KZfaq must think very highly of me.

This is a superb, highly detailed account of a topic that is usually glossed over. There are far too many videos on youtube that 'pretend' to explain a topic, but ultimately leave you feeling empty because they have explained nothing. This is the first time that I have seen (and understood) a detailed derivation of the ultraviolet catastrophe and Max Planck's route to a solution. Genius. Thank you for taking the time to make this video.

The Ultraviolet Catastrophe sounds like a band from the 60s.

"Theoretical physicists wanted more" They always do.

It’s unbelievable that most text books skip over the detailed math behind the ultraviolet catastrophe. For gods sake this is the origin of quantum mechanics. This is similar to Newton’s observation that apple falls, or Einstein’s derivation of consequences caused by the constant speed of light. You can’t just say speed of light is constant, then something is wrong, therefore time slows down when speed is up. The details are extremely important. Because this detail is skipped, I had the feeling that quantum mechanics is dropped out of nowhere for a long time.

Would have loved to have seen Plancks "Holy Fook!" expression when he first plotted his function and found it matched experiment.

Why am I understanding this... where were you when I was in physics class. You are brilliant!

I thought KZfaq was going to give me some historical background noise that I could relax to and learn about. What I got instead was mini PTSD back to my days of getting a B.S. in Math, where I had feelings of "Oh, I think I get it." and "Wait, could you back up and explain that whole thing again?" and also "Wait, how did you get that equation?". It's like hanging onto a pole for dear life while a tornado barely misses you on it's path of destruction, your house is gone and you got a broken leg or two, but you're still alive. Alternatively, it's like getting shitfaced at a club and being sober enough to get home, but there's puke in your pockets and you'll never fully remember what questionable things happened that night. All this writing and similes aside, I enjoyed watching this video despite the migraine, hunger, and the feelings of loss and confusion that ensued afterward. Good shit, buddy.

Many here will probably know that when Planck was deciding whether to seek a PhD in Physics, one of his advisors told him not to do it because, after Maxwell and Boltzmann, everything that could be discovered in Physics already had been. Around the same time, the great telescope builder George Ellery Hale was told that his desire to build bigger and bigger telescopes only resulted in counting more and more stars and we already knew that space was filled with them. So, bigger telescopes were a waste of money.

We need another Max Plank to solve the gravity catastrophe and create a new branch of physics

As someone who studied physics, this is by far the most thorough and yet simply explained video on this topic. It was always glossed over in both my modern physics and quantum courses, thus its significance glossed over. Thank you for this!

I am bowled over by the depth and clarity of the presentation. When I was studying engineering at the Indian Institute of Technology, the instructor spent a half hour on this topic, skipped the Raleigh -Jeans derivation entirely, and went straight to Planck's formulation. I was dissatisfied at that time with the transition but, after decades, have finally found a satisfying exposition. Thanks so much. I am certainly going to subscribe.

This is really wonderful STEM-to-STEM exposition. This is a hard level to hit square in the nuts, and you did it. Well done sir.

I understood EVERYTHING up untill "Towards the end of the 19 century...".

This is the third time I very carefully went over this presentation. My compliments and immense gratitude to the author, especially for rigorous derivation and historical content - simply amazing !!!!

This was fascinating and an extraordinarily well-done presentation, marred only by some need to pause a few times to allow my dense brain to catch up, to make sure that I truly understood. Haven't been hit by that feeling (the "slow down, you move too fast" feeling) in a while. Thank you.

Absolutely fantastic video, this was the only one I could find that actually explained why the UV catastrophe occurred and how planck's constant solved it. And you derived everything using maths and physics I (mostly) knew, where my physics teacher refused to even go near this topic. Many thanks!

