If this is how maths and physics is taught in schools, we would be having many more scientists and humanity will achieve 10 times more in 30 years compared to last 100years… Hats off to Mahesh sir🙏
@@guydude3320 Ehm, scientists still have to originate in the educational system. So yeah, this level of education would ignite the crave fro knowledge for much more people
Loved the video. Just wanted to point out that the use of the binomial expansion and limiting to first order makes it sound like E=mc^2 is an approximate equation. A more formal derivation shows that it is in fact exact and not an approximation. It appears you needed to use the approximation because you took kinetic energy to be 1/2mv^2 in your derivation. That is only true at low speeds. It is in fact your kinetic energy equation that is the approximation and not E=mc^2. The use of the binomial expansion simply reconciles E=mc^2 with that kinetic energy approximation. Actually, it is a very nice way of showing how 1/2mv^2 come about at low speed. A more formal derivation would use the full relativistic kinetic energy equation (derived from the work principle) and then you end up with E=mc^2 being exact. I hope you don't mind me mentioning it but I didn't want people to come away thinking E=mc^2 is not exact.
Very valuable comment! In fact, this was exactly the impression I had: The famous formula surprisingly only the result of an approximation. Not something one would expect from Einstein. Until I stumbled over your remark. Initial disappoinment eliminated now. Many thanks!
@@Wouter10123 The derivation is straightforward in principle, but nasty in practice. Kinetic energy can be derived using the work-energy principle that says the change in kinetic energy of an object is the work done on it to take it from stationary to some velocity, v. You calculate the work as the integral of force over distance. You integrate Fds. But Force is also the rate of change of momentum, p, so you can integrate (dp/dt)ds instead. This is the same as (ds/dt)dp, which is vdp. Still not nice but using the product rule you can convert this to d(vp)-pdv, and integrate that. That is vp minus the integral of pdv. Relativistic momentum, p, is 'gamma'mv, where 'gamma' is the familiar 1/sqrt(1-(v/c)^2) term of relativity. Substitute that in and the final integral is ugly by doable. The answer is (gamma-1)mc^2. That is relativistic kinetic energy! Not at all familiar is it? However, by doing a binomial expansion of it and dropping the higher terms, you're left with 1/2mv^2 believe it or not! To keep things familiar and intuitive, Mahesh started with 1/2mv^2 so had to apply the same approximation to the left side of his equation (so to speak) to make them consistent. You can see the derivation and discussion in more detail on Wikipedia at en.wikipedia.org/wiki/Kinetic_energy#Derivation_2. Hope that helps.
I was hoping someone would clarify this in the comments. That bit felt a bit disappointing after an otherwise excellent explanation. So thanks for the clarification!
@@mnjammnjamm Not TOTALLY, but RELATIVELY happy... Because he is happy only from (y)our perspective. Reality is not known, though Relativity can be! 😊
You’ve got to be one of the best science communicators on this website, every video I’ve seen of yours is so intuitive and as a biologist I sometimes worry about getting too deep into physics and math but your videos help with the pursuit for knowledge
But the information he communicated is not actually real physics truth. Einstein's theories have been debunked many times already. But the easiest way to find why they are wrong is to read the ebook, Dave Vs Hal 9001. Anyone with any ability to think, can now see that Einstein's theories are nonsense. No math required, just logic and reason.
@@everythingisalllies2141Source:Trust me bro. Dave vs Hal 9001 is a fictional book not an academic book. Also, where on actual earth did you see that Einstein's theories have been debunked. Edit: Ah, just checked your channel and found it's a book written by you. Self promotion.
@@NorthMavericks-ow7jk The lie is that they have been "proved" over and over. But you don.t care if this is true or not. Your mind is set like concrete. The theories have no real proof, not one scrap.
I grew up with the assumption that only a tiny group of elite physicists could understand the math of the Theory of Relativity. But you clearly go through the math so that it's comprehensible even to me (who struggles with very basic calculus). Your intuitive approach really brings the theory alive and makes it something we, like you, can marvel and wonder at, rather than regard it as too complicated and remote. Kudos to Mahesh!! (P. S. I was a librarian in Jerusalem and got to know the head librarian of Hebrew University, where the original manuscripts of the theory, special and general, are kept. She gave me the wonderful privilege of seeing the manuscripts in person. It was a very powerful experience, seeing these documents that fundamentally changed our view of the universe.)
You still need to understand the math in detail to do anything useful with it, but it's good to have at least an intuition of it rather than none at all.
Hey Mac what do you do? Do you work in academia or engineering? Or are you doing "ery basic calculus just for fun?... I'm curious about it, as my own practice of maths was left way back..
@@everythingisalllies2141The SR theory is rational all over. A perfectly logical model that explains real-world observable phenomena with ease and high precision. It has been validated thousands of times.
@@Grecks75 Nope. Its not rational at all. You have been TOLD that its great, but its just not. It doesn't explain real world anything. It does create opportunities for paradoxes. And its never been validated. Faked experiments and misinterpreted observations are not validation. The fact that you have not figured any of this out, is evidence that you are too trusting of your superiors.
Mahesh sir always rocks ❤ You are doing an extremely good job and you have a good will. This will help the lot of learners around the world. Hats off to you sir
@@Mahesh_Shenoy I have said that I will say again that in this whole concept one very important variable is forgotten and must be taken into account and that is ACCELERATION of the shot out particle from the atom. NOTHING and NOTHING happens in zero second? Can you run 100 meters sprint in zero seconds? Can you say a word verbally in 0 seonds? NO! Thefore, the particle shot out from the atom must be accelerated by force F and that is equal to ma. Therefore, the equation of kinetic energy KE=1/2mv squared is derived from FORCE applied to an object times distance it moves is equal to the change in its kinetic energy by ACCELERATION. And now the question? The particle does not ''move'' instantaneously from the atom. That's impossible. And where did the FORCE COME from? And why did the particle accelerate to c? In even simpler equation of momenta p=mv, the velocity is gained by acceleration. So, acceleration distorts the E=mc2 because as small as ACCLETERATION may be, it is NOT 0! Something does not jibe here because it looks like the finished product without pointing to the process of acceleration.
If that was any other video going through algebra I would have had to stop watching. The way you explained it so clearly, so logically, keeping it tied to the reality of the original experiment, reminding us what we were trying to solve, reminding which formulas we'd already done. You actaully made it make sense to me, and I genuinely got enjoyment from following it. Thanks buddy. You're an amazing teacher
This is actually, intuitively, very appealing! It is quite fascinating that Einstein should have derived this (and speed of causality mentioned in a pervious videos) purely on eliminating what cannot be and accepting whatever that remains! logic following intuition=genius. Thanks for making this video.
