First I thought when I clicked the video that “ohh, ultraviolet catastrophe? What a boring topic” But you managed to suprise us again, thank you Mahesh❤
Great video. Love the intuition you offer. To add some historical perspective, Plank did not expect or like this result. He was a classical guy. His technique was a very traditional application of calculus. His intent was to treat the quanta as an intermediate step. He was trying to reduce the size of the quanta like you would with and infinitesimal in calculus. He expected to be able to make it go away in the final result. He was not happy that the only way things worked was to keep a finite, but very small h-bar in the equation and worked for quite a while to eliminate it. Keep the great videos coming, Thanks!
Your videos are really intuitive. You should probably start a series in quantum physics next. Starting from inteference pattern, de broglie, schrodingers eq, dirac eq all the way to qft. It would be great to have a intuition for everything with a sprinkle of maths at high school level
Sir why do electrons move faster when we increase voltage and if all the energy gained by the electron loses it all energy in the resistor so why does it come back it shouldn't because it doesn't have energy
I have been chomping at the bit for the release of this final video on the subject. Great job. I have been wanting to understand BBR for years and I think i finally do. Great job and TVM.
total banger of an explanation. The only thing that will leave us scratching our heads it that mystery "2" in front of the BB equation, and this of course is because for every state you described, there are 2 polarization states in which to radiate.
Best explanation of the quantized vs continuous aggregate I have heard, making the avalanche of counterintuitive concepts you learn along the way less daunting. I don't know why we simply accept not being able to visualize and just move on. I think that limits creative analysis and observation. I admire Planck more now.
I was eagerly waiting this video since the last, and you did not disappoint. This makes so much more sense than the explanations I'd been given about quantization before.
That analogy with the tennis balls is pretty convincing. But is there also physical evidence of the energy emitted when the "balls" fall to the lower floor?
So, that’s just a way to think about it. First start with the ‘would be’ situation if classical physics was true, and then add quantisation. That way of thinking makes intuitive sense. O’course in reality, there is no would be, and no falling. There is only the distribution with quantised levels. Does that make sense?
@@Mahesh_Shenoy no, I think the analogy is better than that. The tennis balls are hot, so they are jumping around (and you show their average distribution). Same for BB, the photons are in thermal equilibrium, so they're bouncing around and being radiated.
great video and very interesting way too look at it. i've seen the derivation first in introductory modern physics 1 class, then in statisticall physics class, but i never thought of it like that, nice.
The peak appears to shifts because the graph scales up in the X direction. This is actually a hint that the speed of light is constant. Scaling in the X axis (wavelength) means that energy affects frequency itself…which can only happen if frequency and wavelength are related a.k.a constant speed.
Hi Mahesh, according to quantization of energy according to frequency while keeping wave theory intact, it means that the amplitude of the wave then depends upon sqrt(freq*int).
2:30 Dear Mahesh, there was no "Ultraviolet Catastrophe" in 1900, the year Planck proposed his radiation law. In 1900, Lord Rayleigh published a brief paper in which he proposed an ad hoc formula, but it wasn’t until 1905 that he actually applied the equipartition theorem to the blackbody radiation problem. Almost every time I watch a video on blackbody radiation, the sequence of events is often confused. There was no concept of "classical" physics during Planck's time-it was simply physics. When Planck derived his radiation law, he didn’t give much thought to the issue of quantization in terms of the energy emitted and absorbed by bodies (rather than the energy itself). Although he initially guessed his radiation law (and there’s much more to that story), he later provided a theoretical foundation based on Boltzmann's statistical interpretation of entropy, which, unfortunately, you did not mention.
Mahesh, you are the professor most of us always dreamt of, but could never get. I would be a much better engineer today had my professors been 10% of what you are.
Everyone commends you on your teaching style and everything that you explain through your videos. I'm going to point out something different. The T-shirts in the videos - I'm love with your wardrobe 😂😂 Second: There are few creators on UA-cam that can implement a sponsor ad in their videos like you do!!!!! So fuckin seamless (pardon my french)!!!
Mahesh sir, as very usual, totally admire your dedication and work. But as a very very true and long term fan, I missed something. I absolutely loved the explanations. Fresh intuitive and enlightening as always. But there could be another practical explanation behind the E = hf equation! Firstly ofcourse as the temperature of a body increases, so does the thermal energy. Just like you mentioned in the previous videos, thermal energy is essentially the kinetic energy of molecules due to vibration. Hence, greater temperature = more energy = quicker jiggling movement and vibration of atoms. Now since the electromagnetic (EM) field permeates all of space, a quicker vibration = shorter wavelength disturbance in the EM field = greater frequency in the field. And lastly, as we all know, light is EM radiation. Acceleration charges produce light. Hence, charges at greater temperature, having greater energy, vibrating with greater frequency, produce light of greater frequency!!!! That's also why the peak shifts with temperature. Concluding, at a particular temperature, it peaks at some wavelength because that amount of energy corresponds to a maximum vibration of particular frequency in general. Since no material is perfect, the vibrations spread out a bit, some of larger wavelengths some of smaller, smoothening the curve....
And this was just my humble understanding. You would surely be aware of this and you not including it in the video must have some respectable reason sir. Nonetheless enjoyed it as always. Greetings and best wishes.
The best video Mahesh sir has published till date. This video truly blew my mind and opened up a new perspective for me. I want to learn everything like this. But I can't always rely on just your videos for my understanding. So could you please tell me how to learn like you do? How do you understand things intuitively? What is the algorithm or procedure you use to learn? Could you share the secret? Please reply sir.
Have you covered the Wien approximation in one of your videos before? I'd love to see an intuitive explanation of the difference between Maxwell-Boltzmann statistics and Bose-Einstein statistics!
