[HN Gopher] The Ultraviolet Myth
___________________________________________________________________
The Ultraviolet Myth
Author : Luc
Score : 167 points
Date : 2024-02-12 15:11 UTC (7 hours ago)
(HTM) web link (www.arxiv.org)
(TXT) w3m dump (www.arxiv.org)
| tremarley wrote:
| Quantum physics: where the only certainty is that even scientists
| are uncertain, but don't worry, nobody understands it, not even
| the scientists themselves!
| zamadatix wrote:
| This is about misunderstanding purely of history, the actual
| derived physics are not mistaken in either version of the tale.
| alecst wrote:
| It's so interesting. This isn't the only paper written about
| this, because I actually came across this same idea last month in
| a much older paper. Here's an extract from it:
|
| > It might have been thought, by some scientists in the 1890's,
| that refined mathematical analysis of this kind would play a role
| in resolving the fundamental problems of classical physics
| associated with the apparent failures of the equipartition
| theorem. But that is not what happened.
|
| > Although the quantum hypothesis did dispose of the paradox of
| specific heats of polyatomic gases, and eliminated the
| possibility that ether-vibrations (having an infinite number of
| degrees of freedom) would drain an indefinite amount of energy
| out of material systems at any finite temperature, these were not
| the anomalies that provoked the introduction of the quantum
| hypothesis in the first place. Max Planck was not one of the
| physicists who worried about the validity of the equipartition
| theorem before 1900, and the myth that his distribution law for
| blackbody radiation was concocted merely to escape from an
| "ultraviolet catastrophe" predicted by the Rayleigh-Jeans law has
| now been thoroughly demolished. It was Paul Ehrenfest who
| invented the ultraviolet catastrophe (eleven years after the
| publication of Rayleigh's and Planck's papers in 1900) in order
| to dramatize what would have been the consequences of the
| equipartition theorem if it had been valid for all classical
| dynamical systems (though neither Rayleigh nor Planck believed
| that it was).
|
| I have this saved as a note, but can't find the exact source atm.
| Here's another source though, from the 60s:
|
| https://sci-hub.ru/https://doi.org/10.1007/BF00327765
| crdrost wrote:
| I would be very interested to read this. I found one comment in
| the abstract a little bit off-putting:
|
| > Planck did not consider this a quantization, but merely a
| mathematical trick to be able to calculate the entropy of the
| oscillators.
|
| My understanding was that Planck absolutely understood that his
| approach _would have been_ a mathematical trick _if_ he took
| the limit _h_ - 0, but that in stopping at a nonzero small
| number he was explicitly aware that he was saying something
| peculiar about the energies in the system, and had strayed far
| away from that realm of pure mathematics into something that we
| would today effortlessly identify as quantum, even if that word
| did not exist at the time.
| lumost wrote:
| Often, when inventing something new - it can be difficult to
| assess how novel the "new" thing is. Particularly when there
| isn't yet a word for it. Planck may have simply believed that
| this hinted towards something equivalent of an "atom" of
| light. Atom's were after all a relatively recent discovery in
| 1827, why couldn't you have an atom-like construct for light?
| and why would light atoms be any different regular atoms?
|
| While we now know a great deal about this topic - placing
| such speculation in a paper would be problematic.
| Hypothesizing that such quantizations are common for other
| quantities would be even more problematic.
|
| EDIT: Removed eroneous mention of michelson-moorly instead of
| milikan oil drop experiment.
| DiogenesKynikos wrote:
| I think you mean the Millikan oil drop experiment.
| tangj wrote:
| ... Since Michelson-Morley was supposed to show the
| relative speed of the Earth through the ether, but
| instead showed there was no ether at all.
| lumost wrote:
| :doh: good catch :facepalm: it's been too long since
| physics undergrad.
