm's "Quantum Theory". It was such a pleasing thing and wasn't too difficult to follow at all. It uses classical electrodynamics to get an expression for the energy contained in the box with respect to frequency, which of course disagrees with experiment. Then he supposes that energy could only be transferred in certain chunks, and uses statistical mechanics to show what the new distribution looks like. As you say, the existence of photons wasn't immediately jumped to. All that he deduces is that energy transfer must be quantized, and this is the real insight of quantum mechanics, but it gets lost in the woo-ey clickbaity world of modern pop sci. It was so nice to read the derivation from the point of view of a contemporary 20th century physicist, made me want to start reading a bunch of other 20th century physics papers in their original form.

hilbert42 4y ago
David Bohm is an interesting physicist, he often gets 'eggs' chucked at him for his Pilot Wave interpretation of QM but that shows he was a lateral thinker trying to find an explanation for one of physics' most intractable problems. But he was no lightweight either as we've seen with his work on the Aharonov–Bohm effect. That said, I'm ashamed to say I've not had a copy of his book Quantum Theory in my hands. You're one of many I've seen mention it in recent times so I'll have to remedy that. :-) Incidentally, I have read the original Aharonov–Bohm paper. Understanding that physics I reckon is crucial to getting a good handle on EM, potentials, etc.
- capn_duck 4y ago
  I'd strongly recommend it! I think it's worth the price of admission for the first few chapters alone, although I admit that at a certain point, I was struggling to keep up with all of the mathematical arguments as I am not a trained physicist. But I was able to keep up by hand through all of the thermodynamic, electromagnetic, and statistical mechanical arguments of the black box portion. But the first few chapters are so conversational and grounded in historical context that it's a real joy to read, even if you're not following along on pen and paper through all of the steps. If you know of any other "must reads" of the 20th century like this, please let me know! I love to hear the arguments presented as they were actually discussed at the time, not just what was settled on as the end result a century later.
  - hilbert42 4y ago
    Ah, damn, that's enough, I'm ordering a copy of it now. Thanks! Edit: I've always considered this historical context most important and we do not stress it enough in teaching physics (same in math and chemistry or in just about every subject that has developed and progressed over the years - 19th C. scholars translating ancient Greek texts for instance). As far as far as is possible, we need to get inside the heads of these people and try to picture the obstacles and difficulties they were facing at the time. Moreover, it's my experience that if I try to understand where they are coming from then I find that I get a much deeper appreciation (and better understanding) of the subject. Similarly, old scientific and engineering textbooks of the era are very useful in further illuminating this historical thinking; for example, 19th C. postulations about how the sun got its energy before we knew anything about nuclear fusion. That said, it seems we largely ignore this historical context because it is hard to do well and that most courses are already short of time. Still, if any subject needs it, it's QM and I've said so here on HN and elsewhere on many occasions: https://news.ycombinator.com/item?id=31980008 https://news.ycombinator.com/item?id=31980008. Big warning, here I'm in long-rave mode! Re: other good reads on the subject, at short notice I'm at a bit of a loss. Your best bet are textbooks on HPS - History and Philosophy of Science (which was one of my subjects decades ago). The trouble is comments on this topic soon time out, so in future when I think of them I won't he able to update you. (Much of my knowledge comes from snippets in individual texts, unfortunately, it's not all collected into one volume.)
  - hilbert42 4y ago
    Later.... I already have a downloaded version and I like very much what I see. Soon I'll have a hardcopy. Still not sure how I missed this given its prominent position amongst texts on the subject. Anyway, glancing through the book pretty much at random I've seen many phrases that tickle my fancy and pique my interest. For instance, take the 2nd para on p151 wherein he's discussing Newton's Laws of Motion and force, it's pretty hard to stop reading a paragraph that begins "It is a curiously ironical development of history that,....". Further down the same page when discussing gravity he makes a very straightforward statement but with a twist: "Thus, the laws of gravitation can be expressed as follows: Two bodies suffer a mutual acceleration, in the direction of the line adjoining them, which is inversely proportional to the square of the distance between them." Here, 'suffer' conjures up the notion of imposition - of gravity imposing an acceleration on bodies which otherwise wouldn't be the 'natural' order of things. Had he used words like 'experience' or 'influence' it wouldn't have been nearly as effective writing. From the little I've read so far I note the way he writes forces me to think laterally, in effect he's forcing me to perceive things from a different perspective. In fact, I'm already half way through Chapter 8, An Attempt to Build a Physical Picture of the Quantum Nature of Matter, as it's a breeze to read it's so well written - it's not only informative but also entertaining which is a rare quality for a physics textbook. Mind you, that's an easy chapter as there's not an integral sign to be seen anywhere. ...But I note they're not forgotten, they reappear in great abundance in Chapter 9! :-) It's excellent stuff, thanks again for the info.
