Quantum Field Theory: What is a particle?

Quantum Field Theory: What is a particle? 608,312 viewsFeb 7, 2021 Physics Explained 120K subscribers This video provides a very basic introduction to the idea that a particle is an excitation of a relativistic quantum field. The video begins by looking at Hooke's Law and the mathematics of simple harmonic motion, before moving on to explore the mathematics of waves and a possible modification of the wave equation. The quantum harmonic oscillator is discussed, as well as zero point energy. The basic definition of scalar and vector fields are discussed, along with the concept of a relativistic field. Finally, by combining the ideas of quantum mechanics with the concept of a relativistic field, it is shown that a particle is the smallest possible vibration of a quantum field. This presentation is inspired by the following sources of information: Quantum Field Theory in a Nutshell - Anthony Zee Of Particular Significance (Blog) - Matt Strassler Quantum Field Theory - Mark Srednicki Quantum Field Theory for the gifted Amateur - Stephen Blundell and Tom Lancaster The Feynman Lectures - Richard Feynman You can help support this channel via the Physics Explained Patreon account: https://www.patreon.com/physicsexplained You can follow me on instagram: https://www.instagram.com/physicsexpl... You can follow me on Twitter: https://twitter.com/PhysicsExplain1 Chapters Strategy 0:51 Hooke's Law 1:18 A bit of theory... 3:11 SHM Displacement Function 4:36 Time period and frequency 7:12 Energy of an oscillator 7:58 1,662 Comments rongmaw lin Add a comment... Jacobo Blanco Jacobo Blanco 10 months ago PhD in Particle Physics here. This was probably the most cogent presentation of this topic I’ve ever seen. You never lose sight of the question you’re trying to answer or get bogged down in details. Brilliant. 298 Physics Explained Hadi Farhan Hadi Farhan 1 year ago (edited) Having a quantum mechanics playlist with this level of rigor for math (not to overwhelming but not too little) would be freaking amazing. Some youtube videos just skip some of the math because they are worried that the viewers gonna be afraid. We have enough videos like that. Some rigor of math like you did, would be extremely appreciated. Thank you again and looking forward for your future videos 311 Physics Explained UnPureMaddness UnPureMaddness 1 year ago This is insanely well done. I never felt so satisfied after a physics video. 35 Physics Explained Emmett Griner Emmett Griner 1 year ago That was more than a little bit thrilling. You integrated a few hundred years of physics in one seamless, beginning-to-end, worked-out example and presented it all in about half an hour. Working through the specifics on my own will require several days (probably more than that), but when I'm done I will have in place the beginnings of a foundation to build on going forward. Thanks much and please keep these kinds of videos coming. 312 Physics Explained Ativ Joshi Ativ Joshi 8 months ago This video is an absolute gem. It does probably the most important thing in education: connecting the dots, and it does so very neatly and in an accessible way. And this whole channel is full of such beautiful videos. This is a top-notch 12th grade classroom material. 25 Physics Explained Mazahir Anwar Mazahir Anwar 1 year ago Wonderful, my entire graduation knowledge on physics just covered in 37 minutes. Hats off to creator of the video. Beautifully explained with equations and illustrations 142 Physics Explained David David 1 year ago (edited) Excellent presentation. I like how math is used to develop concepts, but also how the math is not overwhelmingly complicated. The graphics, animations, and even text colors used also help to make things clear and are not distracting. Another interesting take on what a particle is is Quanta Magazine's article "What Is a Particle." The article supports the video's closing quote by Pauli. 63 Physics Explained Karan Gupta Karan Gupta 1 year ago I love the fact that you started from the most basic thing there was and built upon it as the video progressed.... It encourages people to keep up with the concepts as they get more complex. 👍 22 Physics Explained VFAHSN VFAHSN 8 months ago Man. This video is a gem. And I trully believe it. It should be used in schools and I'm not talking about just university. Wave equation... you managed to give me something more even if I'm an energy engineer and I've seen a lot of it. Thank you. 6 Physics Explained Cole Coughlin Cole Coughlin 1 year ago This was an awesome overview that points out some wild implications of our theories. I have never had any of these concepts explained to me in such a concise way and I'm almost done my undergraduate. I appreciate it! 145 Physics Explained Rasmus Madsen Rasmus Madsen 1 year ago Honestly your videos are so good. I like that you also include the algebra and formulas, and I haven't really seen anybody explain something like this in this way. Keep up the good work! 16 Physics Explained pipertripp pipertripp 1 year ago A fabulous way to spend 37 minutes on a Sunday morning. Thoroughly enjoyed it and learned a lot. Thanks! 