I wonder if we could find more physics through this method but not eliminating other 'impossible'maths. Something about negatives and imaginary numbers comes to mind
This is my first time on this channel, and I just wanted to share my excitement for the descriptions of the relationships among space, time, momentum, energy, mass, etc., the aesthetic feels genuine and I’m only just starting to understand how some of the relationships work, and I’ve little to no practice beyond algebra. I’m missing some details, but that’s what repeated viewings and further familiarization with the subject matter are for. Your intuition based delivery was a unique way to handle that whole area. Thanks so much!
I may feel sad about many things in my life but I always, strangely, find peace in physics. Big thanks for this beautiful video, I will keep coming back to it 🎉
Lucky students that have you as their teacher. Providing an intuitive understanding of the subject matter for students to take with them as they dive into the details is I am sure invaluable. Well done indeed.
You can't even imagine how happy am I about finding your channel. You are educational genius, people like you are moving humanity forward and I sincerely dream I can be someone like you. You are giving people new conceptions about the world we live in, transforming information about it into knowledge about it's laws. Thousands of years people paid money for conversations with people who have looked a little bit further in the ways of understanding this world, but now we can listen you for free and I'm grateful for that. If half of the people, who watched your videos will get new knowledge (not as information,but something they will understand) then you are making tremendous work for all the humanity.
I admit that I can barely follow because this is not my profession, but I was always interested in physics and I think it is a shame that most people do not get to know or understand these greatest achievements of humanity and I truly admire your work to teach this extraordinary relevant topics. I like your admitation and fascination for science and gave you a like and a sub. Please keep going! ❤
There was a point in time when I was satisfied deriving E=mc^2 only using four-vectors and calculus. Now I know how much of a fool I was back then. This is the most beautiful/intuitive reasoing behind the connection between mass and energy I have ever seen. Thank you so much for putting in all of this effort to make reality make just a little bit more sense for the rest of us.
Mahesh, I love your videos! I want to study quantum physics and love your intuitive videos and I am happy to tell you that I share your passion for physics!
Your explanation of the relativistic Doppler shift is spectacular! But a subsidiary point of the video is a bit lacking. When you drive by a stationary sound emitter, you do indeed hear a change in pitch. Your presentation of the doppler effect for sound makes it sound like you wouldn't hear a pitch change.
Thank you! Yes, I noticed that. I wanted to put a small disclaimer at the bottom. But forgot to add that. You are right, there is pitch change in sound as well. But, the pitch change is due to the apparent change in the velocity of sound. Not the wavelength. I think that’s the key point.
@@juliensalemkour5708 It is exactly the same for light as for sound ^ orbs= ^s/ 1+ V/C, 1- V/C. If you say the ^ Observer wavelength, ^s the source of wavelength, V is the relative velocity of the source observer and C is for light you are not worried about the speed of light. One easy way to think about it is with white light or white noise both have every spectrum of frequencies in it. So if you say the source is further away you will observe lower frequencies, if it is closer you will observe a higher frequency and between both of those you can observe the medium frequency. This is part of perceived observation because not everyone will perceive the same thing
I came across your channel just recently and absolutely love it! It would be fantastic if you touched on the topic of time paradoxes, time travel and general relativity! Have a great day!
I have a question about the final stage of your calculation Mahesh. When you carry out the binomial expansion to finally determine that E=mc^2 you ignore the higher powers of x(v^2/c^2) as the velocity(v) is much smaller than the speed of light(c). Doesn't this mean that E=mc^2 is also an approximation and so would not hold for values of v approaching c?
I was a little worried people might think that when I saw the video. Be in no doubt, E=mc^2 is exact. It is not an approximation. In the video kinetic energy was taken to be 1/2mv^2. THIS is the approximation. Kinetic energy is only 1/2mv^2 at low speeds. What Mahesh was doing was using the binomial expansion to reconcile E=mc^2 with the kinetic energy approximation that we are all familiar with. In fact the binomial expansion is a nice way of showing that kinetic energy becomes 1/2mv^2 at low speed. If you use the full, relativistic kinetic energy (derived using the work principle) then you do not need the binomial expansion and E=mc^2 ends up being exact. I hope that puts your mind at rest.
All observers , regardless of what frame they are in, will agree that the atom has intrinsic mass, m, with energy equivalence given by E=mc^2. The atom may be ascribed kinetic energy in addition to this due to its motion relative to individual observers. Kinetic energy depends on the relative velocity of the atom and therefore different observers will ascribe different amounts of kinetic energy. But they will all agree that the rest-mass energy must be exactly mc^2.
Bro I am a 25 year old guy. Watching your videos like a 20 year kid and learning my favourite subject with so much detail. You made my heart cry bro. How you are putting up with expenses for such crazy animation and time investment. Start memberships of youtube channel if you need. I would love to support you. You totally deserve it.
That means a lot, Harsh. A few more folks have reached out to support. As long as I can manage at my end, I wouldn't want to take anyone's hard earned money. But, thanks again for the concern. :). And thanks for watching.
Another doubt is that, in 9.04 part of the video, when you said the atom must have lost mass after it emitted out light, shouldnt the atom on the right (from the girl in rocket perspective) also lose mass after it emitted light?
Yes, it lost mass. But we observed the mass at two different times, one before it emitted photons, and after it emitted photons. This is why we see a diffrence in mass
I was never good at math , science . I'm into accounting. But with this kind of videos on TH-cam my interest in science has grown and I'm fascinated by this. I sleep most of the time while the video is playing in the background sometimes. It's kind of calming strangely.
I heard a story once--- There was a dull kid and his father hired many tutors but they eventually left that kid saying he was too dull, finally he found one tutor and the kid started doing well in school.... The problem was never the kid, rather it was the previous tutors who lacked in-depth understanding about the subject. The more you understand a topic, the broader your range and simpler the moves are - you can even get a kid dance to the complex tunes. Thanks....
The equation you're citing is called the Relativistic Dispersion Relation, which is the norm of the 4-momentum,||P||^2=P^ag_{ab}P^b, expressed in component form: m^2=E^e-p^2.
Please keep these videos coming! These are so helpful in explaining concepts intuitively which is something I always look for and love the content you post! Recently came across this channel and have been hooked!
@@Mahesh_Shenoyfrankly, I felt the video like casual physics lecture 😆. I'm so sorry to say this 🙏🥲. . . . . . . . Let me watch it again in a free time 😅
I really feel like I'll need a bit to get a hang of it. Really nice work sir ngl even a toddler in physics would understand this as you even try to explain the slightest of things. I just want to know that if E/c2= ∆m is an approximation, so it won't be able to work for high velocities right? Like those approaching quite much the speed of light like an electron in a bohr's orbit or can it tolerate that much? Lastly, really thank you for keeping me interested in physics even when on the verge of losing it 'cause of this rat race.