- uoaei 4y ago
  > he often gets 'eggs' chucked at him for his Pilot Wave interpretation of QM The funniest part of all that is, Bohm's pilot wave theory isn't even wrong. It's one possible interpretation of many, and definitely isn't falsified yet (none of the others are, either), though it does carry some unsettling implications if it happens to be accurate, most notably that it is predicated on determinism, which is probably most of the reason why it's been marginalized. Aside from, of course, the Copenhagen fiasco.
  - hilbert42 4y ago
    The funniest part of all that is, Bohm's pilot wave theory isn't even wrong. It's one possible interpretation of many,... First, everything I've read and learned about Bohm tells me I would have liked the man had I ever met him - even the well-known portrait photo of him hints at his maverick nature. We need more troublemakers in science and physics to stir up the orthodoxy. :-) Second, I rather like the Pilot Wave theory despite, as you say, its unsettling implications. It sort of makes sense to my simple mind. I don't consider myself sufficiently expert to say how much leeway there is in the theory but I'll say this, others such as Many Worlds seem somewhat even more incredulous to my mind (despite Carroll's eager proselytizing the cause), but I'm open enough to be convinced come more evidence. Re Copenhagen, yeah it's a 'fiasco' even though it works. Had I had sufficient brains and been around at Solvay I'm damned sure I would have had arguments with Bohr. Despite Bell, the EPR Paradox mob were onto something, at least they didn't take 'no' for an answer, similarly so with Bohm. Intelligent-thinking dissenters are good for physics.
    - uoaei 4y ago
      Many Worlds Interpretation suffers from a more catastrophic and incredibly strong assumption, namely that all of the possible universes are real. That seems far-fetched on its face, though could still in principle be possible I suppose. Quantum Bayesianism ("QBism") softens the strong claims about reality to merely those about subjectivity, i.e., you cannot know that which cannot be represented by the configuration space of your lightcone. In other words, possible futures are possible only when there is an unbroken causal chain from your present to that future, and you will be ignorant of anything outside of your lightcone. It stresses the uncertainty inherent in a singular perspective of spacetime's unfolding, rather than an uncertainty of some mythical "wavefunction collapse mechanism".

hilbert42 4y ago

David Bohm is an interesting physicist, he often gets 'eggs' chucked at him for his Pilot Wave interpretation of QM but that shows he was a lateral thinker trying to find an explanation for one of physics' most intractable problems. But he was no lightweight either as we've seen with his work on the Aharonov–Bohm effect. That said, I'm ashamed to say I've not had a copy of his book Quantum Theory in my hands. You're one of many I've seen mention it in recent times so I'll have to remedy that. :-) Incidentally, I have read the original Aharonov–Bohm paper. Understanding that physics I reckon is crucial to getting a good handle on EM, potentials, etc.

capn_duck 4y ago
I'd strongly recommend it! I think it's worth the price of admission for the first few chapters alone, although I admit that at a certain point, I was struggling to keep up with all of the mathematical arguments as I am not a trained physicist. But I was able to keep up by hand through all of the thermodynamic, electromagnetic, and statistical mechanical arguments of the black box portion. But the first few chapters are so conversational and grounded in historical context that it's a real joy to read, even if you're not following along on pen and paper through all of the steps. If you know of any other "must reads" of the 20th century like this, please let me know! I love to hear the arguments presented as they were actually discussed at the time, not just what was settled on as the end result a century later.
