Field Theory Fundamentals in 20 Minutes!

Field Theory Fundamentals in 20 Minutes! Physics with Elliot 184K subscribers Join Subscribe 22K Share Download Clip Save 716,315 views Feb 11, 2022 Field theory is the mathematical language that we use to describe the deepest theories of physics. I'll teach you the basics in about 20 minutes. Get the notes for free here: https://courses.physicswithelliot.com... Take my full course on Lagrangian mechanics! https://courses.physicswithelliot.com... The most fundamental laws of nature that human beings have understood---the standard model of particle physics and Einstein's theory of gravity---are written in the language of field theory; quantum in the first case and classical in the second. The first field theory that you're likely to meet in your physics classes is electromagnetism, which describes the electric and magnetic fields through which light waves ripple all around us. But electromagnetism is actually fairly complicated; to learn field theory, it's better to start with a simpler example, and that's what I do in this video. I'll teach you the fundamentals using the Klein-Gordon theory of a real, scalar field. We'll see how to write down the Lagrangian, apply the principle of least action to obtain the Klein-Gordon field equation, how to solve it using plane waves, and how relativity is built in from the beginning. We'll also take a peek at quantum field theory along the way. Get all the links here: https://www.physicswithelliot.com/fie... The principle of least action: • Explaining the Principle of Least Act... The Lagrangian for a special relativistic particle: • The Special Relativistic Action, Expl... The Lagrangian for a general relativistic particle: • How Einstein Uncovered the Path a Par... Tutoring inquiries: https://www.physicswithelliot.com/tut... If you find the content I’m creating valuable and would like to help make it possible for me to continue sharing more, please consider supporting me! You can make a recurring contribution at / physicswithelliot , or make a one time contribution at https://www.physicswithelliot.com/sup.... Thank you so much! About physics mini lessons: In these intermediate-level physics lessons, I'll try to give you a self-contained introduction to some fascinating physics topics. If you're just getting started on your physics journey, you might not understand every single detail in every video---that's totally fine! What I'm really hoping is that you'll be inspired to go off and keep learning more on your own. About me: I’m Dr. Elliot Schneider. I love physics, and I want to help others learn (and learn to love) physics, too. Whether you’re a beginner just starting out with your physics studies, a more advanced student, or a lifelong learner, I hope you’ll find resources here that enable you to deepen your understanding of the laws of nature. For more cool physics stuff, visit me at https://www.physicswithelliot.com. Transcript Follow along using the transcript. Show transcript Physics with Elliot 184K subscribers Videos About Patreon 20:38 DERIVING the Orbit of Our Home Planet from Newton's Law of Gravity: Physics Mini Lesson by Physics with Elliot 17:55 Explaining the Principle of Least Action: Physics Mini Lesson by Physics with Elliot Patreon Support the channel! 20:10 The Special Relativistic Action, Explained by Physics with Elliot 22:36 How Einstein Uncovered the Path a Particle Traces Through Spacetime! by Physics with Elliot 689 Comments rongmaw lin Add a comment... @theinspector7882 3 years ago 1:38 So Newton failed by saying "instantaneously" instead of "eight minutes latter". Well, that's enough time for the Dems to Repent from having Biden as their PRESSident 😁😁 1 Reply @JanPBtest 3 years ago 1:59 I think field theory is not needed for this particular problem. In fact, special relativity (which accounts for the time delay due to the finite speed of light) is not a field theory. THE reason for fields appeared for the first time in classical electricity and magnetism. Specifically, magnetism, or even more specifically: the fact that the magnetic force is a sideways force (perpendicular to the velocity). The fact that this force acts at right angles creates a huge problem for Newton's Third Law: the electromagnetic action and reaction forces acting on charges do not necessarily point in the opposite directions! This in turn implies a violation of the Newtonian conservation of energy and momentum! So this is a HUGE deal. The only way out of this conundrum is to assign quantities of energy and momentum (incl. angular momentum) to the space surrounding the charges: one number or vector per spatial point. In other words, a field. When all this is cooked up properly, the energy and momentum conservation is restored. But the price we pay for it is that unlike the equations of mechanics, where particles' movements is all that's needed to compute things, in electrodynamics we use equations that also involve those fields (Maxwell's equations). Einstein's gravity theory can be thought of as Maxwell's theory on steroids as it uses a classical-style field but a more sophisticated one. Reply @konradswart4069 9 days ago A brilliant video! Have you noticed that Reduced Compton wavelength = hbar/mc = 1/kappa? In other words, kappa is the curvature belonging to a particle having total energy E with a radius equal to the reduced Compton wavelength lreduced. Reply @kka107 3 years ago (edited) Yes, I’m very very interested in learning all of it. Your channel is unique in that you’re able to teach very difficult topics in just 20 minutes and not only do you do it by giving us the big picture, but also by getting into the math. You’re helping us learn things in minimum time and with minimum effort. Thank you for your contribution. 576 Reply Physics with Elliot · 14 replies @DigiBentoBox 7 months ago A bit jealous of everyone here with the advanced knowledge and math skills to be able to understand and get the most out of the video. I can’t wait to be there one day. In the meantime, this video has given me a very valuable target which to for and guide my studies in the hopes of one day intuitively understanding these topics and the field theories that underlie Physics at large. 6 Reply @Byron_Vega 3 years ago The square is always so funny to me because the first time I saw it in a book I thought it was a symbol that couldn't load properly and I kept closing and opening the book until I decided to finally search for the "missing" symbol online and found out that there was never a problem. Please upload more, this was awesome! 42 Reply 1 reply @jacobsilver2476 3 years ago You've just taught the Lagrangian in the most straight forward and intuitive way that I've ever come across, and did it as a sidenote to a main topic. Thank you for your brilliant teaching. Keep up the good work. 157 Reply Physics with Elliot · 4 replies @jpa_fasty3997 2 years ago This is about 2 lectures worth of work in the maths/physics degree I took. You presented it in 20 minutes, and I genuinely gained more from this than those lectures. Incredibly succinct and clear. Really good video. 60 Reply @wayneyadams 2 years ago 10:38 Partial derivatives seem intimidating at first, but here is a simple way to understand them. By the way, this is how I taught them to my students. You are standing at the base of a hill. The slope changes differently depending on the direction you walk. You want to walk up the hill and retrieve your drone which just crashed on the hill northeast of you. Let's say the hill slopes upward one foot for every five feet you walk toward the east. This is like the partial derivative, it gives you the slope in the easterly direction only, ignoring any slope to the north (or south). You begin to walk east until you are directly south of the drone, in other words, it is due north of you. Let's say you walked 20 feet to the east. How high are above your starting point? That's easy, it's simply the slope (partial derivative) multiplied by the distance you walked. Remember that the hill rises one foot for every 5 feet you walk. 1ft/5ft x 20ft = 4ft. You are now 4 feet above your starting point. Now you turn north. At this point the hill is much steeper, sloping upward one foot for every three feet you walk toward the north. Again, this slope is like the partial derivative, it gives you the slope in the northerly direction, ignoring any slope to the east or west. This time you walk 15 feet to reach the drone. 1ft/3ft x 15ft = 5ft. You are now 9 ft up the hill, 4ft from walking east, and another 5 from walking north. You could have walked north first then east in which case you would have to know the slopes at two points, the first to the north of your starting point then the slope to the east at the point where you turn east. Regardless of the route you take, using the slope in one direction at a time allows you to calculate the height of each leg of your walk which you then add together to get the total height. Just like this imaginary walk up a hill, partial derivatives allow you to calculate changes in steps by calculating how the change in one variable affects the change in your target variable. The first partial derivative on the right side tells you how the field changes with position, while ignoring the position (just like we ignored the slope northward while walking eastward). The other partial derivative tells you how the field changes in time while ignoring any changes from position. In this way the total change can be calculated. Wayne Y. Adams B.S. Chemistry M.S. Physics R&D Chemist (9yrs.) Physics Teacher (33 yrs.) 173 Reply 6 replies @TakesTwoToTango 3 years ago "You'll learn about the Maxwell Equations in university, but probabely in a notation that makes them look much uglier". That one hit home. Nice! :D 3 Reply @douglasstrother6584 2 years ago You crammed a lot of Physics into 20 minutes, Elliot! Herbert Goldstein concludes his "Classical Mechanics" with Field Theory. Michael Faraday's concept of the electric and magnetic fields, and his collaboration with James Maxwell were the first steps in a modern unified field theory. 9 Reply @ClemoVernandez 3 years ago You're very talented at presenting and teaching. I've never seen such highly quality, clear explanations for such advanced topics. The animations and drawings add an aesthetic touch which makes it even better. You deserve so much for this kind of dedication man. Keep it up! 175 Reply Physics with Elliot · 2 replies @owen7185 3 years ago I love how so many areas of physics and mathematics come out of something so elegant yet powerful 3 Reply @shubhsrivastava4417 3 years ago There are many science channels on YouTube which get into the detail of the topic but don't quantitatively explain the concepts. Since I like getting into the rigors of calculations, your channel helps me a lot in gaining interest in new topics. Thank you Elliot! 6 Reply @bartpastoor1028 3 years ago So exited you are started posting these videos on Field Theory now, together with the handouts. All of your videos and handouts, not shying away from math, are of an exceptionally clarity and even entertaining. They close the gap between (semi)popular video´s and semester long university courses you sometimes too can find on YT. But the latter, how good they may be, are very long and you easily lose the full picture of it. I studied Theoretical physics in the eighties and then drifted to ICT. Last couple of years taking it up again and am hoping to get some more insight into QFT, which we barely touched at the time. After some MIT Moocs, am now into the very good book of Robinson: Symmetry and the Standard Model. It goes slow, but then I have the time. Your videos so far and the ones hopefully to come, are of tremendous help in getting a fresh expose on the subject. Proud to be one of your patreons. 74 Reply Physics with Elliot · 2 replies @speeshers 3 years ago This is, without exaggeration, one of the best videos I've ever seen. I'm a first year PhD student in physics, and this connected so many distant ideas and everything just clicked in place. Thank you so much!!!!! You method of explaining is extraordinary, and also really appreciate you going through some of the math and rigor, since a qualitative description can only go so far. :D 33 Reply @SliversRebuilt 3 years ago (edited) This is everything I've ever wanted out of a physics education. Thank you so much, man. Plus this video reminded me to buy in on your patreon now that my financial aid refunds came through (I certainly feel comfortable calling it an educational expense lol) May many more follow in your footsteps. Think of the things we could achieve with the fruits such efforts bear across even one generation. 96 Reply Physics with Elliot · 1 reply @georgekomarov4140 3 years ago You're natural born teacher. I'm not unfamiliar with the topic (as far as a non-physicist can be), and still I feel I understand the topic more clear than ever before. Thank you. 5 Reply @tomgraupner171 3 years ago Please, Elliot, I need "the rest" for the other spins as well. All insights in this topic is wonderful! Thank you so much for your efforts !!! 3 Reply @mjackstewart 3 years ago Dude, I’ve been poking around in physics for over a year. This is the FIRST video I’ve seen that integrates all the concepts I’ve learned individually! And notice I used the word “integrate.’ GET IT? Leave? Now? That’s fair … 1 Reply @afshinsadeghi8074 2 years ago Thrilled to see this on YouTube. I always was watching the pop science clips but my search was giving zero results on formulas explanations in the YouTube. The more I searched the less I found. And I am not so in favor of reading the boring textbooks. This is well delivered. Now I can self teach a bit real field math. Thank you. 1 Reply @mhinz80 3 years ago I am honestly impressed with anyone who understood even a little bit of what this guy was talking about. Reply @trumpetdude320 4 days ago Dude, I LOVE that this video seems like it’s just a bunch of crazy math, yet I’m kind of understanding what the math means and how it relates to field theory! I’m excited to dig around this channel and see what there is; I’m just getting really freaking excited about physics right now lol Reply @sifeyanis591 3 years ago I'm very grateful that I've met Elliott he's much better than my college professors 2 Reply Physics with Elliot · 1 reply @Cowux 3 years ago Your explanation is so GREAT. If I had these videos in my PhD years, probably I would not give up my journey in theoretical physics........ 6 Reply 1 reply @cezarionescu75 3 years ago This is quite impressive, even for someone who has studied the field its lovely to gain new insight on the subject matter. 12 Reply @brendanfan3245 2 years ago your deep understanding of the physics principle is fantastic. 1 Reply @jaimeduncan6167 2 years ago It’s the cleanest explanation I have ever seen. Reply @aleksandr_berdnikov 3 years ago I'd love to see your explanation of how one can visualize QFT. Usually, for QM the algebraic perspective (vectors-operators-eigenthings-commutators) and the geometric one (functions-bundles-connections-PDE's) are both talked about a lot, so that it coalesces into a construct that is convenient to handle from any side. But for QFT I found the introduction to be (most of the time) quite "procedural" (again, operators-commutators or Feynmann integrals) and not providing the glue of "visual manifestations" of the concepts to tie them in my head into a coherent picture and tie it back to QM... 3 Reply @stevewhitt9109 3 years ago After studying tensors, I am now understanding this video. You say things that relate different areas of science: like the math that is used in both QFT and cosmology. I can't really put it into words, but thanks. The math of Dirac fascinates me. 3 Reply @alkiviadiskaminaris1594 3 years ago This channel is exceptional. 1 Reply @fuencisclobuenasfuentes4523 3 years ago Superb work!!! As a physics student, I can say videos like these are extremely usefull for understanding the concept behind many tools we use. A lot of times this point of view of physical theories is lost in many textbooks in favour of mathematics and calculus (which is usefull too), so it’s extremely helpfull that people like you make this kind of videos. Pd: english is not my native language, so sorry for any mistake I might have made in the coment :) 32 Reply Physics with Elliot · 1 reply @kgblankinship 3 years ago This is a very clear exposition of field theory; I got a lot out of it. 2 Reply Physics with Elliot · 1 reply @_Noopy_ 1 year ago Finally a physics channel that doesn't dumb down things/rigour...... Please make more, encore! I'll pay for your full course on QFD. Reply @Pro-ish 3 years ago you are not worry about presenting the technical mathematical equations that underlay the theories of physics, this is fantastic ! 1 Reply Physics with Elliot · 1 reply @saqlainkhantrex4273 3 years ago Finally, someone came up with an actual physics video with math. Thank you!! Reply @joaopedrogoncalves6505 3 years ago Please continue these videos! They have really helped me when studying Theoretical Physics at the University of Birmingham and I really would like to see a video about spin ½ and 1 5 Reply Physics with Elliot · 1 reply @feynstein1004 3 years ago Wow this was really well done. Although I found it to be a bit too advanced at times. Will have to give it a few rewatches 😁 4 Reply @trtess 3 years ago Yes, more field theories. All of the field theories. 1 Reply @Celastrous 3 years ago Amazing video! Keep up this level of content. It is advanced yet easy to follow 5 Reply Physics with Elliot · 1 reply @otakarbeinhauer 3 years ago Just another positive feedback comment. It's just the right level of "math vs ideas behind it" that I was looking for. Reply @zacwarnest-knowles9139 1 year ago Videos like this are what’s made me want to become a theoretical physicist. Incredible content. Reply @martineli15 3 years ago I love when the math is presented because that's the true lenguage of this topics. Very cool! Reply @sambhavgupta4653 1 year ago You are the best explainer in Physics. Please continue making these videos! Thanks Reply @maxamadamiin 3 years ago I love physics for the sake of it, even though it is not what went for college. For these twenty minutes really helped me excited about field theories. In the begginning, I was little hesitant to look unto QFT due to the weird notations, but now you gave me a push to dive into. I love your videos Ellisiot. Thank you alot. 2 Reply @zeratulg 3 years ago Perfect !! If it is possible to conduct two dedicated series, one for special relativity and another for general while diving into details , that would be great !!!! Thanks for these videos in all cases :) 3 Reply @SquashyPan 3 years ago This video is gold and a deeper dive in QFT in a similar fashon would be even more gold Reply @vtrandal 2 years ago Thank you! I became Patron today. Your teaching is absolutely refreshing. Reply Physics with Elliot · 1 reply @joelcurtis562 1 year ago Amazing pedagogy here. Yes please, more field theory videos! Reply @panoskotoulas759 2 years ago That's actually a GREAT explanation. I can't think of anything you left out. You provided all relevant information in an easy to digest way. It was both formalistic and intuitive at the same time. I have no words, probably the best physics explanation video I have ever seen. 2 Reply @bulldozer6710 3 years ago I WANNA LEARN MORE! This was done so elegantly and was so incredibly helpful. My professor explaining this was the first time I'd heard of Field Theory, this video cleared my many misconceptions up a ton. Thank you! 3 Reply Physics with Elliot · 1 reply @AndyGD137 3 years ago This content is amazing, I can´t thank you enough for all this hard work and yes, we want to learn more about everything ;) 24 Reply Physics with Elliot · 1 reply @Slu54 3 years ago This has been a great video, it is the clearest explanation I've ever heard actually. Please do continue on field quantization and also the fields of other spins. 2 Reply @pipea1512 2 years ago Absolutely incredible. Didn't think it could be possible to explain this topic with such clarity and conciseness while maintaining engagement through the narration and great aesthetics. Thanks a lot 2 Reply @sbrunetton 3 years ago it's a king of magic !!! Thanks for these beautiful explanations !!! 1 Reply @joquino73 3 years ago Excellent video I will used in my classes. Excellent job. 4 Reply Physics with Elliot · 1 reply @BeAndNBovee 1 year ago I wish I'd had you as a math professor when I attended college: your explanations are super-clean and high quality. I would greatly appreciate if you'd "go down the rabbit holes" of the notations describing particle spins and their semantics. Reply @sungbeom8796 11 months ago (edited) I'm graduate student and really enjoying your series nowadays :) If I would go back to the past, I'd say myself watch yours. Reply @vsevolodnedora7779 3 years ago Outstanding. I've heard tons of lectures on physics and field theory (I am a physicist myself), but this is just perfect. If I ever end up teaching this subject I will come back to this. Thank you. 2 Reply @hendriksdf5570 2 years ago Explained twenty times better than anyone before you!! Ty <333 Reply @fugitive6549 3 years ago Wow, this is amazing. I always wanted to learn about the Field Equations and now I have the basic idea where it all come from. Please continue with this series. This definitely guaranteed a sub. 8 Reply @diraceq 3 years ago This was amazing and super informative. Everything made perfect sense to me as someone taking the second term of quantum mechanics. I would love more of this. 7 Reply Physics with Elliot · 1 reply @Lavabug 2 years ago Incredible stuff, I wish I had this resource during undergrad. It would've saved me countless hours trying to understand Landau's field theory book. I think I learned most of this from Dirac's GR book but it was almost as impenetrable. 1 Reply @danjunker3920 1 year ago Excellent whirl wind tour. It helps me understand the big picture behind the stuff I’ve studied. Reply @I-M-2. 3 years ago Elliott, you are the best! This is the best and most coherent intro I heard of field theories. Your content is gold. Please do one on the Dirac field. Thank you so much! 3 Reply Physics with Elliot · 1 reply @michaelpotter3418 1 year ago Thank you! It’s hard to find such a superb tour of this subject that includes the basic mathematical concepts. Lots of your audience have studied introductory quantum physics, but never got to see the next level. Reply @paulschmidt4095 1 year ago Thıs video is just awesome. Contrary to other pop sci videos that just tell stories and doesn’t explain anything this video helps people conceptualize both the mathematics and the logic behind this theory. Whoever makes these videos is pretty good at their job Reply @paoloazzini9003 3 years ago Really appreciated this video! This finally helps me to connect the dots of many concept i encountered during my physics degree, without having to take a full semester theoretical physics class. I'd really appreciate a video on spinors' lagrangian too. 6 Reply @frequency8612 1 year ago I really wanted to thank you because you pass by the mathematical developments in a logic way that really help to understand Reply @Adeodatus100 2 years ago You make these topics much, much easier to understand than my undergraduate physics tutors did 40 years ago. I seem to go through your videos saying "Oh, that's how that works!" about every 2 minutes! 5 Reply @pacotaco1246 1 year ago You forgot your base e's at 16:30 This video is smooth, and the videos make reviewing graduate physics more fun! 1 Reply @danielxf1353 2 years ago Amazing video, love the way you present the math! 1 Reply @joshuanicholson23 3 years ago Amazing, as a senior physics student this is very accessible coming from undergraduate courses. 1 Reply @BlueSoulTiger 3 years ago Lucid [in my view this is a big compliment as it's not attained so often. Excellent stuff Elliot] Reply @mayatrash 2 years ago This is the level of 3blue1brown if not better since it is really really useful for any physics students. Superb work! Never had Patreon for anyone in my life, but I will start to make an account in some days. Perfect content! Reply @namitshah9535 1 year ago This channel is good I understood this easily. You just have to know basics physics and calculus and you can understand the math. Reply @jennj8149 3 years ago You’re my new favorite youtube channel! You’re also very great at explaining this in simple terms! Keep making good content man! 👍🏼 2 Reply Physics with Elliot · 1 reply @theobolt250 2 years ago (edited) I am a mathematical very heavy challenged individual. (I hear some one thinking "then why do you watch, i..t"). That Lagrange stuff? Like some one puts a buzz saw through my head! But still... I want to understand field theory! The consept of fields I get! Or is that weird? Well, no gain without trauma I guess. Wrote this after the introduction of Langangian. Back to the tranches. From there on in it got way worse!!! Does somebody know a good trauma surgeon? My head just split! But... still... I got a better idea of the depiction of fields, they're spacial, 3d! With time! And Lagrangian is a kind of particle/energy hunting. And I even see a connection with a very fundamental depiction of space where space is just space, a vacuum! And the cosmic rest energy that still pops up there. So, there's always a field. An active field! Was that field the always? Reply @cicik57 3 years ago wow this video is awsome, it made me finally understand what lagrangian is :D 1 Reply @DominicProMax 4 months ago I am glad to say that having watched 4 times since my first watch 2 years ago I finally understood everything Reply @kka107 3 years ago I would love to learn more about the details of spin-1/2 (Dirac) and spin-1 (Maxwell) fields. I also love to see how the 4 del-based Maxwell equations can be re-formulated in such an elegant way. I thought Maxwell made it elegant enough. Apparently not. I love your approach to teaching physics. And I love that you spend a great deal of time on classical formulation rather than jumping to quantization. This way I can get the big picture and compartmentalize the key ideas in my brain before I get into the implications after quantization which are much harder to grasp or visualize. I am an engineer but have learned a great deal of physics on YouTube from people like you. Your channel is unique because you’re not afraid get into the math. Thank you. 1 Reply Physics with Elliot · 1 reply @AngadSingh-bv7vn 3 years ago (edited) Its incredible the quality of content you have created that doesn't leave any gaps in math or understanding. I'm beginning to look forward to every video you put out :) keep up the good work! Well maybe not a completely rigorous math lesson but definitely super motivating to check out your notes. 4 Reply @RonSonntag 1 year ago Would love to see how Lagrangians are used in General Relativity (if they are). Excellent video. Will take me hours to absorb. Reply @richard_darwin 1 year ago Wow the first part really reminds me of weighted residuals for finite element method but in reverse. Thats pretty cool Reply @mikstern5471 3 years ago Thanks for the fantastic videos. I would love to learn more about field theory and in particular about Dirac’s equation. 