#science #physics #ideas The Biggest Ideas in the Universe | 3. Force, Energy, and Action

#science #physics #ideas The Biggest Ideas in the Universe | 3. Force, Energy, and Action 147,153 viewsApr 7, 2020 Sean Carroll 154K subscribers The Biggest Ideas in the Universe is a series of videos where I talk informally about some of the fundamental concepts that help us understand our natural world. Exceedingly casual, not overly polished, and meant for absolutely everybody. This is Idea #3, "Force, Energy, and Action." Already I have backslid on my idea that every idea would be encapsulated in just one word, but these three seemed to flow together. My web page: http://www.preposterousuniverse.com/ My YouTube channel: https://www.youtube.com/c/seancarroll Mindscape podcast: http://www.preposterousuniverse.com/p... The Biggest Ideas playlist: https://www.youtube.com/watch?v=HI09k... Blog posts for the series: http://www.preposterousuniverse.com/b... Background image: https://www.freeimages.co.uk/gallerie... #science #physics #ideas #universe #learning #cosmology #philosophy #math #force #energy #action #classicalmechanics 371 Comments rongmaw lin Add a comment... colossalfart colossalfart 2 years ago I work in railway engineering. "Jerk" is most definitely a used word and an important concept for passanger comfort and safety inside a moving train. Imagine if a train started moving from zero at a constant rate of acceleration (linear increase of velocity). A passenger inside the train would feel a sudden "jerk" from the instantaneously applied acceleration. This is obviously not only uncomfortable but dangerous, since it could cause one to lose his balance. It's exactly what happens when someone pulls the emergency brake. This is why in normal operation, not only the velocity needs to increase gradually, but the acceleration also, in order to keep the "jerk" below a certain value that is deemed safe (this value is dependent on the acceleration). Snap, crackle and pop, however, are concepts I've only come across at breakfast when I was a kid. 186 Alex Paven Alex Paven 2 years ago Don't force yourself to make these shorter, they're great as they are, and this includes the Q&A! Great stuff! 148 Veroosh Tarot & Astrology Horoscope Veroosh Tarot & Astrology Horoscope 2 years ago I like the 1 hour sessions, keep going. Its a meditation. 26 terrypussypower terrypussypower 2 years ago (edited) Sean is my favourite scientist. Even when I don't understand what he's on about, the tone of his voice makes me feel smarter. 60 Giorgos Tsiledakis Giorgos Tsiledakis 2 years ago The Principle of Least Action seems to be one of the deepest 'laws' of our universe. But why is this the case? Are there any insights about that? I guess a 'Principle of Random Action' could actually be kind of more 'natural'. By following the Principle of Least Action, the universe seems to know in advance the value of all possible actions and then always choose the one with the lowest value. Isn't that strange and wonderful at the same time? Thanks for the amazing content by the way! 17 Rogério Pereira Rogério Pereira 2 years ago All your technological improvements are good. Many thanks for these lectures and keep up the excellent work. Cheers. 14 Edward Cosio Edward Cosio 2 years ago (edited) I am having so much fun with these. I’ve always wanted to get into and visit the ideas you present in these videos. The entirety of the natural world, to be honest. My interest was absorbed entirely into my undergraduate studies of music composition and, until recently, has reignited recently as of maybe this past year. Thank you again for your insight, I can’t get enough of it. 👍 5 Carl Malone Carl Malone 1 year ago Sean, you really found the "sweet spot" for teaching physics. Nice work ! 6 DarlEng DarlEng 2 years ago I really like this higher level approach to physics, digging into metaphysics more like. Way better than any of the science classes I've taken at Cal. 11 Sayed Rahim Rahimi Sayed Rahim Rahimi 2 years ago Thank you so much for the precious content. It’s such a great luck and blessings to have access to such quality content put in such an eloquent way. Thank you so much dear Sean. You have been of the few best educators I have had in my life. Have been knowing you since quite a long time through your lecture in The Royal Institution. 🙏🙏😍 2 Patrick Hoyle Patrick Hoyle 2 years ago Keep up the amazing content, have been a fan for years. 12 Mohammad Reza Mohammad Reza 1 year ago Great video! And I liked your closing sentence: "To improve our current understanding of the laws of physics, we have to be open to the possibility that we're gonna invent more words, more concepts, and more ways of looking at the same universe, that help us recast those laws, extend them, generalise them, and go beyond what we currently know, into the physics that we don't yet understand but hope someday to do." 2 A Kumar A Kumar 2 years ago Watching in UK England, how lucky we are to get to benefit from such a brilliant series. 39 Atbinix Atbinix 2 years ago Thanks you Sean! It's awesome videos, please keep them long, we have lots of free time in isolation to contemplate every minute of them :) Ali Karimi Ali Karimi 2 years ago I'm watching your videos and reading your book at the same time. Keep up the great job Sean. Thank you so much 🙏 1 Cyclopropane Cyclopropane 1 year ago Love the lectures! Thank you for doing this. Love the Mindscape podcasts as well! 2 laastchild laastchild 2 years ago I appreciate your efforts to improve these presentations, and thank you. You have been my favorite physicist to listen to. I have downloaded some of your work on TTC , The Great Courses. I, also, am an Everttian, and am anxiously waiting for some kind of collective decision on wtf are the fundamentals, the reason why, quantum mechanics works the way it does. I am glad that I am not the only one, by far, to appreciate your ability, Sean, as one of the very best communicators, and teachers, of the secrets, history, discoveries, and cutting edge research that is going on in all the various fields of science you work on, and expound on. llaauuddrruupp llaauuddrruupp 2 years ago I really, really like these videos! I truly hope you keep making them. 2 Corr Pearce Corr Pearce 1 year ago Thank you Professor Carroll for creating this series, you have given us a tremendous gift 1 Henrik Wannheden Henrik Wannheden 2 years ago I absolutely like the iterative process with how to do these videos. It shows that Sean is a man with teaching skills. By the time this series is done, he'll probably a full time Youtuber. Erick Moya Erick Moya 2 years ago Love the concept of this series Prof. Carroll! 4 James Edward James Edward 9 months ago "Maybe you need to know the hopes and dreams of particles" .....made me laugh out loud. Sean is awesome. 1 BZ BZ 2 years ago Trauma and critical care surgeon here. These videos have been a saving grace for me in the time between taking care of the COVID patients and ensuring my wife does not kill my 3 kids now being homeschooled. Please keep these coming. You obviously have limited time and many responsibilities so thank you for taking the time to reach the common folk! 32 Alina B. Alina B. 1 year ago Thank you for explaining all of this. Priceless knowledge and so interesting Paweł Rynowiecki Paweł Rynowiecki 2 years ago Really appreciate the series, thanks for it! Question: Why do light propagates slower in water and yet there is a constant speed of light? Ronan Mehigan Ronan Mehigan 2 years ago Hi Sean - great video. Can you discuss how the Lagrangian relates to the Conservation Laws in Physics ? 2 Gilda Stigliano Gilda Stigliano 2 years ago these classes are excellent! keep 'em comin' please!!! 2 bryan roland bryan roland 2 years ago Lucid and accessible to innumerate viewers like me. Long too. Love it! Thanks for making staying in more interesting. 