I've studied this stuff, but I finally feel I understand it after this video. I've long been confused by mixing up quantisation of energy levels in atoms with Planck's idea. I understood how the Schrodinger equation gave rise to discrete energy levels for bound electrons, and that the difference in energy levels gave rise to the discrete frequencies associated with spectral absorption and emission lines. Having encountered these concepts before Planck's black body function, I'd always assumed that the solution to the ultraviolet catastrophe was something to do with quantisation of frequencies. But there's still an infinite number of frequencies or vibrational modes, even though the frequencies are limited to stationary wave values. I've finally realised that Planck's solution was to quantise the amount of energy in _each mode_ ! With classical waves of a given frequency the amplitude is continuously variable, so the energy is too. I finally get that the energy _within any mode_ for EM waves is _not_ like that. It's split across a discrete number of quanta. Then the energy conservation principle dictates how the energy is statistically distributed across the modes, just like with the Boltzmann distribution for gases in statistical mechanics. Essentially the discrete number of quanta plays the same role as the discrete number of molecules in a gas. (Which probably explains why I've heard the term "photon gas"). Eureka! In turn, I've realised Einstein didn't _discover_ quantisation with his analysis of the photoelectric effect, it was already there in Planck's work. Einstein simply intuited that energy was transferred to electrons in the same discrete quanta.

You put a lot of work into this video.Probably more than 99% of other youtube videos out there.This is really professional and well thought out you are certainly getting a like from me.

You’re an excellent teacher. If that is your profession outside KZfaq, your students are incredibly lucky.

whenever i feel i am a smart human being, i just watch your video and it put me where i belong which is to be humble again..

My mind blew up and then reformulated itself... you are never to old to confront your long forgoten nightmares and finally see a glimer of light that says all is not lost. I will now go back to the begining, a time I left behind 40 odd or more years ago and perhaps enjoy a stress free journey where not completely understanding is OK but enjoying the trip non the less. Thank you.

I wanted to say thank you from a true layman. I do not even have a High School Diploma but the way you explained the problem and the solution step by step was fascinating to me. The math was way above me but the way you presented it made it very interesting to follow. Excellent work. I can only hope you are some kind of teacher to the future generations.

Imagine if someone told the flat earth people that the sun is really a hyperdimensional jeans cube with the hole only seemingly appearing to us as a sphere of plasma while in reality being a pinhole in the side of a hot, massive hypercube on another plane of perception. I hope one of them reads this comment now.

I learned this topics in a physics seminar a few years ago and roughly have an idea of what's going on in this video. My limited mathematics capabilities at the time did not permit me to understand it in full detail. Thanks for the wonderful presentation, allowing me to revisit this topic with greater depth and getting a more comprehensive understanding!

Wow. Back to the second year of college, but without the stress.

This is really neat. I... honestly understand almost nothing of this, but it's very interesting and what parts I did get were amazing. Thank you for your hard work and a terrific video :)

It's also the name of the metal band I'm starting with a bunch of physicists

I took Calculus 30 years ago. The best part of this video was actually seeing Calculus used. I've been a software engineer since and I have never used Calculus before! Seriously, great video. You break things down well and you have an easy to listen to voice. I especially enjoy your pronunciation of "but."

My favourite part is how they used that Jeans box to create a blackbody because they knew this was the simplest way to study the phenomenon.

Full stop dude, this is up there with the best of the youtube educators. You should do videos on transport phenomena (heat, mass, momentum)

Wow, I never knew this was how the theory of energy quantization came into being. So well explained, thanks. It's going to take me a couple more watches to digest the math - but this is the first time the math I've learned has made it possible for mde to understand something I really wanted to understand.

This is one of my favorite physics stories. It’s challenging to understand, and it is such a innocuous setup for a major physics revolution

This is, by far, the best treatment of this topic on KZfaq. Bravo.

33:05 Am I the only one hearing the reference: "All that is gold does not glitter, Not all those who wander are lost; The old that is strong does not wither, Deep roots are not reached by the frost. From the ashes a fire shall be woken, A light from the shadows shall spring; Renewed shall be blade that was broken, The crownless again shall be king." LotR, JRR Tolkien

The cube concept created by James Jeans was further expanded upon with the Sweatpants Sphere, theorized by Martin Sweatpants in 1946.