2 Reply @stefanogallina3643 3 years ago Just discovered your channel and already binge watching all your videos. Keep up the amazing work! 3 Reply Physics with Elliot · 1 reply @hrperformance 1 year ago I have a very good lecturer that taught this material to us (in my opinion) very well. But it was very easy to get lost in the detail and forget the big picture. This video sums up all the key points of about 6 hours worth of lectures unbelievably well. Having watched this video after struggling to grapple with my uni's material, I feel soooo much more confident. Thank you so much for this video AND the notes. You are awesome Elliot! Reply @MrFischvogel 2 years ago Please make a video especially about quantum field theory or maybe even 'Matrizenmechanik'. This was a very, very good video. Thank you so much, Sir. Reply @alifeleparanj3688 3 years ago I'll definitely be a patron to find more videos on field theory. Your channel is awesome Reply @namehkoudsie6075 11 months ago This is amazing mate, one of the best and simplest ways to introduce such a complex topic. Cheers! Reply @janeclark1881 2 years ago Yes, please do add videos developing field theory and particle physics. Reply @ManasSarkar-cp6rk 7 months ago "Great video! 🌟 It's impressive how you packed such clear and concise information. I really appreciate how easy you made it to understand the topic! Keep up the awesome work! 👍" Reply @samanthabuck3978 1 year ago Would love to see a follow up video outlining QFT. Very concisely explained; well done! Reply @lardmaster4349 3 years ago Excellent, excellent explanations for what even universities struggle to teach in an intuitive, easy-to-grasp manner. Great job with the concrete examples, the explanation of physical meaning and intuition behind the maths, the overall structure of the lesson, the motivation behind the concepts and maths, the animations to illustrate the point, the reminders of what we’re measuring - I cannot express just how excellent this is as a science communication and educational video! Reply Physics with Elliot · 1 reply @samsyet-0074 3 years ago I would definitely want more of these videos, your videos are super nice for me! As a High school student with interests in maths and physics, its hard to manage doing college level books and preparing for entrance exams, but your videos really help me freshen up with something exciting. So its a no brainer for me to say yes to more of these 3 Reply Physics with Elliot · 1 reply @Starlite4321 1 year ago LOVED this video, thank you ! If you would just continue explaining quantum field theory right on from here it would be fantastic ! Reply @teddymanguerra 2 years ago Still amazed with the elegant presentation! Cheers! Reply @xavidoor 3 years ago Excellent introduction to field theory! Thanks! 1 Reply @waynelast1685 1 year ago Very elegant explanation. thank you . Yes please continue. It would be nice to see real simple examples illustrating the math and concepts. Reply @TheCrunchyGum 3 years ago Very nice video. I'm takin qft next fall and this was a good intro. The derivation with the differential of curly L broke the pace a bit since it wasn't immediately obvious what steps you were taking between subsequent results, but everything flowed smoothly otherwise. I hope you continue to make videos on the topics mentioned at the end. The videos make field theory seem very accessible with basic undergraduate knowledge. 2 Reply @LoomMexatron 3 years ago Impressive work as always! Your ability to explain even one of the most complicated things such as field theory is genuinely fascinating! 3 Reply @MrOvipare 3 years ago I started reading a QFT book some time ago and while I was able to progress in the frist chapters, it got so dense that I couldn't really see the big picture. Your videos help a lot! Looking forward to see more details on spin 1/2 and 1 field theories :D 2 Reply @Danial.Ghamari 2 years ago Your video was absolutely incredible. Thank you so much. And yes, I am tremendously intrigued by the other things you mentioned at the end and will deeply appreciate it if you make videos on them as well. 1 Reply @anoimo9013 1 year ago amazingly simple explanations of the gist of very convoluted and intimidating concepts¡¡ Reply @TheZoneTakesYou 2 years ago 3:25 'we're getting ahead of ourselves' bro thats what im here for, can you jump around within the topic more frequently? It honestly helps continuity and focus so much when you talk concretely about use cases for the equation prior to explaining the variables. would prefer units too, but this is 10/10 stuff Reply @dlrmfemilianolako8 3 years ago Obviously facinating . Thank you very much 2 Reply Physics with Elliot · 1 reply @fazilnajeeb 3 years ago hEY Elliot, first of all, i wanna thank u for making this video. This video was sort of a semester worth of content so beautifully presented. Keep up the quality. Also it would be kind of u to make more of this field theory videos. It surely be very helpful. I know its a tremendous work, but this is my request. 1 Reply Physics with Elliot · 1 reply @rahulmathew4970 3 years ago Bring it on man, really excited!!! Reply @dirichlettt 3 years ago Yes, I'd love more videos on field theory! Reply @punditgi 3 years ago A mind blowing video! Many thanks for this and all your others. 👍 2 Reply Physics with Elliot · 1 reply @matteo_0039 2 years ago Really nice content. I suppose it might have opened a can of worms, but I think it would have been nice to mention that the solution of the energy/frequency eigenvalue equation force the introduction of antiparticles. Besides learning to deal with the math, that is probably the most striking feature of the actions that we can write for fundamental fields. Reply @amane49 3 years ago Awesome lecture! Succinct and very clear! Thanks 1 Reply @YossiSirote 2 years ago (edited) The best video ever!!! Thank you!!! We want more! Much more! Reply Physics with Elliot · 1 reply @trambakphysik7 3 years ago (edited) Wow, wow, wow, cannot be any better summarized, loved it!! Just a sidenote, maybe we can go about in the same way for a general Lagrangian density, (like not considering the Lagrangian density for the KG field theory), and derive the classical field equations in terms of the Lagrangian density. After that we can use any Lagrangian density and get the corresponding equations representing particles for eg the choice of Lagrangian density in the KG field theory would give us the KG eqn for free spin 0 particles, similarly the choice of Lagrangian density in the Dirac's field theory would give us the Dirac eqn for free spin 1/2 fermionic particles. Please clarify I'm wrong anywhere. Reply @pRolk12 3 years ago A video about quantum field theory can be realy cool ! and Thank you for this amazing video !! Reply @DmitryAblov 3 years ago Just say 'Thank you' - says nothing. It's really amazing, interesting, well prepared and illustrated, and clear for understanding! Reply @joehitchen9311 3 years ago Yes, please do show us more classical field theories! Reply @gabrielmotterjonk559 3 years ago This is the best presentation i've seen so far of Field Theory. Wish i had it earlier on my studies of the subject. I will certainly recommend this video in my department. Reply @marcaurel1830 3 years ago I'll take a course in classical field theory next semester and quantum field theory eventually so I'm definitely interested :). Great video btw 2 Reply Physics with Elliot · 1 reply @mihagolod2393 3 years ago Incredible that we have access to content such as this video. Thank you very much! Reply @jazzlehazzle 1 year ago I'll have to watch this a few more times, but it was a great into that makes sense! Reply @1495978707 3 years ago Really good shit man. I would like some more explanation if possible on why the gradient potential is a thing, and what the field is, or at least what the field can be used to calculate. Because sure you can get a dispersion relation and model wave propagation, but of what? The field isn’t the same as a wave function which can at least be used to tell you measurement distributions Reply @johnchessant3012 3 years ago That was really neat! I'd definitely be excited to learn about quantum field theories, I didn't get to it in university and I wish I did 2 Reply Physics with Elliot · 1 reply @pastorericardo 3 years ago better explanation ever! Congrats! Reply @damienthorne861 1 year ago You do have an amazing way of imparting knowledge. You obviously understand the material quite well. Thank you. 🤘 Reply @noahwilliams9231 3 years ago This was fabulous I cannot say that enough unbelievably well done Reply @mattstarbuck7484 3 years ago I think that you should have a go at explaining something even more advanced than this, such as the path integral formalism of quantum mechanics and how it leads to Feynman diagrams. Keep up the amazing work! Reply @hakizimanaomar6 1 year ago This video is really very interesting. Please tell us more about these fields! Reply @robertschlesinger1342 3 years ago Excellent video. Very interesting, informative and worthwhile video. 1 Reply Physics with Elliot · 1 reply @ThurVal 2 years ago Hi! Best explanation of KG eq i ever found! Reply @darkol93king34 3 years ago This is really wonderful. I wish you continue to develop on these field theory topic which is very interesting to say the least. Thank you for sharing your knowledge🤗 1 Reply Physics with Elliot · 1 reply @Draginx 3 years ago I've just started studying quantum field theory and finished my courses on general relativity and have been extremely curious about what is to learn and confused about how my professor teaches. I love this video. Please make more like these describing different spin particles, quantum fields and especially spin 2 fields. It's all so interesting. You explain extremely well and have amazing editing. You've earned a sub from me. Thank you. Reply 1 reply @kaducarlos9961 3 years ago I don’t usually write under YouTube videos but I genuinely love physics like I deeply love it and seeing this kind of videos are amazing and so beautiful thank you for these and keep making these videos man Reply @g3452sgp 2 years ago This video is great!! I want to see more videos about lagrangians of different kind fields like dirac lagrangian, maxwell lagrangian, and einstein hilbert lagrangian. Thanks a lot. Reply @andytroo 3 years ago Loved the video, gave an overview for a few very complicated things in a few short sentences, keeping the core ideas, but also keeping it understandable. Reply Physics with Elliot · 1 reply @MikeOxmol_ 3 years ago Elliot, I love you videos so much that if you released a series of 20 lectures on any given topic I would watch them in one sitting. Absolutely brilliant stuff. On a side note, what's the tablet/software you use to write the formulas in you videos (at least the previous ones)? The letters always seem so nice and even, lines are always straight etc. 6 Reply Physics with Elliot · 1 reply @maheshkanojiya4858 1 year ago ❤ you are great you made it possible to understand such topics Reply @MDExplainsx86 3 years ago Thank you very much! I'm very glad that you're making these physics videos, they are making me love learning more about Physics and I'm very excited about learning more of it! Please Keep Making these videos and thank you very much .. you deserve more support! As Feynman puts it: "If you cannot explain something in simple terms, you don't understand it. " And you're really doing great job at explaining! Thank you very much 2 Reply Physics with Elliot · 1 reply @darkside3ng 1 year ago You did an amazing work. Thank you by the effort and the clear explanation. Reply @bingusiswatching6335 3 years ago Absolutely amazing. I love how much you get into the nitty gritty of the mathematics. And your videos explain it so well, especially combined with the visuals. Great job man 1 Reply Physics with Elliot · 1 reply @zachzanal1067 2 years ago Fastest 20 minutes in this year so far. Pls do make more videos on Dirac field in future Reply @jonathanamar1 3 years ago I'm taking a one-semester introductory QFT course and your video just appeared in the recommended videos. I found it amazing! I've already subscribed to the channel to wait for the sequence! Reply @christopherkulink3091 3 years ago Wow, I love it, I think you just filled a couple holes I had in my understanding, and answered some questions I’d actually been wondering about for the last month or so. All in all this was not only great in that regard, but I think covered the math pretty well and in such a way that I’m going to have to reference and rewatch this video several times as I keep absorbing everything here. Great work! 1 Reply Physics with Elliot · 1 reply @Jack-py7zf 3 years ago Hi I am a highschool student .I love physics . I personally find your vedios useful and informative .keep up the good work Reply Physics with Elliot · 1 reply @leoberges1705 3 years ago Thank you very much for this amazingly clear explanation. I never had a field theory lecture and thank's to you I now understand the link of Lagrangian mechanics and Klein Gordon equation, and I am so glad I do !! 1 Reply @tornadospin9 3 years ago I am currently learning physics from an algebraic standpoint and have taking Calculus BC. I do not know the nature of partial differentials or physics with calculus applied to it so I do not follow along. However, this looks like amazing channel to follow for once I do learn these topics. You bridge the gap between Newtonian to Lagrangian and introduce field theory. I look forward to returning then Reply Physics with Elliot · 1 reply @AmrFoxy93 2 years ago I love this channel so much, thank u for ur effort dude ❤️ Reply @Aloka145 3 years ago (edited) amazing thank you so much ! helping me through my class of field theoretical aspects of GR Reply @bromanHenk1 3 years ago Id love to see more on the notations you mentioned at the end of the video, and perhaps a full video explaining the different fields and their interactions! Reply Physics with Elliot · 1 reply @KeithZSD 3 years ago Thank you so much! This is such great video. I'd like to see all other related videos you mentioned. Thank you! 1 Reply Physics with Elliot · 1 reply @maheramer5459 3 years ago Great video. Your presentation approach is phenomenal. I am definitely interested in learning more about quantum field theory. 