| alacritas0 wrote:
| Even though this is tangential, I think it's important to
| note that this experiment should be called as the
| Millikan-Fletcher oil drop experiment to acknowledge
| Harvey Fletcher's contribution to this experiment as a
| grad student which he was coerced into relinquishing to
| receive his PhD
| Sharlin wrote:
| The question of whether light is a particle or a wave dates
| back to at least Newton (who thought it was a particle) and
| Hyugens (who thought it was a wave). By the end of the 19th
| century, before Einstein brought up the photoelectric
| effect, the consensus opinion was pretty firmly on the
| "wave" side of the dispute, and apparently Planck was not
| an outlier. See another comment:
| https://news.ycombinator.com/item?id=39349027
| btilly wrote:
| Yet another example where it is tempting to retrofit a modern
| understanding onto a historical debate. We're tempted to do this
| because when you're embedded to the modern worldview, it is hard
| to remember that others were once possible. And it is tempting to
| believe that history was a straight arrow to modern truths. In
| fact it was seldom such a straight path.
|
| Kuhn complained about this in _The Structure of Scientific
| Revolutions_. When trying to teach the history of science to
| scientists, you have to work to get them to stop trying to think
| the "correct" way, so that they can understand the actual
| historical debate.
| bee_rider wrote:
| I wonder if it might be pop-sci vs science, rather than modern
| vs historical.
|
| Physicists (from the outside at least) have always seemed more
| like hunters than the town watch, they go looking for the
| problems. There isn't some catastrophic looming threat of
| physics approaching that they have to deal with, haha.
| Unexplainable data is an opportunity and all that.
| btilly wrote:
| What I'm talking about is very much modern vs historical.
|
| To take a trivial example, most of us would like to draw a
| straight line from Darwin writing _The Origin of the Species_
| to the current acceptance of his theory of evolution. We have
| no particular desire to follow how Darwin 's work inspired
| Francis Galton to study heredity. Unfortunately Galton
| discovered regression to the mean when he did. Further
| experiments undermined Darwin's theories as it uncovered
| evidence for "natural types". The result was that a half-
| century after Darwin's great book, many scientists doubted
| Darwin's theories.
|
| But then R. A. Fischer managed to explain the mess with
| population genetics based on Mendel's theories. "Natural
| types" disappeared from the literature, and Darwin was back.
| Today Galton is likely to be remembered as a dilletante who
| invented the idea of eugenics. And Fischer as a genius in
| statistics. We retrofit a story with heroes (Darwin and
| Fischer) and villains (Galton). We skip over the bad parts,
| and focus on the good.
|
| In the process we forget that Darwin also took it for granted
| that blacks must be inferior to whites. And that Fischer was
| also a supporter of eugenics. And that Galton set out to
| confirm Darwin, then accepted the data that he encountered.
|
| We want a story, not a mess. But history is full of messes.
| Arranging the right ideas in the right ways involved a whole
| lot of trial and error that wasn't obvious at the time. While
| some of us enjoy learning about the history, it actually
| isn't very helpful for scientists. Because there is little
| point in learning every wrong idea that people used to hold,
| only to immediately learn that you can forget it again
| because it was wrong.
|
| But while that exercise does not help us learn what is
| currently known, maybe it can help give us more humility
| about what it is we think we know today?
| CamperBob2 wrote:
| _Because there is little point in learning every wrong idea
| that people used to hold, only to immediately learn that
| you can forget it again because it was wrong._
|
| Of course there's a point, one you suggest yourself. "If
| great scientists like Darwin could be wrong about X, is
| there a chance that I'm wrong about Y?"
| btilly wrote:
| That point can be reached with a relatively small amount
| of history. Nobody could possibly learn all of it.
| csours wrote:
| One could easily adopt the idea that the history of science is
| "Some smart guy figured this out" over and over again.
|
| The real history of science is: A lot of people became
| interested in problems and worked on theory and test apparatus
| and put their ideas into public discussion and eventually and
| sometimes suddenly we developed narratives and equations that
| explain observations. Along the way there was a lot of
| contention and conflict.
| btilly wrote:
| It is easy to retrofit many simple stories onto science.
|
| In this case the "smart guy who figured it out" usually
| didn't understand the discovery in the same way that we do
| today. Something was figured out, but typically not in the
| modern glory that we explain it with today.
| leephillips wrote:
| The equations don't just congeal out of the air, no matter
| how many people are thinking about the problems. They are
| indeed the results of some smart people figuring things out.
| sgdpk wrote:
| To be fair, I was taught exactly what this paper claims in my
| Physics degree. Although I was also taught what they call the
| "myth" in other classes.