92 Physics Explained H P H P 1 year ago This is an excellent presentation. Recommended. 194 Physics Explained DoS - Domain of Science DoS - Domain of Science 1 year ago Instant subscribe! This is really cool. I very much enjoy your use of colours to highlight the different things that are related to each other. It helps to visually parse the information. Great video! 351 Physics Explained George Lafner George Lafner 1 year ago I LOVE the mathematical analysis of these topics. This is good revision as well as an introduction to uni physics and beyond. Thank you for making these!! 7 Physics Explained Kendall Knight Kendall Knight 1 year ago This is a great video. Going from SHM to relativistic fields seems disconnected at first but then watching the math go through made a lot of sense 21 Physics Explained J. J. Thompson J. J. Thompson 7 months ago This is one of the best physics videos I have ever seen. Perfectly explained and at the end, you are left with a hunger learn more. 10/10 easy 2 Travis May Travis May 1 year ago This is what people need. This entire channel. 342 Physics Explained ps200306 ps200306 1 year ago (edited) Delighted to see another outstanding video. I've studied undergrad physics, and this definitely joins a lot of dots for me. I'm looking forward to sitting down several more times with this video and working through all the equations for myself. That's the joy of this particular medium -- I'm glad you keep things at a pace where the concepts can be imparted fairly quickly and the details mulled over later. It's got real pedagogical value and, unlike "pop science" channels which might be more instantly entertaining, I've stored all your videos away for constant referencing. I'd definitely also recommend them to anyone studying or trying to understand physics more formally. I think they might finally give me the courage to open a book that's been sitting on the shelf for far too long -- Quantum Field Theory for the Gifted Amateur (Lancaster & Blundell)... edit: which I've just noticed you reference in the video description! Keep the vids coming, they are very much appreciated. 11 Pierre T Pierre T 10 months ago Hello I think there are 2 problems with the math: - 21:58 : why vy isn't A*w*sin(kx-wt) since (cos(a))'=-sin(a) and (kx-wt)'=-w . In anycase, this isn't a big problem because it is squared just after so the minus simplify - 24:10 : why did the wavelenght disappear in the 2nd expression of E ? . You used this expression for the energy of a quantum wave later so it may be a bigger problem I thank you very much for this video. I am doing the math with you all along the video and it's super helpful to have this kind of video on yt. 2 J-rho J-rho 1 year ago This was well done! The mathematics took me a bit to understand, but reasonings were well explained. It's beautifully mind-blowing. So glad this video was made! 10 112BALAGE112 112BALAGE112 1 year ago This is the best physics lecture I've ever seen. 40 Physics Explained Tony Stone Tony Stone 6 days ago I love the Pauli quote to the effect that progress in quantum physics is measured by “the ability to misunderstand but at a deeper level.” I taught intellectual history at the college and grad school level specializing in the Enlightenment and the Scientific Revolution. Back then, the field was rather unspecified as to academic training to teach such an inherently multidisciplinary subject. So I did a PhD in European history and completed a second one in Physics at Cal Tech. Take that, C.P. Snow! By the way, I not only had classes with Richard Feynman, he supervised my dissertation. But a whole book deserves to be written on that extraordinary experience. Off course, despite the scientific education, I was still a history professor teaching history students at the graduate and undergraduate level. As you can imagine, the level of fear and trepidation upon watching the unfolding mathematics among history students was positively palpable! This was not the reason they chose to study history! Needless to say, I exposed them to a great many mathematical narratives as here but never required them to become mathematicians or physicists. However it was fascinating to witness the degree to which they became fascinated by the processes. They were particularly delighted to learn that a particle was an oscillation rather than an M&M. Some thought it might make a great pick up line. 1 Physics Explained Joe Marz Joe Marz 1 year ago This is how science should be explained in all universities: Clearly and concisely. Congratulations! 