Feynman's Lost Lecture (ft. 3Blue1Brown) 

I know what you're thinking: Either Henry is taking some well-deserved time off and I'm just helping to fill in during that vacation, or else he's currently tied up in my basement providing me occasional sound bites for food while I slowly take over the channel for good. To anyone worried about case #2, don't be silly. He's in the attic. Way too many escape routes in the basement.

As Feynman once said "...it takes tremendous strain on the mind to understand certain concepts.." now I know he was right.

"What special curve satisfies the property that the tangency direction for a point theta radians off the horizontal is given by this vector from the special eccentric point from the circle to a point theta degrees around that circle from the vertical? Okay... Is the question clear?" Uhhhhhhhhhh... *infinite intelligence load error*

Ohhhhhh, it all makes sense now. Not to me but I'm sure to someone it does.

“You don’t need calculus to understand this” *3 minutes later* “As you can see, if you keep adding infinitely small sections to this polygon, it trends toward a circle”

I find it fitting that a guest video was used to talk about a guest lecture

Man, this 3b1b guy (grant sanderson) really deserves more recognition and some prestigious awards. He is one of the most influential math guy in present history, so many people like me are everyday getting inspiration to study mathematics from him.

"Stay focused" I see what you probably weren't intending to do there.

Newton - "OMG they don't understand my physics!" Feynman - "Hold my beer."

ooh this gonna be good

Thanks a lot for the video Grant...You really tried your best to keep it simple...even though I had to occasionally pause and ponder. I wish 3blue1brown makes a collection of all the lectures of Feyman !!!

Once I get into, and then through college, I'm definitely going to build a time machine and yank Feynman out of some class just to show him this video adaptation of his lecture. Beautifully conveyed!!

"Surely you're joking, Mr Feymann !" is one of the best book I have ever read. Its deep, it's mind-boggling, and much more, it's fun !

New MinutePhysics video notification: "oh neat, I'll add it to watch it later" Topic is "Feynman's Lost Lecture": "Maybe I'll listen to it in the background" Featuring 3Blue1Brown: **heavy breathing** Video duration is 21 minutes: **drop everything I'm doing and hit the fullscreen button**

Thank you for this! Several, "That is so cool!" moments in this video, and...as much as I love learning...I only went as far as Physics 101 in college. Thus, it's not just cool how all of this works out; it's cool that it can be broken down into individual pieces that are each relatively easy to digest. I'm suddenly reminded of Zen Archery. Don't think about the target; just get each individual step right, and your arrow will arrive at its target "on its own".

3blue1brown: *explanations*, Right? Me: Uhhh *brain.exe is not responding* 3Blue1Brown: *continues explaining* Me: *brain.exe crashed*

Twenty One Minutes Physics

Minutephysics + 3blue1brown + Feynman? Knowledge-gasm!

Can you imagine what sort of lectures and presentations Feynman would have produced if he had access to the same animation software used to make this video...? 😮

I've seen this video 3 times already. I understand what he's saying everytime I watch it, and then forget how he did it the next time I come around.

My head hurts a little, but I think I understand most of it. Remembering it on the other hand.....

As my eyeballs glazed, I realized fully that I do not have 'infinite intelligence'. I guess it's good for us to run into a wall now and then. Wow.

Thanks for the easy and simple explanation. Every thing is clear now.

I find it simply amazing we can know so much and yet understand so little. Thanks for sharing!

I'm afraid I only have a finite amount of intelligence.