| pdonis wrote:
| I was never taught the myth in an actual class. Every time I
| have seen it has been in the context of a pop science article
| or book.
| Sesse__ wrote:
| Seemingly also the Wikipedia article
| (https://en.wikipedia.org/wiki/Ultraviolet_catastrophe)
| claims the pop-sci ordering: "As the theory diverged from
| empirical observations when these frequencies reached the
| ultraviolet region of the electromagnetic spectrum, there was
| a problem.[3] This problem was later found to be due to a
| property of quanta as proposed by Max Planck: There could be
| no fraction of a discrete energy package already carrying
| minimal energy."
| josh-sematic wrote:
| Agreed; my professors did use Planck's trick to introduce
| quantization, but made it very clear that he was just fitting
| the data and thought the discretization would disappear with
| further analysis.
| adtac wrote:
| Douglas Hofstader has a talk on this topic called "Albert
| Einstein on Light; Light on Albert Einstein" that I often
| revisit: https://www.youtube.com/watch?v=ePA1zq56J1I (watch 10:30
| to 12:00 if you're pressed for time, but I recommend the whole
| thing)
| agonz253 wrote:
| Indeed. I recommend also checking out the 2nd volume of
| Einstein's collected papers. There is one with the proceedings
| from a conference on the subject, and Einstein is basically
| alone in trying to convince his peers, including Planck, of the
| reality of "quanta" of light, independent of the process of
| emission and absorption or mathematical tricks.
| fsmv wrote:
| This video talks about this story and in particular acknowledges
| that it was called the ultraviolet catastrophe after Plank
| https://youtu.be/gXeAp_lyj9s
| DrDroop wrote:
| I wanted to post the same thing, quiet a coincidence I watched
| it yesterday.
| SKCarr wrote:
| Seems to have come out one day before this paper was
| submitted, which is quite a coincidence.
| csours wrote:
| In which a more satisfying story "beats" the messiness of true
| history.
| bjornsing wrote:
| I have a masters degree in physics from a Swedish university, and
| I don't think I've ever heard the "myth".
|
| But the actual story as described in the paper is vaguely
| familiar. Before reading it my mind wandered to Einstein and
| quantization of light.
|
| Is this mainly a US myth perhaps?
| pif wrote:
| Same here, Italian background.
| bowsamic wrote:
| We were taught this myth in the UK
|
| EDIT: both at high school and across multiple different
| lecturers at university
| bananskalhalk wrote:
| I was taught this in a Swedish high school and it was repeated
| at a Swedish university one year later.
| BoardsOfCanada wrote:
| Same here as for at Swe university
| bananskalhalk wrote:
| Added:
|
| Please not that the authors are Norwegian at a Norwegian
| university, and the first citation are "KVANTEFYSIKKENS
| UTVIKLING i fysikklaereboker, vitenskapshistorien og
| undervisning" by Reidun Renstrom at the University of Oslo,
| all proclaiming the myth being perversive.
|
| I would be careful proclaiming this being some kind of
| American phenomenon.
| BeetleB wrote:
| Same here. Studied it in 2 different countries, and it was
| always presented as "trying to explain black body radiation". I
| think UV catastrophe was merely mentioned as a side note.
| redavni wrote:
| It has been repeated by YouTube "science communicators" quite
| frequently and very recently.
| dr_dshiv wrote:
| It might not be historically accurate, but it's easy and
| valuable to learn
| smcin wrote:
| Since we're on that beat, do we really believe an apple
| fell _on Isaac Newton 's head_?
|
| Rather than merely that he saw an apple fall nearby, and
| wondered why it fell downwards.
| bgirard wrote:
| It's very common on Youtube physics education videos. My take
| away from was exactly what the article states. That the
| ultraviolet catastrophe was observed and that the study of it
| lead to Quantum physics because it was noted that it could only
| be explained if things existed in discrete energy levels.
| jerf wrote:
| I'm not even entirely sure the article establishes that it
| was false. The wrong equations really had a problem with an
| ultraviolet catastrophe. If the physicists of the time don't
| seem to be running around panicking about that, it's because
| equations not being entirely correct as they are in the
| process of being refined was even by then a relatively
| mundane thing, obviously part of the process.