48 Andrey Lebedenko Andrey Lebedenko 10 months ago 7:49 No, it is not easy to measure the spring constant without taking into account the same elements of the equation, meaning that we will reuse the same data twice -- for calculation of the constant and later to prove that this formula is right. 35:57 In essence we declare the particle as the smallest vibration of a quantum field, but at the same time, we declare that relativistic field as a fundamental medium for the given type of quanta (particle) with observed physical properties (including mass and energy). Which is, surprisingly, fine. But we should not forget the most important part here -- the word "observed". The fact that we see, say, the photoelectric effect to happen in chunks of energy is just the fact that matter absorbs energy in chunks. That's it. It does not mean those chunks exist by themselves, it just means that matter absorbs electromagnetic waves this way. One may say "So what? If we can't detect something, it shouldn't bother us". Not exactly true. It means that it is possible that certain "particles" exist, which change fundamental properties of reality, yet do not interact with matter at all. Shh... did you hear that? Someone just said "Dark matter" ;-) P.s. the "particle" is the way we interpret the result of a given experiment. A deceiving term with too many false assumptions (e.g. "size", "location", "contents" etc). 1 Princeofcups Poc Princeofcups Poc 10 months ago This video is well appreciated. It represented highlights from 4 years of my own study, called college. And thank you for NOT glossing over the math. These concepts CANNOT be understood without understanding the underlying math. For those who have a glimmer of "not quite understanding," you know the task ahead. For those who believe they understand, without understanding the math, then PLEASE do not try to explain to others, because you cannot. Sorry. The concepts DERIVE from the math, not the other way around. Brush up on your algebra, learn calculus, learn basic mechanics, learn electro-magnetism, and ONLY THEN attempt to tackle this subject. 4 John Isles John Isles 1 year ago Really nicely explained. I like that you don't skip steps, that makes it easy to follow the logic. 7 EpikFail EpikFail 1 year ago It amazes me how simple and intuitive all this extremely complicated stuff can be if explained properly. I feel like I just shifted to the next level of understanding. Thank you so much for your work! treborg777 treborg777 6 months ago Wonderful presentation. In my retirement, I’ve started studying quantum field theory, and this is the best description I’ve seen. Bravo! 1 Veg Ahimsa Veg Ahimsa 1 year ago You've certainly deepened my misunderstanding. Thank you! I find it Incredible (unbelievable) that the fundamental field(s) of reality are discrete, as if we've mistakenly assumed our graph paper literally represents nature. Further, relativism (speed of light equal to all reference frames) seems to suggest solipsism. Or in summary, we've very deeply encoded our misunderstandings. 1 Isomer Soma Isomer Soma 1 year ago How amazing is that we live in times where you have such content for free? Access to knowledge has never been greater. 14 Ashitosh Kamble Ashitosh Kamble 1 year ago One of the best explanation I had ever encountered at least for Quantum stuff. Thank you so much. I know so many pieces but problem is with stitching them together and this video did it for me. But again few questions remains. Like, with which relative position particles oscillate? or what about damping in oscillation?, do equation for wave still holds if oscillating system - I mean particle/wave here - when system is in motion? There remains too many questions. Also please could you provide us the references you used for study? pretty please! 1 Physics Explained Regal Regal 1 year ago I'm a chemist but I really enjoy these videos, it really puts another perspective on what I used to consider a science that is just used to model things in chemistry 11 Physics Explained Suresh Deshpande Suresh Deshpande 7 months ago What an outstanding teacher you are. I am thrilled. 2 Physics Explained Clay Miller Clay Miller 1 year ago (edited) FINALLY a video explaining the topic without handwaving its way through every aspect of the math. Subbed. Can't wait to hear your explanation of the Higgs field and the origin of those minimum field vibrations, even if it takes a few more videos to build up to that. Also I'm a math tutor in my spare time and you've convinced me to go out and buy a pack of colored pencils. The color coding of equations made it exponentially easier to follow along with the derivations. 