There is no such equation. The equation is E=m, which defines the mass in the zero-momentum frame. You can have ΔE=Δm in the absence of change in the 3-momentum. [note: c=1]
E=mc^2 is not an approximation. Be in no doubt about that. The derivation in the video uses 1/2mv^2 for kinetic energy. THIS is the approximation. It is this equation that only holds at low speeds. The use of the binomial expansion reconciles the derivation with this approximation. If you do the analysis using full relativistic kinetic energy (derived using the work principle) then E=mc^2 is exact. This would make the story a lot more complicated though and I can see why Mahesh didn't go there. The key idea in the video is jumping between frames of reference, assuming physics should behave the same from both points of view, and thinking about what that must imply if the speed of light is the same. That is relativity theory.
@@robwilliams4773 No. The accurate equation is E = 'gamma'mc^2. E = mc^2 only works for low speeds or when things are at rest. As mentioned, it's a first order approximation!
I never knew that I could derive E=mc^2 without even holding a pen and paper and just by visualizing things looking at a youtube video. Just amazing. Loved it~
Dude...the craziest thing about this video was learning what Albert learned by himself way back in the day...in just under 30mins...this was amazing...
Lack of use and 50 years time since college physics hinders me, but I found your enthusiasm and explanations delightful. I had long forgotten how to resolve nothing travels faster than the speed of light versus Einstein's energy-mass conversion process being dependent on the speed of light squared.
If you understand that mass is just confined energy, it's easy to understand why the atom loses mass, it lost some of that confined energy. If you know the mirror box example with photons bouncing inside, if you push the box the photons that bounce push against your hand so the box feels like ir resists (inertia). It the box loses photons, less of them bounce when you push it, so you feel less resistance (inertia), so the box lost mass. Mass is just an emergent property of light speed particles (which have momentum) confined inside a certain space, because they bounce on whatever resists moving the system. Everything moves at the speed of light, what doesn't is just a system of multiple particles, and the system can stay still but it's made of all light speed moving elements internally. Nothing moves slower than light, only emergent objects.
You've reignited my passions for physics, I watched a vid on a whim and i've been watching them one by one since, you've captured all the things that makes this topic so interesting and explain it so well! Best physics channel I've seen so far!
24:30 I feel like we should divide both sides by v^2 and take lim v->0 instead of using not so rigorous and accurate approximation. The answer is the same. If we would take more terms in binomial expansion the answer would be different, i think it is a very nice coincidence that only two first terms of binomial expansion (which only applies to integers) gives corrent answer but it is like taking dx^-2/dx, dividing numetator and denominator by d, "-" next to 2 with "-" in fraction, rerranging and getting 2x.
A tenth grader learning feynman lectures, theory of relativity, electromagnetism and Lots of works in the field of science.... I am really very thankful to you sir, Even though I study in 10th grade I learnt from your videos so much things... Thanks for introducing me to a very open and thoughtful world.
Mahesh, this is the most intuitive physics channel I have encountered so far! Big Gratitude!🎉 Perhaps could you please at some point make videos about AI/ML topics?
You are awesome, Mahesh! I've been watching all your videos since I found out about your channel. I love your excitement and your intuitive take on hard topics!
Not only a beautiful explanation of the derivation, but this actually allows us to see why the often heard statement 'mass is converted to energy' is misleading: no 'conversion', no 'alchemy', is required, only the consistent following through of the original postulate - that c is constant for all observers - and the consequences of this for objects and observers in motion. Look at Nature and wonder that such simplicity gives rise to such an amazing universe...
This is a BRILLIANT exposition. Thank you! Its only when the explanation is this good, so eliminating the pervasive obfuscation in this realm, that we see clearly what a intellectual magician Einstein really was; this entire edifice is a nonsense. The egocentricity at the core of Einstein's physics is stupefying - I don't mean his own personal ego but his fixation on observer-centric, "reference frame" effects that don't exist in reality....or to put in Einsteinian lingo, don't exist in the reference frame of the thing itself. To pick just one example here, the observer simultaneously "seeing" red-shifted and "blue-shifted" radiation from his "balanced momentum" source is a foundational contradiction. Mahesh gets to the heart of Einstein's philosophy at 07'30" with "you don't say it's impossible, instead you ask what needs to happen in order for it to be possible"....and so we get "lateral thinking" run amok, then thought-experiments turned into declarative statements, and ultimately into dogma. How do we replicate Lavoisier's conservation of mass experiments at the atomic level? The E-mc^2 proposition is circular; binding energy is released when matter dissociates but the protons, neutrons & electrons are all conserved! The eV can be defined and usefully converted to kg the same way a mass of gold can be converted to USD but that doesn't mean gold is made out of paper or that the bills in my wallet are made out of metal. We've made Einstein into a God-like figure similar to how the ancients did with Aristotle, in the long term, their 'hit rate' will be similar I suspect.
Mahesh, it starts off with Einstein and the Radioactive Mass (RM) neither detecting any relative velocity. With the release of the two photons and no recoil, the RM still displays no relative velocity to Einstein, and he observes no Doppler effect, no red or blue shift and concludes/confirms the RM is not moving relative to him. This is also the same conclusion one would get from the RM reference frame. Now Einstein joins the rocket ship which he says is moving towards him at velocity ‘v’. he proceeds to assign his perspective obtained when outside the rocket, that is, the rocket is stationary, and the RM mass is moving with velocity v in the opposite direction he had determined for the rocket before he got in. The RM reference frame could make the same claim, that is that the RM is not moving, and the rocket is moving as first viewed by Einstein to the right at velocity ‘v’. Now, we find, in this final offered frame that the Rocket has considered the RM as moving to left at velocity ‘v’ even before the photons are released. Only the Rocket reference frame assigned the condition of the RM in motion before any photon release. Moving the observer from one frame of reference to another or combining reference frames leads to errors when the speed of light is involved. Newton’s Law tells us constant linear motion cannot be confirmed or denied and under that condition the speed of light will always be ‘c’ per Maxwell’s equations. That applies to any attempt of the above reference frames measuring light speed. It is not valid for the rocket frame to determine the velocity of the RM to be ‘v’, and the photons will be moving at ’c’. Only the moving frame ‘sees’ a loss of mass with an energy gain in the photon. The claim is that light does not need or travel in a medium. The fact that the speed of light can be calculated from two real measurable qualities of space itself should be convincing that space is more than an empty void, is more than a vacuum. It follows then that the speed of light has a specific velocity because this is the velocity of transverse waves in the medium of space, and this velocity is a function of the elasticity and density of this medium. Conversely, if space was a true vacuum, there would be no specific velocity attributed to light, since the only property of emptiness is that it has no properties.
I hope your channel blows up my friend ur enthusiasm combined with story telling and clarity helped explain this concept in such a digestable way. I learned alot from this! :)
I loved it and i strongly recommend this video to anyone who wants to understand energy-mass equivalence intuitively from an elementary point of view assuming that we are interested in negligible velocity massive objects
I've never been able to understand why the speed of light had anything to do with mass or energy ... let alone why it made sense to square c. This all finally makes sense. Thank you.