|
| We (hopefully) historically stand in a similar position with
| regard to General Relativity and Quantum Mechanics. We know
| they don't go together. We don't know what the correct answer
| is. It's an understood problem. But it's not like physicists
| spend their days running around and shrieking and breaking
| down into tears about it, and in the meantime, we get on with
| using GR & QM to predict things.
|
| It may be too strong to say "Physicists observed this issue
| with the equations and their freakout about them directly led
| to quantization." But it was a real problem with the
| equations, and it's certainly related to what led to
| quantization, and if the story glosses over yet another
| instance of what a physicists perceived as a mathematical
| convenience that turned out to be quite physically real, I'm
| not sure that's a vital detail for every high school student.
| twoodfin wrote:
| Is it possible there's some confusion here about the
| understanding (then and now) of "catastrophe"?
|
| As I understand, it wasn't meant to mean that the theory
| had a catastrophic flaw, but rather that the infinite
| energy implied at the asymptote itself represented an
| (obviously unobserved, thus curious) physical catastrophe.
|
| I agree with your characterization that an unresolved
| catastrophe of the latter kind does not imply a crisis of
| science the way an unresolved "catastrophe" of the former
| kind might.
| jerf wrote:
| Could be. My understanding of the term is the same as
| yours, but reading it the wrong way would fit the facts,
| and I have to admit in general I can't be _too_ critical
| of such a reading. The physics sense of "catastrophe" in
| use here is pretty obscure; I'm not sure I can think of
| another instance of it I've come across in English.
| Nevermark wrote:
| "Catastrophe" or "crisis" have a long history of use for
| sudden change phenomena, especially associated with some
| major failure or blow up of a previous pattern of system
| behavior.
|
| "Critical" may be a more familiar word used in similar
| contexts, honed in on a specific threshold of a dramatic
| behavior change.
|
| None of these words in this usage style refer to the
| scientific social process, but to the phenomena.
| ThrowawayTestr wrote:
| There's a whole Wikipedia page for it:
| https://en.wikipedia.org/wiki/Ultraviolet_catastrophe
| littlestymaar wrote:
| There are millions of "whole wikipedia pages" for things most
| poeple will never hear of in their life...
| f1shy wrote:
| So was explained to me in another non us university. We used
| books used in MIT, Caltech and Stanford; in all books there was
| a mention to it.
| kurthr wrote:
| I've seen many mentions of the Ultraviolet Catastrophe, but I
| don't remember reading that it directly caused Plank to look
| for (a quantized) solution. That seems like a historical
| justification that a QM physics class doesn't need. I looked
| through both Liboff and Baym and don't see even a mention of
| ultraviolet (other than problem sets) or catastrophe, but
| maybe I missed it. These are searchable.
|
| https://archive.org/stream/LIBOFFIntroductoryQuantumMechanic.
| ..
|
| https://archive.org/details/lecturesonquantu0000baym/mode/2u.
| ..
|
| I don't think the Mechanical Uselessverse (as we referred to
| it) would be a text for these schools, thought it was
| produced at caltech and it apparently does refer to the
| ultraviolet catastrophe. I think you're more likely to find
| it in videos and narrative historical materials where story
| is more important.
|
| https://archive.org/details/beyondmechanical0000olen/mode/2u.
| ..
| prof-dr-ir wrote:
| This paper is nice but appears to stretch its result quite a bit.
|
| First, the authors make a general claim about "most physics
| textbooks" without providing a single example. I think one will
| often encounter more nuanced statements in the better and more
| widely used textbooks.
|
| And I think the paper sorely lacks evidence for the general claim
| in the concluding sentence: "The idea that physics progress
| through a series of crisis, is hard to defend." Not only do they
| present only a single example, but even in that case one could
| claim that the "crisis" started _after_ the discovery of Planck
| 's formula! After all, it fitted the data supremely well but
| required this mystery constant: h.
|
| It took physicist a quarter century to resolve the deeper meaning
| of Planck's constant. If that was not a crisis in physics then I
| do not know what would qualify as one.