The Great Physicists' Road Trip by Ms. Rachel C. Millison Great physicists from the past decide to return to Earth for one last road-trip vacation to the coast together. They all appear on Earth on the appointed evening. Heisenberg pulls up behind the wheel of a gigantic 1930's car, a huge grin on his face. As they're getting in the car, Hubble looks up and says "What a wonderfully dark sky". "Shouldn't be" responds Olbers. "Always has been" says Hoyle. "No, it hasn't" says Lemaitre. "I knew that!" says an embarrassed Einstein. Once they're all in, Teller says "Hey guys, this trip is going to be The Bomb!". "Yeah, but why do I always have to organize?" asks Oppenheimer. "Where exactly will we end up?" asks Kepler. "That's impossible to predict" says Bohr. "I just can't believe that's true" says Einstein. Heisenberg punches the throttle and the old car roars off. "Say - this thing sure accelerates" says Newton. "I don't know, Isaac. It feels like gravity to me" smirks Einstein. Later that night, as they are speeding down a country road, a police car catches up to them and pulls them over.[1] "Do you know how fast you were going?" the cop asks. [1] "No, but I know exactly where I am" Heisenberg replies. [1] The cop says "You were doing 55 in a 35" [1] Heisenberg throws up his hands and shouts "Great! Now I'm lost!" [1] The cop thinks this is suspicious and orders him to pop open the trunk. He checks it out and says "Do you know you have a dead cat back here?" [1] "We do now, asshole!" shouts Schrodinger. [1] "I think it's time to split" says Everett. "Say, how did you manage to spot us on such a dark night?" asks Hubble. "I saw the light from your head lamps" says the cop. "How fast was *it* going?" asks Michelson. "That's simple addition" giggles Galileo. "Not exactly" says Lorentz. "Look here" says Heisenberg, "how do you know I was going that fast?" "I clocked you over a measured distance" says the cop. "How often?" asks Hertz. "I disagree with your measurement, officer" interjects Einstein. "Don't start tonight, Albert" says Bohr, shaking his head. "What Herr Einstein is trying to say" continues Heisenberg, "is that time was running at a different rate for you than for us". "WHAT!!!???" exclaims Newton. "It's true" says Maxwell. "We're all famous scientists and, believe us, Herr Einstein has proved it, though it came as no surprise to me". "Sounds complicated" responds the cop. "I'll draw you a simple diagram" says Feynman. Totally flummoxed, the cop lets them go with a warning. As he drives away, Doppler cocks his head and listens to the sound of the receding police car. "Gotta love that" he says. "Amen" responds Hubble. Returning to their car, Lord Kelvin remarks "Sure is warm tonight" "Yep - lots of disorder" replies Boltzmann. "In places you'd never expect" adds Hawking. "I was lucky to get away with that" says Heisenberg. "Most cops think they're better than everyone else". "Yes - I hate inequality" adds Bell. "Though you *were* speeding" says Faraday to Heisenberg. "I carefully observed the needle creep from 35 to 55". "Actually, it was jumping, Michael" replies Planck. As they pile back into the car, Bohr says "See here - you must fill the seats in order - no empty spaces allowed. And stop interfering with each other!" "Only one of you can sit next to me!" yells an agitated Pauli. "Say, Werner - it's stuffy in here. Be a good chap and crack the window a bit" says Hawking. "Sorry, Stephen. It can be all the way up or all the way down, but nowhere in between" replies Heisenberg. "Hey guys - Albert and I just figured out a great shortcut. Only one bridge" announces Rosen. "It will save us a lot of distance" says Einstein, "but it might get spooky". Arriving at the beach the next morning, they hurry from the car and stand looking out over the ocean. "Look at the wonderful waves" says Schrodinger. "They don't look like waves to me" says Bohr. Looking down at the fine sand, Dirac exclaims "Look at all the particles!" "Now *those* look like waves" says De Broglie. "This is great!" exclaims Feynman, rubbing his hands together. "Now, lets go meet some girls!" "Let's delay" says Wheeler. "We have to be discrete" warns Bohm. "Girls? NEVER!" exclaims Newton. 1 Based on, and including the original, attributed to Rich Granger, engineer, Battelle.

I think the visuals made it elementary to understand, but I loved the linguistic complexity needed to be able to effectively communicate the concept in the first place. Granted without the visuals I probably would not have understood, nor would I have wanted to understand. Great video!!!

Keep up the asking questions out loud stuff with a slight pause. It aids learning and facilitates the drawing together of seemingly unrelated threads within the consciousness of the viewer. Good work.

10:48 *3B1B* : Well, specificly it says that this quantity times the mass of the object stays constant, but, I mean, the mass of the orbiting object isn't gonna be changing. *Michael* : Or is it?

I admit I'll need to watch this many times before I might have a decent grasp of it. I'm in my 60's & was a high-school dropout. I went on to get a modest amount of formal education & training in a limited variety of subjects. I did okay with electronics algebra & basic trig, but then I hit a plateau. It took me a good decade to recover from that setback, and begin to realize that math can be awesome, beautiful, and even entertaining. I became a person who wished they could have been an astrophysicist. Part of that desire came from finding my way back to a youthful obsession with the nature of the universe, of which I'd all but forgotten. Later, I began to see how impressive were the skill sets of many of the world's physics giants. In the last several years, while I mainly do more-mundane, day-to-day achievements of a kind, I spend a lot of time examining everything I can find on the laws of nature & the stories of science. I can't seem to get enough of it. But I'm too often struggling with concepts that are way over my head, and I've wished to find an easy way to learn some of the fundamentals. Meanwhile, I've tried hard to acquaint myself with every existing variety of fields in which the highest math skills are put to work. I've gotten some great books from the library, and have devoured countless, thrilling stories of the history of science. I've been given or purchased several of my own, too, and have read all the magazines for the last 15 years.. I've learned about the important breakthroughs of Aristotle, Ptolemy, Newton, Brahe, Copernicus, and quite a few others, including Johannes Kepler. I have an awareness of a good number of modern-day achievements, along with today's heavy hitters. too. I can't entirely explain this fascination I've developed. It has a grip on me, and sometimes I think life would just be a lot easier, if I dropped the whole thing, but but just won't go away. Fortunately, like Ron Burgundy once said, that is in no way depressing. For all these reasons, I found a great deal of enjoyment in your fantastic video presentation. It's one of the most helpful demonstrations I've yet come across. You are to be commended, for providing the layman with such a near-intuitive overview of this sort of topic. I'm anxious to see what else you've posted. excellent job!