2 Xavier Gamer Xavier Gamer 2 years ago (edited) We love these videos. Thank you. We specially loved where some cereal companies came out with “snap, crackle and pop” for their commercials. 3 jkinkamo jkinkamo 2 years ago Thanks for this great lecture! There was a question of lecture length. I'd prefer one hour or even longer ones as it seems to be more or less "industry standard" in online open university lectures. In my opinion combination of the main lecture and the following QA-video is rather nice lecture package for one day while forced to stay at home. Also one can rewind and replay the points of interest while studying the topic further with additional web material from other websites. Of course, thanks to the Internet and Youtube one can divide one longer lecture or multiplex shorter ones in order to achieve optimum length for himself. CatZ CatZ 2 years ago Very cool video, thanks! I think it may feel less astringent to conceptualize of nature as "efficient" instead of lazy. I'd wager that's the shorter (more efficient) path for the idea to flow into another's brain if that's your goal, nature. 1 Rihards Geidans Rihards Geidans 2 years ago Thanks for the excellent content! I have a few suggestions however...To make the videos shorter and flow better, i think it would be better if you sped up the parts where youre drawing and not speaking. Also its sometimes a bit hard to know which part of the board i should focus on when youre referring to "this, that, here, there" since i cant see what youre pointing/looking at, so maybe just draw more arrows/points/circles around stuff youre referring to and then just press undo when you move on. 1 Iyad Sarhid Iyad Sarhid 2 years ago Thank you for the effort and determination! Great video! 1 EasterDeer EasterDeer 2 years ago These videos are fantastic. Thanks Sean! Roman Travkin Roman Travkin 2 years ago 41:50 Actually, for large time intervals, it could happen that the real path is a point of zero "slope" (a.k.a variation/differential/gradient) of the action—it does not need to be even a local minimum (e.g 100 revolutions of a spinning top). 1 X95 23 X95 23 2 years ago Sean, these are great. But it's hard to get my mind in gear to learn right now. I'm sure I'll come back to them later. Thanks a million for doing this! Jason Beary Jason Beary 2 years ago I teach physics but I still love to hear Sean's explanations. They go very far back in the developement of the ideas. I think something from each "Biggest Ideas" will be used in lessons with my students. JohnE JohnE 2 years ago (edited) Thank you for explaining action. I got a BS in physics in early 60s and it was not really taught. Actually it was defined with some examples examples and then we almost never heard about it again. 3 Alex Cherfan Alex Cherfan 2 years ago Loving these videos man. Thank you! 2 Paul Brown Paul Brown 1 year ago Thank you Sean, your doing an immense public service here Edward Lee Edward Lee 1 year ago Certainly not the first one to draw me in, but definitely the one to keep me in. Making particle physics interesting, grace it in the splendor of humility and authority. Thanks for the efforts and keep up with the good work. From Hker worldwide 1 Zhiqiang Yan Zhiqiang Yan 2 years ago Question: the minimizing principle seems arbitrary in "what needs to be minimized". Are the minimization of action for particles and the minimization of time for photons related? Is there an underlying principle that rules both situations? 1 bestape bestape 2 years ago Thank you for connecting these concepts so simply. The principle of least action is fascinating in comparison to life, which I assume is a subset of Nature. As Schrodinger put it, life is order from order, not order from disorder like the rest of Nature. Aperiodic least action then, which can be as commonplace as n*arctan(a/b). And how to distinguish n*arctan(1) from the other a/b spins? Jose Ramirez Jose Ramirez 2 years ago Keep up the good work, thanks for expanding my thirst for knowledge. Allan Zed Allan Zed 2 years ago (edited) Thank you - I learnt a lot. It was a bit of a slog but philosophically very significant. What has a name doesn't confer existence on it - that's a biggie especially for Force. Gravity as being due to geometry is another. You have an amazing mind - I love your work! John Kallbrier John Kallbrier 2 years ago Sean, I really enjoy your talks! There are however times in every lecture of yours I've seen that you get a sheepish, rye smile on you face, looking directly into the camera, that makes me feel like you're putting something over on us or maybe a inside joke. De-rails my thought process while I try to figure out what I missed. Keep up the good work 👌 robert w robert w 2 years ago Thanks Sean, love fundamentals, you’ve struck a nice balance between Feynman and Leonardo, Feynman is amazing, but his public lectures are a little too watered down, Suskind is at the opposite end, while brilliant and interesting, is a bit too dry with verbose mathematics, at least for the layman who wishes to understand more deeply without attaining a formal degree on the subject. Redressing Reason Redressing Reason 2 years ago Hello Sean, a question : I have read in books that when we minimize the action to get the EOM, it is only a local minimum, I never could think of any example to understand this point. Could you explain it in your next video? Brian Cannard Brian Cannard 1 year ago Took notes watching the previous video, raising questions about the concepts of "Force", "Energy", and "Potential", and here there are, the answers. Thanks so much Sean! Helen Williams Helen Williams 2 years ago Love these videos and follow your mindscape pod cast to. I'm not academic so these are a little bit difficult for me to completely understand. It's the same with all the Astro physics and partial physics I'm interested in. Lots and lots of it goes over my head but I'm so fascinated by the subjects I keep watching and listening until something goes in. Thanks for making my brain hurt. Stay safe, stay in and save lives. 💙NHS 🇬🇧 🌈 Hawthorne Hill Nature Preserve Hawthorne Hill Nature Preserve 11 months ago You are such a genius and wonderful teacher! It is so exciting to listen to you and you make it so accessible. No judgement or airs. I’m not made to feel dumb when you present such intricate theories and physical laws. You demand intelligence and critical thinking but deliver it in such a palatable way that I’m given the room to learn and think. Favorite professor I never had. R C R C 2 years ago The quality of the presentation and the production value of the content is very well done! This is basically as if we are students in a classroom with Professor Sean Carroll. Personally, I am enjoying every minute. fsmv fsmv 2 years ago I noticed that 1/2mv^2 is the integral of mv dv i.e. momentum. Also mgh is the integral of mg dh i.e force due to gravity. Is there some meaning to this in the definitions of K and V? Or is it just a coincidence? I would find this more compelling if the variable they were integrals with respect to was the same. 1 fsmv fsmv 2 years ago I would love to have an extra part video for the math nerds showing equations and derivations. Personally I'd understand it much better I think. Lautaro Kinalczyk Lautaro Kinalczyk 2 years ago Im loving the math in this videos! Keep it up! elenteny elenteny 2 years ago (edited) Thank you for what you do. I decided to go back to school for physics largely due to a series of lectures I heard from you from the Great Courses series. That and your books, so thank you for all you do and keep up the great work. Also, I believe that "Phase Space" comes from trig. Phase shifting is shifting the origin of the functions graphical representation, so "Phase Space" seems as though it should be roughly understood as the total space in which we may shift the origin to any given starting point.........maybe. The Derivation Channel The Derivation Channel 2 years ago Okay... so I may be here to plug my channel a little bit, but I am so pleased that Sean Carroll is digging in to the philosophy of physics. There are so many physicists unwilling to dive into the ramifications and meaning behind the equations. Besides the fact that equations have a "predictive" quality, there is a beauty in being able to explain the equations and therefore understand the universe. So glad that this content is reaching people. Thank you, Dr. Carroll. Colby Nye Colby Nye 1 year ago Thank you for taking the make these videos! I appreciate learning from you 1 Renaud Kener Renaud Kener 2 years ago Superb videos. Now, I have time to open my old books of physics and re-learn maths :) Nicholas Piacsek Nicholas Piacsek 2 years ago I love what you share Mr. Carroll. Also a big fan of the "dark mode" format. 