1 Dory Sheldan Dory Sheldan 3 days ago (edited) This is superb! It reminds me why I believe that simple harmonic motion should be taught in high school, even if the students don't have calculus. The idea of a restoring force that is proportional to displacement should be at the centre, along with the contrasting influences of restoring force and inertia on increasing or decreasing the rate at which a system returns to its equilibrium point. In high school setting, presenting the already derived formulae for period, frequency, and wave velocity and noting that these formulae have factors of either sqrt(restoring force/inertia) or sqrt(inertia/restoring force) shows the influence of restoring force or inertial on the rate at which a system returns to equilibrium. Differential equations are not even necessary. I believe this is superior to the approach of just teaching period/frequency/wavelength/refraction/interference of waves that is typically used. I believe the typical approach does not lead students to an actual understanding of what a wave actually is. Students usually just memorize a few tricks to get questions correct on tests. Specifically, starting with a mass oscillator is magic for comprehension...it is easy to demonstrate, and has clear principles of motion (Hooke's Law). This presentation highlights the fact that SHM leads to many profound principles in modern physics. It should be more widely taught. John Rako John Rako 5 months ago Wonderful. I’d love to see a concentrated presentation on when in the history of physics did the concept of a field go from a mathematical idea to a physical reality that could store energy etc Br0nyAn0myn0u5 Br0nyAn0myn0u5 1 year ago These videos truly enhance my knowledge on physics in a way that would never have been taught to me anywhere else 9 Michael Bishop Michael Bishop 1 year ago Truly excellent. I had never learned about the modified and unmodified wave equations. I sorta skipped right to the Dirac equation mixing left and right-handed components of the wave function to give mass, as I learned about the Higgs mechanism. I hope that in future videos, you can help me build a more fundamental misunderstanding of all this, how symmetries and broken symmetries, etc, all come into play. Thank-you for your great work. 9 Physics Explained felipeohyeah felipeohyeah 4 months ago (edited) Bravo! I’m almost at a loss for words. This was masterfully done. It condenses the intuition that a college physics degree strives to give over 4 years into a beautiful 40 minute video that anyone can follow. The mathematics can be disregarded, but if you can also follow it, it shows how beautiful relationships can be and shows people that math is really a language you can have a conversation with. 2 JonArt JonArt 1 year ago I love it when he says things like "As every child learned in school"....Those are not the schools I went to. 403 Phylos0ph1a Phylos0ph1a 1 year ago Would be very cool to have a video about the physical meaning of stuff like hermitian operators, unitary operators, Hilbert spaces, etc. I never really understood the meaning behind the math of these concepts in my QM courses :( 1 Tequehead Tequehead 1 year ago This is probably my favorite channel on here now, and these are perhaps the best explanations of these topics I've seen. Thanks so much and I hope you keep making videos. meneeRubieko meneeRubieko 1 year ago Rewatching this after some time made me realize how absolutely awesome your video’s are. Not only do you describe all the freaking details as if it were a master degree college, you complement it outstanding visual explanations. Applause! Vasilis Mich Vasilis Mich 1 year ago I am always baffled how videos like this manage to condense hours of classes in a few minutes while also inspiring the viewer to work through the problems on their own and derive their own conclusions. Amazing video, I hope all the work you've put and will put into this channel pays out for you with interest. 2 Physics Explained BlueScream0 BlueScream0 1 year ago Sir, thank you. I am not sure if words can describe how much i loved and enjoyed this video. You gave me a sense (a grasp) of understanding a field that felt previously out of reach for me. I really really like your work, and I am looking forward to the next videos. Thank you so much for doing this. 1 feandil666 feandil666 1 year ago Love it. I was taught quantum physics through pure maths and couldn't get any physical intuition. With this it makes so much more sense. 