Once again, a wonderful presentation!! Thanks.

The video that introduced me to 3Blue1Brown last year. I was so obsessed with Feynman and his works and I landed here.

Thank you for the effort that was put into this. Amazing people, teaching millions of anonymous people, you deserve more gratitude that can be offered in a comment!

The video currently has 467,294 views including my 467,200 views to understand it That too at 0.5X speed

This is AWESOME ~ Thanks for sharing this!! Love 3Blue1Brown! You summed this up awesome!!

Bravo 3b1b- it's like watching an art and just enjoying the moment without understanding !!

I am fully convinced that the term 'Quantum Electrodynamics' was coined solely to make the 'QED' joke

2000 years later: The physics/maths behind creating level II universes. Animated and taught by 3b1b the 500th.

Grant: "Ok? is the question clear?" Me: Nods in liar liar pants on fire

Great video. It's a bit like the classic Cambridge natsci/physics interview question "describe how you might approach proving the following or what laws you would need to invoke'. Thankfully mine was simpler however. We had a first edition of Newton's Opticks in the college library and I was kind of thrilled to request it and read a chapter... in a long-gone innocent age where there was no door security on the college or the reading room.

That's a pretty *_normal_* way of constructing an ellipse!

“So I’m gonna draw it nice and thiccc” *12 year olds have entered the chat

Just loved this video ! 3Blue1Brown : you are the best at explaining complex concepts step by step with very elaborated (and beautiful !) animations. thank you

2 GREAT LEGENDS IN A VIDEO HOPE U BOTH MAKE MORE VIDEOS

Holy crap, I suggested this topic to Grant on his subreddit. I can't believe you guys are actually doing this! Awesome!

Somehow this seemed even denser than most of 3blue1brown's other material. I feel like I could probably get it all if I spent a couple hours working it out for myself, but right now my head just kinda hurts.

Love the conceptual simplicity of this.

Amazing video. This channel is so impressive. Thank you!

I appreciate your through discussion of this. It really reminds me of my grandfathers explanation. I was looking forward to your method of explanation, and was quite entertained

I am definitely gonna have to rewatch this several times but I look forward to it

Gorgeous collaboration!

A beautiful geometric expression of this interesting orbital relationship with mathematical proofs how it derives into such fascinating vectors from the gravitational pull.

Didn't think it was serious until he said Go full screen.

Newton started off with a bet to prove this (the ellipse being a consequence of the inverse square law) and produced a series of publications, eventually compiling the principia mathematica out of this seed. However, although he never states this clearly, I'm sure he realized that the proof he gave was for the converse: that given an elliptic orbit, an inverse square force law follows. This was much easier at the time because so much was known about the geometric properties of the ellipse than was about F=m a. In fact, Newton couldn't really mathematically use velocities because they compare two quantities with unequal units (distance, time). Also of course algebraic notations and vectors weren't invented yet. But still Newton claimed to have won his bet, and the Principia avoids any clarity about proving the inverse square law vs. the converse (proving the elliptic shape). I'm sure Newton would have LOVED this type of proof, and this proof in particular! Although I'm sure he'd appreciate how much more powerful modern mathematical notation and ideas such as vector or Lagrangian calculus are. And that's where Feynman and 3blue1brown comes in: Elementary proofs just are the next level of understanding: being able to explain something seemingly complicated in simple terms. With intuitive concepts, but with methods not more complicated that what was available to Newton.

I was a math major for 1 year before I switched to mechanical engineering. I'm now retied and can indulge my first passion. I simply loved this video. I do believe, though that the constructs are merely consequences of natural laws without any useful knowledge.

I highly recommend this excellent presentation. Bravo.

I just found this video ... BEAUTIFUL ... Richard Feynman is who I want to be when I grow up ... what an Alchemist ... I believe everything he touched turned to gold ...!!! and Grant, you should win some sort of video award for content (I know they give Creator Rewards for subscriber count) ... Hey RU-vid, this guy's content, production and presentation values are nonpareil ... this is a magnificent presentation and should be the standard for all other content on the web ... BRAVO Sir! Also, thank you for pointing me to the free online Feynman Lectures ... Thumbs Up...WAY Up!!!

I've commented this in many 3blue1brown videos but not enough times. This was BEAUTIFUL.