Excellent video! Thank you! Nevertheless I would like very much if there were another one explaining more intuitively about the “quantization”.. and the relation to the frequency and the “fall”
Wow, this video is fantastic! Thank you very much, it is one of the best videos about this topic 👏 Please, could you make a video in which you talk about the interaction of light with matter? For example absorption, transmission, emission and scattering mechanisms of materials from a microscopic point of view? It would be an interesting way of explaining quantum effects from macroscopic everyday observations! It is only an idea, however thank you again, you are the best! 👋💪
4:15 What a well made video! But I see one problem with the _classic_ theory in it self: if you combine points 1 and 3 (infinite D.O.F. because there are infinite wave length possible in the cavity + every wavelength has a tiny bit of energy); there should already be an infinite amount of energy (covered by the graph, so the area below it). So point 2 is kind of not even "needed" for getting the catastrophe. In olving point 2 is kind of multiplying infinities, but there is infinity in the first place. Is there something wrong in my POV?
4:15 What a well made video! But I see one problem with the _classic_ theory in it self: if you combine points 1 and 3 (infinite D.O.F. because there are infinite wave length possible in the cavity + every wavelength has a tiny bit of energy); there should already be an infinite amount of energy (covered by the graph, so the area below it). So point 2 is kind of not even "needed" for getting the catastrophe. In olving point 2 is kind of multiplying infinities, but there is infinity in the first place. Is there something wrong in my POV?
Sir you have referenced Feynman lectures in many of your videos. Can you please make a playlist explaining every chapter of Feynman lectures for those of us who are lazy to read it or can’t remember all the details by listening to it?? I am currently a 11 th grader aspiring to be a theoretical physicist all your videos have sparked my curiosity. Thank you
I hold a strong belief that everyone is dumb, even Einstein (yes, the person who defines the word "genius"). Now you might say, "Really? No I don't believe you, Einstein was the smartest person, he discovered relativity, he got a freaking NOBEL prize!" And I will say, "no Physics guy, EVEN Einstein was dumb" But here's the difference my friend. Einstein read a lot of books. Maxwell read a lot of books. Newton read a lot of books. Feynman read OH so many books. Every single person became smart at what they do because they spent such a long time with their craft. Alone. In their formative years. Reading, analysing, making improvements, getting better everyday. They weren't born geniuses. I encourage you to watch Feynman's video where he said the same thing. He says he's not special at all, and he just read a lot of books. So my point is, don't shy away from Feynman's lectures because they are a treasure trove of knowledge. They are very intuitive and very very interesting. Please give them an honest chance, and then, who knows, you'll be the person to reconcile gravity with the standard model of physics! Best of luck! ^_^
If you want to be a theoretical physicist, then "lazy" is not going to work. No one learns new physics from videos. You may learn new relations or perspectives, and perhaps get some premature visualizations, but if you want to understand it, you have to read the text books and grind the problems within....so when you view the next 3B1B animations, you say to yourself: that's exactly how I imagined it in my head. Get Feynman, Vols I, I, II (irrc) and start grinding. Good luck.
How many people know that the equation E=hf is actually proposed by Einstein? Plank only proposed some statistics using a very normal looking permutation-combination. It's Einstein who refined out that fundamental equation from Plank's work.
Thank you for the explanation but I have a doubt that when you said the wavelengths "drop" due to quantisation like the tennis what actually happens, like the tennis balls fall but then what happens to waves, they cannot fall obviously. I know you are just trying to relate but I am just curious that how does quanta actually does to the waves.
Well that is easy we know that light travels at the speed of light so if light particle or photon encounteres electron the electron will bounced in direction perpendicular to its collision of the photon and the photon in the opposite direction now do that for large amount of electron and you will get that light bends in slightly different direction and the bending is proportional to the frequency of the photon at small scale and the density of the medium in large scale if it's encountering if it's monochromatic light then heavier or denser medium will bend it more and since light travels the same speed no lower this causes the light to bends slightly in different direction and higher frequencies bends more since they transfer more energy and more momentum to the electron which will transfer the same momentum to the photon and the other things when people say that light travels slower in denser medium it's not true light travels the same speed but it's bouncing in every direction electron will come to it so it will travel more distance per the same time then traveling in straight line so it appears to travel slower here is the answer from your question I hope it helps
@@AhmedYare-i3d hey ahmed , thanks for the reply but tell me one thing that , as you said in the beginning that when light particles (photos) encounters electron the electron will bounced in direction perpendicular to it's collision of the photon, is that mean that electron will be bounced in higher energy level? And if it is then the light should bend away from normal not towards it (same as X rays)
Wow, this means that the radiation of a blackbody is associated only with quantum transitions between quantized energy levels, like in an atom, and is absolutely unrelated to the fact that electrons emit electromagnetic waves during acceleration
since wave speed is a contant (c), the product frequency (f) times wavelength (L) has the following restriction when taking intervals (delta: D): c = f*L -> 0 = Df*L + f*DL + Df*DL as in calculus Df*DL :=0 implies DL = -L*Df/f and times 1=f/f DL = -c*Df/f^2 So intervals of constant wavelength would match intervals of constant frequency divided by a square law of frequency. I thought that this were why at high frequency there are no power, since DL are to small for having some energy within them, but I think now is wrong. Have you seen this relation DL=-c Df/f^2 while researching Plank/Feynman sources?
So, the Universe stores frequency and amplitude in the same variable and the more frequency value is - the less bits remains to encode the amplitude :)
Classical physics consider many quantities to be continuous, like position is continuous, time is continuous, energy is continuous. But among them Democritus, Maharshi Kanad and John Dalton proposed matter to be discrete. How could they know that without sufficient technology? What made them think that matter is discrete and made of countable atoms? I know this would be useless to think about since we know it today that matter, energy and many other physical quantities are discrete at the quantum level. But if I were a middle age physicist, I would argue against Dalton's atomic theorem and propose continuous matter.