1 Reply Physics with Elliot · 1 reply @doit9854 3 years ago (edited) Just found this video. Great explanation of the topic. Beyond subbing, I checked out your Ph.D. Dissertation. I dove into a few chapters while skimming through it (where I could understand). Would love to have you teach us all about it. Thanks! 1 Reply @alexandreraulikneto3062 3 years ago Please continue this series! 1 Reply @katgirl3000 3 years ago Nice! I was just going to look at the Klein-Gordon Eqn as part of my review! 1 Reply Physics with Elliot · 1 reply @rodrigohy6 3 years ago Please Elliot. Make a video explaining how and why each particle, model or theory has a different expression of the Lagrangian. Reply @leandronavarro554 3 years ago I just suscribed and loved the video. Looking forward to watch the rest and waiting for more of your content. Greetings! 1 Reply Physics with Elliot · 1 reply @omargaber3122 3 years ago you are amazing teacher,wonderfull professor Reply @hrkalita159 2 years ago no one can match him. Just extraordinary 1 Reply @gintoki6811 3 years ago Pls continue, ur course’s gonna be cool Reply @debunkthis 3 years ago Absolutely fantastic lecture. Reply @abraham.alebachew 3 years ago so much enlightening! Thank you💖💖💖 1 Reply @jirimarek112 1 year ago Vynikající. Velmi děkuji. Reply @MaxxTosh 3 years ago This was such a beautiful video! Thank you for such a great production 1 Reply Physics with Elliot · 1 reply @shutupimlearning 3 years ago to me, this video seemed to be perfect with someone who has already been taught field theory, as it was pretty hard for me to follow in the given amount of time, and I had to pause and think for a bit a lot. Very insightful though! Reply Physics with Elliot · 1 reply @alirezaakhavi9943 1 year ago such a wonderful and amazing and informative and well structured tutorial! Thank you very much. subbed! :) Reply @comoenclase 4 months ago very good explanation!!! congratulations!! Reply @narfwhals7843 3 years ago This was a really interesting intro to field theory. I have a few questions. at 15:26 you say if we set kappa=0 we get a wave traveling at c. So a massless particle. Is this what the higgs mechanism does? Give us a kappa term for the wave equation? I've been struggling to understand what the Higgs Field actually means mathematically for a while. You also say that Newton's Gravity acts instantaneously, but can't we also formulate it in terms of delayed potentials like electromagnetism? And should this not also immediately give us gravitational waves? What are the shortcomings of this? Lastly do you have a video on how to get the equations of motion for light in a medium from the Lagrangian formalism? I see how we get f=ma, but that doesn't apply to light. 1 Reply Physics with Elliot · 1 reply @77ferrum 2 years ago I thank you for this presentation. I would be interested in how this theory leads to the existence of the fifth force and how this force makes possible to travel through time. Reply @jeffalbertson804 3 years ago Thank you for this! Great stuff! 1 Reply Physics with Elliot · 1 reply @Taky055 3 years ago I am not a phisycist or a scientist or any of that for that matter, but I had a sort of relevational moment not long ango. Since then I have spent time to observe something called time blindness in my condition called ADHD. The base of all that is properly identifying the the poles, extremes of anything and put them into a 3dimensional 9 corner point system. With that beeing said, and hearing time is relative and how it is connected to light, one big problem I have with all the equations, and that is existing in given timeline here and now. With adhd connected to brain waives I have found that our hyperfocused state is connected to our gamma brain waive. Thats the high freq suggesting to me speed. Thats covered in e=mc2 which for me translates as : right here, right now, to me. Now I saw that velocity came into play especially the relation to the observer thus creating the sense of time but for me this is still just now. So what if, I propose, light and darkness beeing only opposite to one another in any different time frame as now. So darkness is the space reserved for light, and/or the space it filled before now. Meaning existence of something can only be observed beeing definite here and now. Any time further or back could only be assumed and relative to the actuall time used, that assumtion hence the existence of said anything blurres. Leading us to memory, and prophecy as opposed to another as blurry as both can be! So not knowing anything about any of this I would say t as time implemented would leave us with: -tE = (mc2)t Does this make any sense at all? Reply @aviahh 3 years ago amazing video, this is a very tough subject and you make it very friendly! thank you for this great content Reply @craighadley-m8b 5 months ago searching for the mathematics that support quantum entanglement, a movie for nerds? You've helped me realize my true fate, I need help with theoretical chemistry? The energy states of life. Reply @saudyassin5352 3 years ago (edited) Thank you so much for digging deep into the mathematics and showing all the intricate details. I am very excited for the course that you will be me making about classical field theory and Lagrangian mechanics. This course would be of great benefit to me since i am self studying physics during weekends when i don't have school work. High school physics does not bring me closer to understanding the fundamentals of this universe. 4 Reply Physics with Elliot · 1 reply @tedward191 3 years ago Brilliantly explained, thank-you! Reply Physics with Elliot · 1 reply @snehasismaiti342 3 years ago Thank you very much for making us understand such a difficult concept in about 20 minutes 1 Reply Physics with Elliot · 1 reply @danko6yg411 2 years ago Yes I want to learn more. Thanks. Reply @luissanchezpolo8723 3 years ago Simply wonderful Reply @noahwilliams9231 3 years ago This video might be the best on YouTube Reply @mohameda.444 3 years ago I have seen many teachers describing the first terms of the equation you boxed @20:48 as the kinetic terms and the second term as the potential term.. given your back of envelope description of how the lagrangian density is coming from, it seems they are wrong.. it is only the temporal parts of the first term is the kinetic contribution while the potential contribution is attributed to both the spatial parts of the first term as well as the second term.. does that make any sense? 1 Reply Physics with Elliot · 1 reply @berkayyalman6142 3 years ago (edited) it's a very good work,i love your videos,please keep doing these videos👍 1 Reply Physics with Elliot · 1 reply @dev-t1o5e 3 years ago This was amazing!!!! Learned more from your channel than my 2 years of college Reply @sagarverma1489 3 years ago This is an amazing video! Thankss! I completed my theoretical Physics msc recently. Your research papers too are very exciting for me! Reply @jezza10181 2 years ago Superb presentation. Many thanks Reply @ajeetkumar5453 5 months ago Learned something new. Thank 😊 Reply @notlessgrossman163 2 years ago (edited) Great but this is a whole course in twenty minutes! Lagrangian plays such a big role it could be a multi part series. Then I realized it is. Thanks again Reply @nijram15 3 years ago I didnt follow any field theory coarses during my physics education, but this video has the perfect pacing for me! I love it! I also liked how you connected it to the wave equation and plane wave solutions. As a now optical engineer I use Fourier optics to describe optical system and use very similar strategies to solve these. One question: the introduction of the harmonica oscillator potential seems arbitrary to me. What is the rational to use this? Reply 1 reply @maurocruz1824 3 years ago This channel give me more life! Keep going! Reply Physics with Elliot · 1 reply @hugopristauz3620 1 month ago very nice and clear explanations Reply @rickkeam 1 year ago That was excellent. Well done sir Reply @mastershooter64 3 years ago 0:09 shouldn't the scalar value in front of the energy momentum tensor be 8piG/c^4? like it's missing c^4 1 Reply 1 reply @farazahmad364 2 years ago Perfect explaination Reply @RadioPhy 3 years ago Excelente Work. Thank You! Reply @RaiyanSyazani 3 years ago This was an amazing introduction to field theory! Thank you! Reply @frankreashore 3 years ago Wonderful talk. Thanks so much. Reply @cs_i_r_i 4 months ago (edited) Thank you so much for providing notes for me and subscribed your channel for more videos.❤❤. Your explaination is clear. Reply @khaledhosseini2030 3 years ago Wow! Fantastic! 1 Reply Physics with Elliot · 1 reply @SpecOps140 1 year ago 8:25 thank you for explaining a derivative that the Goldstein book literally just dismisses as "obviously disappears" Reply @otakarbeinhauer 3 years ago Just another positive feedback comment. It's just the right level of "math vs ideas behind it" that I was looking for. Reply @antoniocotarodriguez5732 2 years ago What a great work, thanks! Reply @massimoacerbis8138 2 years ago Simply amazing Reply @sigurdvargdal3313 3 years ago Yes! More! Reply @alejandroaguilar3816 3 years ago I’m interested in learning more of this in future videos :) 1 Reply Physics with Elliot · 1 reply @ianmcewan8851 3 years ago Excellently done. Reply @waynelast1685 1 year ago 13:17 Is there such as thing as Lagrangian density for non conservative forces? In other words does this Lagrangian density only apply to certain potentials? Reply @arasgoshayeshi9156 1 year ago The fact that i can even understand these stuff as a person who has just started physics shows your talent😂 Reply @8zczff491 3 years ago Hello! I would also be very grateful, if you could do videos about the different Lagrangian forms, especially about the Dirac Lagrangian. Thank you so much! Reply @waynelast1685 9 hours ago (edited) 4:37 Can a Lagrangian be derived WITHOUT advanced knowledge of the equations of motion, in case of conservative and nonconservative forces, even without using T-V for conservative forces? Reply @smartdoctorphysicist3095 1 year ago Hi thank you very much, I will try and get the note at another time. Reply @121192ri 3 years ago I definitely want to learn more about quantizing the scalar and spin 1/2 fields. Reply @dhimanbhowmick9558 2 years ago Thank you so much very very useful Reply @dhimanbhowmick9558 3 years ago Thanks a lot, Elliot Reply @mansouryoutubization 2 years ago as always very insightful and informative!! please also elaborate on the topics toward the end of this video clip Eistein Hilbert, Maxwell, Dirac Lagrange. Thanks. Reply @tanchienhao 3 years ago Yes please teach spinor fields!! Reply @jatinsoni1979 3 years ago (edited) This content is amazing, I can´t thank you enough for all this hard work and yes, we want to learn more about everything. Also brother could you suggest some online courses to learn the field theory in detail, i am really interested in joining a genuine course? I am currently a under-grad Computer science student, but physics has always fascinated me which is why i want to learn these in detail with the mathematics. 3 Reply Physics with Elliot · 2 replies @nindybear946 2 years ago Very well explained 🙏👍 Reply @AJ-et3vf 2 years ago Great video. Thank you Reply @censoredamerican3331 2 years ago Perfection! Reply @Anassokp 3 years ago great video, thanks a lot 1 Reply Physics with Elliot · 1 reply @gabrielmazante3877 2 years ago Congratulations dude, very good content Reply @barrerasciencelabuniverse6606 1 month ago Hello! Relativistic equations are elliptic here light has the speed limit c, but in hyperbolic geometry this is not the case. Elliptic and Hyperbolic spaces or manifolds have different metrics, and so also in time. Reply @agrajyadav2951 3 years ago Ur awesome professor 1 Reply @trigocuantico 3 years ago Its very hard to find the math on this like in this video, loving it!!!! I'm curious on applying this concepts, are you thinking on doing examples? 