5 Physics Explained Víctor E. Franquelo Gil Víctor E. Franquelo Gil 11 months ago Great, brilliant! This channel has become a "must-have" for me after watching a few videos. I look forward to informative videos on new content (e.g. on gravity as a result of the curvature of space-time). Des vel Des vel 1 year ago (edited) 25:10 This has clear implications for causality. The properties of a fundamental particle would be determined by measurements that can be made on it only in the future. If a handle is jiggled, the shape of the wave created depends not just on what is happening at the perturbed end but what happens at the other handle... Robert Gift Robert Gift 8 months ago Well done, clearly illustrated and well spoken. Thank you. 1 Physics Explained Parker Trofatter Parker Trofatter 1 year ago This was an excellent video. It would be nice to visualize what solutions to the modified wave equation are. I look forward to more on the subject. 2 Robert Phillips Robert Phillips 1 year ago (edited) A delightful little essay. Everything is now singing like an orchestra!! Thank you! Just one more question, I know you gave the definition of a "field", scalar or vector fields, but what exactly is the field, pure energy?? And even if there is no waveform propagating through it, it just sits there and jitters and shimmers!!! What IS it? 2 David Saintloth David Saintloth 1 year ago (edited) That's better done than the 2 years of study it took me as an undergrad to piece it together on my own. Another Brilliant work! 10 Christian Faust Christian Faust 1 year ago Yes, you definitely succeeded to deepen my misunderstanding 😉. I am really impressed about your strict approach in comparison of classical mechanics, motions and fields and the quantum mechanics analogion. I studied electrical engineering and knew from school about the wave/particle dualism of light. On university we were then confronted with the Schrödinger wave equation for the electron and had to "accept" that particles can behave like waves (of course not really understanding what that should mean). But it helped us to understand the band model of semiconductors. I specialized then in my diploma in laser technology and fiber optics. We created a fiber optical gyroscope (bending fiber to a circular spiral) with two ends. In the first end you pump laser light with high intensity and the second end has a detector. Through a nonlinear effect in the fiber material a sound wave is generated when injecting the laser light modulating the refractive index of the fiber. The incoming laser light is then back scattered on the moving grid of sound waves with maxima of refractive index within the fiber. If you pump enough energy into the fiber the back scattered light creates a laser light on its own but in opposite direction on the incoming light (known as Brillouin ring laser) . The decisive thing is that the interference of incoming and back scattered laser light creates an intermediate frequency which is strictly proportional to the rotation of the fiber spiral. With this set up e.g., you can measure the earth rotation. But what I could not understand at this time (28 years ago 😉) was why I could derive the intermediate frequency by a total classical approach. We used Maxwell for the optical wave and classical mechanical wave approach for the sound wave combining it nicely and got perfectly the intermediate frequency aligned with theory and measurement. But there was no quantum mechanics involved at all. Though you can understand laser light only by its quantum nature. This I could not accept somehow. Now I know why it worked with the classical approach. The photon is a massless particle. THANK YOU!!! Larry Dykes Larry Dykes 1 year ago This is the most elegant coverage of the basis of quantum field theory I have ever seen. The explanation is as beautiful as the theory it exposes. ricomajestic ricomajestic 1 year ago Very well explained! Excellent presentation too. Would love to see more videos on Quantum Field Theory. 