I have a question about Doppler effect with sound. It seems from you explanation that there would be no Doppler effect in the case where there is a transmission medium. It seems to me that there is a classical Doppler effet with blue shift when the speaker is heading towards you and red shift when the speaker is heading away from you, but in Newtonian mechanics the two corresponding shifts of energy cancel out.
10:45, there is no change in wavelength for sound waves but according to my IITJEE textbook the frequency would be experienced differently by the moving observer to account for the increased speed (relative speed). And the general eqn has a v+vo term in the numerator
I compare this video to dialect's video. According to dialect, the equation is T2 = T1 + ε (T3 - T1), where the light leaves the source, say clock A, at time T1 according to A, bounces off clock B at time T2 and hits clock A at time T3, and 0 < ε < 1. Here, Einstein is assuming ε = 1/2 exactly (hence the derivations in this video), but ε need not exactly be 1/2 according to dialect. We could easily exploit this loophole to restore Newtonian physics (and that's exactly what dialect does in that video), and this "ether" that actually turns out to be an electromagnetic field is a suitable substitute for a medium as if light was sound.
That was a beautiful video. It helped me clearly understand so much more of the details. Thank you for patiently walking me, baby step by baby step. Very well done.
Mahesh, firstly your enthusiasm, for this stuff is infectious, secondly your intuitive explanations make it almost understandable for a dummy like me. Quantum mechanics and relativity have always messed with my sanity but your explanations are so sanguine I almost understand them
The way I see it, energy is not a thing that exists out there or that a particle possesses. It's a measure of "how energetic is an interaction" instead. If you are in a slower frame, your interaction with the photons will be less energetic than if you are in a faster frame relative to the atom. That's where the "energy" comes from... it is the relative motion between the participants that creates a more or less energetic interaction. Without interaction, there is no "energy" at all.
There is a flaw in that logic: in the rest frame it also lost mass. You use m_rest(before emitting photons) - m_moving(after emitting photons). There is a double difference. You must prove m_rest(before emitting photons) = m_moving(before emitting photons).
I love how you simplify very complex subjects, and "ask" the questions we all have to get to the answer. Would you please do one on the "twin paradox"? Also, would you please explain in a "thought experiment" how someone in a spaceship moving at a constant velocity can measure the speed of light moving in either forward or backward direction to be "c"?
You have a gift of going into detail and can explain in a way that many viewers can relate to. I appreciate that. I also understand that you have a comical and conversational way of presenting. But I cannot help saying that, in invoking great names such as Albert Einstein and Richard Feynman in the dramatic conversations and more importantly in your intonations, they do not come out in quite the respectful way toward the two great geniuses as probably all scientists would do. Even in a dramatic conversation when invoking such towering personalities, the intonation should not sound like you and them are equals. They did everything, and they dedicated their lives to doing so, you are just re-telling their findings in a way many people may find easy to understand. But for this important point, that I could not help pointing out, everything else is good! So, please keep it up!
In other words, the science deities are beyond humanizing, right? We must all bow down in supplication in their presence,yes? Yours is the attitude that has got high energy particle physics & cosmology into the mess they are both in.
I have been searching for the original proofs of the equation for a while now. All the sources out there hardly match the profundity of the original proof. The rest of the proofs which I've encountered yet seemed somewhat vague or conditional. I wanted to study the original derivation. But couldn't find the original English translation of German manuscript on Scholar (** or was too much lazy to delve further). That's when I saw this video and I have to admit it is much more profound than I imagined. and of course excellent presentation too. Good work and keep doing it. N.B. I was also fascinated by your video on how can light waves carry momentum.. and again Keep going.
![PURPEECH - นี่ฉันเองคนที่... (It's me) [Official MV]](http://i.ytimg.com/vi/NuhHd0hOOg8/mqdefault.jpg)
If this is how maths and physics is taught in schools, we would be having many more scientists and humanity will achieve 10 times more in 30 years compared to last 100years… Hats off to Mahesh sir🙏
No scientists won’t need this simple explanations I just like how he has made it easier for dumb ppl like me to understand it
Let's face it, we haven't achieved much in the last 100 years. 🙄🙄🙄🙄🙄
@@guydude3320 Correct… thats why I said schools not universities 😊… dum
@@mkpatel981 schools are not there to make smart scientists and succesful people... its to train peoplpe to work a 9-5
@@guydude3320 Ehm, scientists still have to originate in the educational system. So yeah, this level of education would ignite the crave fro knowledge for much more people
Loved the video. Just wanted to point out that the use of the binomial expansion and limiting to first order makes it sound like E=mc^2 is an approximate equation. A more formal derivation shows that it is in fact exact and not an approximation. It appears you needed to use the approximation because you took kinetic energy to be 1/2mv^2 in your derivation. That is only true at low speeds. It is in fact your kinetic energy equation that is the approximation and not E=mc^2. The use of the binomial expansion simply reconciles E=mc^2 with that kinetic energy approximation. Actually, it is a very nice way of showing how 1/2mv^2 come about at low speed. A more formal derivation would use the full relativistic kinetic energy equation (derived from the work principle) and then you end up with E=mc^2 being exact. I hope you don't mind me mentioning it but I didn't want people to come away thinking E=mc^2 is not exact.
Very valuable comment! In fact, this was exactly the impression I had: The famous formula surprisingly only the result of an approximation. Not something one would expect from Einstein. Until I stumbled over your remark. Initial disappoinment eliminated now. Many thanks!
like @stolgos8964 I thank you for this precision
That was exactly my question, thanks. Any pointers on how to derive the relativistic kinetic energy?
@@Wouter10123 The derivation is straightforward in principle, but nasty in practice. Kinetic energy can be derived using the work-energy principle that says the change in kinetic energy of an object is the work done on it to take it from stationary to some velocity, v. You calculate the work as the integral of force over distance. You integrate Fds. But Force is also the rate of change of momentum, p, so you can integrate (dp/dt)ds instead. This is the same as (ds/dt)dp, which is vdp. Still not nice but using the product rule you can convert this to d(vp)-pdv, and integrate that. That is vp minus the integral of pdv. Relativistic momentum, p, is 'gamma'mv, where 'gamma' is the familiar 1/sqrt(1-(v/c)^2) term of relativity. Substitute that in and the final integral is ugly by doable. The answer is (gamma-1)mc^2. That is relativistic kinetic energy! Not at all familiar is it? However, by doing a binomial expansion of it and dropping the higher terms, you're left with 1/2mv^2 believe it or not! To keep things familiar and intuitive, Mahesh started with 1/2mv^2 so had to apply the same approximation to the left side of his equation (so to speak) to make them consistent. You can see the derivation and discussion in more detail on Wikipedia at en.wikipedia.org/wiki/Kinetic_energy#Derivation_2. Hope that helps.
I was hoping someone would clarify this in the comments. That bit felt a bit disappointing after an otherwise excellent explanation. So thanks for the clarification!
Who wants Mahesh sir to upload more videos like this ? And increase the frequency of uploading videos.