I think you're COMBINING two different ideas and misinterpreting their significance. When Democritus, Maharshi Kanad, and Dalton proposed that matter is discrete, they were suggesting that if you keep dividing matter into smaller and smaller pieces, you will eventually reach a fundamental, indivisible unit-which they called "atoms." These atoms are discrete in the sense that you cannot divide them further into smaller pieces, unlike continuous matter, which can be divided infinitely. There’s no classical theory that suggests atoms themselves are continuous or some sort of unbroken lump. What they meant by "discrete" is that matter is made up of these individual, countable particles (atoms), not an unbroken continuum. Regarding your point about the quantization of other things (like energy at the quantum level), the people you're talking about (Democritus, Kanad, Dalton) had no knowledge of quantum mechanics or the existence of subatomic particles like electrons or quarks. Their theories were based purely on trying to answer the question: "What is matter made of?" They were not concerned with quantization at the quantum level, since they didn't even know about the internal structure of atoms. TLDR; So, the idea that matter is discrete in the form of atoms is SEPERATE from the quantum-level discussions about energy, time, or space being quantized. "atoms are quantised/discrete" makes no sense(within our context). [Also sorry for so long para...and hope it kinda made sense of the point i was trying to convince] -------------------------------------------------------------- kinda useless talk below, if you really care/not convinced: If you want to expand on the idea of continuous matter and why it might not be the right question at first place (atleast in the context of what we are discussing here, quantisation of things), here you go: When you talk about continuous matter, i think you might be envisioning a scenario where matter can be divided infinitely without ever reaching a fundamental unit. This was a common belief before the atomic theory gained traction, with the idea that matter could be split endlessly, much like how you can infinitely divide a line in geometry. However, the question itself-whether matter is continuous or discrete-assumes that there's a simple choice between the two, but this binary perspective doesn't fit well with how the concept of matter evolved. The ancient philosophers like Democritus, Kanad, and Dalton weren't concerned with proving that matter was discrete in the modern quantum sense; they were responding to the question, "How far can matter be divided?" Their answer was based on thought experiments, not empirical technology. The key issue is that the notion of "continuous matter" is problematic because it lacks practical utility. If matter were continuous, there would be no smallest building block, no basic structure on which chemical properties could rely....its same way as saying a building has no fundametal units (bricks), why? becos the idea of a building becomes abstract and impractical.
I agree about Dalton--he got it from chemistry though--stoichiometry points to atoms? But at the time, classical physics says a discreet bunch of atoms should crumble like sand, unless they're charged: then they have to radiate away all their energy. So I agree--I'd probably be in the wrong camp, too.
@@endersteveee thanks for developing my concepts on Dalton's atomic theory since I am just a 14 year old boy. As you showed that continuous matter is like saying that a building has no bricks. Here my point of argue is what the bricks are made of. Bricks are made of soil and it is seen that we can make houses with just soil(not making bricks out of it). But for long-lasting of the house we make bricks out of soil and then house out of bricks. Just like that think a continuous lump of hydrogen and a continuous lump of oxygen. We can have as small part of it as we want. Now let's take 1 liter of oxygen and 2 liters of hydrogen and mix it. It would be a mixture. But to be more stable in this condition oxygen and hydrogen will make bonds and make a particle of water. You could say that now water is discrete but since we can have as small part of hydrogen and oxygen as we want, we can also have as small part of water as we want. So water is also continuous. Oxygen and hydrogen can make bonds in different proportions, so we can get hydrogen peroxide. But they can't make bonds in all proportions. Consider it to be their chemical property. All the chemical processes seems consistent. Hence I would stand for continuous matter. And now I don't feel it completely useless because unique thoughts make revolutionary theories.
@@DrDeuteron can you give me the key concept? I didn't really understand what classical physics theory you are talking about. Is it something about Coulomb's law?
@@NAMITADALAL-pz9wj According to newton's laws, a bunch of neutral atoms will just fall to the ground. If you make up some kind of electrical force to hold them together, then you will BB radiate all energy per the UV catastrophe. (though charge does not appear in Planck's law..just c). Now Dalton predated Maxwell, so idk how they thought structures worked when made from atoms. But non-continuous solid matter really only makes sense with quantum mechanics.
1:52 Planck's eyes, that's EXACTLY it. There's your quantum, it comes from the eyes. But what comes from the eyes? - a rapid contraction of the pupil, blackbody radiation, a lump of warlike virtue experienced as a sharp point such as a dart, arrow or dagger etc. The eye is not only a perfect absorber of light, it is also a perfect EMITTER. So what? What does that mean? This is not the place to explain further.
At the end you showed the quanta size changing with temperature but the quanta size should stay fixed with respect to the x axis as it is equal to hf right?
Great explanation but one question wasn't answered intuitively. How is the process of balls falling to the quanta levels reflected in real life with the standing waves? It's not like there are actual planks below the standing waves and the waves physically fall to these levels. In my head what is happening in the real life is these waves that are not exactly at their quanta levels lose some of their energy until they reach that quantized level. But what is the intuition behind this loss of energy. Also, what happens to that energy that gets lost? Is it emitted somewhere or it didn't exist in the first place? Maybe you could dig deeper into that topic. Again, great video but it opens more questions that need intuitive explanations.
Sir,please solve my doubt.In LCR circuits,why we draw phasors for resistance and reactances since there aren't a vector and there aren't changing with time.And one more thing ,in your Maxwell equation videos,you said that the workdone in a closed path is not zero for electrical circuits,but when we take a closed path within the electrical circuit as you did in radially symmetrical charges ,it appeares to be zero.please explain sir
The argument does not follow from the premises. The blackbody spectrum depends uniquely on temperature, this is true. But the temperature of the box does not depend uniquely on its energy: the size of the box matters as well, since its size will determine the possible wavelengths of the normal modes. If you give x amount of energy to a box of a small size its temperature will increase by some amount (assuming reached equilibrium). Give x energy to a box the size of a truck, its temperature will increase way less than the first box. This is important because it is wrong to assume each frequency receives a discrete amount of energy if we also assume the energy of a mode depends on its amplitude. The physical reason the blackbody spectrum does not diverge at larger frequencies is exactly because larger frequencies have much more degrees of freedom that must be "occupied" before the amplitude of that same mode can increase. For the zero-node mode, there is only one degree of freedom. Thus any energy associated with this mode will inevitably increase its amplitude, but not infinitely: the maximum amplitude is set by the size of the box. As soon as the energy exceeded such a limit the energy would be instead distributed to the next available mode. This means that at higher energies the bulk of the energy is distributed to shorter wavelengths. Remember that for higher temperature the blackbody spectrum only apparently changes by simply moving the peak to shorter wavelengths. In truth what happens is that the spectrum is also scaled up intensity, meaning the absolute intensity of the "red part" to the far right for a lower temperature is actually the same as that of the spectrum at a higher temperature: it looks smaller because more energy is distributed to higher frequencies. The increasing degrees of freedom of the higher frequencies is the true source of the quantization, nothing to do with "energy coming in chunks".
so you want to say that amplitude sets limit to carry energy by a particular mode of wave and the increase in d.o.f causes more distribution of energy with growing frequency resulting reduction of intensity after a point?