I get it and then I lose it then I get it then I lose it ... it’s like my understanding is a wave ! 🤷🏻‍♂️

This was one of the first topics we covered in my Chemistry degree, genuinely fascinating

16:36 Oh wow, it is at this exact moment that Quantum Mechanics was born. As a Chemist I don't know much about the mathematical details of QM but this is the basic principle behind Quantum Chemistry that you will find again and again, especially in Spectroscopy, Electron Orbitals, Bond Oscillations etc.

I'm going back to watching goats get scared and fall over

"So lets do that" needs to be the channel tagline.

Just going into my 2nd year of A level and this video really helped answer some questions I had about how some of the equations I've learned came to be. Thank you for this amazing video!

Not gonna lie, I was expecting a low quality video but this was actually great 👍🏼

This is an excellent video, and goes very in-depth in mind-bending ways for which I'm grateful. For everyone who, like me, didn't realize that this video contained only a very thin (in some ways) and rather convoluted (in other ways) introductory synopsis to set the stage for the rest of the video: The Ultraviolet Catastrophe refers to the realization of the "catastrophic" difference between the mathematical prediction (made via the Raleigh-Jeans Law) of a blackbody's energy output based on its light's wavelength vs. the real-world observations. The real-world observations revealed that at shorter wavelengths (going towards ultraviolet), a blackbody's emitted energy was *far* below what the Law predicted. An uppity physicist named Max Planck (who wasn't even a Lord or a Sir or *anything*) made his own mathematical predictions and theoretical models based strictly on the observed data, and in so doing realized that energy is quantized, meaning split into discrete sections (rather than just being a smooth transition up the energy scale). Think of it like this: physicists thought the Universe's energy ran on analog signals like a record player, and Max Planck revealed that energy is delivered similar to digital music, in discrete bits and levels. This realization upturned every apple cart in the physics world at the time, and was considered a "catastrophe" for anyone who thought we were even remotely close to figuring out how the Universe works. Further explanations just to help anyone who might get lost in the wonderful details in this video: a "blackbody" is a useful physics model in the same vein as an "infinite flat plane with zero friction" from high school physics. It is an object that only emits light due to its temperature, regardless of any other property (like charge, radiation from particle decay, phosphorescence, etc.). Make a blackbody hot, it will start to emit light. Blackbody radiation is the reason why hot metal glows. In other words, the concept of a blackbody was the first realization among physicists that, for any object that is so hot it emits light (from an incandescent lightbulb all the way up to stars), there are fundamental and invariable correlations between energy output, brightness, and color wavelength. Scientists noticed that, as a blackbody got hotter, it would both get brighter and its emitted light would increase in frequency (meaning it would have a smaller wavelength). Two scientists named Lord Raleigh and Sir James Jeans, using the best mathematics and theoretical thinking of their day, made a mathematical prediction of how the emitted wavelength of a blackbody can tell us about its energy output. This sort of prediction, if accurate, would be very useful for figuring out the temperature (and through that, many other properties) of objects we can't yet get close to, like stars out in space, our own sun, or even our neighboring planets. Their mathematical prediction was at first very useful, and became called the Raleigh-Jeans Law. Unfortunately for those two (but fortunately for everyone else), as scientists began testing this mathematical concept against real-world observations, they realized that the Raleigh-Jeans Law worked great for "long" wavelengths (< 10^5 GHz) in the infrared spectrum, but as the wavelength got shorter into the range of visible and then ultraviolet light, the amount of energy output observed was *far* less than the Law predicted. Enter a young upstart physicist named Max Planck. Out of frustration, he made the try-hard move of just brute-forcing an equation and set of theoretical models out of the observed data. In so doing, he created the mathematical and theoretical concepts that led to the discovery of quantum mechanics, and, as I believe is stated somewhere in this video, physics students have been cursing Planck's ingenuity ever since. This video goes into superb mathematical and theoretical detail as to how Planck ended up rustling the jimmies of pretty much all his contemporaries. Thanks for reading! If I'm wrong in any particulars, please let me know and I will happily correct them. I'm no scientist, only an enthusiastic amateur learner. Hope this helps some folks!