Yes. Will do. Have a list of videos ready already
U can use Doppler effect to increase frequency 😂😂😂
@@sgiri2012 I typed velocity by mistake. (Don't take it serious)
Notifications ON!! Yes
Everyone 😅
I have never seen anyone explaining with this energy and so much interest.
Much appreciated :)
His ability to talk to dead scientists is an unfair advantage
But Einstein seems totally happy with that
😂😂
@@mnjammnjamm Not TOTALLY, but RELATIVELY happy... Because he is happy only from (y)our perspective. Reality is not known, though Relativity can be! 😊
@@talatdhk LOL
@@talatdhk this guy relativates
You’ve got to be one of the best science communicators on this website, every video I’ve seen of yours is so intuitive and as a biologist I sometimes worry about getting too deep into physics and math but your videos help with the pursuit for knowledge
This means a lot! :)
But the information he communicated is not actually real physics truth. Einstein's theories have been debunked many times already. But the easiest way to find why they are wrong is to read the ebook, Dave Vs Hal 9001. Anyone with any ability to think, can now see that Einstein's theories are nonsense. No math required, just logic and reason.
@@everythingisalllies2141Source:Trust me bro. Dave vs Hal 9001 is a fictional book not an academic book. Also, where on actual earth did you see that Einstein's theories have been debunked.
Edit: Ah, just checked your channel and found it's a book written by you. Self promotion.
@@everythingisalllies2141 Don lie bro. Einstein's theories have been proved over and over again.
@@NorthMavericks-ow7jk The lie is that they have been "proved" over and over. But you don.t care if this is true or not. Your mind is set like concrete. The theories have no real proof, not one scrap.
I grew up with the assumption that only a tiny group of elite physicists could understand the math of the Theory of Relativity. But you clearly go through the math so that it's comprehensible even to me (who struggles with very basic calculus). Your intuitive approach really brings the theory alive and makes it something we, like you, can marvel and wonder at, rather than regard it as too complicated and remote. Kudos to Mahesh!! (P. S. I was a librarian in Jerusalem and got to know the head librarian of Hebrew University, where the original manuscripts of the theory, special and general, are kept. She gave me the wonderful privilege of seeing the manuscripts in person. It was a very powerful experience, seeing these documents that fundamentally changed our view of the universe.)
You still need to understand the math in detail to do anything useful with it, but it's good to have at least an intuition of it rather than none at all.
Thats some cool stuff to see writing of such a person.
Hey Mac what do you do? Do you work in academia or engineering? Or are you doing "ery basic calculus just for fun?... I'm curious about it, as my own practice of maths was left way back..
You are a fantastic communicator of high-level concepts. I love your enthusiasm!
All his enthusiasm is not able to make this explanation rational. Like all of SR theory, its not rational.
the fact that he smiles and shows excitement about the subject is infectious.
@@everythingisalllies2141The SR theory is rational all over. A perfectly logical model that explains real-world observable phenomena with ease and high precision. It has been validated thousands of times.
@@Grecks75 Nope. Its not rational at all. You have been TOLD that its great, but its just not. It doesn't explain real world anything. It does create opportunities for paradoxes. And its never been validated. Faked experiments and misinterpreted observations are not validation. The fact that you have not figured any of this out, is evidence that you are too trusting of your superiors.
Mahesh sir always rocks ❤
You are doing an extremely good job and you have a good will. This will help the lot of learners around the world.
Hats off to you sir
Thanks a lot :)
@@Mahesh_Shenoy I have said that I will say again that in this whole concept one very important variable is forgotten and must be taken into account and that is ACCELERATION of the shot out particle from the atom. NOTHING and NOTHING happens in zero second? Can you run 100 meters sprint in zero seconds? Can you say a word verbally in 0 seonds? NO! Thefore, the particle shot out from the atom must be accelerated by force F and that is equal to ma. Therefore, the equation of kinetic energy KE=1/2mv squared is derived from FORCE applied to an object times distance it moves is equal to the change in its kinetic energy by ACCELERATION. And now the question? The particle does not ''move'' instantaneously from the atom. That's impossible. And where did the FORCE COME from? And why did the particle accelerate to c? In even simpler equation of momenta p=mv, the velocity is gained by acceleration. So, acceleration distorts the E=mc2 because as small as ACCLETERATION may be, it is NOT 0! Something does not jibe here because it looks like the finished product without pointing to the process of acceleration.
If that was any other video going through algebra I would have had to stop watching.
The way you explained it so clearly, so logically, keeping it tied to the reality of the original experiment, reminding us what we were trying to solve, reminding which formulas we'd already done. You actaully made it make sense to me, and I genuinely got enjoyment from following it. Thanks buddy. You're an amazing teacher
Here we learn important topics of physics while having fun.
Keep making more videos like this sir.
Gladly!!
This is actually, intuitively, very appealing! It is quite fascinating that Einstein should have derived this (and speed of causality mentioned in a pervious videos) purely on eliminating what cannot be and accepting whatever that remains! logic following intuition=genius. Thanks for making this video.
Thanks a lot for the feedback. Awesome to hear that.
"eliminating what cannot be and accepting whatever that remains!" Just like Sherlock Holmes!
"When you eliminate the impossible, whatever remains, no matter how strange, must be the truth.
I wonder if we could find more physics through this method but not eliminating other 'impossible'maths. Something about negatives and imaginary numbers comes to mind
This is my first time on this channel, and I just wanted to share my excitement for the descriptions of the relationships among space, time, momentum, energy, mass, etc., the aesthetic feels genuine and I’m only just starting to understand how some of the relationships work, and I’ve little to no practice beyond algebra. I’m missing some details, but that’s what repeated viewings and further familiarization with the subject matter are for. Your intuition based delivery was a unique way to handle that whole area. Thanks so much!
I may feel sad about many things in my life but I always, strangely, find peace in physics.
Big thanks for this beautiful video, I will keep coming back to it 🎉
Lucky students that have you as their teacher. Providing an intuitive understanding of the subject matter for students to take with them as they dive into the details is I am sure invaluable. Well done indeed.
You can't even imagine how happy am I about finding your channel. You are educational genius, people like you are moving humanity forward and I sincerely dream I can be someone like you. You are giving people new conceptions about the world we live in, transforming information about it into knowledge about it's laws. Thousands of years people paid money for conversations with people who have looked a little bit further in the ways of understanding this world, but now we can listen you for free and I'm grateful for that.
If half of the people, who watched your videos will get new knowledge (not as information,but something they will understand) then you are making tremendous work for all the humanity.