2 Alexander van Dijk Alexander van Dijk 2 years ago (edited) Sean, I much enjoyed the philosophical note with which you ended this video (starting at 52:52). It reminded me of your podcast conversation with Daniel Dennett earlier this year which I am in the process of listening to, and discussing at length with, a good friend of mine. One of the questions we had after listening to the first section of your Dennett interview is: what is the fundamental nature of these patterns that you and Dennett speak of? Agreed, we have evolved to be ruthless pattern finders, but does that mean these patterns exist out there in the world (and we 'lock' in on them), or do we ourselves 'create' these patterns. And if they do exist out there in the 'most real' universe, what is then the underlying fundamental nature of these patterns? Thank you. (ps. I would love a Q&A solely focused on your interview with Daniel Dennett) abdessadak Sallam abdessadak Sallam 2 years ago i really appreciate the idea of presenting and explainning physics concepts and laws with a philosophical and historical views, respect from Morocco WeeWeeJumbo WeeWeeJumbo 2 years ago Major improvements to the production! Fantastic, Doc Mohammad Khan Mohammad Khan 2 years ago Can you please also talk about elastic potential energy? If there is elastic potential energy in the system, would the force still be equal to negative of the derivative of gravitational potential energy? 1 Ray Guest Ray Guest 2 years ago Secondary to my last question. Photons acquire mass inside of superconductors and electrons in superconductors form a Bose Einstein condensate. If memory serves Bose Einstein condensates have been used in experiments designed to slow light down or even to stop it. Could the water be doing something to cause photons to acquire some small mass? 1 Qingyang Zhang Qingyang Zhang 2 years ago I love the way you explain the Laplace paradigm versus the Lagrangian paradigm. When you are actually calculating the equations of motion using the principle of least action though, don't you need to also know the velocity as well as the position, and also two times, in order to do the calculation? From what I have read in "Classical mechanics, the theoretical minimum", it seems to me that the Lagrangian is a function of position and velocity. Partha Deka Partha Deka 2 years ago (edited) I keep waiting for your lecture everyday during lockdown.. All the love from India Sir.. Namaste🙏 7 Connor Wiebe Connor Wiebe 1 year ago I think it's fairly simple why we use position and velocity (or momentum) What you want as an answer is the position of every particle at every point in time. So you definitely need the position in the present, but to avoid needing to just make infinite measurements, you also take the first derivative with respect to time. It's conceivable you would need more than that (and you do, you need all the properties of all the particles etc etc) but space and time are the two things we implicitly want to know about. Shaun Morgan Shaun Morgan 2 years ago Hi Dr. Carroll, I was curious about your thoughts on Eric Weinsteins Geometric Unity? I would appreciate a professional opinion on whether his ideas hold any water since the majority of the technicalities are well over my head. Been a fan for years and love ALL your content, thank you for the knowledge and wisdom you share. 15 Fast Fitness Fast Fitness 2 years ago I’m becoming a bit of a groupie for Sean’s work at the moment. This is great and the podcast is the amazing. I know something about these subjects but I always come away refreshed. Sean’s Easy Pieces, like Feynman but with video. Marwan El Mobader Marwan El Mobader 8 months ago I am so happy to know about this series of lectures Fascinating Facts Fascinating Facts 2 years ago Watching from Portugal - Thanks again Sean... These scientific vids are literally the only thing able to distract my mind from the news.....Thank you....... PS. Skyrim is also a good distraction.... Peace folks. 1 Craig Brown Craig Brown 1 year ago It's interesting to imagine how an intelligent alien civilization might choose to construe the same mathematical and physical reality. Perhaps they would find "principle of least action" (or something else entirely) more elegant and useful than making up an idea like "force". Jean-François Dorval Jean-François Dorval 2 years ago Geez, it was touch and go there for a moment... My brain couldn't keep up with the "simple" math content, but you kept it on the road. Good job and thanks! Robert Madden Robert Madden 2 years ago Question: If Einstein tells us that there is no such thing as absolute time for all observers, then how can Laplace's demon ever know the position and velocity of all particles at any given time? 3 Eugene Novikov Eugene Novikov 2 years ago Question: If all you are given is position and momentum of each particle in the system, how do you derive whether a particle is on an inertial trajectory, or whether there are forces acting on it (much less what those forces are)? Mauro Cruz Mauro Cruz 3 months ago La simetría hace intectable la posición y la velocidad dentro de un sistema inercial. La acción cambia una condición inicial por dos condiciones de frontera. Ronan Mehigan Ronan Mehigan 2 years ago Hi Sean - Can you explain why the so called "3 body problem" cannot be solved ? Why is the dynamics of more than 2 bodies travelling on non-trivial trajectories in a gravitational field unsolvable ? Seneca Music Seneca Music 2 years ago In your Great Courses series on the Higgs boson, you say that a volume about the size of a ping pong ball where the Higgs field has a value of zero would have the same mass as the earth. This volume is quite near to the Schwarzschild radius of the earth. Is this just a weird coincidence, or is there some connection between the Schwarzschild radius of a given mass and the corresponding mass an equivalent volume of energy Higgs field would have? Apologies if the question is ineloquently posed, but hopefully you can get the gist. 1 Shantanu Pawar Shantanu Pawar 1 year ago 50:59 also explains light bending under gravity (General Relativity) 1 mnkosho mnkosho 2 years ago Hi Sean. Can you do why linearity is so important in the Schrodinger Equation? That really ties into the Everettian interpretation of quantum mechanics. It would be awesome if you can explain the equation and link it to linearity. 