Mahesh, I can't understand why do colored objects continue to absorb light? After absorbing light, if the electrons of the colored object absorbed light and go higher level then If it radiates wave, then the total light absorbed by the object is zero. Also why does the electron go to a higher level and go to a lower level after getting energy?
Well becouse they are absorbing sunlight which is polychromatic which means it's multitude of colors it will absorb the color which the electron orbital of its atom will absorb which is unique to every material so it will continuesly absorb sunlight and reflect the light it will reflect so I hope you understand it
good question. vague answer: 1) the time scale for energy losing inter-molecular collisions is much shorter than that for radiation (> 1/f), so it doesn't need to take the same path back to the ground state. 2) even in rarefied gases (say, stellar atmospheres), where BB radiation is being absorbed by atomic lines and emitted at the same frequency (doppler notwithstanding), the emission is into 4 pi steradian which is much larger (in the divisor) compared to the line-of-sight from the star to a telescope on Earth, so the power-per-steradian is small, and the lines are dark.
But couldn't you also argue that when you introduce quanta, all the tennis balls / photons in-between get moved up instead of down, thus making the graph explode even more?
Hey can you please explain, that why are more, less amplitude waves and less, high amplitude waves, is it some kind of axiom, or is there any real proof for it?
I must be missing something: The equation E = hf is a straight line where "h" is the slope. So how does that explain the curve in the video? yes I know the graph shows E vs wavelengh and wavelength = C / frequency.
The black body radiation curve shows the energy density of radiation emitted from a black body at each frequency. E = hf is the energy of a single photon of that frequency.
As the frequency increases there are more ways for standing waves to be set up - all contributing to the energy density. But with quantization it limits the energy to fixed intervals and causing an ulitmate reduction in energy density emitted at very high frequencies.
But Mahesh, 12:41 isn't the Energy of a standing wave = m(A^2)(W^2) {W--> Omega} and isn't Omega (W) = 2pi times the frequency ? help me i am confused , please.
while the Planck formula is thermodynamic (k_B), it was also prematurely quantum (hbar) and special relativistic (c), the Planck units require general relativity (G), and that is not part of Planck's law. If you want cut off the formula at 3e42 Hz, go right ahead, no one will notice.
absolutely you can read the feynman lectures, best source getting physics intuitively (basically there are 3 vols of feynman lecture books...these are almost semi transcript of his original taught lectures at caltech for ug students)
The name UV CATASTROPHE is not because of it's disastrous effects the name came because of the phenomenon of the decline of all radiations including the UV
Can anyone please tell then, who gave plank that graph or result to compare and find out or figure out the value of h should be what is it today ? I mean in this video, basically it was assume that the graph should be this and concept of quanta and h was introduced to make the catastrophe match it. Also, wasn't this graph a result of plank thinking of quanta then quantizing the energy or frequencies then the graph came, so thinking it the other way round feels wrong , so what exactly made plank think of quanta and discretizing them ? Do anyone know about it?
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wormhole vid .... plz i hav been askin for idk how long
First I thought when I clicked the video that “ohh, ultraviolet catastrophe? What a boring topic” But you managed to suprise us again, thank you Mahesh❤
Great video. Love the intuition you offer. To add some historical perspective, Plank did not expect or like this result. He was a classical guy.
His technique was a very traditional application of calculus. His intent was to treat the quanta as an intermediate step. He was trying to reduce the size of the quanta like you would with and infinitesimal in calculus. He expected to be able to make it go away in the final result.
He was not happy that the only way things worked was to keep a finite, but very small h-bar in the equation and worked for quite a while to eliminate it.
Keep the great videos coming, Thanks!
he worked on it for 3 years, no?
Your videos are really intuitive. You should probably start a series in quantum physics next. Starting from inteference pattern, de broglie, schrodingers eq, dirac eq all the way to qft. It would be great to have a intuition for everything with a sprinkle of maths at high school level
That's the plan! :)
Sir why do electrons move faster when we increase voltage and if all the energy gained by the electron loses it all energy in the resistor so why does it come back it shouldn't because it doesn't have energy
@@shiekh366 The energy is mostly in the electric and magnetic fields surrounding the electron.
@@Samu2010lolcats that is about poyting vector but iam taking about book that teaches us
This can't be explained better. ❤ officially the best video on the topic.
This is the best video on quantization ever made!
Best content on UA-cam. Thanks Mahesh.
you, kurgesagt, and minuteearth have all uploaded all on roughly the same time.
the stars have aligned, it is time for me to binge.
Snap! 😄
Thank you so much for making the videos on the Ultraviolet catastrophe and the black body radiation. This really helped me
mahesh this time you absolutely knocked it out of the park 🎉🎉🎉
This is the 1st time I see how Plank achieved it step by step, most videos out there just jump to result and consequences, thanks a lot for fixing it.
I went back to watch the previous two videos, and was totally worth it. Thank you again for such clever, clean explanations.
I have been chomping at the bit for the release of this final video on the subject. Great job. I have been wanting to understand BBR for years and I think i finally do. Great job and TVM.
The last video on bbr i was waiting for this less goo
total banger of an explanation. The only thing that will leave us scratching our heads it that mystery "2" in front of the BB equation, and this of course is because for every state you described, there are 2 polarization states in which to radiate.
Best explanation of the quantized vs continuous aggregate I have heard, making the avalanche of counterintuitive concepts you learn along the way less daunting. I don't know why we simply accept not being able to visualize and just move on. I think that limits creative analysis and observation. I admire Planck more now.
I was eagerly waiting this video since the last, and you did not disappoint. This makes so much more sense than the explanations I'd been given about quantization before.