Wow this is the best physics video I have seen on yotube! History, rigorous math, comparison with experiments. It was simply amazing! Thanks for putting this out.

Thanks to your video, I can finally understand what no physics teacher at the institute could explain, simply because they did know no better. Good job!

My Friend recommended your channel, now I can't stop watching your videos :) I hope you upload more!

I finally get the understanding of how discreet energy comes into play in explaining black body radiation. Excellent explanation.

This is the best description of Blackbody Radiation I've ever seen. Well done.

I wasn’t expecting a 40 minute adventure into this, but I’m happy I did! Really great video

The best video on this topic. I have been searching for the right explaination to me for couple of days but i was not satisfied. Finally this video took me to the satisfactory zone. Thanks! Love from Bangladesh 🇧🇩

I respect anyone who understands this. Good job MegaMind

This is genius work. So detailed that and perfectly presented. KZfaq needs more creators like you.

Subscribed after less than 20 seconds because i just knew this was going to be good

This is by far the best black body video on KZfaq and deserves more love! Max Planck, Raleigh and Jeans were sharp dudes.

This topic is notoriously hard to explain without the mathematical derivations. I don't think there is a better explanation out there then this. Thank you so much for this contribution.

I still find it quite mysterious how the frequency /wavelength in these cases concern only integer values in the denominator, its a deep link between math and physics

You know... I was just asking myself this exact thing

I've been searching for a logical explanation of blackbody radiation-derived quantum concept. I found it nowhere else other than this video. What an effort. Thank you

I had the honour of attending a semester of lectures by this dude. Awesomeness

38:05. "When Planck plotted his energy density function..." ...it just occurred to me that he couldn't just open his MacBook Air and type "ipython" and "plot(f, h*f.....)..."... I mean how long did it take to plot back in the day? 5-th powers, exponentials.... how did he know what h was without scipy.constants.h ?

Elegant, beautiful and consistent line of thought

Every single time I watch this video, it gives me chill🥶 Max Planck was truly a genius, I don't think he has anything less than Einstein. One of the best video's in KZfaq imo❤️

I cannot emphasize enough how effective the teaching style of this video is where it combines all the necessary topics in a storytelling manner while keeping an endgoal in mind. All the physics classes i’ve taken would teach topics like blackbody radiation, wien’s displacement law, wave function, etc. etc. until we just felt like we were jumping from one topic to another without ever drawing a connection/motivation through them all. I feel exhilarated now knowing that all these ideas were individual puzzle pieces that eventually fell in right places, but at the same time I feel so so frustrated that the university lecturers failed to help us understand the big picture.

The Stephan Boltzmann law is strangely the most counter intuitive. Temperature being a measure of kinetic energy one would never at first intuit that intensity would grow as the 4th power of T.

Damn, son. That Planck dude was pretty smart.

It is a Crisp, and Valiant explanation. Two Thumbs up as far as I am concerned.

I love this channel does not shy away to get into the nitty gritty. I hope that someone does similar videos about molecular biology. I think this could ease the fears and highlight the risks about vacciantion. So much in our comlicated world is decided based on how it feels to one's gut

I needed this video two years ago...

Very well done and educational video! I learned a lot from this lecture, in spite of having studied graduate level physics for many years. Good job!

Physics student here, this is quite literally how this was presented to me in the first Quantum Physics lecture I attended. Well done.

absolute best video on the ultraviolet catastrophe😁

Well I was going to go back to sleep because I’ve only slept 3 hours, but this is too interesting

What an interesting problem nicely exposed. Well done, you got my instant sub. Planck must have been thrilled to realise the enormous implications of his discovery despite of the many years of failure, which makes it even more compelling. I'm quite positive that we are yet to discover many implications of his theory. Videos like this definitelly deserve more attention as they elegantly manage to achieve what school failed: Genuine interest for domains once though too hard or too useless to understand. Someone told me once "Learn math now, you won't have time or interest for it later." - boy was that person wrong.