1 Steve Krahn Steve Krahn 11 months ago That was an amazingly informative explanation! Is it possible that the dark energy effect could be zero point energy in the quantum foam in voids between the cosmic web below minimum quantum energy level state, or all the remainders, adding up to an increasing energy state in the spacetime field? And maybe the dark matter effect could be the loss of energy above a maximum quantum state, either near blackholes or any accumulation of matter (galaxies), or all the remainders above a frequency threshold as well? Also, if blackholes retain angular momentum, how can the radius of the singularity be zero? Jean Corriveau Jean Corriveau 1 year ago Fantastic explanations!! Bridging Maxwell's electromagnetism with quantum fields. This is what I have been looking for. Over ten years ago, I had derived a couple of those equations without any knowledge of QP at that time. Mostafa Mostafa 1 year ago Great, pls continue to dive deep into the math and not skip it like other “science” channels 5 SBora SBora 1 year ago I am overly impressed by the fact that a very high concept have been explained by comparatively much easier mathematics of physics. Loved it. p2 p2 p2 p2 1 year ago A beautifully made piece, thank you. 9 Stromboli Stromboli 1 year ago (edited) Great video. A ton of concise, complete info in a very clear, well done presentation. Awesome! 🙌👌🙏 However to answer the question: what is a particle, am I right in concluding that particles are fundamentally only math? In other words, matter is not made of anything other than abstract numbers and mathematical functions? So for example solid matter is typically considered to be 99% empty (considering the subatomic model). But in fact it’s 100% empty. There is no “thing” at all, only abstract, virtual math. This also means that mathematical models are not just models describing how our physical reality behaves, it IS our reality. 1 Physics Explained Steven Schilizzi Steven Schilizzi 1 year ago This was absolutely brilliant - and it warrants a second and third viewing, for it is quite dense and may sound deceptively simple! Thank you for making this effort at communicating otherwise subtle concepts. More videos like these would be fantastic. Thanks heaps. 1 Nout Nout 9 months ago I like that though I'm no math Wiz, the way these videos explain topics actually allows me to track along and get me excited for more. Good job! 1 Physics Explained Radical Moderate Radical Moderate 9 months ago Love these video's, wish I could understand the math but they are still great. I have a question if anyone who knows could take the time to answer. How large are these Fields, or is there just ONE universe sized field per "particle"? What I mean by this, are their gazillion of tiny electron fields through out the universe or is there just one large electron field that spans the entire universe? Raphael Klaussen Raphael Klaussen 9 months ago Fantastic presentation, clear, well-paced, and a joy to listen. J L J L 1 year ago Awesome video! Each seemingly trivial transition in “let’s assume...” was a significant leap of faith at that point in time. Also, the existence of all these constraints and constants lead me further down the rabbit hole of simulation theory. The math is too clean and robust for sustained existence in a random macro system. I cannot imagine how order was created and sustained from randomness. Universal constants also make no sense to me- they sound like global parameters set for a software system. Why is there a limit to the speed of light, hence speed constraint of anything and everything? 4 Alexandre Lollini Alexandre Lollini 1 year ago Thank you for this very well made document. I'm still stuck at the "relative" concept. The same when I read Einstein "the relativity". This concept even negates the idea that spacetime can have a shape. So I am not convinced neither by redshift/big bang nor dark matter. There must be a big error in reasoning somewhere. I still "hope" there is some sort of light fatigue. Vi VaRo Vi VaRo 4 months ago Fantastically well explained for my level of understanding, me being a mechanical engineer. Thank you! Émile Émile 1 year ago A video on the Eisenberg uncertainty principle would be great! The explanations are remarkable in this video, but that part seem to come out of nowhere in my eyes compared to the rest. Keep up the good work! Vikram Chauhan Vikram Chauhan 9 months ago A wonderful video!! - A particle is nothing but a ripple in the quantum field! - Thank you for the enlightening lecture 🙏🙏🙏. 1 Physics Explained Euquila Euquila 1 year ago Loved this. I haven't studied physics for quite a number of years but could follow along with everything you did because the steps were so clearly laid out. Bravo! anatoleus anatoleus 1 year ago (edited) Fantastic lecture! This lecture connects so many dots in physics! Congratulations and many thanks to the lecturer! Great great great job! 3 Physics Explained Chris Star Chris Star 1 year ago Thank you so much for this clear and well organized explanation. I very much appreciate the effort behind this presentation as well as the insights I have gained from it. JP JP 1 year ago Now that this interpretation of QM has been made, could you please also do an explanatory video on the de Broglie-Bohm interpretation? Thanks thenorthernclouds thenorthernclouds 1 year ago Thank you for this short and well understandable summary. It helped me a lot to review the material. It has clarified a few connections for me that were not so clear before. ConraddGG ConraddGG 4 months ago You honestly make great quality videos, and your explanations are seamless. Continue being the amazing content creator you are man Rina Sunar Rina Sunar 1 year ago Three years of undergrad physics and i had almost forgotten why i liked physics. Watching your video was like sum up of what I have and will achieve if i continue. Thanks for the nudge in the right direction. Keep your videos coming. 