I got really worried when Mahesh was excited, then started talking about Planck and his cup of coffee. I thought he was going to burst an aneurysm.
I didn't find a single guy who explained the "meaning" of mathematics of blackbody radiation on all of u tube ,well done Mahesh
You've described the concepts nicely .. Great video!
i was WAITIN FOR THIS (feels like since years) finally, i can brag / flex (😎) my intuitions on my friends
Waiting impatiently for your next video.
We missed you man!
Nice explanation of a very obscure subject! Great video. :)
That analogy with the tennis balls is pretty convincing. But is there also physical evidence of the energy emitted when the "balls" fall to the lower floor?
So, that’s just a way to think about it. First start with the ‘would be’ situation if classical physics was true, and then add quantisation. That way of thinking makes intuitive sense. O’course in reality, there is no would be, and no falling. There is only the distribution with quantised levels. Does that make sense?
@@Mahesh_Shenoy Thank you for your insight. I love your fresh style, it is a lot of fun thinking about your Gedankenexperimente
@@Mahesh_Shenoy no, I think the analogy is better than that. The tennis balls are hot, so they are jumping around (and you show their average distribution). Same for BB, the photons are in thermal equilibrium, so they're bouncing around and being radiated.
great video and very interesting way too look at it. i've seen the derivation first in introductory modern physics 1 class, then in statisticall physics class, but i never thought of it like that, nice.
The peak appears to shifts because the graph scales up in the X direction. This is actually a hint that the speed of light is constant. Scaling in the X axis (wavelength) means that energy affects frequency itself…which can only happen if frequency and wavelength are related a.k.a constant speed.
Hi Mahesh, according to quantization of energy according to frequency while keeping wave theory intact, it means that the amplitude of the wave then depends upon sqrt(freq*int).
That knuckle crack at 19:33!
2:30 Dear Mahesh, there was no "Ultraviolet Catastrophe" in 1900, the year Planck proposed his radiation law. In 1900, Lord Rayleigh published a brief paper in which he proposed an ad hoc formula, but it wasn’t until 1905 that he actually applied the equipartition theorem to the blackbody radiation problem.
Almost every time I watch a video on blackbody radiation, the sequence of events is often confused. There was no concept of "classical" physics during Planck's time-it was simply physics. When Planck derived his radiation law, he didn’t give much thought to the issue of quantization in terms of the energy emitted and absorbed by bodies (rather than the energy itself). Although he initially guessed his radiation law (and there’s much more to that story), he later provided a theoretical foundation based on Boltzmann's statistical interpretation of entropy, which, unfortunately, you did not mention.
Mahesh, you are the professor most of us always dreamt of, but could never get. I would be a much better engineer today had my professors been 10% of what you are.
Well done sir, excellent job, keep it up
FAB explanation 🙏🏼
Everyone commends you on your teaching style and everything that you explain through your videos. I'm going to point out something different.
The T-shirts in the videos - I'm love with your wardrobe 😂😂
Second: There are few creators on UA-cam that can implement a sponsor ad in their videos like you do!!!!!
So fuckin seamless (pardon my french)!!!
Man pls do vedio on field equations
Yeah that would be great
you mean G = 8piT? Those field eqs?
Mahesh sir, as very usual, totally admire your dedication and work. But as a very very true and long term fan, I missed something.
I absolutely loved the explanations. Fresh intuitive and enlightening as always. But there could be another practical explanation behind the E = hf equation!
Firstly ofcourse as the temperature of a body increases, so does the thermal energy. Just like you mentioned in the previous videos, thermal energy is essentially the kinetic energy of molecules due to vibration.
Hence, greater temperature = more energy = quicker jiggling movement and vibration of atoms.
Now since the electromagnetic (EM) field permeates all of space, a quicker vibration = shorter wavelength disturbance in the EM field = greater frequency in the field. And lastly, as we all know, light is EM radiation. Acceleration charges produce light. Hence, charges at greater temperature, having greater energy, vibrating with greater frequency, produce light of greater frequency!!!! That's also why the peak shifts with temperature.
Concluding, at a particular temperature, it peaks at some wavelength because that amount of energy corresponds to a maximum vibration of particular frequency in general. Since no material is perfect, the vibrations spread out a bit, some of larger wavelengths some of smaller, smoothening the curve....
And this was just my humble understanding. You would surely be aware of this and you not including it in the video must have some respectable reason sir. Nonetheless enjoyed it as always. Greetings and best wishes.
please make a video explaining intermediate axis theorem intuitively
tldr; They switched from analog to digital and then everything worked! ;)
The best video Mahesh sir has published till date. This video truly blew my mind and opened up a new perspective for me. I want to learn everything like this. But I can't always rely on just your videos for my understanding. So could you please tell me how to learn like you do? How do you understand things intuitively? What is the algorithm or procedure you use to learn? Could you share the secret? Please reply sir.
I'll tell you: get the text books and do the homework. No peeking. After 10,000 hours of that, you'll have some intuition, too.
@DrDeuteron thanks for you suggestion. But just doing the same thing as everyone but more will not get any better results will it?
You need to stop believing in fairy tales and some supernatural Godfather (∆llah) to understand physics mate.
I am ex muslim too.
@@sorry6726 I also ex-muslim but I still have the same name
@@sorry6726You said it correct.
That ad transition was genius 💀
Have you covered the Wien approximation in one of your videos before? I'd love to see an intuitive explanation of the difference between Maxwell-Boltzmann statistics and Bose-Einstein statistics!
Excellent video! Thank you! Nevertheless I would like very much if there were another one explaining more intuitively about the “quantization”.. and the relation to the frequency and the “fall”
Our eyes are tuned to detect the wavelengths most commonly emitted by any source. Makes sense.
Awesome content, glad I found your videos
Oh my God! I finally understand!!! Thank you!