1 Reply @ent-r7w 3 years ago Amazing video! I immediately subscribed and look forward to next videos! Reply Physics with Elliot · 1 reply @surendrakverma555 1 year ago Very good. Thanks 👍 Reply @sarajamil-m6c 3 years ago You are awesome, great job Reply @TheJara123 2 years ago It would be great if you can make more videos on the last part of your video thus Dirac equation, Einstein eq, Maxwell...thanks for the efforts. Reply @fergusbabb9722 3 years ago Love it! Reply @hrperformance 1 year ago more field theory videos please!!!! Reply @gani9176 3 years ago Finally someone who goes into the math and that too in such a short time Reply @puneettripathi740 1 year ago Dear sir, can you suggest some books to start with to understand field theory, I was just curious to learn it and one more thing please what are pre-requisites to understand this subject? Reply @NopeNopeNopeYeap 2 months ago Please make videos about Dirac equation and Maxwell Lagrangian and Einstein Hilbert Lagrangian! Reply @smartdoctorphysicist3095 9 months ago Hi Maxwell never was able to solver is own equations , can you tell of good and easy field theory book. Which will help me under stand this better? Thank you Reply @jtxx34xx 3 years ago (edited) The statement that the action is minimized (or maximized) is refuted by the counter-example of a statue sitting in a temple for a thousand years: Temporarily moving the statue up to the roof or down to the basement for a sufficiently long time (say another thousand years) before returning it to the pedestal will change the action by an arbitrarily large amount in either direction (as the potential energy change gets integrated for an arbitrarily long time), dwarfing the finite change in action that occurs while the statue-moving company is on site. This is why it is better to use the term "flat action", which is correct, instead of "least action", which is not. Furthermore, it is worth mention that in classical mechanics, what one really wants is to show that equations of motion in Lagrangian form are unaffected by changes of coordinates. This may be proved in general by using the chain rule for derivatives. The proof is not as motivated, but it has the virtues of being correct and simple, and worth presenting to alleviate doubts. This may prevent the more mathematically able students from simply dropping the class because of mathematical confusion on behalf of the professor. I'm not saying that the calculus of variations shouldn't be presented as a derivation, only that it's better to give an actual proof without the unnecessary assumptions and complexity. Reply @guywilliams9 1 year ago Want to see more of this. Reply @vwcanter 1 month ago Which term in the lagrangian would be omitted, for a field of a massless particle? Trying to understand where the mass comes from. Reply @bishwajitbhattacharjee-xm6xp 1 year ago In presence of time derivatives of phi for Lagrangian density the role of x-derivatives as gradiant energy is not clear . What density a function of gradiant ? And why not just only space time in exchangeble. Shape , size or geometry of field. Thank you a good channel. Fantastic tutorial. Reply @adamfattal9602 3 years ago Great video!! Reply @alikarimi-langroodi5402 2 years ago excellant. thank you Reply @prithwiraj1462 2 years ago Sir Please do more videos on field theory and symmetry conservation on Particle Physics ..It will be helpful for my post graduate coursework Reply @joquino73 3 years ago Excellent video Reply @gowrii7 2 years ago (edited) Sir, I am very much interested to learn about field theory's more...and also Einstein Hilbert lagrangian.... Thank you sir 1 Reply @kquat7899 3 years ago Excellent. Reply @SamiulIslam-vv5vc 3 years ago It was really a great one.pls try to make an other video on qft, specially on dirac equation.... Reply @bdas641 1 year ago so good.. loved it.. please suggest a text book that is reasonable enough and not to hard to learn the math of QFT.. Reply @markusheimerl8735 3 years ago (edited) Great content, but please please please add small practices in between where the viewer can pause. I understood everything until 6:20 but before going further I would feel more secure if I had a small problem to solve with the knowledge just aquired. As a CS student, you lost me after 6:20. Just FYI. Reply Physics with Elliot · 2 replies @BlueSoulTiger 3 years ago I'm keen on getting a better gauge on what a gauge is! All in the due course of time perhaps? Reply @waynelast1685 8 hours ago excellent video... just what I was looking for.... I would only add another reason for developing QFT is to be able to explain creation and destruction of particles, since SE ( or Dirac equivalent) does not do that. Does that sound accurate? Reply @alimoufid8899 3 years ago well done. Can you please do a serie about the spin 1,1/2 and the graviton fields? Reply @tetrahexo5592 3 years ago I love your content and i would really like to see topics from qunatum field theory ans gr explained in more details, i wish to understand them mire deeply😁👍 Reply Physics with Elliot · 1 reply @amirvahid7143 2 years ago Please post a video about Dirac-Lagrangian, Einstein-Hilbert, and Maxwell-Lagrangian. Reply @oluwaholy6197 2 years ago I really gained a lot in this video. I will like to know how to solve the spinors Solutions to Klein Gordon and Dirac Equations sir Thanks. Reply @bluecheez555 1 year ago (edited) Thanks for the overview. Just wanted to point out that I felt that the "gradent energy" felt very handwavy. It's very much not something that I would expect in the potential (as this is never done in classical mechanics), and here you explain how it "makes total sense to include it" but then use some very vauge reasonings for its inclusion. Furthermore, you add a term to the potential energy which is the potential for a harmonic oscillator, but then say that this describes the physics of a free particle. Why would a free particle have a harmonic oscillator potential in general?) Reply @javitomj 3 years ago Very didactic video, thank you. Do you know any good introductory book to field theory? Reply @GaryBernstein 11 months ago Please make videos for quantum & the spin details as you said Reply @TheJara123 3 years ago Well done👍 Reply @rarichie3829 3 years ago I'm so glad I found this channel 1 Reply Physics with Elliot · 1 reply @alexgodeye3031 1 year ago 9:00 we would be assuming that only energy-conservative forces are acting on the particle here, right? Reply @nellvincervantes6233 3 years ago In hawking radiation or unruh effect, the particle being radiated is a photon (spin 1). Then why klein gordon equation is used to derive hawking and unruh temperature Reply @lachlananderson872 3 years ago I loved the video and your channel, however I have one question. You got the Klein Gordon equation by minimising the action of the field and in your video about Lagrangian mechanics, you used the Euler Lagrange equation to do so. Is there any difference between the EL equation in that video and one which could be used in the case of a field? I though maybe a d/dx with the d/dt. 1 Reply Physics with Elliot · 2 replies @I_am_Dipanjan 3 years ago Please do make a video on Einstein-Hilbert Lagrangian and Einstein's Equations.Anyway this video was awesome 😊😊..... 1 Reply @alipedram5720 3 years ago Keep up the good work. Reply @2tehnik 3 years ago I’d be interested in seeing these kinds of derivations in specific cases. Reply @rickyconsta 7 months ago GREAT VIDEO Reply @waynelast1685 8 hours ago 10;55 that's assuming there are conservative forces.... is that true all the time with quantum fields? Or is there just another way to write the Lagrangian density? Reply @vaibhavrawoot 3 years ago Great video Reply @varunahlawat9013 1 year ago Hello Elliot, congratulations for 100K subs!! Reply @filippotamassia981 3 years ago Congratulations for your videos! On this topic, I would be very interested to hear your description of "virtual photons" and virtual particles" in general. Despite all explanations, even by many important physicists who don't always agree, I'm still confused about the nature of those particles. Are they real? Are they mathematical tools? I know that there is something like the Casimir effect and the Lamb shift but I'm still missing something. Thanks very much. Reply 2 replies @pierusa123 2 years ago I have spent many years, trying to study the nature of time, so I study standard model, general relativity, black hole, cosmology, quantum gravity, supergravity, gravitational wave, super symmetry, symmetry breaking, qft, qed, qcd, they are related to time, but none could explain time. Any guidance? Reply @AMADEOSAM 3 years ago Great! 1 Reply @alirezam.toroghi2450 1 year ago thank you so much Reply @deborahkeesee7412 3 years ago The equation on the upper left is wrong because it should be V < C for anything with mass! For some reason this is never clarified even by physicists, and it's rather important to say the least! Reply @doshbrix143 1 year ago Im still in high school and want a basic grasp on these concepts. I understood a good chunk of the maths, but for now am wanting to confirm whether I know the physics. So am I right in saying: scalar bosons can be thought of as propagations (taking the form of wave functions) in the Klein Gordon field. These waves evolve in accordance with the Klein Gordon equation, which is relativistic. Am I right? Reply 1 reply @federicopagano6590 3 years ago (edited) The prview of the video has a formula with m^2 but it should say k^2 not the mass^2. Awesome video Reply @waynelast1685 8 hours ago 20:28 I like it the long way actually Reply @NovaWarrior77 3 years ago This man has so much strength. 1 Reply @shuewingtam6210 3 years ago At 7:48 you wrote Action dS= . It should be written as S= , which is consistent to the previous equation. Is that right? Reply Physics with Elliot · 1 reply @solitarygrimreaper 1 year ago please teach about Dirac Lagrangian, Maxwell Lagrangian and Einstein-Hilbert Lagrangian Reply @Tomyb15 1 year ago 10:11 "we write down an L, and take it..." Yeah, sound about right when doing advanced math 😂 1 Reply 1 reply @htikeaungwai5513 3 years ago Hello, Elliot. May I ask a question? What's the difference between Klein Gordon equation & Dirac equation? And, how did the latter predit the existence of anti-matter? Reply @General12th 3 years ago This video was glorious! Reply Physics with Elliot · 2 replies @louis4798 2 years ago definitely wanna learn more Reply @peggi3561 2 years ago Plz ans my question: Isn't the idea of potential of a particle comes from field theory? But we know Maxwell was the first person to develop field theory(electromagnetic), but when in elementary physics classes we study some works prior to Maxwell which also involves potential and field strength, concepts like this. What is happening here? So was there concepts related to field before field theory was developed? A similar question:- was there a concept of potential energy of a particle in Newton's work. Without the concept of field how the idea of potential energy came? Reply 1 reply @rufismalan 1 year ago This channel is salvation for the uncountable victims of rigid university curriculum. Reply 1 reply @vivientane3060 1 year ago Hello! Is the Schrodinger Equation also a consequence of this principle of least action through the minimization of a given action ? Reply 1 reply @filipepgoes4528 2 weeks ago Great! 🎉 Reply @chyldstudios 3 years ago Perfect! Reply @alejrandom6592 1 year ago I love these videos 1 Reply @vwcanter 3 months ago The gradient energy- is that another way of accounting for the fact that a shorter wavelength (higher frequency) has more energy? Reply @thomasolson7447 4 months ago (edited) I was running with the notion that x is a constant that moves the phase around. But since you did an integral on it, I'm thinking this is a t[real]+i*t[imaginary] situation. So, it's not a wave then, it's a conformal 4d space [t, x, Re(f(t+i*x)), Im(f(t+i*x))], projected to a 3d sphere where t+i*x=1? This seems wrong, the x would be messing with the inverse amplitude of the wave, not the position, depending on the wave. But I can make it work to affect position, provided I can make changes to f(t,x). Kind of a f(t,x)=f(t+i*(-i*x))=f(t+x) situation. If we're adjusting position with respect to time. Or maybe f(t+x*ln(a+i*b)) Reply @doomstarks182 1 year ago Question. The light from the sun takes 8 bc of how the sun bends spacetime. If the sun disappears and spacetime goes back into the form it had before the sun was there doesn’t that mean the rays from it would reach us sooner bc the spacetime is no longer bent from the mass of the sun? 1 Reply 1 reply @BadAss_691 1 year ago Please teach full field theory course at a beginning graduate course level… other than that, please do a full advanced math playlist, tensors, groups, green’s function! pDE etc…. Reply @VercilJuan 1 year ago Very good video, new sub! I hope you can teach us tensors too sometime Reply @fabiosalvi9035 1 year ago (edited) Thank you very much for your interesting video.Why in the dL expression is to find mdx/dt*de/dt? Ii would expect dx/de*de/dt. Reply @arekkrolak6320 3 years ago why do you put dt before the function in an integral? it is not only wrong notation, but it also looks like you want to take the integral of 1 and then multiply by the funtion Reply @baglesac5806 3 years ago As always great videos. BUT ... Could you please change the grainy background ? It is very distracting. Continue your good work. Reply @andrewbenbow9257 1 year ago So instead of taking the derived sum as a calculation, we derive a new movement based on it's field interaction? Reply @marfmarfalot5193 1 year ago Mmm im curious wouldn’t it be insightful to derive the lagrangian density by taking n oscillators and taking their seperation limit to 0? Reply @underfilho 3 years ago great video Reply @howwitty 3 years ago Thank you. Reply @yashshah5727 10 months ago Plz make more videos on this. Reply @volkglasba 3 years ago Is GR a field, as you say "having a value in space and time", while GR is a change in spacetime, in contrast of the concept of a field. Reply @wdobni 1 year ago what is any of this used for? is field theory the basis for quantum computers and fusion thermoelectric power generators? i can see field theory being taught endlessly to an infinite line of college students as an exercise in mathematical theory and mathematical logic but in the external world where is it useful? do we use field theory to make iphones? Reply 1 reply @JustinHsia 1 year ago Great videos. Thank you! I have a very fundamental question that probably stems from the fact that I don’t understand field theory. Do fields carry energy? If so, where does it come from and can it be depleted? Based on Einstein’s GR, a marble in space will bend the space surrounding it. If that space (or field) carries energy, does that mean the mass of the marble is slowly diminishing? Reply 1 reply @aviaviavi123 3 years ago Hey Elliot, could you do a video about the bracket notation, it would be great! Reply Physics with Elliot · 1 reply @johncampbell9120 1 year ago (edited) Do any particles behave like stem cells in that they become what they will be depending on their destination? Or can a particle pop into existence in earth's oxygen with the purpose of forming oxygen or nitrogen? 3:34 Reply @sushobhanmandal9844 3 years ago Dr. Elliot Schneider, which software/app do you use for preparing these animations/presentations? Reply @sirknightartorias68 3 years ago Thank u. 