This is the best video explaining the Ultraviolet Catastrophe in great detail and how the culmination of classical physics represented by the Rayleigh-Jeans model fails and what motivates the need for modern Quantum theory.

This video is freaking brilliant. Such a great explanation. I've been literally studying this topic for years. Slightly obsessed

I know most of this from having studied physics for a while, but sadly my professor had some type of aversion to quantum mechanis, so even when discussing electro dynamics he carefully circumvented any and all discussion of things related to quantum mechanics. Looking back that was kind of impressive on it's own, but obviously this compartmentalized approach left out most important connections and ultimately made the topic harder to understand. I had other reasons for dropping out, but I made the final call during one of his lectures, when he reiterated again how any quantum related explanations would have to wait another two years and I just realized I couldn't keep it up for that long.

Thank God that u uploaded it again ..I was worried

KZfaq obviously think i like catastrophes. But this video piqued my interest, because a catastrophe is just a word. I wanted to see what is behind it and you nailed the explanation. Thank you!

You just watched a decent chunk of undergrad Quantum Mechanics course done in 40 mins...and much clearer than I experienced

Thank you for revealing the maths behind this magic, that Planck performed, in an understandable way! Clever guy that Planck.

What a great explanation at the start. I wonder why none of my physics or chemistry teachers at high school couldn’t have explained the origin of Plancks work instead of just dropping the constant on us out of thin air in quantum theory. Neither did text books do it well back then. I think it was dur to the fact that even for teachers they felt uncomfortable with the ideas and really didnt understand them enough to explain them with confidence as they did the much older laws of people like Boyle firmly grounded in tbe classical idea of the atom consisting of particles behaving in a newtonian way. Thanks again

I love how in my general thermodynamics course my professor bored me to sleep with this stuff and yet im interested af in this video

This is very good. So nice to see a thorough explanation devoting most of the time to the wrong explanation and not be afraid of formulas or mathematics.

Possibly the best physics video I've seen on KZfaq

Thanks for covering this. Having λ instead of f on the horizontal axis is screwing me up pretty badly, but I'll adjust. I sometimes teach a class where we touch on the UV catastrophe and I'm always hoping nobody questions me too closely on it. :(

KZfaq showed me a neat video about colors and all of a sudden my adult nightmare of being late for highschool again flared up. I really didnt understand most of this video but it was still amazing to listen to. So thank you!

This is the greatest explanation of the problem of blackbody radiation that I have come across throughout my career; this is awesome! Thank you.

This channel is revolution for me 🗿 thanks again! Keep growing buddy.

I think this video is the first I've watched that really puts Planck's work into perspective, humanity would of been in a really tough spot if he hadn't introduced all these fundamentals that solved the massive problems classical physics was being presented with.

thankful there are resources like this for a student in a small physics program, the UV catastrophe never really clicked in until now!

The best explanation I have ever ever seen on the subject!

This is suspiciously similar to a lecture I had while doing my physics degree. I'll share a tip from my quantum mechanics lecturer, "anytime I see the words 'obviously' or 'clearly' in a description I start to worry". Me too boss Thanks for the refresher course, well spoken, well done, but no more obviouslies or clearlies please ;-)

It's comforting being back at school when things weren't so tough. I want to go back. Though I would be rather a Brian Johnson-lookalike by now.

An ideal strategy to explain, it looks as you tell a story (All the details in a precise way, step by step chronologically, including all the concepts and ideas and all the mathematical proofs and demonstrations).

Fantastic. Thanks for this. Clearest explanation of how Plank used quantization to solve the ultraviolet catastrophe, perhaps anywhere.

Wonderful video, thank you!

I loved this video when I first watched it, and I'm definitely going to watch this reupload as well in the next few days (a quick refresher is never a bad thing), but for now I'm just gonna leave a thumbs up :) Really love your way of explaining things!

I remember encountering BBR in astronomy class, and it was my gateway into quantum physics. Thanks for doing an in-depth discussion on this!

Time to watch a 40 minute video on a subject I have ZERO advanced or even passable knowledge in just because T sounds interesting and the narrator’s voice sounds really really nice and well spoke.