Tremendously clear!!!! Great job.

Feynman was an artist who had shown us some ultimate beauties of universe through the colours of physics.... This is a gem.... 💎💎

Was I the only one that forgot this was a minute physics video?

20 minute Physics Even better!

The incredible nature of the rubber band. Think like Feynman. He amazed me when I found his lectures on you tube. I love this man

Wow, this is mind blowing. Very well explained - one thing you and Feynman have in common.

*Yes, I'm going to pretend like my brain has enough computing power to fully comprehend every single word in this video and instantly apply it to every subject previous brought up, and watch the video a ×1 speed without pauses.*

This is the most satisfying maths/physics video I've ever watched period.

This is really challenging stuff to conceive. Appreciated .

This channel is amazing. Minute physics, your channel is one of the best out there. Keep it up!

I thought it was 3blue1brown who uploaded video

Everything to know about physics relates to geometry. This was such a pleasure to watch

thanks so much for the knowledge

A guest lecture about a guest lecture! Excellent! Hopefully this will never become known as "3Blue1Brown's Lost Lecture"

I LOVE ANYTHING AND EVERYTHING FEYNMAN!!! This was a great video, and I love seeing the cooperation between math/physics/science channels.

Appreciate the explanation as I know there are a lot of proofs of Kepler's laws, but I have found very few videos explaining Newtons conclusion on why orbits must be ellipses. That part of the story where Halley requested his analysis has always fascinated me. Thanks

At 6:13, I love the animation of the focus acting like a sprinkler! I played it 10 times.

Grant not only is a genius but he is also a fantastic teacher. Honestly, every time i didn't understand a specific part of the proof he addressed it right away, almost as if he could read my mind! That is, in essence, teaching, and he's brilliant at that!

Goddammit grant. You couldn't just be a teaching god on one channel, you gotta invade minute physics too? Jk, love you both. Henry, you got me into physics when I was in middle school (going into uni in 2 months) and Grant, recently you made linear algebra make sense. Which was strange for me, because my teacher did an absolutely awful job. Thank you both, you've helped me and many others immensely.

Grant has for sure the most awesome voice on RU-vid. I catch myself drifting away when he speaks all the time. O how I would love he would read bedtime stories for us (albeit probably in a separate channel)...

fantastic presentation of a difficult but interesting subject

"So the question is: What special curve satisfies the property that the tangency direction of the slope for any point theta-radians off the horizontal is given by /this vector/ from a special eccentric point on the circle to a point theta-degrees around that circle from the vertical? Okay, so is the question clear?" XD

The best thing about this is that I understand very little of it but it still manages to amaze me :)

I just wanna thank you I did not completely grasp it but I do have some insights on it Thank you very much to Grant Anderson and Richard Feynman And of course Newton

Props for all the effort that went into this, I kind of expected a more intuitive overview with some examples of why this is useful, but we can't really expect you to be Feynman

Latin focō (as in the video) is the ablative of focus, which means at the fireplace. the form focus derives from the nominative which is focus not foco.

Wow...loved this one...

its beautiful. When i first learned about the focal length constancy in ellipses it drew all my attention. Maybe should have looked deeper. Maybe thats what makes a Feynmann

This is probably my favorite video on youtube.

Loved this collab. Thanks for this video! Knowledge just blasting off from this video, like water sprinkler.I don't think I managed to catch all the water.

Woah 3blue1brown! :)

omg please more physics videos you are great!

That was great! I'll have to watch it again.

1:00 top row 2nd square *GRID-CEPTION*

That black dot on the screen from 1:43 to 1:48 got me! I was pawing at my screen trying to remove the 'spec'. How dare you! :3

Beautifully explained thanks

this was a strange experience for me and i dont know what to make of it- but despite never seeing this idea before, almost as soon as i heard the introduction i knew almost every step we were going to use to get there (of course it wasnt a full proof in my head using theories and all, but like the vectors making a circle and the rotations and some of the perpendicular bisector stuff, really all the visual ideas). it just... came to me at the start. never had that happen before.

The PCA explanation by 3blue1brown got me a job ❤️

you know its good when minutephysics realeses a vid with Feynman in the title

Wall...so nice and not complicated at all. I think would be so hard to come with concept but once it is done is not that hard at all. He is basically using some calculus and geometry concepts. It is unbelievable how the graphics help the understanding of these things. Imagine Newton doing this from scratch with no visual aid. Also we need to congratulate Blue Brown, the way he explain it is so clear. It is like he sees inside your brain and trace the path to make your neurons flow. I didn't even had to focus that much, I just laid back and let the lines do the work for me. Awesome.....

Absolutely fascinating Explanation. Thanks.

minute physics+3b1b+Feynman what could i want more, best day of this month