🥰 Reply @TurtlesWayDown 1 year ago Hi Elliot, great videos! Do you have any on QUANTUM Field Theory? Thanks Reply @qdwkurama 3 years ago I have a question. With respect to the deepest theories of physics, what mathematics must one at least learn to be able to understand virtually all of it. Is Calculus sufficient? Does one need to look at something "more advanced" or "higher" than Calculus? I really want to truly appreciate the science behind these theories, but I don't know where to start. Reply Physics with Elliot · 1 reply @seanmortazyt 3 years ago fantastic Reply @Robinson8491 3 years ago More about the spin 2 particles Fields Einstein equations Reply @philoso377 1 month ago (edited) Page 1:50 v < c didn’t came out of deep research or verification. It is imagination driven dogma but knowledge. Reply @absolute___zero 3 years ago could you please make the video of why does a photon reflection off the mirror doesn't collapse the wave function? I am really lost in this one, help!!! Reply @petergreen5337 1 year ago ❤Thank you Reply @drdca8263 3 years ago Oh! I had never seen the one for the spin 1 particle! Huh! (And also I hadn’t really realized the Klein Gordon was for spin 0. I had seen the Klein Gordon equation, but I don’t think I had seen the corresponding lagrangians for any of these.) So, for the equation of motion for the spin 1 case, is that, for each value of mu, a separate equation, Where, I’d imagine, in the spacelike directions are making the components of, idk whether the field E or what, but, specifying what the components should be, or something like that? I need to be studying for a test, not thinking about this. I hope to read more on this later Reply Physics with Elliot · 2 replies @Treasures_of_Teddy_Miljard 3 years ago Great explanation, thanks! Can you solve my "Mystery of the two race car?" Reply @aidenwinter1117 3 years ago I have a question. In this video I'm seeing 1/2 mv^2 everywhere, but isn't it just an approximation? Wouldn't that deviate from the solution at high speeds? Reply Physics with Elliot · 1 reply @waynelast1685 8 hours ago 15:09 So the KGE is similar to the Euler equations in typical classical mechanics. Reply @v3le 2 years ago How about the quantum entanglements? With the same logic, there must be hidden variables, how 2 particles can communicate with each other instantaneously, right? Reply @kristim1 2 years ago Can you make a video on Dirac equation Reply @charmetroldendk 3 years ago Idk if its for pedagogical reasons, but why use dL for a functional derivative and not \delta L? Reply @michaelhudson6359 3 years ago Very interesting and intriguing Elliot thank you. Maybe Quantum Field Theory makes Quantum Mechanics less weird and more understandable? Reply Physics with Elliot · 1 reply @roberttarquinio1288 2 years ago You mention Maxwell’s equations what about Proca - Proca’s equations Many years ago I combined them in what I call Maxwell-Proca equations 1 Reply @chiragsharma1219 3 years ago (edited) Kinda intricate for a weak undergrad student like me but u explained it quite well.👍 Reply @aidabach 3 years ago thank you Reply @UKsebstack 3 years ago What about Alan Aspects experiment in the 60ies? Reply @meestyouyouestme3753 3 years ago I know it’s just a thought experiment but can you go into more depth what the sun suddenly disappearing would cause? Because that’s a lot of volume to suddenly be empty. Would a vacuum that big cause a pressure difference in an already empty Space? Would different sizes disappearing like a proton vs sun vs black hole vs SMBH cause different sized ripples from spacetime snapping from wrapped to notwarped instantaneously? Reply @scienc-ification2539 1 year ago thank you Reply @nandhakumar3665 1 year ago (edited) Awesome explanation 😊 Relativity : that is time component is not applicable for E = mc2. How come time vanishes Reply 1 reply @aaravkansal4087 3 years ago Thanks YouTube algorithm for showing this channel to me 2 Reply @Brown_Potato 11 months ago Nice video man Reply @jeff5881 2 years ago This is explained in every textbook on QFT except at a faster pace.. When topics get more difficult people just regurgitate or they can explain it with a depth and clarity to help people understand. the latter are very rare. Sorry to say this video is more of the former. I didn't see anything different than if you were to read Peskin or any other book. Reply @darkrozen4110 3 years ago Very cool Reply @tokajileo5928 2 years ago can u explain whay is the so called Higgs branch and Coulomb branch? Reply @mandar.deodhar 3 years ago I haven't understood much. Still, if relativity and quantum field theory is similar concept, why they are said to be not compatible with each other? Reply @Yamahog 2 years ago Well Said. Reply @roberttarquinio1288 2 years ago What about Hamiltonian field theory and equations classical and quantum Reply @charbeleid193 1 year ago PLEASE FULL QFT SERIES I'M BEGGING YOU Reply @anamannu3882 3 years ago Please give us more series Reply @TheDRAGONFLITE 3 years ago What animation software are you using? Reply @BlueSoulTiger 3 years ago Had you thought about saying "del" instead of "dee" for the partials (leaving the latter for the ordinaries)? Just a thought. Reply @IamCaptainDeadpo0l 1 year ago I am trying to live a normal life and this course here is telling me that it is fun-to-be-mental. Reply @barissannan2731 3 years ago Is there such a thing as the speed of gravitaional force? Einteins says it cant be more than the speed of light. but is it at the same speed or how much lower? If only someone cleared that up for me. Reply @andrewbenbow9257 1 year ago Point to function is derived by linear z, but what if z as a function derived from mass is instead a measure of volume. Reply @tdavis0525 6 months ago Great video. Plenty fast Have you any QCD ? Reply @ghadaamer6148 4 months ago I didn't get why do you integrate by parts? what is the need for it at this point? Reply 1 reply @lagrangian143 3 years ago This guy is slowly trying to turn us into theoretical physicists! 1 Reply @modisakgotlabogosi5493 2 years ago Hey guys, I've noticed there are two representations of Einstein's field equation. One has the cosmological constant by the metric tensor as a third term on the left, also the single term on the right get's divided by speed of light raised to 4. This one doesn't have the aforementioned terms....can anyone please explain, why this is the case. Thanks Reply 1 reply @SixtysymbolsSymbols 1 year ago You are my professor bro love you💔 Reply @papetoast 3 years ago I found that the constantly changing background to be a little bit too distracting (and kind of looks like my monitor is dirty). I think it would be better if the background changes less frequently Reply @williambunting803 2 years ago Clever maths for sure but you haven’t shown how that translates in to actual particles are stationary, moving slowly and or spinning. These waves are 4D in 4D space where wave energy would be sloshing around in every spherical direction. Waves would be being cancelled out by coincident waves with particles popping out of existence with no conservation of their energy or reality. What does the translation of wave energy into actual particles look like, and how would this define a Proton with Quarks gyrating wildly and other gluons and bosons interacting. And further how do waves deflect off one another rather than passing through one another? I’m more interested in the narrative rather than the maths. Reply @mrcleanisin 2 years ago Your mathematics to explain physics is intriguing, but can it be applied to my stick puzzle? I am suggesting that a stick is faster than the speed of light. I have had this idea since the 70's and I have presented it to many people, but of course I have no way to actually conduct the experiment. We know that light travels at 186,000 miles per second and that the moon is 240,000 miles from earth, and it would take 1.3 seconds for light to reach the moon. If a bell was placed on the moon and could be rung by a photo sensor on the moon activated by someone firing a laser beam at it from earth, it would ring 1.3 seconds from the button being pushed. Now if it were possible to extend a solid object from the earth to the moon and that object was an inch away from the bell and the earth end was pushed, how long would it take to ring the bell? [Note: On 2-2-2023 I am adding this clarification to this puzzle because all the other comments to questions similar to mine focus on the stick traveling at some ridiculous speed that causes it to explode or whatever. My stick is not moving fast at all. It's taking 1 second to travel 1 inch, but it still rings the bell before the laser which takes 1.3 seconds.] In the experiment I used wires to run to my simulated moon because I don't have a photo sensor setup. Note: light and electricity both travel at the same speed. Reply 3 replies @toymaker3474 3 years ago so why did einstein in the end ( in a letter to lorentz) concede their has to be an aether? can u even define a field? Reply @jeeram77 3 years ago if the sun pulls the earth, rather both attract each other, the example of the rope is the opposite (as if both repel each other and the rope is what keeps it in place). if they attract each other, when the sun disappears, inertia also disappears.? Reply @vincentzevecke4578 3 years ago I want more about Lagrangian Dirac equation Reply @user_2793 3 years ago Mathematicians : Wait what 157 Reply 12 replies @condinigenie3006 2 years ago Could someone try explaining how this connects to the fact that this theory only describes particles with spin 0? Would appreciate it :) Reply @probablyshadman 3 years ago Watch "Physics with Elliot", he is the master of us all - Pierre-Simon Euler 2 Reply @Prof.LamMath 3 years ago love it Reply @vannanilavan2777 3 years ago Can you please do a playlist explaining about Newtonian mechanics 1 Reply Physics with Elliot · 1 reply @physdb 3 years ago It would be even more complete if you can continue to irreps of field under Poincare' symmtry. Reply @mjackstewart 3 years ago Do I want to learn more? Yes, please! Reply @messapatingy 2 years ago When I was at school, the dt came after the integrand. You put it after the integration symbol. Reply @thelegendofsheboo7048 3 years ago A question always baffled me is that do charge particles emits field (electric field ) out of them or does the electric field exist everywhere in space and the existing of a charged particle causes the field to change values around the particle, Reply Physics with Elliot · 1 reply @adeyeyeisaac7113 3 years ago Please more Reply @ezeldintayel6247 2 years ago ًAlthough I love physics very much , I didn’t understand a word . I hope I understand everything in this video one day 1 Reply @gmtoomey 2 years ago You talked about field theory without explaining what a field is. Temperature is a field. Gravity is a field. You need to explain why, Reply @KW-12 3 years ago I wonder how one can model a contiuum media using field theory. Its pretty interesting. Reply @barissannan2731 3 years ago (edited) It's great. Reply @FigmentHF 1 year ago I think more people who are creative and smart, but not technical and mathematical, should try to get a low resolution intuition about this stuff, it’s as though the literal fabric of reality is only supposed to be understood by a very specific kind of intelligence, Reply @nevokrien95 3 years ago i think calling the metric tensor (what I am guessing you are refering to based on common notation) a gravitational field is very missleading Reply @firstdrx1435 3 years ago Please make videp for spinner field!! Reply @aidenwinter1117 3 years ago "You write down an L, and take it" Oof this burn hurt the version of me before I discovered this channel Reply @empireempire3545 3 years ago Ehh, the problem with formulating everything with Lagrangians is that they are nice as long as you want to work with analytic methods, but if you want to do numerical simulations, they are imho very unwieldy. Hamiltonian formulation is not only much easier to code but also MUCH more intuitive imo. Reply @1134_BAVANESH 3 years ago coincidentally,today is Julian schwinger's birth anniversary.he was one of the important people who led to qft's growth 1 Reply @wulphstein 1 year ago What is spacetime made of? If we knew that, we could dig deeper into the laws of physics. Reply @tejasshetty519 1 year ago If the earth stays and the sun disappears your explaination of the sun being visible for the next 8 mins is right, but not if the earth gets slungshot because our eyes are actively registers the rats that have already travelled the distance and since rays travel everywhere it doesn't mean that what ever we observing currently is the whole truth a different observer 1000 miles away would see the sun smaller at the same time as you see it bigger because the rays are everywhere all at once if you understand what i mean so because of that if the earth gets slung shot we would instantly observer because the sun's the one emitting the light we aren't the ones absorbing it it's just happens so the earth was in the path of the rays of the sun which allowed us to observer its state from that distance, basically the image of the sun at any distance always exists Reply @NegativeAccelerate 1 year ago Bruh why are mathematical fields in abstract algebra called fields. Theres too much overlapping language. Reply @charbeleid193 1 year ago You, my man, are doing god's work Reply @martynewport 1 year ago excellent. Some disagree on GR Reply @JgvnkhgbbKhrfhutfhk 3 years ago Great content, but allow me to digress a bit: I thought my screen were dirty because of your background so I used alcohol to clean my screen, then I realized that had nothing to do with my screen. Reply Physics with Elliot · 1 reply @williamwalker39 1 year ago No, Gravity acts instantaneously