- hilbert42 4y ago
  Ah, damn, that's enough, I'm ordering a copy of it now. Thanks! Edit: I've always considered this historical context most important and we do not stress it enough in teaching physics (same in math and chemistry or in just about every subject that has developed and progressed over the years - 19th C. scholars translating ancient Greek texts for instance). As far as far as is possible, we need to get inside the heads of these people and try to picture the obstacles and difficulties they were facing at the time. Moreover, it's my experience that if I try to understand where they are coming from then I find that I get a much deeper appreciation (and better understanding) of the subject. Similarly, old scientific and engineering textbooks of the era are very useful in further illuminating this historical thinking; for example, 19th C. postulations about how the sun got its energy before we knew anything about nuclear fusion. That said, it seems we largely ignore this historical context because it is hard to do well and that most courses are already short of time. Still, if any subject needs it, it's QM and I've said so here on HN and elsewhere on many occasions: https://news.ycombinator.com/item?id=31980008 https://news.ycombinator.com/item?id=31980008. Big warning, here I'm in long-rave mode! Re: other good reads on the subject, at short notice I'm at a bit of a loss. Your best bet are textbooks on HPS - History and Philosophy of Science (which was one of my subjects decades ago). The trouble is comments on this topic soon time out, so in future when I think of them I won't he able to update you. (Much of my knowledge comes from snippets in individual texts, unfortunately, it's not all collected into one volume.)
- hilbert42 4y ago
  Later.... I already have a downloaded version and I like very much what I see. Soon I'll have a hardcopy. Still not sure how I missed this given its prominent position amongst texts on the subject. Anyway, glancing through the book pretty much at random I've seen many phrases that tickle my fancy and pique my interest. For instance, take the 2nd para on p151 wherein he's discussing Newton's Laws of Motion and force, it's pretty hard to stop reading a paragraph that begins "It is a curiously ironical development of history that,....". Further down the same page when discussing gravity he makes a very straightforward statement but with a twist: "Thus, the laws of gravitation can be expressed as follows: Two bodies suffer a mutual acceleration, in the direction of the line adjoining them, which is inversely proportional to the square of the distance between them." Here, 'suffer' conjures up the notion of imposition - of gravity imposing an acceleration on bodies which otherwise wouldn't be the 'natural' order of things. Had he used words like 'experience' or 'influence' it wouldn't have been nearly as effective writing. From the little I've read so far I note the way he writes forces me to think laterally, in effect he's forcing me to perceive things from a different perspective. In fact, I'm already half way through Chapter 8, An Attempt to Build a Physical Picture of the Quantum Nature of Matter, as it's a breeze to read it's so well written - it's not only informative but also entertaining which is a rare quality for a physics textbook. Mind you, that's an easy chapter as there's not an integral sign to be seen anywhere. ...But I note they're not forgotten, they reappear in great abundance in Chapter 9! :-) It's excellent stuff, thanks again for the info.
uoaei 4y ago
> he often gets 'eggs' chucked at him for his Pilot Wave interpretation of QM The funniest part of all that is, Bohm's pilot wave theory isn't even wrong. It's one possible interpretation of many, and definitely isn't falsified yet (none of the others are, either), though it does carry some unsettling implications if it happens to be accurate, most notably that it is predicated on determinism, which is probably most of the reason why it's been marginalized. Aside from, of course, the Copenhagen fiasco.
- hilbert42 4y ago
  The funniest part of all that is, Bohm's pilot wave theory isn't even wrong. It's one possible interpretation of many,... First, everything I've read and learned about Bohm tells me I would have liked the man had I ever met him - even the well-known portrait photo of him hints at his maverick nature. We need more troublemakers in science and physics to stir up the orthodoxy. :-) Second, I rather like the Pilot Wave theory despite, as you say, its unsettling implications. It sort of makes sense to my simple mind. I don't consider myself sufficiently expert to say how much leeway there is in the theory but I'll say this, others such as Many Worlds seem somewhat even more incredulous to my mind (despite Carroll's eager proselytizing the cause), but I'm open enough to be convinced come more evidence. Re Copenhagen, yeah it's a 'fiasco' even though it works. Had I had sufficient brains and been around at Solvay I'm damned sure I would have had arguments with Bohr. Despite Bell, the EPR Paradox mob were onto something, at least they didn't take 'no' for an answer, similarly so with Bohm. Intelligent-thinking dissenters are good for physics.
  - uoaei 4y ago
    Many Worlds Interpretation suffers from a more catastrophic and incredibly strong assumption, namely that all of the possible universes are real. That seems far-fetched on its face, though could still in principle be possible I suppose. Quantum Bayesianism ("QBism") softens the strong claims about reality to merely those about subjectivity, i.e., you cannot know that which cannot be represented by the configuration space of your lightcone. In other words, possible futures are possible only when there is an unbroken causal chain from your present to that future, and you will be ignorant of anything outside of your lightcone. It stresses the uncertainty inherent in a singular perspective of spacetime's unfolding, rather than an uncertainty of some mythical "wavefunction collapse mechanism".