2 ShadowZZZ ShadowZZZ 1 year ago Interesting. I took note while watching. The middle part was quite math heavy with the 2. Order differential Equations derivation. It's exiting to see all these areas of physics coming together when inquiring about quantum mechanics. 4 Fruityoverlord Fruityoverlord 3 months ago Loved it! Looking forward to more videos. Feynman would be proud of the how you explained such a deep topic in simple terms. D Lim D Lim 1 year ago Somehow this video filled in a lot of gaps I have in my understanding between waves, harmonic oscillators and fields, those constraint equation relations really helped! Thank you! 4 Physics Explained primerib01 primerib01 1 month ago Nice job! I enjoyed your visualization of a charged particle in a field. The ripple effect is helpful. Wave particle duality further explained. The Pauli quote sums it up. I am concerned about the photon effect that is similar to normal gamma radiation which seems to be a taboo subject among electrical engineers. Magnetic fields generate secondary voltages that seems to ruin all forms of living creatures. And perhaps the end of Earth Biosphere? Grateful for your presentation! Cheers! Aaron Eiben Aaron Eiben 1 year ago (edited) Excellent video! This is one I'll be using to understand and explain particles in QFT long into the future. I have a question, however. At 24:10, λ disappeared from the right side of the final form of the equation for E_λ. Is this a typo, or was the factor divided away to compute the "energy per wavelength?" If the latter, how does that differ conceptually from the energy of a wavelength computed by integrating dE from 0 to λ (other than having units of energy/length)? Thanks! 2 electrospank electrospank 1 year ago One of the most easily consumable and thorough videos I've seen. Well done! 1 Physics Explained WissenSync WissenSync 1 year ago (edited) Great video as always!. Also, I would really like a video about the disagreement between quantum physics and general relativity. I keep hearing that if you combine both, non existant black holes keep appearing, but why? 1 Physics Explained Aiden Wagner Aiden Wagner 1 year ago Topics, narration, story-telling, visuals... all great. Always looking forward to new content. Keep up the good work. 3 Tanel Gülerman Tanel Gülerman 1 year ago Amazing video! I am waiting for a video about the radiation of electromagnetic waves from accelerating charges. 18 Physics Explained Rob Ryan Rob Ryan 9 months ago (edited) My degree is in math so a field is something different for me! That said, this video and this series are absolute gems, thanks! Old Tom Old Tom 10 months ago Superb presentation! However I believe that a particle must be restricted volume (possibly a point?). Why is a minimum energy vibration (ie quanta) restricted in volume? Could it not be spread across space? Clinton Statham Mind of Things Clinton Statham Mind of Things 6 months ago I did Applied Physics in my Degree level and this was my favorite derivative. For us was "a particle in a box" in atomic physics and quantum mechanics units. 1 jboy55 jboy55 10 months ago Great Video, I think one thing that needs to be discussed though is that these equations didn't come up by these great minds finding how the maths would work together, but rather from independent observations that were tied to mathematical models. When these maths suggested new phenomena, like the mass of the Higgs, subsequent tests and observations verified them. ViaScience ViaScience 9 months ago Outstanding explanation! 2 Physics Explained Emmanuel Landwehrle Emmanuel Landwehrle 1 year ago 32:53 suddenly everything clicked together and i had chills all over my body from the revelation you were able to provide me after 30 minutes. thank you. 6 Physics Explained John Christian John Christian 10 months ago Great video! I really like that you include all the maths, this makes you appreciate the subject matter more! bravo! David Orr David Orr 1 year ago The entire series is very well done! Thank you. Pedro Teixeira Pedro Teixeira 1 year ago Outstanding presentation of the topic. In line with all the other topics you already covered. You have a very rare gift. Thank you. radwizard radwizard 1 year ago Hands down the best video in youtube explaining the basics of Quantum Mechanics 101. Bravo. 