| alacritas0 wrote:
| i wouldn't consider a quarter century of work by the field a
| crisis
| littlestymaar wrote:
| > to defend." Not only do they present only a single example
|
| Really? When there Mercury's perihelion mystery at the exact
| same period? (Which got us general relativity)
| alecst wrote:
| It's not a stretch at all in my opinion, not only was I taught
| this myself (multiple times at two separate universities in the
| US) but there was a paper addressing this myth as far back as
| the 60s.
|
| Though I do agree with your second point. I can name two crises
| off the top of my head: the black hole information paradox, and
| the galaxy rotation curves which some claim are due to dark
| matter. One is a major theoretical problem, and the other is a
| major experimental problem. And though crises they may be, it's
| not like people are running around with their hair on fire.
| d0mine wrote:
| There is a crisis in cosmology right now e.g., the apparent
| conflict in our measurements of the expansion rate of the
| early versus the modern universe. https://youtube.com/playlis
| t?list=PLd19WvC9yqUf5TRqYoMYxEwjT...
| btilly wrote:
| I have no idea about current textbooks. But certainly the
| physics textbook that I learned from quoted the myth. And it is
| easy to find examples online, like https://chem.libretexts.org/
| Bookshelves/Physical_and_Theoret..., that still do.
|
| I wish it were otherwise, but there are some weird dynamics in
| the textbook industry that reward looking like other textbooks
| more than accuracy and usefulness.
|
| A classic essay showing this is "The Case of the Creeping Fox
| Terrier Clone" in Gould's book _Bully for Brontosaurus " that
| traces the history of textbooks comparing _Hyracotherium* to a
| fox terrier. This, despite the fact that most students and
| authors have absolutely no real idea how big a fox terrier is.
| And it wouldn't help if they did know, given that
| _Hyracotherium_ actually weighed over twice as much!
|
| Another classic essay showing how textbooks repeat other
| textbooks without properly questioning what should be taught is
| https://web.williams.edu/Mathematics/lg5/Rota.pdf. If you've
| taken some variant of the differential equations course that he
| discusses, I highly recommend reading his essay. I guarantee
| that it is far from the only standard course with such levels
| of silliness.
| ilya_m wrote:
| > Another classic essay showing how textbooks repeat other
| textbooks without properly questioning what should be taught
| is https://web.williams.edu/Mathematics/lg5/Rota.pdf. If
| you've taken some variant of the differential equations
| course that he discusses, I highly recommend reading his
| essay. I guarantee that it is far from the only standard
| course with such levels of silliness.
|
| Thank you for sharing Rota's delightful lecture! I wish more
| professors/instructors took a critical look at their
| material, which is nearly always is taught in the order that
| was put in place for some now utterly irrelevant or forgotten
| reasons. If the science progresses at the speed of the
| hearse, the education of scientific subjects barely moves at
| all.
| f1shy wrote:
| I do not think calling out specific books would be remotely
| good idea in many different levels. There are ao many examples,
| it makes no sense to enumerate any. Virtually every explanation
| I know starts with that myth.
| bmacho wrote:
| Why do you think that?
|
| I think naming 3 of them would be better than naming 0 of
| them.
| _dain_ wrote:
| I don't have a textbook at hand but I remember being taught
| this history by physics lecturers in my undergrad.
|
| I find it strange that many people in this thread are
| gainsaying the existence of this narrative. It's surely a
| commonplace part of physics education?
| vondur wrote:
| My Physical Chemistry textbook also refers to it as the
| UltraViolet Catastrophe.
| pflats wrote:
| I was curious, so I grabbed three undergraduate-level physics
| texts I had nearby.
|
| One explicitly recites the Ultraviolet Catastrophe prompted
| Planck story, complete with Rayleigh's incomplete formula.
|
| One essentially matches the story in section 2, using the
| lesser version of Rayleigh's formula, but (just like the story)
| does not explicitly tie Planck's work to it. (That textbook
| notes "an act of desperation" is a quote from one of Planck's
| letters.)
|
| The third one is interesting! It says that "late nineteenth
| century physicists tried to understand the shape of the
| blackbody spectrum [...] using their knowledge of
| thermodynamics and electromagnetic waves. Their efforts ended
| in failure." This third text never mentions Rayleigh by name
| and doesn't specifically show "Rayleigh's Lesser Formula", but
| it does graph that formula vs. the observed blackbody radiation
| (interestingly, as a function of frequency instead of
| wavelength).