Wow, this video is fantastic! Thank you very much, it is one of the best videos about this topic 👏 Please, could you make a video in which you talk about the interaction of light with matter? For example absorption, transmission, emission and scattering mechanisms of materials from a microscopic point of view? It would be an interesting way of explaining quantum effects from macroscopic everyday observations! It is only an idea, however thank you again, you are the best! 👋💪
Finally i understand this, took many years
4:15 What a well made video! But I see one problem with the _classic_ theory in it self: if you combine points 1 and 3 (infinite D.O.F. because there are infinite wave length possible in the cavity + every wavelength has a tiny bit of energy); there should already be an infinite amount of energy (covered by the graph, so the area below it).
So point 2 is kind of not even "needed" for getting the catastrophe. In olving point 2 is kind of multiplying infinities, but there is infinity in the first place. Is there something wrong in my POV?
4:15 What a well made video! But I see one problem with the _classic_ theory in it self: if you combine points 1 and 3 (infinite D.O.F. because there are infinite wave length possible in the cavity + every wavelength has a tiny bit of energy); there should already be an infinite amount of energy (covered by the graph, so the area below it).
So point 2 is kind of not even "needed" for getting the catastrophe. In olving point 2 is kind of multiplying infinities, but there is infinity in the first place. Is there something wrong in my POV?
LESSS GOOO, early into the video, gotta watch it real quick
Mind blown but in a good way 👍. Great video!
I like your t-shirts - do you sell them so I can order some? Oh - and by the way - excellent job on this mini-series on ultraviolet catastrophe.
Sir you have referenced Feynman lectures in many of your videos. Can you please make a playlist explaining every chapter of Feynman lectures for those of us who are lazy to read it or can’t remember all the details by listening to it??
I am currently a 11 th grader aspiring to be a theoretical physicist all your videos have sparked my curiosity. Thank you
I have reposted this request this sir
This was an excellent video sir❤
I hold a strong belief that everyone is dumb, even Einstein (yes, the person who defines the word "genius").
Now you might say, "Really? No I don't believe you, Einstein was the smartest person, he discovered relativity, he got a freaking NOBEL prize!"
And I will say, "no Physics guy, EVEN Einstein was dumb"
But here's the difference my friend. Einstein read a lot of books. Maxwell read a lot of books. Newton read a lot of books. Feynman read OH so many books. Every single person became smart at what they do because they spent such a long time with their craft. Alone. In their formative years. Reading, analysing, making improvements, getting better everyday. They weren't born geniuses. I encourage you to watch Feynman's video where he said the same thing. He says he's not special at all, and he just read a lot of books. So my point is, don't shy away from Feynman's lectures because they are a treasure trove of knowledge. They are very intuitive and very very interesting. Please give them an honest chance, and then, who knows, you'll be the person to reconcile gravity with the standard model of physics! Best of luck! ^_^
If you want to be a theoretical physicist, then "lazy" is not going to work. No one learns new physics from videos. You may learn new relations or perspectives, and perhaps get some premature visualizations, but if you want to understand it, you have to read the text books and grind the problems within....so when you view the next 3B1B animations, you say to yourself: that's exactly how I imagined it in my head. Get Feynman, Vols I, I, II (irrc) and start grinding. Good luck.
How many people know that the equation E=hf is actually proposed by Einstein? Plank only proposed some statistics using a very normal looking permutation-combination. It's Einstein who refined out that fundamental equation from Plank's work.
Sir, you are great❤
Where do u buy ur shirts man they are so good
13:11 You know what's crazy the planck name, hinted to quantasized level of energy :)
So good!
Thank you for the explanation but I have a doubt that when you said the wavelengths "drop" due to quantisation like the tennis what actually happens, like the tennis balls fall but then what happens to waves, they cannot fall obviously. I know you are just trying to relate but I am just curious that how does quanta actually does to the waves.
Please make a video on "why the ray of light bends when going though rare to denser medium and visa-versa"
I am very curious about this 🤔
Well that is easy we know that light travels at the speed of light so if light particle or photon encounteres electron the electron will bounced in direction perpendicular to its collision of the photon and the photon in the opposite direction now do that for large amount of electron and you will get that light bends in slightly different direction and the bending is proportional to the frequency of the photon at small scale and the density of the medium in large scale if it's encountering if it's monochromatic light then heavier or denser medium will bend it more and since light travels the same speed no lower this causes the light to bends slightly in different direction and higher frequencies bends more since they transfer more energy and more momentum to the electron which will transfer the same momentum to the photon and the other things when people say that light travels slower in denser medium it's not true light travels the same speed but it's bouncing in every direction electron will come to it so it will travel more distance per the same time then traveling in straight line so it appears to travel slower here is the answer from your question I hope it helps
@@AhmedYare-i3d hey ahmed , thanks for the reply but tell me one thing that , as you said in the beginning that when light particles (photos) encounters electron the electron will bounced in direction perpendicular to it's collision of the photon, is that mean that electron will be bounced in higher energy level? And if it is then the light should bend away from normal not towards it (same as X rays)
He has already made videos on that. Please check his playlists
Hey mahesh try to do video on thermodynamics...I also could not understand it..
Wow, this means that the radiation of a blackbody is associated only with quantum transitions between quantized energy levels, like in an atom, and is absolutely unrelated to the fact that electrons emit electromagnetic waves during acceleration
Very nice!
since wave speed is a contant (c), the product frequency (f) times wavelength (L) has the following restriction when taking intervals (delta: D):
c = f*L
-> 0 = Df*L + f*DL + Df*DL
as in calculus Df*DL :=0 implies
DL = -L*Df/f and times 1=f/f
DL = -c*Df/f^2
So intervals of constant wavelength would match intervals of constant frequency divided by a square law of frequency.
I thought that this were why at high frequency there are no power, since DL are to small for having some energy within them, but I think now is wrong.
Have you seen this relation
DL=-c Df/f^2 while researching Plank/Feynman sources?
So, the Universe stores frequency and amplitude in the same variable and the more frequency value is - the less bits remains to encode the amplitude :)
Classical physics consider many quantities to be continuous, like position is continuous, time is continuous, energy is continuous. But among them Democritus, Maharshi Kanad and John Dalton proposed matter to be discrete. How could they know that without sufficient technology? What made them think that matter is discrete and made of countable atoms? I know this would be useless to think about since we know it today that matter, energy and many other physical quantities are discrete at the quantum level. But if I were a middle age physicist, I would argue against Dalton's atomic theorem and propose continuous matter.