1 TheKoopaKing TheKoopaKing 2 years ago For the derivatives of position beyond acceleration - what would be an example of a force or process that could produce these changes in position? If F=ma, it seems like we would need to be squaring the force or something to get acceleration differentiable on the other side. 1 Eric Bilodeau Eric Bilodeau 2 years ago (edited) How could knowing the position and momentum of every particle be sufficient to determine the future states of all these particles? For example, suppose we have two particles. We know their position and momentum. So we can project outwards the path on which they will travel. Now suppose these two particles are not traveling directly towards each other but their paths do intersect at some point ahead (picture two particles traveling at a right angle, where their paths cross in a t shape). Now the particles will only collide if they both reach that intersection point simultaneously. If one comes a bit later no collision. But knowing their momentum is not sufficient to tell us whether they will meet or be offset in time. Because momentum is mass x velocity, depending on the mass of the particles in question their velocities could either be such that they meet or not meet. So unless we also know the mass, there is no way to know the velocity and if we don't know the velocity we have no way of knowing if our particles collide. It would seem we would at least need to know position, mass and velocity rather than just momentum. Am I missing something? 1 Sam Kratzer Sam Kratzer 1 year ago I think you underestimate the length of content that people are willing to pay attention to. This is great; the more the better as far as I’m concerned. 1 Barefoot Barefoot 2 years ago The discussion about position-velocity-acceleration-jerk-snap-crackle-pop reminded me of the Area Rule in aerodynamics. As you approach the speed of sound, the drag at the trans-sonic region of velocity gains a very strong term called Wave Drag that doesn't exist at lower speeds and is significantly mitigated at higher speeds. The Wave Drag of a body is related to the rate of change of the cross-sectional area along the length of the body in question along the axis of motion, which is also the second derivative of the volume distribution of the vehicle. This seems a bit like Jerk to me. Also, as others have mentioned, Jerk is very important in transportation engineering, as it is one of the primary elements of motion related to passenger comfort. On trains, busses, and planes where people can walk around inside the vehicle, a sudden acceleration (high Jerk) can be dangerous, while smooth changes in acceleration can be compensated for. The Jerk value is in a sense why turbulence is uncomfortable and frightening, while the smooth change in acceleration as the plane takes off and begins to climb is comparatively comfortable. So I guess a good distillation of these comments into a question for the Q&A might be "What physics or engineering situations exist in which Jerk, Snap, Crackle, or even Pop are important, along with other similar examples of second, third, fourth, and fifth derivatives?" I'm thinking along the lines of Snap perhaps being important in something like roller-coaster design in which you want to shake people around in a way that's thrilling but not dangerous, which I suspect might involve a low Snap. For Crackle and Pop, all I can think of is maybe some underlying sensation of smoothness vs. roughness, though that's getting into trigonometric terms in which one can differentiate indefinitely, which might make such derivatives redundant. Still, thinking of Snap as sort of the level of "violence" of an oscillation might be useful. 2 Brendan Murphy Brendan Murphy 2 years ago What about situations where the acceleration is changing constantly like on a rocket? How is the the Rocket equation derived? Thanks for the great content. 1 Green Coder Green Coder 1 year ago [54:00] Words are tools, becoming real only by being particularly useful for talking about the universe, grasping and interpreting it, as well as anticipating one's future experience to be able to decide what to do. Kamran Razvan Kamran Razvan 2 years ago Back in 1990 when I did my oral exam, the very last question, after being tortured for 4 hours by 8 committee members, I was asked what is Force! I still remember the look on my face, even though I could not see myself. It was a great question and one that I had no idea how to answer. I wrote F=ma on the board and thought.. I don't remember the answer but 30 years later, I think I finally can think of an answer. Thank you! H. I. H. I. 2 years ago (edited) This is what the internet was made for. Pure intellectual gold. Keep them coming, Professor. With a Capital P. Thank you from Romania. Simon Convey 1 year ago Wonderful ! Jerk and snap are used in engineering. Think of a camshaft in a combustion engine which rotates at half the rotaional speed of the crankshaft. The lobes on the camshaft open the inlet / exhaust valves. Engineers would like to control these events very accurately, and they do consider the acceleration of the valve opening and closing. ( They are masses acting against springs ). They also consider jerk, and to a lesser extent "sanp". ( Snap is called "quirk" in camshaft engineering. ) The noise, vibrations, harshness, power and ecconomy of an engine all rely on these calculations. ManWhoUsesComputer 2 years ago If I assume spacetime is emergent from entanglement, is it reasonable to think dark matter may be a form of entanglement? Nnotm 2 years ago Intuitively, it seems like simulating a system with the principle of least action should take more computational effort than with Newton's equations - is that right? It feels a bit like if a way if thinking about something requires less computational resources, it has a somewhat higher probability of being more fundamental, though I imagine I'm on very shaky ground there. 1 Fausto Piovan 2 years ago Sean, this serie is really awesome.... May we drop into the free will for a while please? I know you love philosophy as well... Thanks a lot for your great effort... Christoph Hipp 2 years ago This is a really good series. 👍 Just a quick question: What is original meaning the "x not" in "x0"? Is it "not" or "knot" or what? I just have no idea. AJBtheSuede 1 year ago "Jerk" and "Snap" are two perfectly valid and often used parameters or talking points when you tune s suspension system for cars.... They define the variations in the road condition that you tune the handling and comfort parameters of a suspension to. Qingyang Zhang 2 years ago In the end when you talk about reality, you say "the universe is real", which I agree with. I think that statement is true by definition. Your definition of "real" will be based on some physical stuff in the universe, so the statement is kind of analytic (as opposed to synthetic). Maybe that's exactly what you meant when you said the sentence, and I am just rambling on. Thank you for making this series. Iulian Bercuci 2 years ago (edited) Isn't the normal force a consequence (action - reaction principle) of G (mg) and you decompose this vector in the orthogonal system perpendicular to the surface and parallel to the surface ? so the normal force and the force that moves the object are just sin and cos functions of G (mg)? Ray Guest 2 years ago I am interested in the ideas of least action and least time. For light the fastest path to the eye through water is longer than the straight line path. It takes a shorter path to the surface and then bends to your eye. There is nothing to bend or reflect the light when it enters the air, yet it takes that path to your eye. In the principal of least action, it makes senses that a ball would follow the easiest path because any other path would effectively be using energy that it does not have to get from point a to point b and would presage perpetual motion machines, i.e. there would be an energy tariff to follow a different path . Individual photons of light don't have a red shift in water so there does not appear to be an energy tariff for the light, but while individual photons do not lose energy, photons are more likely to be absorbed in water such that collections of photons do pay an energy tariff for hanging around in water too long and could the least time argument for light in water also be explained by the collective wave nature of light? Shaun Lanighan 3 weeks ago These videos are so helpful. Randen Pederson 1 year ago Is a marble dropping through a pachinko board still taking the path of least action? Can it be calculated? Athlete Ruined By Picture Olympic Athlete Refuses To Pole Vault Anymore All Because Of Viral Picture Ad trendscatchers.com 53:23 NOW PLAYING The Biggest Ideas in the Universe | Q&A 3 - Force, Energy, and Action Sean Carroll 59K views 2 years ago NOW PLAYING Mix - Sean Carroll YouTube 1:05:28 NOW PLAYING The Biggest Ideas in the Universe | 7. 