I admit that I can barely follow because this is not my profession, but I was always interested in physics and I think it is a shame that most people do not get to know or understand these greatest achievements of humanity and I truly admire your work to teach this extraordinary relevant topics. I like your admitation and fascination for science and gave you a like and a sub. Please keep going! ❤
Your enthusiasm for this subject is contagious 😊
Damn Einstein and Mahesh conversations really go deep
This has to be one of the best physics videos on TH-cam
There was a point in time when I was satisfied deriving E=mc^2 only using four-vectors and calculus. Now I know how much of a fool I was back then. This is the most beautiful/intuitive reasoing behind the connection between mass and energy I have ever seen. Thank you so much for putting in all of this effort to make reality make just a little bit more sense for the rest of us.
That’s a really wholesome comment. Made the effort that much worthwhile:)
Functional equations are need, www.casanchi.org/fis/dinamicafuncionales01.htm
Mahesh, I love your videos! I want to study quantum physics and love your intuitive videos and I am happy to tell you that I share your passion for physics!
Your explanation of the relativistic Doppler shift is spectacular! But a subsidiary point of the video is a bit lacking. When you drive by a stationary sound emitter, you do indeed hear a change in pitch. Your presentation of the doppler effect for sound makes it sound like you wouldn't hear a pitch change.
Thank you! Yes, I noticed that. I wanted to put a small disclaimer at the bottom. But forgot to add that.
You are right, there is pitch change in sound as well. But, the pitch change is due to the apparent change in the velocity of sound. Not the wavelength. I think that’s the key point.
Could explain how the Doppler effect with light does lead to a drastic doubling in frequency versus in sound, only leading to a minor change in pitch
@@juliensalemkour5708 It is exactly the same for light as for sound ^ orbs= ^s/ 1+ V/C, 1- V/C. If you say the ^ Observer wavelength, ^s the source of wavelength, V is the relative velocity of the source observer and C is for light you are not worried about the speed of light. One easy way to think about it is with white light or white noise both have every spectrum of frequencies in it. So if you say the source is further away you will observe lower frequencies, if it is closer you will observe a higher frequency and between both of those you can observe the medium frequency. This is part of perceived observation because not everyone will perceive the same thing
These videos are making me fall in love with physics. All of it makes so much more sense now. Keep it up! :)
Such intuitive explanation. Such infectious energy. Kudos bro. You took simplifying complex physics concept to the next level. Keep up the good work 👍
It's all scam look it up make no sense
i love your channel. i started watching you because i needed to for my e&m class, but you made me actually appreciate the subject. great content.
Ihv never seen such simplification of such a complex topic. Absolutely outstanding piece of work you've uploaded sir. 👏👍
fantastic! I'm 59 and I've long understood the concepts, but never thought I could understand the underlying math.Now I do, thanks!!!!!
I came across your channel just recently and absolutely love it! It would be fantastic if you touched on the topic of time paradoxes, time travel and general relativity! Have a great day!
This really shows how smart Einstein actually was!
Thanks for the explanation mate! This was a great video!
I have a question about the final stage of your calculation Mahesh.
When you carry out the binomial expansion to finally determine that E=mc^2 you ignore the higher powers of x(v^2/c^2) as the velocity(v) is much smaller than the speed of light(c). Doesn't this mean that E=mc^2 is also an approximation and so would not hold for values of v approaching c?
I was a little worried people might think that when I saw the video. Be in no doubt, E=mc^2 is exact. It is not an approximation. In the video kinetic energy was taken to be 1/2mv^2. THIS is the approximation. Kinetic energy is only 1/2mv^2 at low speeds. What Mahesh was doing was using the binomial expansion to reconcile E=mc^2 with the kinetic energy approximation that we are all familiar with. In fact the binomial expansion is a nice way of showing that kinetic energy becomes 1/2mv^2 at low speed. If you use the full, relativistic kinetic energy (derived using the work principle) then you do not need the binomial expansion and E=mc^2 ends up being exact. I hope that puts your mind at rest.
@@robwilliams4773Thank you very much
@@robwilliams4773 Thank you
@robwilliams4773 Thanks.
I am still a bit confused. Does the atom have different energies when viewed from a rest vs. moving frame?
All observers , regardless of what frame they are in, will agree that the atom has intrinsic mass, m, with energy equivalence given by E=mc^2. The atom may be ascribed kinetic energy in addition to this due to its motion relative to individual observers. Kinetic energy depends on the relative velocity of the atom and therefore different observers will ascribe different amounts of kinetic energy. But they will all agree that the rest-mass energy must be exactly mc^2.
Bro
I am a 25 year old guy.
Watching your videos like a 20 year kid and learning my favourite subject with so much detail. You made my heart cry bro. How you are putting up with expenses for such crazy animation and time investment. Start memberships of youtube channel if you need. I would love to support you. You totally deserve it.
That means a lot, Harsh. A few more folks have reached out to support. As long as I can manage at my end, I wouldn't want to take anyone's hard earned money. But, thanks again for the concern. :). And thanks for watching.
Mahesh, please make a video on force upon a charge by a magnetic field. Hope you take any action, you may either make a short.
👍🏻✌️🤜🏽🤛🏼
My favorite channel in all of TH-cam. Great instruction and enthusiasm. Keep it up.
Another doubt is that, in 9.04 part of the video, when you said the atom must have lost mass after it emitted out light, shouldnt the atom on the right (from the girl in rocket perspective) also lose mass after it emitted light?
Yes, i have the same question
Yes, it lost mass. But we observed the mass at two different times, one before it emitted photons, and after it emitted photons. This is why we see a diffrence in mass
I was never good at math , science . I'm into accounting. But with this kind of videos on TH-cam my interest in science has grown and I'm fascinated by this. I sleep most of the time while the video is playing in the background sometimes. It's kind of calming strangely.
Wow!! Really intuitive ❤
Never understood it this better! Thanks
Wow, awesome to hear that :)
The single most important physics video on youtube. Nothing else come even close. Thank you.
Pls make a video on the derivation of length contraction
I heard a story once--- There was a dull kid and his father hired many tutors but they eventually left that kid saying he was too dull, finally he found one tutor and the kid started doing well in school....
The problem was never the kid, rather it was the previous tutors who lacked in-depth understanding about the subject. The more you understand a topic, the broader your range and simpler the moves are - you can even get a kid dance to the complex tunes.
Thanks....
Can you also do the derivation of the complete mass equivalence equation[(E^2=(mc^2)^2+(pc)^2] intuitively....
This is total energy Et = mc²+ Ec
Ec = kinetic energy
The equation you're citing is called the Relativistic Dispersion Relation, which is the norm of the 4-momentum,||P||^2=P^ag_{ab}P^b, expressed in component form: m^2=E^e-p^2.
Please keep these videos coming! These are so helpful in explaining concepts intuitively which is something I always look for and love the content you post! Recently came across this channel and have been hooked!
High expectations.... The intro looks amazing... Lemme watch...
Let me know!!!
What about now 😂
@@Mahesh_Shenoyfrankly, I felt the video like casual physics lecture 😆. I'm so sorry to say this 🙏🥲.