I think you're COMBINING two different ideas and misinterpreting their significance. When Democritus, Maharshi Kanad, and Dalton proposed that matter is discrete, they were suggesting that if you keep dividing matter into smaller and smaller pieces, you will eventually reach a fundamental, indivisible unit-which they called "atoms." These atoms are discrete in the sense that you cannot divide them further into smaller pieces, unlike continuous matter, which can be divided infinitely.
There’s no classical theory that suggests atoms themselves are continuous or some sort of unbroken lump. What they meant by "discrete" is that matter is made up of these individual, countable particles (atoms), not an unbroken continuum.
Regarding your point about the quantization of other things (like energy at the quantum level), the people you're talking about (Democritus, Kanad, Dalton) had no knowledge of quantum mechanics or the existence of subatomic particles like electrons or quarks. Their theories were based purely on trying to answer the question: "What is matter made of?" They were not concerned with quantization at the quantum level, since they didn't even know about the internal structure of atoms.
TLDR; So, the idea that matter is discrete in the form of atoms is SEPERATE from the quantum-level discussions about energy, time, or space being quantized. "atoms are quantised/discrete" makes no sense(within our context).
[Also sorry for so long para...and hope it kinda made sense of the point i was trying to convince]
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kinda useless talk below, if you really care/not convinced:
If you want to expand on the idea of continuous matter and why it might not be the right question at first place (atleast in the context of what we are discussing here, quantisation of things), here you go:
When you talk about continuous matter, i think you might be envisioning a scenario where matter can be divided infinitely without ever reaching a fundamental unit. This was a common belief before the atomic theory gained traction, with the idea that matter could be split endlessly, much like how you can infinitely divide a line in geometry.
However, the question itself-whether matter is continuous or discrete-assumes that there's a simple choice between the two, but this binary perspective doesn't fit well with how the concept of matter evolved. The ancient philosophers like Democritus, Kanad, and Dalton weren't concerned with proving that matter was discrete in the modern quantum sense; they were responding to the question, "How far can matter be divided?" Their answer was based on thought experiments, not empirical technology.
The key issue is that the notion of "continuous matter" is problematic because it lacks practical utility. If matter were continuous, there would be no smallest building block, no basic structure on which chemical properties could rely....its same way as saying a building has no fundametal units (bricks), why? becos the idea of a building becomes abstract and impractical.
I agree about Dalton--he got it from chemistry though--stoichiometry points to atoms? But at the time, classical physics says a discreet bunch of atoms should crumble like sand, unless they're charged: then they have to radiate away all their energy. So I agree--I'd probably be in the wrong camp, too.
@@endersteveee thanks for developing my concepts on Dalton's atomic theory since I am just a 14 year old boy.
As you showed that continuous matter is like saying that a building has no bricks. Here my point of argue is what the bricks are made of. Bricks are made of soil and it is seen that we can make houses with just soil(not making bricks out of it). But for long-lasting of the house we make bricks out of soil and then house out of bricks. Just like that think a continuous lump of hydrogen and a continuous lump of oxygen. We can have as small part of it as we want. Now let's take 1 liter of oxygen and 2 liters of hydrogen and mix it. It would be a mixture. But to be more stable in this condition oxygen and hydrogen will make bonds and make a particle of water. You could say that now water is discrete but since we can have as small part of hydrogen and oxygen as we want, we can also have as small part of water as we want. So water is also continuous. Oxygen and hydrogen can make bonds in different proportions, so we can get hydrogen peroxide. But they can't make bonds in all proportions. Consider it to be their chemical property. All the chemical processes seems consistent. Hence I would stand for continuous matter. And now I don't feel it completely useless because unique thoughts make revolutionary theories.
@@DrDeuteron can you give me the key concept? I didn't really understand what classical physics theory you are talking about. Is it something about Coulomb's law?
@@NAMITADALAL-pz9wj According to newton's laws, a bunch of neutral atoms will just fall to the ground.
If you make up some kind of electrical force to hold them together, then you will BB radiate all energy per the UV catastrophe. (though charge does not appear in Planck's law..just c).
Now Dalton predated Maxwell, so idk how they thought structures worked when made from atoms.
But non-continuous solid matter really only makes sense with quantum mechanics.
So, Is it the quanta that gets bigger, or is it the energy/vibrational modes that get smaller?
In the ball analogy, why does it assume the ball pick a lower level :). If it pick the higher level, average energy increases?
20:37 What does falling of waves mean?! 🤔🤔
its simply in context of the analogy used by him...falling of wave analogous with falling of tennis balls....just for explanation
1:52 Planck's eyes, that's EXACTLY it. There's your quantum, it comes from the eyes. But what comes from the eyes? - a rapid contraction of the pupil, blackbody radiation, a lump of warlike virtue experienced as a sharp point such as a dart, arrow or dagger etc. The eye is not only a perfect absorber of light, it is also a perfect EMITTER. So what? What does that mean? This is not the place to explain further.
At the end you showed the quanta size changing with temperature but the quanta size should stay fixed with respect to the x axis as it is equal to hf right?
Great explanation but one question wasn't answered intuitively. How is the process of balls falling to the quanta levels reflected in real life with the standing waves? It's not like there are actual planks below the standing waves and the waves physically fall to these levels.
In my head what is happening in the real life is these waves that are not exactly at their quanta levels lose some of their energy until they reach that quantized level. But what is the intuition behind this loss of energy. Also, what happens to that energy that gets lost? Is it emitted somewhere or it didn't exist in the first place?
Maybe you could dig deeper into that topic.
Again, great video but it opens more questions that need intuitive explanations.
A standing wave has a random number of photons in it, and when kT
Sir,please solve my doubt.In LCR circuits,why we draw phasors for resistance and reactances since there aren't a vector and there aren't changing with time.And one more thing ,in your Maxwell equation videos,you said that the workdone in a closed path is not zero for electrical circuits,but when we take a closed path within the electrical circuit as you did in radially symmetrical charges ,it appeares to be zero.please explain sir
Can you please link to whatever video you were talking about at the end? I looked in the description but it isn’t there
Babe wake up, Mahesh just dropped new vid
Does this also help explain the energy rings of an electron in an atom?
nice video
The argument does not follow from the premises.