and if the sun where to disappear, then the effect would be felt instantaneously at the earth. Analysis of the gravitational fields generated by an oscillating mass show that the fields propagate instantaneously near the source and reduce to the speed of light in the farfield at about one wavelength. The same is true for electromagnetic fields generate by an oscillating charge. Since the earth is in the farfield of light from the sun, then if the sun disappeared, then the effects would propagate at the speed of light, resulting in about 8 sec delay. But since we are in nearfield of the gravitational effects of the sun, then if the sun disappeared, the effects would be felt on earth instantaneously. The instantaneous gravitational nearfield behavior was proved experimentally by Simone LaPlace in the late 1700s, where he showed that the stability of the orbits of the planets would not be stable unless the speed of gravity is infinite. in the farfield, LIGO recently measured that farfield Gravity waves arrived at the speed of light. For electromagnetic fields, the propagation of electromagnetic pulses in the nearfield have been shown to be instantaneous, and in the farfield they have been observed to propagate at speed c. This propagation behavior has been observed theoretically using Gravitational theory and Electromagnetic theory. See the links below for details. Since Relativity assumes light only propagates at speed c, then it is wrong. A derivation of Relativity using instantaneous nearfield light, yields Galilean Relativity. This can easily be seen by inserting c=infinity into the Lorentz Transform, yielding the Galilean Transform. So a moving object observed with farfield speed c light will yield Relativistic effects. But if the frequency is reduced, such that instantaneous nearfield light is used, then no Relativistic effects will be observed. Since time and space are real then it should not depend on the frequency of light used to observe its effects. So Relativistic effects are not real and must be a optical illusion. So the correct theory of Relativity is Galilean Relativity, where time is the same for all inertial frames, hence time is absolute, only the present exists, the past is gone, and the future is yet to be. Since General Relativity is based on Special Relativity, then it has the same problem. A better theory of Gravity is Gravitoelectromagnetism which assumes gravity can be mathematically described by 4 Maxwell equations, similar to to those of electromagnetic theory. It is well known that General Relativity reduces to Gravitoelectromagnetism for weak fields, which is all that we observe. Using this theory, analysis of an oscillating mass yields a wave equation set equal to a source term. Analysis of this equation shows that the phase speed, group speed, and information speed are instantaneous in the nearfield and reduce to the speed of light in the farfield. This theory then accounts for all the observed gravitational effects including instantaneous nearfield and the speed of light farfield. The main difference is that this theory is a field theory, and not a geometrical theory like General Relativity. Because it is a field theory, Gravity can be then be quantized as the Graviton. Lastly it should be mentioned that this research shows that the Pilot Wave interpretation of Quantum Mechanics can no longer be criticized for requiring instantaneous interaction of the pilot wave, thereby violating Relativity. It should also be noted that nearfield electromagnetic fields can be explained by quantum mechanics using the Pilot Wave interpretation of quantum mechanics and the Heisenberg uncertainty principle (HUP), where Δx and Δp are interpreted as averages, and not the uncertainty in the values as in other interpretations of quantum mechanics. So in HUP: Δx Δp = h, where Δp=mΔv, thus HUP becomes: Δx Δv = h/m. In the nearfield where the field is created, Δx=0, therefore Δv=infinity. In the farfield, HUP: Δx Δp = h, where p = h/λ. HUP then becomes: Δx h/λ = h, or Δx=λ. Also in the farfield HUP becomes: λmΔv=h, thus Δv=h/(mλ). Since p=h/λ, then Δv=p/m. Also since p=mc, then Δv=c. So in summary, in the nearfield Δv=infinity, and in the farfield Δv=c, where Δv is the average velocity of the photon according to Pilot Wave theory. Consequently the Pilot wave interpretation should become the preferred interpretation of Quantum Mechanics. It should also be noted that this argument can be applied to all fields, including the graviton. Hence all fields should exhibit instantaneous nearfield and speed c farfield behavior, and this can explain the non-local effects observed in quantum entangled particles. References: Nearfield electromagnetic pulse experiment paper proving information propagates instantaneously: https://www.techrxiv.org/doi/full/10.36227/techrxiv.170862178.82175798/v1 YouTube presentation of above arguments: https://www.youtube.com/watch?v=sePdJ7vSQvQ&t=0s More extensive paper for the above arguments: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: http://vixra.org/abs/2309.0145 Dr. William Walker - PhD ETH Zurich, 1997 Reply @lex4478 2 years ago Plz make more Reply @waynelast1685 1 year ago But why are particles represented as fields? Is this just an "averaging effect" where are particles are actually strings? Reply 8 replies @RogerFederer-ip9er 1 year ago thnaks 1 Reply @jllshih137 1 year ago We should be careful in using the term of particle field. Field is not produced or due to particle. In quantum field theory, particles are excitation of fields. Particles can be created and annihilated by field operators. Reply @peterjones7886 1 year ago when you teach on a blackboard with chalk while you're writing the next line students have time to grasp what was going on and you do not talk too. Here with software you constantly replace any written line withe next line and you constantly talk sppedy to follow the machine software. It is a fact many you tube lecturer do not pay attention. soon they become obsolete and some people try faster, more animated and more colourful software to occupy their position. Where is paedagogy? Reply @JamesHawkeYouTube 3 years ago Mathematical concepts that describe nature should never be confused with actual nature or real science. Reply @JackMroczkowski 9 months ago This video was well put togther, but fell apart in many places with the rushed narrative in many places. This is a common problem with people who are very familiar with their subject, but don't know when to slow down at critical places. Sorry for the negative part of my commentary... but you do need that feedback. Retired physicist Reply @scottessex952 3 years ago their is only 1 field and its electromagnetic universe.. gravity is tbe radiation from the dipole of an electro magnet and it creates density... any questions Reply @kx4532 3 years ago Got to sign up :P Too expensive. Reply @sidexside1439 2 years ago I like the contents, but I HATE the dynamic background. Those moving dots are distracting. Reply @IN2FPA 2 years ago Perhaps Gravity is not a force at all. Is it possible the phenomenon is caused by Neutrino 'friction' ? Reply @ravigautam8685 2 years ago Registered in gravitational field? Reply @jkli6031 3 years ago I thought it was a field theory in math before watching the video. Apparently it is the field theory in physics Reply @chikokolat5989 2 years ago I regret not paying more attention to my calc classes, it's where the magic happens Reply @garyliu6589 3 months ago Forget about the math...describe the world model qualitatively first...otherwise you don really understand the math... Reply @drmathochist06 3 years ago Do the little "dust specks" in the backgrounds drive anyone else crazy? I keep thinking my screen is dirty and can't pay any attention to the content! Reply @DeepLyricist 3 years ago This video is like physics ASMR 2 Reply @TyroPirate 2 years ago What exactly is "information"? Reply @schitlipz 1 year ago How is quantum theory more precise than general relativity? I hear this everywhere. Sometimes a number or two are attached. Never, however, has it been explained how any one is one iota more accurate than the other at anything. It all boils down to your calculation and how many significant digits you have, not the framework within you are working. Reply 1 reply @irinaratushinskaja7900 3 years ago Answer: YES! Reply @johnstfleur3987 2 years ago YES. Reply @leontancfa 3 years ago It's so funny that Einstein cartoon pointing to the field theory formula!!! Reply @Mahito22222 1 year ago Anyone else still have no clue? 10 Reply 4 replies @vinciousmacabre8193 4 months ago Where did the e go? Reply @starryfolks 3 years ago Yesssss Reply @bharath__100 1 year ago We want dirac equation!!! Reply @Yahya-t8j 8 months ago F = ma is true wth did you try to say it us wrong bro go learn some classical mechanics then talk about fields Reply @RichardAlsenz 2 years ago The energy field is where rationality takes place in physics, In mathematics, axiom generates nonscientific delusion, for a point has no part, is a Euclidean absurdity that began with this element of irrational mathematical deduction. No human has observed a point; only irrational mathematicians have postulated the conception in their minds of such irrationality. The scientific method requires human observation, yet mathematicians only require someone to postulate. Irrational Mathematics is not consistent with the Scientific method, and the physicists using irrational mathematics are not scientists, Pi is just such and absurdity for no one is capable of adding sumations for ever (Mother Nature would not have time to calculate the first irrational number) the infamous sums that never cease. There is no such thing as space. If you doubt space's rationality, demonstrate what you use to measure space. In physics, the electric field can measure time in the Doppler Shifiting of the electromagnetic field; space has nothing to do with the Doppler Shifiting. The variance in energy fields happens with respect to timef. The only geometry which contains time is Planck's geometry E=hv, yet it alone forms a geometry. When Einstein and Debroglie convinced Planck his electric energy was equal to Planck's energy, the stupidity of Euclid was added inappropriate since Euclid maintained a point has no part. Gauss to Bessel Goettingen 27 January 1829 _ …There is another topic, one which for me is almost 40 years old, that I have thought about from time to time in isolated free hours, I mean the first principles of geometry; I don’t know if I have ever spoken to you about this. Also in this I have further consolidated many things, and my conviction that we cannot completely establish geometry a prioir has become stronger. In the meantime it will likely be quite (space) is missing that complete conviction of necessity (thus of absolute truth) a while before I get around to preparing my very extensive investigations on this for publication; perhaps this will never happen in my lifetime since I fear the cry of the Bocetians if I were to voice my views. It is strange, however, that except for the well known gaps in Euclid’s geometry which till now one has tried in vain to fill, and never will fill, there are other defects in the subject that to my knowledge no one has touched, and to resolve these is by no means easy (but possible). Reply @GreenDayFanMT 2 years ago I would like to have seen metric units. Reply @jonathanhockey9943 2 years ago I really don't like the constant spiel about how predictive it is, Ptolemy's epicycles were very accurately predictive, but it was a terrible theory. I think there is some value in the reality that is being pointed to with these things, but still the fact is that QED is still not a complete theory, it has no good explanation of what is actually happening and is all built around assuming that both relativity and quantum theory are correct and finding the best way to reconcile them and meet somewhere in the middle. But, its much more likely one or both of those theories are incorrect in a true understanding, so reconciling them could be akin to Ptolemy's epicyles reconciling with the geocentric view of the universe. Reply @eugenprinz5367 5 months ago I am now a medical student After seeing this I decide to go back to physics major Reply @ralphacosta4726 3 years ago I think i need to go about ten steps back in math to understand even this simple explanation. Thanks for trying, though. Reply @marianaldenhoevel7240 1 year ago Whenever I watch Physicists do Math it leaves me feeling a little dirty. I trust them as much as I do magicians telling me "this is a perfectly normal piece of rope". Love it, though. Great show :-). Thank you. Reply @billy-cg1qq 3 years ago Me watching this at 2AM: yes, I definitely understand everything 🙂 Reply @Starmystik 1 year ago (edited) I find the topic so interesting and want to learn more about it, but I watch videos like this and feel so dumb because I just don't understand the mathematics behind it with all of the symbols. :( Reply @lowersaxon 1 year ago (edited) Completely illogical. That light takes time (8 min) doesnt mean anything. Do you think nothing happens as long as its dark? Btw, fields are constructs of theory to describe something, there are no „fields“. Nothing is changed or added to Newton by the introduction of the word „ field“. The central problem of how gravity is ‚communicated‘ remains. By „gravitons“? By a field of gravitons? Find the mysterious gravitons! The very „impressive“ math of Lagrange, Hamilton etc. are descriptions of what you think actually happens, no more, no less. Thanks for the math lesson. But the underlying field theory is speculation so far. Reply 2 replies @egay86292 3 years ago fields do not exist in an unexcited state. if there was no mass in the universe there would be no gravitational field, would there? physics