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Space News Unfold 50K views 3 days ago New 3:35 NOW PLAYING Geometric Analysis of Special Relativity and Light Cone Beyond The Present 23K views 1 year ago 58:06 NOW PLAYING The Birth of Civilisation - The First Farmers (20000 BC to 8800 BC) The Histocrat 3.3M views 1 year ago 1:19:37 NOW PLAYING Large Amount Fish Catch and Various Fish Cutting Skills 大量捕撈及各種切魚技能 Terry Films 5M views 5 months ago #science #physics #ideas The Biggest Ideas in the Universe | Q&A 3 - Force, Energy, and Action 59,275 viewsApr 12, 2020 Sean Carroll 154K subscribers The Biggest Ideas in the Universe is a series of videos where I talk informally about some of the fundamental concepts that help us understand our natural world. Exceedingly casual, not overly polished, and meant for absolutely everybody. This is the third Q&A video, following the idea "Force, Energy, and Action" discussed here: https://www.youtube.com/watch?v=sZb64... My web page: http://www.preposterousuniverse.com/ My YouTube channel: https://www.youtube.com/c/seancarroll Mindscape podcast: http://www.preposterousuniverse.com/p... The Biggest Ideas playlist: https://www.youtube.com/watch?v=HI09k... Blog posts for the series: http://www.preposterousuniverse.com/b... Background image: https://www.freeimages.co.uk/gallerie... #science #physics #ideas #universe #learning #cosmology #philosophy #math #force #energy #action #classicalmechanics 140 Comments rongmaw lin Add a comment... Sebastian Clarke Sebastian Clarke 2 years ago Thanks once again for such a wonderful Q&A session. I'm truly humbled by your effort towards communicating these fascinating theory's in such a digestible manner. You truly are one of the worlds best teachers of physics, keep up the excellent work! 47 A Kumar A Kumar 2 years ago Watching in England UK, I have only really started being interested in Sceince in the last few months, most particularly I find space / time /universe of interest. Really so recite the time and effort you are taking in preparing your presentations. I watched your discussion with Roger Penrose in relation to CCC theory, which I found fascinating, you are my favourite scienctists. 18 First-Person Science First-Person Science 2 years ago (edited) Thanks so much for doing these Q&A's Sean! Although physics goes far over my head, you explain these complex topics with such simplicity and I come away with such great perspective even if I dont fully comprehend the entire theories (functional derivatives, etc). You've given out so much knowledge for free and produced such terrific content for years now. Sean's videos were what inspired me to jump out of my comfort zone and, along with a couple of close friends with Neuroscience PhDs, we started a podcast (First-Person Science Podcast) to improve communication of published neuroscience research to the public! Each episode we interview a neuroscientist on their recent published manuscript. We've released several video podcasts over the past couple of months including a recent vid on learning & memory mechanisms of addiction! We'd love to get any feedback possible to best reach our goals of bridging gaps between scientists and the public! 29 TimboJohn TimboJohn 2 years ago Thanks for the videos, Sean! They're helping to keep my brain alive during the lockdown! :-) 5 Pieter Steenekamp Pieter Steenekamp 2 years ago Thanks very much for the excellent series Sean. I want to comment on "how does the particle 'know' how to get to another point with given coordinates in given time"? I'd like to offer my thinking on it and ask whether I'm wrong. Of course the particle does not 'know' that, but neither does the particle 'know' that you want it to get there in the given time. Every different initial velocity will result in a different time for the particle to get to the second point. The particle only "knows" how to get to the next infinitesimally small instant and proceeds like this. If you want to know the initial velocity for the particle to get to the destination in a specific time, you can use the minimum action principle, instead of Newtonian mechanics, to get the answer. What I'm saying is: horses for courses. Depending on the problem, it's sometimes easier to use minimum action and calculus of variations and for other problems it's easier to use Newtonian mechanics to get the answer. Is my explanation valid? 2 Caleb Nastasi Caleb Nastasi 2 years ago It's so interesting to see how you view and heuristically explain mathematics. Thanks for the great content! 2 Lambda Lambda 1 year ago Thank you! Very interesting stuff. I’m so glad you’re doing this. You are becoming one of the great communicators of physics. Physics needed this. 1 Jainal Abdin Jainal Abdin 1 year ago Your passion for making these videos really shows, and is really appreciated. 1 Mike Mike 2 years ago Thanks Sean! Really great stuff, as are all of your talks. PK PK 2 years ago Sean thank you for telling us how you make these videos! 1 Christoph Hipp Christoph Hipp 2 years ago Thank you very much! This format is so useful and intersting! 👍 3 Richard Tarr Richard Tarr 1 year ago What an amazingly brilliant teacher you are. After watching this video has made sense to so much. Thank you Sean ☺ 1 D Wnright D Wnright 2 years ago Happy easter Sean. Thanks for this. Really interesting. Keep em coming. 2 Barefoot Barefoot 2 years ago (edited) Neat! I also use Camtasia when I make videos. Your setup looks pretty good. The only thing I'd suggest adding from my experience would be a backlight for yourself. That would get rid of the little green halo at the edges of your hair. It doesn't need to be anything like as powerful as those big studio lights with the umbrella diffusers; just a desk lamp on the floor or a small box or chair or something would be fine. I personally have found warm light to look best for that one, so a "warm white" or "soft white" maybe, around 2700 or 3000k. 1 Alex Wilson Alex Wilson 2 years ago Thank you for working hard for us! No one else does what you do Boris Petrov Boris Petrov 2 years ago PS: An amazing effort in production of these masterpieces... 1 Luke Lutio Luke Lutio 1 year ago I'm watching from Switzerland and have been following this new series with great pleasure. I consider myself to be a youtube educated scientist aka taking the path of least action :-) and this sort of material has effects of mind blow and entertainment to me aside from it's educational value. I'm using this series to reconnect to all the unpleasant maths I've learned over the course of my life because using this sort of math (e.g. calculus) in the physics context is so much more satisfying than just memorizing formula over formula. To me it is still painful, but with all the added meaning and applications it makes wrapping my head around it much more efficient. Sean, with this segment, especially with your 'making of' section at the end, you've once more presented the passion you put into these productions and I enjoy that at least as much as the scientific content. Sincere thanks! 