|
| The text then eventually says that in 1900, Planck used a
| photon argument "to make a theoretical prediction that is in
| excellent agreement with the experimental spectrum". It does
| not explicitly state cause and effect, but it's kinda implied
| from the structure of the writing.
|
| Reading into the third text a smidge, it feels like the result
| of wanting to use the Rayleigh/Catastrophe story and yet
| knowing it wasn't quite true.
| stracer wrote:
| The third source is still wrong, as Planck certainly would
| not agree that he used the photon argument to make a
| prediction. He tried to explain the experimental data on
| blackbody radiation, which manifested the spectral peak, and
| an agreement with the Rayleigh-Jeans and Wien laws in the two
| frequency limits. Thus not a prediction, but an explanation
| of the observed thing.
|
| And he did not believe in photons, he interpreted his work in
| terms of classical EM radiation obeying some entropy
| condition, and quanta of energy that he used were considered
| either a math trick to make calculations with that entropy,
| or a condition on the emission process only in his later
| theories. He never assumed or believed that EM radiation
| consists of quanta.
| smcin wrote:
| Useful to give the title, author, and date of those three
| texts.
| cyberax wrote:
| Realistically, the UV catastrophe was not a crisis. Simply
| because pretty much nobody understood its implications. It was
| like: "Quantization of light makes this formula work? OK,
| whatever".
|
| At that time, the main catastrophe was caused by the null
| results in the search for the luminiferous aether (Michelson-
| Morley experiments).
|
| At the same time, questions about the structure of matter and
| the composition of the atom were another crisis point.
| Earnshaw's theorem states that matter can't be held together by
| electromagnetic forces alone.
| adrian_b wrote:
| Besides the myth busted in this paper, that the actually later
| work of Rayleigh could have influenced Planck, there is another
| incorrect myth, that Planck has introduced the "constant of
| Planck" in his publication from 1900, where he presented the
| deduction of the Planck formula from the supposition that the
| emission and absorption of electromagnetic radiation are
| quantized.
|
| This frequently seen claim is also wrong. Planck has introduced
| the constant of Planck and he has also computed its value with
| excellent precision for that time (4% relative error) in an
| earlier work published in 1899:
|
| Max Planck, "Ueber irreversible Strahlungsvorgaenge",
| "Sitzungsberichte der koeniglich preussischen Akademie der
| Wissenschaften zu Berlin. Jahrgang 1899", pp. 440-480.
|
| There Max Planck has presented deductions of the formulae
| previously established by Wien for the blackbody radiation, where
| he replaced the empirical constants of Wien with functions of
| other universal constants and of the new universal constant
| introduced by him.
|
| Already Maxwell, a quarter of century earlier, had shown that it
| is possible to determine the units for all physical quantities
| with a single arbitrary choice (in his example, the wavelength of
| the yellow light emitted by sodium vapor).
|
| In 1899, Planck has shown that the law of blackbody radiation
| provides an additional relationship between the units of length,
| time and energy, which, together with the previous relationships
| considered by Maxwell, can determine the units of all physical
| quantities without any arbitrary choice.
|
| So at the end of this work from 1899, where the constant of
| Planck has been introduced, he has also presented the system of
| natural units known now as the Planck units.
|
| Nevertheless, the system of Planck units cannot be used as the
| base of a practical system of units, because the uncertainty of
| measuring the Newtonian constant of gravitation is huge. This
| makes useless one of the equations that connect the units of
| length, time and energy.
|
| Because of that, any practical system of units must contain a
| single arbitrary choice of a unit, which in the case of SI is the
| frequency of a certain hyperfine transition of the cesium-133
| atom, while all the other units result from this choice by
| adopting conventional values for the universal constants, except
| for the Newtonian constant of gravitation, which must be measured
| experimentally (some constant determining the intensity of the
| electromagnetic interaction, e.g. the fine structure constant,
| must also be measured experimentally, but for that the
| uncertainty is extremely low).