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Let me watch it again in a free time 😅
@@Mahesh_ShenoyAmazing 🤩
I never figured it could be derived through such simple means. Easily understandable even for the physics layman. Thanks for teaching.
I really feel like I'll need a bit to get a hang of it. Really nice work sir ngl even a toddler in physics would understand this as you even try to explain the slightest of things.
I just want to know that if E/c2= ∆m is an approximation, so it won't be able to work for high velocities right? Like those approaching quite much the speed of light like an electron in a bohr's orbit or can it tolerate that much?
Lastly, really thank you for keeping me interested in physics even when on the verge of losing it 'cause of this rat race.
That’s super awesome to hear 🙌
@@Mahesh_Shenoy The question 😅
There is no such equation. The equation is E=m, which defines the mass in the zero-momentum frame. You can have ΔE=Δm in the absence of change in the 3-momentum. [note: c=1]
E=mc^2 is not an approximation. Be in no doubt about that. The derivation in the video uses 1/2mv^2 for kinetic energy. THIS is the approximation. It is this equation that only holds at low speeds. The use of the binomial expansion reconciles the derivation with this approximation. If you do the analysis using full relativistic kinetic energy (derived using the work principle) then E=mc^2 is exact. This would make the story a lot more complicated though and I can see why Mahesh didn't go there. The key idea in the video is jumping between frames of reference, assuming physics should behave the same from both points of view, and thinking about what that must imply if the speed of light is the same. That is relativity theory.
@@robwilliams4773 No. The accurate equation is
E = 'gamma'mc^2.
E = mc^2 only works for low speeds or when things are at rest. As mentioned, it's a first order approximation!
The missing energy is balanced by the amount of energy required for acceleration.
It’s really straightforward.
Love your videos!
Great to hear that!!
I never knew that I could derive E=mc^2 without even holding a pen and paper and just by visualizing things looking at a youtube video. Just amazing. Loved it~
My body is ready, but my mind is not. See in a few days
See you soon 🔜
Mahesh, i love how you interact with Einstein like you just left his lecture. It helps make this so engaging
Nice 👍👍👍
Dude...the craziest thing about this video was learning what Albert learned by himself way back in the day...in just under 30mins...this was amazing...
If E=Expresso and M= Milk , C= Coffie, this is the formula of the “Macchiato” 😂
Haha!
Lack of use and 50 years time since college physics hinders me, but I found your enthusiasm and explanations delightful. I had long forgotten how to resolve nothing travels faster than the speed of light versus Einstein's energy-mass conversion process being dependent on the speed of light squared.
My man doing god’s work. I haven’t completely watched the video, but I bet it is fine!
Thank youuu
If you understand that mass is just confined energy, it's easy to understand why the atom loses mass, it lost some of that confined energy.
If you know the mirror box example with photons bouncing inside, if you push the box the photons that bounce push against your hand so the box feels like ir resists (inertia). It the box loses photons, less of them bounce when you push it, so you feel less resistance (inertia), so the box lost mass.
Mass is just an emergent property of light speed particles (which have momentum) confined inside a certain space, because they bounce on whatever resists moving the system.
Everything moves at the speed of light, what doesn't is just a system of multiple particles, and the system can stay still but it's made of all light speed moving elements internally. Nothing moves slower than light, only emergent objects.
Here before this masterpiece gets viral❤️🔥
🤞
He explained such a vast and complex topic so easily ... Huge respect sir ❤🫡
Light is way cooler😎 when it is wave than it is as particle
🆒
You're my favourite TH-camr I found this year!
Yay!!!🥳
Present sir 🎉
Nicee
You have a great gift for teaching 😎 this is quickly becoming one of my favorite channels
You've reignited my passions for physics, I watched a vid on a whim and i've been watching them one by one since, you've captured all the things that makes this topic so interesting and explain it so well!
Best physics channel I've seen so far!
24:30
I feel like we should divide both sides by v^2 and take lim v->0 instead of using not so rigorous and accurate approximation. The answer is the same. If we would take more terms in binomial expansion the answer would be different, i think it is a very nice coincidence that only two first terms of binomial expansion (which only applies to integers) gives corrent answer but it is like taking
dx^-2/dx, dividing numetator and denominator by d, "-" next to 2 with "-" in fraction, rerranging and getting 2x.
Mahesh sir deserves the best teacher award....
A tenth grader learning feynman lectures, theory of relativity, electromagnetism and Lots of works in the field of science.... I am really very thankful to you sir, Even though I study in 10th grade I learnt from your videos so much things... Thanks for introducing me to a very open and thoughtful world.
You are most welcome. It’s awesome that you are interested in these things!
@@Mahesh_Shenoy ✨😇
Mahesh, this is the most intuitive physics channel I have encountered so far! Big Gratitude!🎉 Perhaps could you please at some point make videos about AI/ML topics?
You are awesome, Mahesh! I've been watching all your videos since I found out about your channel. I love your excitement and your intuitive take on hard topics!
Not only a beautiful explanation of the derivation, but this actually allows us to see why the often heard statement 'mass is converted to energy' is misleading: no 'conversion', no 'alchemy', is required, only the consistent following through of the original postulate - that c is constant for all observers - and the consequences of this for objects and observers in motion. Look at Nature and wonder that such simplicity gives rise to such an amazing universe...
ONE of the best videos I have ever seen! Never will forget
I love your enthusiasm, and the fact that you want to explain things intuitively, it really helps!
This is a BRILLIANT exposition. Thank you! Its only when the explanation is this good, so eliminating the pervasive obfuscation in this realm, that we see clearly what a intellectual magician Einstein really was; this entire edifice is a nonsense. The egocentricity at the core of Einstein's physics is stupefying - I don't mean his own personal ego but his fixation on observer-centric, "reference frame" effects that don't exist in reality....or to put in Einsteinian lingo, don't exist in the reference frame of the thing itself. To pick just one example here, the observer simultaneously "seeing" red-shifted and "blue-shifted" radiation from his "balanced momentum" source is a foundational contradiction. Mahesh gets to the heart of Einstein's philosophy at 07'30" with "you don't say it's impossible, instead you ask what needs to happen in order for it to be possible"....and so we get "lateral thinking" run amok, then thought-experiments turned into declarative statements, and ultimately into dogma.
How do we replicate Lavoisier's conservation of mass experiments at the atomic level? The E-mc^2 proposition is circular; binding energy is released when matter dissociates but the protons, neutrons & electrons are all conserved! The eV can be defined and usefully converted to kg the same way a mass of gold can be converted to USD but that doesn't mean gold is made out of paper or that the bills in my wallet are made out of metal.
We've made Einstein into a God-like figure similar to how the ancients did with Aristotle, in the long term, their 'hit rate' will be similar I suspect.
just found the channel. love the enthusiasm. absolute goldmine, will be binging
Great video! Your enthusiasm is contagious and admirable. Simple and rigorous proof.