1 Richard Alan Richard Alan 2 years ago Thank you for the info on your studio setup. Just wanted to mention: for me audio is as more important than the video. I have stopped watching videos with poor sound. Good picture quality helps. Most important is what is said and how it is presented. Last, I can close my eyes and enjoy your presentation. Again, thank you. Sandip Chitale Sandip Chitale 2 years ago (edited) Sean, thanks for these excellent videos followed by Q&A episode. The Q&A episode allows us to ask the questions in the context of the subject of the video. Also, thanks for clarifying where to ask the questions i.e. on you blog entry for the video. Thanks for clarifying the issue around the imprecision around the statement that "all we only need to know is the position and momentum of every particle in the universe to predict how the system evolves" - by making it clear that there are some assumed initial conditions - not only such as mass but also electric charge or color charge in context of quarks (say!). To me mass is to gravitational field as the charge is to electric field with a difference that there is a notion of positive and negative charge. Is there a notion of negative and positive mass. Is the dark energy equivalent of the negative mass via E=mc2? Just like when a lot of mass is concentrated at one point a black hole forms, is there a notion of black hole formed because of the concentration of electric charge? Or because positive charge repels and thus cannot be concentrated and thus cannot form a black hole. It is interesting to note that the formula for the force produced by electric charges does not involve mass of the charge holder thus the acceleration produced by the force of electric charges can produce different acceleration. Whereas the gravitation force depends on the involved masses and hence the acceleration is proportional to the masses. Xavier Gamer Xavier Gamer 2 years ago Love the videos. Thank you Sean. Ali Karimi Ali Karimi 2 years ago I'm enjoying watching your Q&A videos as well. I'm currently stuck with reading your book, Something Deeply Hidden. I'll sure come up with questions to ask you 🙌 Gary Denyer Basses Gary Denyer Basses 1 year ago Fantastic info, Sean! Modern day national treasure! DarlEng DarlEng 2 years ago Try recording in 1080p to keep the file sizes low. Great class as always 5 John Waite John Waite 2 years ago Many thanks for aiding my understanding of the conceptual foundations underlying both classical and quantum mechanics. While I'm far from being either a physics or a math guy, I can at least get a sense of the history behind these two approaches and descriptions of the physical world. You have been so very generous with your time to help introduce these topics to the non-scientific community. In a world where specialized knowledge and expertise is often walled-off and guarded, it is especially gratifying to be given a chance to learn from an authoritative source whose prime interest in this setting is teaching. enkiorenlil enkiorenlil 2 years ago Sean Carrol thanks for your effort. I have started watching your videos but still neglecting a little bit. But I will overcome that. I have a question about dark matter and dark energy. Should I wait for your video about the subject ? James Schinner James Schinner 2 years ago Awesome Mr. Carroll, this is great and enjoyed seeing the setup! Tony Bowen Tony Bowen 2 years ago So good. Thanks for doing these! H S H S 1 year ago Thankyou so much for your time, effort and patience in producing these series of lectures and follow up Q&A. It is very much appreciated. They are so entertaining, informative and thought provoking. Use of technical terms such as, "chug" and "stuff" makes explanations so very palatable. Also, I had a fleeting thought that perhaps you have secretly figured out how to slow time locally in your office for you develop these lectures. Please share if you have. Thanks once again. Kieran Garland Kieran Garland 2 years ago Am really, really enjoying these videos. Answers an awful lot of questions (in my mind, poorly formed) that I've had about many areas of physics. Despite some attempts, I don't think I'll ever study physics formally, but these videos and Q&A follow-ups are improving my intuition and enjoyment of physics no end. Thank you. Ricardo Ricardo 1 year ago Amazing topic with a wonderful lecturer. We should be very thankful for having you around teaching us all these things. It'd be awesome if you could upload the notes from the video so we could keep them as some kind of lecture notes. Apart from that, I'd just like to add that at 24:57 you write the derivative of phi with respect to x, instead of the derivative of eta. Thanks for your dedication. Boris Petrov Boris Petrov 2 years ago Thank you -- outstanding as always. A question on actions, energy, forces epizode: -- Is there any explanation for the "inflation" hypothesis in the first infinitezimal nanoseconds after "Big Bang" -- besides the universal microwave background? Why exactly has that, somebody could say lunatic, hypothesis been universally accepted? Many thanks in advance, Boris PS: Have all your books and videos... charl160 charl160 1 year ago Thanks for sharing your knowledge. Excellent videos! Sonali Sengupta Sonali Sengupta 2 years ago (edited) Bravo ! Professor Carroll. In-depth and nuanced explanations. "Principle of Least Action " explains it. Thank You. Zamu Rahanay Zamu Rahanay 1 year ago Sir, I'm one of ur student who haz been influenced a lot by Carroll's work.... But keeping physics aside for a moment, this video is so good n helpful for ppl who wana help others by making videos az muxh possible az uh did.... Thanks sir a lottttt.... Luv from Kashmir, IOJK.... bestape bestape 2 years ago 37:47 to 44:40 is really good. I was imagining electrons in chemistry and Feynman's "QED: The Strange Theory of Light and Matter" p. 104 during it. When I read Frank Wilczek's "A Beautiful Question: Finding Nature's Deep Design," I got a lot out of it but I didn't realize my mass comes from QCD. Gives me a think about how to reconcile that with the feeling I have hauling myself up the climbing wall. Thank you! Patrick McHargue Patrick McHargue 2 years ago "Thank you for watching." Sure! Thanks for exploring this here with us all. 2 Raymond Nelson Raymond Nelson 1 year ago Great Q&A session. Enjoyed the discussion of QCD contributing most of the mass of the proton and neutron. I'm assuming you are discussing the Strong Nuclear force. Please correct me if I'm mistaken. Also, really appreciated the discussion of your studio setup. It was very useful sir! BobC BobC 2 years ago Would it be useful to discuss path integrals vs. surface and volume integrals? It seems implicit in the discussion, but perhaps a moment should be taken for it to be made explicit. Sully Sullivan Sully Sullivan 2 years ago hi Sean. I know you're always getting wacky questions but I suppose we all have some, and I know you don't have all the answers, but you know how Penrose has his conformal boundaries in CCC but then no two events can be said to be simultaneous in relativity? is it possible his infinite universes could also conformally map onto your many worlds? the photons are always at that infinity... so even though we can think of the universes as cyclical or chained, we could also think of them as stacked and simultaneous right? also I think those people asked about "static time" are referring to B-theory. thanks for all the great content! Tadaaa Tadaaa 2 years ago Privileged to see Sean in London at the RI last January - feels like a lifetime ago, but thats time for you!!! Anyway fantastic as usual, keep it up Sean, science is truly a candle in the dark Roman Travkin Roman Travkin 2 years ago 31:00 For anyone unfamiliar with complex exponentials like e to the i S, it is simply a unit arrow in a 2D plane whose direction is rotated with respect to some fixed initial direction by an angle of S radians. When we think of it as a complex number, it is expressed as the exponential of the imaginary number iS. You can watch this 3Blue1Brown video for an explanation: https://youtu.be/v0YEaeIClKY Luc of Paris Luc of Paris 3 months ago (edited) What I find fascinating is that nowadays, when we examine scientific fields across the board, a continuum becomes apparent: from human actions as explained by sociology and psychology, then generalized by evolutionary psychology, then generalized by the modern evolutionary synthesis, then recontextualized in the origin of life research — to chemical evolution, as part of a broader generalization in thermodynamical terms (with biology and abiogenesis basically steming from the second law of thermodynamics). The interesting part here is that the second law of thermodynamics can be described in two forms: • the evolutionary principle by natural selection • the principle of least action In turn, both can be connected via the fitness criterion when described in thermodynamical terms. At this point, nothing really stops us in principle from conducting an inter-theoretic reduction on human behavior, all the way down to molecular dynamics and nuclear physics even. The question remains whether this can be done all the way down to quantum mechanics however. Zeedijk Mike Zeedijk Mike 1 year ago What you are doing is admirable. The content is very good, though quite a bit of it doesn't stick with me. (Endless re-watching helps 🤔) The quality is brilliant. I do love the black board look. ManWhoUsesComputer ManWhoUsesComputer 2 years ago Great production Sean Carroll! Impressive. I have an amendment to my question, and an addition: Questions: * If I assume SpaceTime is emergent from entanglement, is it reasonable to ask if dark matter could also be a form/effect of entanglement? Or blackholes...for that matter * How would Dick describe/explain entanglement? I've looked here [https://www.feynmanlectures.caltech.edu/], but no chapter title contains "entanglement". PS: the videos are great at a time like this. :) keep it up! yeti yeti 2 years ago Sean, you are quite an intellectual sharing all of these ideas so brilliantly and with simplicity. Selfless act of your generosity will pay off in the long run by making physics more accessible and exciting. It nurtures curiosity too. Many can write complex equations, (I do in my field), but those who can convey difficult theories through simple understandable examples, charts, and themes are the true teachers. Not many have that quality. With your videos, I finally understood the link between Newtonian physics and modern “interpretations,” and to some extent the work of Feynman that I had watched in a video series QED. I look forward to many more ideas. Thanks a bunch! I am a avid listener of your podcast. Keep up the great work you are doing. Mike D Mike D 2 years ago Thank you Dr. Sean Caroll ! This is Amazing !! Thanks ! Gully Foyle Gully Foyle 2 years ago Thank you Dr. Carrol for doing these videos. In explaining physics from first principles, could you inject some humor into the process and in general loosen up a bit. I know you have his chair and desk but maybe you could learn to play the bongos. It's like you are grinding out some 101 physics for freshman class and a bit of that is coming through. I remember Feynman doing a lecture for the general public on QED and I got a real sense of the meaning. Thank you ~ appreciate your work expanding Everett's many worlds! ComisPeritus ComisPeritus 2 years ago Thank you for all you do ! Qingyang Zhang Qingyang Zhang 2 years ago 15:00, in your box example, is the straight path the global minimum of the action, while there are infinitely many local minima (as the particle can bounce infinitely many times back and forth between two walls)? 4 Wha Dahel Wha Dahel 2 years ago In my simple mind I would think that a field would require space in order to exist but has there been any talk about space requiring fields? Are space and fields codependent? What came first the space or the field? Sandip Chitale Sandip Chitale 2 years ago (edited) I liked your explanation of the principle of least action and that the particle does not "know" where it is going such that the action is minimized. Rather the path it takes ends up being the one where the action was minimized. I think the biological evolution should also be thought in a similar way i.e. as a passive process. Many people misunderstand that the biological process drives the organism towards "better" organism such as in "human". It has some kind of a priory purpose. That is a wrong way to think about biological evolution. The process of random mutations operated by the process of natural selection based on the fitness for the environment a species finds itself in, making it better and better for that environment. If the environment suddenly changes the species will suddenly be no longer the "better" species (imagine sudden onset of warm climate or ice age - which will result in dominance of different species). That is why I like to use the passive language such "end up with" rather than "produces" when talking about biological evolution. The artificial selection that we humans practice to produce "high milk producing " cows or "pest resistant" crops does have a "intention" or "purpose" as desired by us. Shoopaah Shoopaah 2 years ago I am doing an astrophysics PhD and I enjoy this very much DANIEL M DANIEL M 2 years ago Thank you, awesome content TheKoopaKing TheKoopaKing 2 years ago 60 gigs sounds accurate. A lot of the file size is probably due to having 40-50 minutes of audio since the video doesn't change frames too often. If you can, export audio as FLAC - it compresses the audio but still keeps it lossless. You might save like 5 gigs of space with that. common sense common sense 2 years ago The path of an object is set by the energy acted upon it, the particle, in this case, taking from that energy a set direction and speed that does not change unless forces act upon it, a new trajectory and speed, thus, occurring. The fact you think a particle knows the best path to take is foolish in my book unless you think particles have consciences. 2 Francis Rodriguez Francis Rodriguez 2 years ago "you take math classes, good for you". HA. I think Sean Carroll and Feynman are the only two guys who regularly make me laugh while giving physics lectures. Kieran Garland Kieran Garland 2 years ago This was waaaay more productive than Mario Kart 8. Vile Live Evil Vile Live Evil 2 years ago The RE 320 is a great choice for your voice, comes over perfectly. 7 Mark Chadwick Mark Chadwick 1 year ago Sean you are so wrong! (tougue in cheek) Good audio DOES matter for YouTube, and green screen is much better than your office when we are watching you for an hour at a time. Thanks for this great series. Robert Molldius Robert Molldius 1 year ago Thank You for explaining about video making! 🙂🙂🙂👍👍 John P John P 2 years ago The tutorial about your recording studio is very useful. 1 Dobby Dazzler Dobby Dazzler 2 years ago Sean you are a handsome man, please don’t disappear anymore behind the green screen than you have 😄. We don’t need discombobulation of our favourite minds and their physical telepresence at this time! OK, that’s just a little humour on my part (Australian spelling). Love how you, Brian Greene and other great thinkers of our time are finding ways into our lives right now. Thank You 😊🎋🌿🦋 Edward Cosio Edward Cosio 2 years ago The microphone really helps, don’t sell it short lol 19 nunya nunya 1 year ago Great show Doc! 😃 Yoda Jimmy Yoda Jimmy 1 year ago I still don't know why I'm viewing this series. I know well of everything he talks about. And then when he goes to metaphysics, I know for sure that's obvious. But then I think of myself an hour before and question, did I know these then? And the answer was, of course I knew, only that it was not in my mind at that time, I could get to it, but not as an instinct. Dennis Constant Dennis Constant 2 years ago Sean, I have watched many, many videos on physics, and there are very few experts who can present complex material as clearly and entertainingly. You, Jim Al-Khalili and David Deutsch are preeminent. Very different styles, but all superb. (Incidentally, Feynman, who was a genius, was, contrary to popular opinion, a lousy lecturer.) : Antypas : Antypas 2 years ago Is special relativity derivable from a least action principle? (a reference) CorwynGC CorwynGC 2 years ago The confusing goes away (for me) when I remember that the particle doesn't know where it is going. It is merely responding to local conditions. 