is having a bad acid trip. Reply @farfa2937 3 years ago I've seen a lot of strange symbols, but this is the first time I see the "emoji not found" symbol used if physics. Reply @claragabbert-fh1uu 1 year ago Be careful to understand that a field theory combined the separate aspects of the reality of source for e behavior (General Relativity) and the APPEARANCE (NOT the reality) of how those forces SEEM (appear) to propagate through the field (special relativity, which is an APPEARANCE of real, but is NOT itself real). Space-time of field DO NOT, canNOT warp! They can only seem to watp because force propagates so as to affect mass trajectory relative to our expectation, that makes it SEEM like space has warped. (ie., a light ray bends rather than proceeding straight as else expected.) Reply @LuisCisneros-wh7lb 1 year ago lamento decirles que aparece un campo eléctrico 1-dimensional ( recta ) y uno gravitatorio cuando se genera una matemática 2-dimensional y se crean puntos ,es decir que hablar de campos sin especificar la matemática de base es algo estúpido Reply @NickUSHOR 3 years ago But what about the poppy fields ? Reply @agrajyadav2951 3 years ago 11:12 lost from there Reply @claragabbert-fh1uu 1 year ago The "principle of least action" is NOT predictively absolute; it us statistical, and therefore probable of a population of many separate observations. How should a particle know the path of least action? From where the particle IS, it will go as it is immediately compelled to go. If that is not the path of least action, then it will compensate by suffering losses in it's REAL path. The principle of least action simulates the ideal path found among a population of observations of similar systems. Reply @jonathanjollimore4794 3 years ago I understand all stuff without the math to back it up visuals how it should work in my mind Reply @raylopez99 2 years ago Time and space are variables? What? I thought space and time are relative, and don't really exist as independent variables? Seems quantum field theory via the Kline-Gordon equation is flawed if it relies on classical constructs. Or it's needlessly complex. What is needed is a birds' eye view that is outside the Hamiltonian local worldview. I could probably solve this if there was a prize associated with it, but I rather be a landlord and gatekeeper. No money in physics and you can't patent a 'discovery' or 'law', one reason nobody interested in money cares about physics. Reply @DellHell1 3 years ago Some things are gonna take longer than 20 minutes. 2 Reply @eulefranz944 3 years ago Where were you two years ago? :'( Reply @xshotgunmessage 1 year ago Einstein's field equations are NOT classical Reply @charlesdrury9712 6 months ago I don’t think my mind is wired for such complex information but if I don’t try I’ll never learn anything Reply @rodrigoappendino 3 years ago (edited) That box to represent de d'Alambert operator is the worst thing I ever saw in mathematics. It looks like it's missing, like the computer couldn't recognize the character. Reply @omarahmed3364 3 years ago Good Reply @jnhrtmn 2 years ago Describing what you see it do with math is not an understanding. Imagine if medicine described symptoms with math and only derived cause from that math. Every time you use a cross product, you are making the numbers perpendicular for no physical reason, and you leave reality at that point. The gyroscopic effect math perfectly describes, but misses the true cause. It also begins and ends with a mnemonic device (right-hand rule, conservation law). Maxwell's equations use a cross product, so no one cares 'why' they are perpendicular. Light speed is 'declared' to be constant relative to YOUR EYES (even though it don't look constant), then math is used to CHANGE the numbers that need to change to make that true for you and all the other following believers. Changing the numbers using the transform equations creates a fork in the road, so there is another fork ignored, it didn't disappear. Time is a sequence marker in math, and it is the ability to remember and anticipate in the brain, and it is changed happily to create relative time. Don't run to GPS. Send a pendulum into space -no clock. This is all a crowd seeing what they want to see. Reply 1 reply @active285 1 year ago Always funny to me how Americans pronounce the name Minkowski ^_^. Thanks for sharing this nice video! Reply @FarmerJud 3 years ago You have officially breached through the average recommendation barrier. Enjoy your passive income and don't forget those who brought you here. Reply @gaminglegend6980 1 year ago Einstein in the thumb nail looked so cute😂😂😂 Reply @tateallen9972 1 year ago Oh, I clicked on this thinking it was about the algebraic structures. Still a cool video though Reply @evenaicantfigurethisout 1 year ago (edited) It all feels so hacky. After Lagrange that is. I still don't know why Lagrange did what he did. Maybe just to flex. Cuz that's what they used to do back then. Oh look lemme reformulate newton with variational calculus. Just because I can. After that we fudge it with phi voila out comes this amorphous thing. Let's make it sound cool and call it a "field". Ok let's fudge it sum more so it gets quantized... Reply @rynebozzell 1 year ago Albert Einstein, Niels Bohr, Stephen Hawking, Oppenheimer, the ostrich: Which one is smarter? Reply @MagnificentCreature 5 months ago Wait what? This isn’t field theory Reply @kainajones9393 10 months ago Yes. Field theory in 20 minutes for those who have taken calculus. 2 Reply @schmetterling4477 3 years ago If you are interested in more then you will have to read 1000 page textbooks. :-) Reply @JeromeCallas 1 year ago I'm gonna do u the good of telling u why I can't hang: u called Newton's interpretation of his share of facts "nonsense", as if u with the same facts could've done better. Look up the words "intellectual" and "hubris", then have a think. Reply @kalaiselvan6907 3 years ago ❤️❤️❤️❤️ Reply @beaconeersofthesevenmaps3467 3 years ago No science video should use Imperial system in the explanation Reply @andrewbenbow9257 1 year ago Why is this s linear equation, Reply @ROForeverMan 1 year ago Consciousness is all there is. 1 Reply @didodido883 5 months ago 11:22 definately no "M" here 😏 Reply @insainsin 1 year ago Einstein notation makes it look much prettier Reply @dcissignedon 3 years ago Need a summary? There is no action at a distance. Reply @bernaridho 2 years ago Change all greek letters with name, please. It is disgusting to learn something the old way with all greek letters. Hello youtube educators. Reply @roselynjrserrano970 1 year ago Understand. Don't memorize the lecture. Reply @ceryngolan3673 2 years ago bro i am going highschool i dont know this shit i just want a answer for the question(didnt finishes yet maybe there is a answer) still watching the video tho Reply @andrewbenbow9257 1 year ago Ok, derived function equating a sum zero. Reply @PhilMoskowitz 1 year ago Einstein teaching the statistical interpretation of the Schrodinger wave. That is oh so wrong. Reply @masternobody1896 3 years ago Thank you but I dont get it Reply Physics with Elliot · 3 replies @buyaport 3 years ago Should be field "doctrine", not "theory". Reply @relaxingpiano855 3 years ago wow Reply @The_Quaalude 2 years ago I don't need to know any of this but here I am... Reply @ColbyFernandez 1 year ago Me confused when he doesn't mention commutative division rings. Reply @crazyoldhippieguy 3 years ago Please please do. Reply @vinnyhorapeti2461 3 years ago Please watch gary yourofsky's speech on veganism on YouTube and end animal cruelty also check out earthling Ed, Dr michel klaper, Dr neil Barnard for more insight and details 💗💖💓💕💞 1 Reply @humanaugmented2525 2 years ago Do symbols Reply @ilteriskagan7305 2 years ago Please add turkish subtitles please Reply @eustacenjeru7225 1 year ago Please introduce MPESA payment system for Kenyans viewers to contribute Reply @SampleroftheMultiverse 1 year ago “U” Shape Waves https://youtu.be/wrBsqiE0vG4?si=waT8lY2iX-wJdjO3 Thanks for your informative and well produced video. You and your viewers might find the quantum-like analog interesting and useful. I have been trying to describe the “U” shape wave that is produced in my amateur science mechanical model in the video link. I hear if you over-lap all the waves together using Fournier Transforms, it may make a “U” shape or square wave. Can this be correct representation Feynman Path Integrals? In the model, “U” shape waves are produced as the loading increases and just before the wave-like function shifts to the next higher energy level. Your viewers might be interested in seeing the load verse deflection graph in white paper found elsewhere on my YouTube channel. Actually replicating it with a sheet of clear folder plastic and tape and seeing it first hand is worth the effort. 13:07 Reply @Gringohuevon 3 years ago Ahh sweet memories Reply @SampleroftheMultiverse 1 year ago Thanks for your interesting article. My intuition said there is something important about this mechanical effect. This model shows how a field represented by a sheet of elastic material under the right initial conditions naturally form quantized energy levels. From there it was easy to form very stable three dimensional structures using a very minimal amount of material. (similar to the way engineers built large light weight space structures) https://youtu.be/wrBsqiE0vG4?si=waT8lY2iX-wJdjO3 You and your followers might find the quantum-like analog useful in visualize nature properties of fields. I have been trying to describe the “U” shape wave that is produced in my amateur science mechanical model in the video link. I hear if you over-lap all the waves together using Fournier Transforms, it may make a “U” shape or square wave. Can this be correct representation Feynman Path Integrals? In the model, “U” shape waves are produced as the loading increases and just before the wave-like function shifts to the next higher energy level. Your followers might be interested in seeing the load verse deflection graph in white paper found elsewhere on my YouTube channel. Actually replicating it with a sheet of clear folder plastic and tape and seeing it first hand is worth the effort. Reply @mallikavilas7188 1 year ago Need time versus einstine Reply @JesusChrist-d2k 2 years ago "L'S RESURRECTION IS NOW ASSURED." Reply @noahwilliams9231 3 years ago If there is anyway I could help just message me through this comment and I would be very glad to Reply @snekmeseht 2 years ago It took seven minutes before I shot myself. Reply @davidwilkie9551 2 years ago Good work, ie "it has to be said." Newton.. "total nonsense"..? If you look carefully at "Field Theory" it is all non sense because the topic is projecting properties onto a possible consequence of intentional action. If the actual cause-effect phenomena in/of pure-math projection-drawing, ie cause-effect Relativity in the Absolute Zero-infinity reference-framing of relative-timing logarithmic time-timing ratio-rates, then attempted Theoretical reasoning proposing tests that isolate empirical laws in "discretised" Reductionist pictures of cross-sectional interpretations, are by this self-defining observable of Absolute Zero-infinity Unity-connection, impossible fantasy. ("Science advances one funeral at a time", "Much ado about Nothing", or, THIS is why BBT = Absolute bs!) Note that this is Critique not of my Opinion. Absolute Zero Relativity => Agnostic neutrality reference-framing. Reply 1 reply @martinnyberg9295 3 years ago 5:49 Who taught you to draw graphs and coordinate systems!? You should get your money back. The arrows go in the direction of INCREASING values, not both ways! 😏😁👍🏻 Reply 1 reply @tomekgwozdz6037 1 year ago Rings with all nonzero elemnts invertable go brrrrrrrr Reply @omarahmed3364 3 years ago Ok Reply @maddscientist1050 3 years ago lol use m as a constant, completely wrong equation Reply @robertadams3630 1 year ago Hardest course I ever took😎 Reply @vincentzevecke4578 3 years ago Elliott, what about giving you Five dollars a month, is this ok Reply Physics with Elliot · 1 reply @chucky428 1 year ago great remedy of insomnia Reply @erikeriknorman 2 years ago Chatbot does it in 20 seconds, js Reply @juantovar4681 1 year ago pensé que sería de álgebra 😔 Reply @sakibesp9910 6 months ago 🥱 Reply @NisseOhlsen 1 year ago "Generelativity"? New Kid on the Block ? Reply @zorand67 3 years ago Sorry, but you are talking nonsense. "If Sun would suddenly ... vanish". That is physically impossible. For sane people, that is also logical, normal. Energy cannot "come out of nothing", nor "vanish". Reply 2 replies @AlvaroZevallosDkP88 3 years ago yeS Reply @SerikPoliasc 8 months ago Lopez Jennifer Robinson Kevin Harris Betty Reply @trewq398 3 years ago show us the ugly details <3 Reply @pakistani7454 3 years ago V wanna know upload videos quickly plz Reply @RydenLovesJuiceWrld 6 months ago ❤💗🥰🤝😇 Reply @jackobrien4638 1 year ago I guess I’m the only one still lost? Reply 1 reply @Ryterick 2 years ago Word salad Reply @มดแดง-ฃ3ข 1 year ago รถทำให้ทุกอย่างง่ายขึ้นไหมไม่เลย Reply @goldnarms435 2 years ago "fundamentals"🤣🤣🤣 Reply @mohammedseid1987 1 year ago 0-0 Reply @JohnSmith-mk4nf 2 years ago Space1999 !!!! Reply @rustyspottedcat8885 2 years ago Jesus .... Reply @YNVNEone 1 year ago .......?!?! Reply @chrisl442 2 years ago In California, any field has now been declared as being racist. Reply @claragabbert-fh1uu 1 year ago Yrw NEED to varefully, judiciously assure that EACH step if a derivation ACCURATELY MODELS REALITY, rather than merely representing a handy way to solve your problem. God cares NOT for solution BECAUSE God's definitions assemble AS the solution. Reply @ca24tamie30 6 months ago Our universe expands faster than the speed of light. Reply @gekkkoincroek 1 year ago Lovely video 4.0 stars