Mahesh, it starts off with Einstein and the Radioactive Mass (RM) neither detecting any relative velocity. With the release of the two photons and no recoil, the RM still displays no relative velocity to Einstein, and he observes no Doppler effect, no red or blue shift and concludes/confirms the RM is not moving relative to him. This is also the same conclusion one would get from the RM reference frame.
Now Einstein joins the rocket ship which he says is moving towards him at velocity ‘v’. he proceeds to assign his perspective obtained when outside the rocket, that is, the rocket is stationary, and the RM mass is moving with velocity v in the opposite direction he had determined for the rocket before he got in.
The RM reference frame could make the same claim, that is that the RM is not moving, and the rocket is moving as first viewed by Einstein to the right at velocity ‘v’.
Now, we find, in this final offered frame that the Rocket has considered the RM as moving to left at velocity ‘v’ even before the photons are released. Only the Rocket reference frame assigned the condition of the RM in motion before any photon release.
Moving the observer from one frame of reference to another or combining reference frames leads to errors when the speed of light is involved.
Newton’s Law tells us constant linear motion cannot be confirmed or denied and under that condition the speed of light will always be ‘c’ per Maxwell’s equations. That applies to any attempt of the above reference frames measuring light speed. It is not valid for the rocket frame to determine the velocity of the RM to be ‘v’, and the photons will be moving at ’c’. Only the moving frame ‘sees’ a loss of mass with an energy gain in the photon.
The claim is that light does not need or travel in a medium. The fact that the speed of light can be calculated from two real measurable qualities of space itself should be convincing that space is more than an empty void, is more than a vacuum. It follows then that the speed of light has a specific velocity because this is the velocity of transverse waves in the medium of space, and this velocity is a function of the elasticity and density of this medium. Conversely, if space was a true vacuum, there would be no specific velocity attributed to light, since the only property of emptiness is that it has no properties.
criminally underrated channel
I hope your channel blows up my friend ur enthusiasm combined with story telling and clarity helped explain this concept in such a digestable way. I learned alot from this! :)
I loved it and i strongly recommend this video to anyone who wants to understand energy-mass equivalence intuitively from an elementary point of view assuming that we are interested in negligible velocity massive objects
Man how I've been looking forward for this video! 😍
This was a brilliant progression! Congrats!
I've never been able to understand why the speed of light had anything to do with mass or energy ... let alone why it made sense to square c.
This all finally makes sense.
Thank you.
Stunning! Thank you. Does binomial approximation mean mc^2 is only approximation? Please make follow-up with clarification.
Yes it is!!
Awesome explanations 🎉... loved your presentation and saluted your knowledge.
I have a question about Doppler effect with sound. It seems from you explanation that there would be no Doppler effect in the case where there is a transmission medium. It seems to me that there is a classical Doppler effet with blue shift when the speaker is heading towards you and red shift when the speaker is heading away from you, but in Newtonian mechanics the two corresponding shifts of energy cancel out.
Mahesh, I totally loved your intuitive approach. 😍😍Love from Bangladesh.
10:45, there is no change in wavelength for sound waves but according to my IITJEE textbook the frequency would be experienced differently by the moving observer to account for the increased speed (relative speed). And the general eqn has a v+vo term in the numerator
Yes, that’s due to the increased speed of sound. I should have been clearer.
That’s why the speed of sound gets a boost in the numerator ;)
I compare this video to dialect's video. According to dialect, the equation is T2 = T1 + ε (T3 - T1), where the light leaves the source, say clock A, at time T1 according to A, bounces off clock B at time T2 and hits clock A at time T3, and 0 < ε < 1. Here, Einstein is assuming ε = 1/2 exactly (hence the derivations in this video), but ε need not exactly be 1/2 according to dialect. We could easily exploit this loophole to restore Newtonian physics (and that's exactly what dialect does in that video), and this "ether" that actually turns out to be an electromagnetic field is a suitable substitute for a medium as if light was sound.
Dialect is an interesting channel indeed.
That was a beautiful video. It helped me clearly understand so much more of the details. Thank you for patiently walking me, baby step by baby step. Very well done.
You are just amazing. And you deserve millions of subscribers! Thanks for all of your videos and surely for your passion.
Mahesh, firstly your enthusiasm, for this stuff is infectious, secondly your intuitive explanations make it almost understandable for a dummy like me. Quantum mechanics and relativity have always messed with my sanity but your explanations are so sanguine I almost understand them
Man, whatever happens in life. Please don't lose your passion for physics. It is precious.💎
The way I see it, energy is not a thing that exists out there or that a particle possesses. It's a measure of "how energetic is an interaction" instead. If you are in a slower frame, your interaction with the photons will be less energetic than if you are in a faster frame relative to the atom. That's where the "energy" comes from... it is the relative motion between the participants that creates a more or less energetic interaction. Without interaction, there is no "energy" at all.
There is a flaw in that logic: in the rest frame it also lost mass. You use m_rest(before emitting photons) - m_moving(after emitting photons). There is a double difference. You must prove m_rest(before emitting photons) = m_moving(before emitting photons).
I love how you simplify very complex subjects, and "ask" the questions we all have to get to the answer. Would you please do one on the "twin paradox"? Also, would you please explain in a "thought experiment" how someone in a spaceship moving at a constant velocity can measure the speed of light moving in either forward or backward direction to be "c"?
I love how you give an intuitive explanation. Please continue making more videos.
You have a gift of going into detail and can explain in a way that many viewers can relate to. I appreciate that. I also understand that you have a comical and conversational way of presenting. But I cannot help saying that, in invoking great names such as Albert Einstein and Richard Feynman in the dramatic conversations and more importantly in your intonations, they do not come out in quite the respectful way toward the two great geniuses as probably all scientists would do. Even in a dramatic conversation when invoking such towering personalities, the intonation should not sound like you and them are equals. They did everything, and they dedicated their lives to doing so, you are just re-telling their findings in a way many people may find easy to understand. But for this important point, that I could not help pointing out, everything else is good! So, please keep it up!
In other words, the science deities are beyond humanizing, right? We must all bow down in supplication in their presence,yes? Yours is the attitude that has got high energy particle physics & cosmology into the mess they are both in.
Super clear and fantastically explained thank you!
This is exactly what I was looking for! Very cool. Thank you , brilliant animations. So well executed
I'm curious though, what happens if v is not _much_ smaller than c and we can not make that approximation?
Please elaborate with real numbers
I have been searching for the original proofs of the equation for a while now. All the sources out there hardly match the profundity of the original proof. The rest of the proofs which I've encountered yet seemed somewhat vague or conditional. I wanted to study the original derivation. But couldn't find the original English translation of German manuscript on Scholar (** or was too much lazy to delve further). That's when I saw this video and I have to admit it is much more profound than I imagined.
and of course excellent presentation too. Good work and keep doing it.
N.B. I was also fascinated by your video on how can light waves carry momentum.. and again Keep going.
Thank you for sharing that vote of confidence!