1 Sandip Chitale Sandip Chitale 2 years ago Sean, what do you think the analogy of molasses for Higgs interaction. If the Higgs interaction was like molasses won't the "viscosity" of the Higgs field sap the kinetic energy of a particle moving through it at the constant velocity and thus contradicting the Newton's First law about constant velocity motion. Instead I like the analogy of photon box (which confines the energy of the photons in a box with perfectly reflective inside walls) for the inertia a massive body. IMO giving a wrong analogy is worse than giving no analogy. Thoughts? rushy scoper rushy scoper 2 years ago am CS major finish two year ago but still love physics couldn't take it because of were i lived CS was just way safer path. anyway i decide that am gonna learn high level physics on my own as a hobby, is their any tips to what field in math i need to learn first before jumping to high level physics? if u can list a math courses/field in order it would be great. Soul DFS Soul DFS 2 years ago 60 gigs wow!!!! That’s huge, well thank you for doing that! Sounds difficult...... Michael Smith Michael Smith 2 years ago Outstanding video! And, I appreciate the description of your setup. Thank you. 6 Simon Hottentot Simon Hottentot 2 years ago How about the minimum of a sinus function ? M S Islam M S Islam 2 years ago I'm waiting for the topic about "symmetry in physical laws" and "noethers theorem" John Walker John Walker 2 years ago The Higgs Boson is the only particle in the Standard Model with a first name. 😂 1 Roger Haskins Roger Haskins 2 years ago in wiki it says - Names for the number 0 in English include zero, nought (UK), naught (US) Theodore I. Theodore I. 2 years ago Please do a related episode about tensors Lrrr, Ruler of the Planet Omicron Persei 8 Lrrr, Ruler of the Planet Omicron Persei 8 2 years ago (edited) Reach out to me if you want more help with your setup. I'm an editor, sound guy, lecturer. doing broadcast editing, mastering et. al. I think for you it would be important to do as much live as possible. Maybe even the keying. And then maybe work a bit with a pro via screensharing. 2 NGC 7635 NGC 7635 1 year ago I understand 75% of this, which I consider a win, haha Steven Lang Steven Lang 2 years ago Is QCD the "strong force"? 1 Peter BARABAS Peter BARABAS 1 year ago Thanks for the extra (studio setup). :) Surfing Moose Surfing Moose 2 years ago As Peanut would say, VROOOOOM. I enjoy listening to these vids. Some ideas stick (but there is some teflon involved), while most VROOOOOM. myutubechannel myutubechannel 2 years ago The principle of least action or more correctly the principle of stationary action. So maybe the S comes from stationary. Todd Desiato Todd Desiato 2 years ago Error at 24:50+, you are saying to take the derivative of Eta but you wrote Phi again as the variable, where it should also be Eta in all 3 terms. William William 2 years ago I thought the answer to "how does it know?" was this https://youtu.be/q4Dj8fq30sk?t=201 So the question is a very good one, that could've led to an early discovery of quantum mechanics. Connor Veenstra Connor Veenstra 2 years ago Is the Feynman you're talking about the same Feynman that's been responsible for the discovery of several other properties related to particle physics? Or am I thinking of somebody else? 4 Qingyang Zhang Qingyang Zhang 2 years ago 44:43, If we think about quarks (as opposed to the colour field around them), can we think of them as field excitations? So for example, would the quark and its colour field be described by how their fields interact with each other? 1 JeKijkbuis JeKijkbuis 2 years ago (edited) 27:42 Don't be I kinda like it....... Sorry, i skipped the last part.. since it's not interesting to me. Did people really ask a professor in physics to explain how video editing works? Sean you're a real nice and friendly person for explaining that to! HypnoticSuggestion HypnoticSuggestion 2 years ago I gotta hand it to you peeps who use laptops, in particular Macbooks for things like video work. You have the patience of a saint and then some. Donbas Parklane Donbas Parklane 1 year ago Thank you 🙏 r2roberts r2roberts 2 years ago So glad you added the video production info at end. Also Sum Over Histories. 1 stevemonkey6666 stevemonkey6666 2 years ago This was extremely interesting. The explanation about how a particle seems to take the best path overtime was something that I had never heard before. Too Bad Too Bad 1 year ago thanks for your effort Brian Cannard Brian Cannard 1 year ago Why integral over Lagrangian density equals kinetic minus potential energy? What is "energy"? Some Creeep Some Creeep 2 years ago What video games would you be playing all day were you not making these videos? Valdagast Valdagast 2 years ago So my plan to construct a gun that shoots Higgs bosons at people to make them heavier is doomed from the start? 1 joshuad31 joshuad31 1 year ago amen to "enormously more rewarding" A. Fleischbender A. Fleischbender 2 years ago 25:00 you define and talk about the field eta, but write down derivatives of phi again :) Quantum Jet Quantum Jet 10 months ago As if being a scientist isn't cool enough, being a theoretical physicist, and a charming one at that, is almost going over the top, but to finish the video with "...I could just play video games all day" is just cheating. Love these videos. Barely understand anything in them, but I live in a foreign country and don't speak the language so maybe that's my destiny as it clearly wasn't to be smart enough to understand everything I find fascinating and interesting. Oh, and Mr C's a cat lover too! Alyssa Taylor Alyssa Taylor 1 year ago I didnt want to get "too math-y?" Physics is math. Yoda Jimmy Yoda Jimmy 1 year ago 4:03 in entanglement, in photosynthesis photons know the best path indeed Nathan Di Noia Nathan Di Noia 2 years ago Hey Sean, sounds like you’re shooting uncompressed footage. If that’s the case then 60GB sounds about right 3 Paul C. Paul C. 1 year ago Reminder - at 23:00 Lagrangian & Lagrange Density explained. Rainer Wahnsinn Rainer Wahnsinn 11 months ago 24:55 typo for the derivatives of the η field 1 Bill Carey Bill Carey 2 years ago Kudos! Yoda Jimmy Yoda Jimmy 1 year ago Which is the type of audience you're making this videos for? What people are in your mind? andrei costache andrei costache 2 years ago How can I give you more 👍 ? 1 Karita Wongtrairat Karita Wongtrairat 2 years ago Subscribed !!! : Antypas : Antypas 2 years ago 🌹🙏 Josè Mario De la Piedra Josè Mario De la Piedra 1 year ago Excelent Abdennour abdennour Abdennour abdennour 1 year ago Thanks once again Tom Ingrassia Images Tom Ingrassia Images 2 years ago Audio is perfect Peter Phil Peter Phil 2 years ago Very good David James Bolger David James Bolger 2 years ago Sean! You’re a top fucking bloke. Hello from Ireland. I’m gargled. WizzelMay WizzelMay 2 years ago that background spredatorify spredatorify 2 years ago Well, I could have told you that. 6 Go Mezant Go Mezant 2 years ago But the slope at the maximum is also 0. 3 myutubechannel myutubechannel 2 years ago he is wrong you know, minimize is that button in the upper right corner of my window Jason Jason 2 years ago I see we both need haircuts, but no one is open. Joaquin Inouye Joaquin Inouye 1 year ago That chick at Samy’s will be bonk you didn’t remember her name, haha. Randy LaMonda Randy LaMonda 2 years ago I kept seeing Covid19 maximums and minimums 2 Goobermint Goobermint 2 years ago naughty boy Patrick TAYLOR Patrick TAYLOR 2 years ago First