The blackbody spectrum depends uniquely on temperature, this is true. But the temperature of the box does not depend uniquely on its energy: the size of the box matters as well, since its size will determine the possible wavelengths of the normal modes. If you give x amount of energy to a box of a small size its temperature will increase by some amount (assuming reached equilibrium). Give x energy to a box the size of a truck, its temperature will increase way less than the first box.
This is important because it is wrong to assume each frequency receives a discrete amount of energy if we also assume the energy of a mode depends on its amplitude. The physical reason the blackbody spectrum does not diverge at larger frequencies is exactly because larger frequencies have much more degrees of freedom that must be "occupied" before the amplitude of that same mode can increase.
For the zero-node mode, there is only one degree of freedom. Thus any energy associated with this mode will inevitably increase its amplitude, but not infinitely: the maximum amplitude is set by the size of the box. As soon as the energy exceeded such a limit the energy would be instead distributed to the next available mode. This means that at higher energies the bulk of the energy is distributed to shorter wavelengths. Remember that for higher temperature the blackbody spectrum only apparently changes by simply moving the peak to shorter wavelengths. In truth what happens is that the spectrum is also scaled up intensity, meaning the absolute intensity of the "red part" to the far right for a lower temperature is actually the same as that of the spectrum at a higher temperature: it looks smaller because more energy is distributed to higher frequencies.
The increasing degrees of freedom of the higher frequencies is the true source of the quantization, nothing to do with "energy coming in chunks".
so you want to say that amplitude sets limit to carry energy by a particular mode of wave and the increase in d.o.f causes more distribution of energy with growing frequency resulting reduction of intensity after a point?
@@lawandorder-e3d the increase of degrees of freedom allows more energy to be stored at the same frequency, so basically yes
Mahesh, I can't understand why do colored objects continue to absorb light? After absorbing light, if the electrons of the colored object absorbed light and go higher level then
If it radiates wave, then the total light absorbed by the object is zero. Also why does the electron go to a higher level and go to a lower level after getting energy?
Well becouse they are absorbing sunlight which is polychromatic which means it's multitude of colors it will absorb the color which the electron orbital of its atom will absorb which is unique to every material so it will continuesly absorb sunlight and reflect the light it will reflect so I hope you understand it
good question. vague answer: 1) the time scale for energy losing inter-molecular collisions is much shorter than that for radiation (> 1/f), so it doesn't need to take the same path back to the ground state. 2) even in rarefied gases (say, stellar atmospheres), where BB radiation is being absorbed by atomic lines and emitted at the same frequency (doppler notwithstanding), the emission is into 4 pi steradian which is much larger (in the divisor) compared to the line-of-sight from the star to a telescope on Earth, so the power-per-steradian is small, and the lines are dark.
But couldn't you also argue that when you introduce quanta, all the tennis balls / photons in-between get moved up instead of down, thus making the graph explode even more?
Gravity is pushing things down
Hey can you please explain, that why are more, less amplitude waves and less, high amplitude waves, is it some kind of axiom, or is there any real proof for it?
Did you reupload this video?
I must be missing something: The equation E = hf is a straight line where "h" is the slope. So how does that explain the curve in the video? yes I know the graph shows E vs wavelengh and wavelength = C / frequency.
The black body radiation curve shows the energy density of radiation emitted from a black body at each frequency. E = hf is the energy of a single photon of that frequency.
As the frequency increases there are more ways for standing waves to be set up - all contributing to the energy density. But with quantization it limits the energy to fixed intervals and causing an ulitmate reduction in energy density emitted at very high frequencies.
But Mahesh, 12:41 isn't the Energy of a standing wave = m(A^2)(W^2) {W--> Omega} and isn't Omega (W) = 2pi times the frequency ?
help me i am confused , please.
That’s for a mechanical wave! Energy of an electromagnetic wave does not depend on the frequency!
@@Mahesh_Shenoy oh thanks
so there are not infinite degrees of freedom ?
Quanta is related to Facebook?
After watching this video 3-4 times, I only have one question: How does E=hf solve the ultraviolet catastrophe? (intuition)
photoelectric effect also needs it
Is there really such thing as infinite frequency? There should be a limit because of Planck length. So the max freq will be 1/10^-35, or am i wrong?
while the Planck formula is thermodynamic (k_B), it was also prematurely quantum (hbar) and special relativistic (c), the Planck units require general relativity (G), and that is not part of Planck's law.
If you want cut off the formula at 3e42 Hz, go right ahead, no one will notice.
Hay ..can you provide me some link to study this intuitively? Is it in Feynman lectures?
absolutely you can read the feynman lectures, best source getting physics intuitively (basically there are 3 vols of feynman lecture books...these are almost semi transcript of his original taught lectures at caltech for ug students)
Yoppp abhi modern physics chal raha hai coaching mei 😂
The name UV CATASTROPHE is not because of it's disastrous effects the name came because of the phenomenon of the decline of all radiations including the UV
What do you mean coffee does not give me infinite energy? lol
Can anyone please tell then, who gave plank that graph or result to compare and find out or figure out the value of h should be what is it today ? I mean in this video, basically it was assume that the graph should be this and concept of quanta and h was introduced to make the catastrophe match it.
Also, wasn't this graph a result of plank thinking of quanta then quantizing the energy or frequencies then the graph came, so thinking it the other way round feels wrong , so what exactly made plank think of quanta and discretizing them ? Do anyone know about it?
It was experimentally measured
I think sci-clique covers that in detail? These were hard measurements 100 years ago.
Great. Now explain it in photon terms
A photon is a mode. That's it.
White breaks special relativity do you not think that
what do you mean? Planck's law is Lorentz covariant--which is a miracle, since it predates special relativity.
Um, either your graph or the explanation is backward.
First
Shit.. entropy is not what it used to be..
9th comment wohooo
Good job bro!!🎉
very sus
what is sus?