|
| BTW, another extremely frequent incorrect claim about the
| constant of Planck is that it is a quantum of action. This is
| very wrong, it is a quantum of angular momentum (the ratio
| between energy and frequency is an angular momentum, like also
| the ratio between their integrals, i.e. between action and plane
| angle). The origin of the mistake is the fact that many follow
| the suggestions of the recent SI brochures (there was a
| resolution adopted by vote that the unit of plane angle is not a
| base unit, which is equivalent with establishing by vote that 2 +
| 2 = 5), and they omit the unit of plane angle in the dimensional
| formulae, in which case it appears that the unit of action is the
| same with the unit of angular momentum, but they are not the
| same, as any attempt to change the unit used for plane angles
| would demonstrate, e.g. between radians and degrees or cycles.
|
| The original constant of Planck corresponds to plane angles
| measured in cycles, while the so-called h bar is the same
| constant converted to correspond with plane angles measured in
| radians.
| sho_hn wrote:
| As a physics layman, I learned his part of history from the book
| "Quantum" by Manjit Kumar, which as far as I can tell got the
| Planck bit right and covered his black body work correctly, FWIW.
|
| It was a good read.
| kazinator wrote:
| > _many of the stories that have become central to the physics
| lore are mere pseudo-histories far detached from the real events_
|
| But, like, you know how Newton discovered gravity when an apple
| fell on his head? Totally true, pinky swear!
| demondemidi wrote:
| Funny I spent Sunday afternoon watching youtubers talk about this
| and they all pretty much said that the catastrophe predated
| Plank's corrections (or caused them). Is this wrong, or is it
| just pedantic?
|
| Most importantly, is the wikipedia page correct:
|
| https://en.wikipedia.org/wiki/Ultraviolet_catastrophe
| lowbloodsugar wrote:
| Never heard of this, despite a physics degree. Is this what
| happens after social media is invented and all sorts of bullshit
| is spread as fact?
| wiml wrote:
| No, I was taught this at least twice before social media became
| a thing.
| mcnamaratw wrote:
| https://en.wikipedia.org/wiki/Rayleigh-Jeans_law
| photochemsyn wrote:
| Pedagogically, this is an argument against teaching physics using
| the historical development model. You end up with post hoc
| arguments and simplified narratives, and I think it it just makes
| life harder for undergraduate students. Maybe 'history of
| science' should be its own subject?
|
| Some textbooks (e.g. Molecular Quantum Mechanics, Atkins &
| Friedman) take a more nuanced view. They present failures of
| classical calculations of the heat capacity of solids near
| absolute zero side by side with blackbody radiation:
|
| > "Einstein recognized the similarity between this problem and
| black-body radiation, for if each atomic oscillator required a
| certain minimum energy before it would actively oscillate, then
| at low temperatures some would be inactive and the heat capacity
| would be smaller than expected."
|
| Debye improved the theory by allowing atoms to oscillate with
| different frequencies. So looking back, one can say matter
| appears to be quantized, and this shows up at low temperatures,
| and radiation appears to be quantized, and this shows up at high
| frequencies - which is a nice symmetric argument, visible in
| hindsight, that probably helps students grasp the concept of the
| quantized harmonic oscillator (and why they need to learn about
| it).
|
| One major development was Bose deriving Planck's radiation law
| using quantum statisical arguments (and no classical physics),
| with further development by Einstein c. 1924 - but this might be
| a difficult place to start from, teaching-wise.
|
| https://en.wikipedia.org/wiki/Bose%E2%80%93Einstein_statisti...
| stracer wrote:
| This particular part of "physicist's history of physics" about
| quantization and Planck's work, promulgated by some sources, is
| well-known to be a false account of history and motivations, and
| has been criticized in mainstream literature before, e.g. by
| Helge Kragh [1] (and probably by many others). The present
| authors apparently are not aware of this, which makes me
| suspicious that they did not do their homework on this topic...
|
| [1]
| https://dept.math.lsa.umich.edu/~krasny/math156_article_plan...
| lewtun wrote:
| The myth is also promoted in Chapter 3 of The Making of the
| Atomic Bomb by Richard Rhodes:
|
| > Plank had taught at Berlin since 1889. In 1900 he had proposed
| a revolutionary idea to explain a persistent problem in
| mechanical physics, the so-called ultraviolet catastrophe
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