1 Hugo Nelsson Hugo Nelsson 1 year ago Absolutely fantastic video. Incredible explanation and brilliant teaching. I look forward to seeing you at 1 million subscribers. dodokgp dodokgp 1 year ago I am telling you..this channel is a goldmine. One day I dream that we can prove Feynman wrong by being able to make everyone understand quantum fields and the laws of small stuff with such analogies and visualizations. 9 e1123581321345589144 e1123581321345589144 1 year ago This is an excellent presentation. Even though I no longer fully understand the math behind it, I was able to follow the flow it quite easily from start to conclusion (with a few pauses along the way to better read the equations). One thing still seems odd to me. the quantum nature of these energy packets. It's just as if on some fundamental level energy would be stored in bits. 1 Ash Roskell Ash Roskell 6 months ago (edited) Ok, so this is an, “almost,” flawless video. My only criticism is that the first part should have slowed down, when you were giving us the terms used to describe the forces and values we’re discussing. Instead of just telling us, “This is called X,” and, “This is called K,” and piling all of the value terms on us, like a list of telephone numbers to remember, it would have really helped if you had just taken a moment to discuss each term? It is fine as it is, for the mathematically minded, or the college level qualified, but not a layman like me. I felt like a student being handed a bunch of books, one after the other, piling up in my arms, and wondering how I was going to remember all this stuff as we went on. If you’d explained how the value terms were assigned, in the same way that you explained that it was Robert Hook doing the investigating at the start; how these terms are chosen; why, for example, use a, “k,” instead of the expected letter, “c,” for a constant, without explanation? Such explanations need only be brief, but they activate other parts of the brain, so the viewer sees the sense of the term and internalises it as having, “meaning,” to them. This video is great for students who are learning for their degrees. But it is SO CLOSE to being far more accessible to the lay learner, like me, and could be so much more. That early part, where you were assigning one value after another, without exploring any one of them, either in terms of the logic of its assignment, its history or its Latin or Greek roots, moved too quickly for the average person to keep up and hold on to their meanings. I think I’m pretty smart, but I couldn’t keep up. But, like I said; if it’s only aimed at a qualified, or student level, niche audience, that’s great. You’re doing a masterful job. But, if you want a wider audience that can really keep up with you, please take a little time to explain or explore each new bit of information, so that it goes in and stays in? Because it really is fascinating stuff, and wonderfully clearly presented. Just slow it down so the rest of us can keep up? Thanks for your attention, if you read this and read this far. ✌️ 6 Efka e Efka e 1 year ago Wow so much quality work put into it! I tried doing a similar, but much shorter video while studying, but couldn't finish. Amazing work! 2 Physics Explained Alexander Daum Alexander Daum 1 year ago (edited) This is an amazing video! I always have problems learning anything about quantum physics, because videos and articles about it are almost always either too unspecific (without any real math / explanation) or the math is way over my head. But the math here was understandable enough to follow for me 1 Physics Explained Ryan Mendoza Ryan Mendoza 9 months ago (edited) Decided to take notes on this video by writing out all of the mathematics as well as terms and their definitions. I somehow turned a 37 minute video into an entire day’s worth of work! Thank you for thoroughly explaining each and every aspect of the concepts described! I just graduated high school and going to be a freshman studying engineering, yet I was able to understand these ideas because of your incredible teaching! Thank you! Santiago G. Santiago G. 1 year ago I want more of this. Amazing explanation. All my physics courses condensed in 37 min. 1 kaan asker kaan asker 1 year ago This channel is the best, the other channels that claim they teach physics commonly don't mention the underlying principles and derivations of equations; they are concerned with the view count, not physics. But you, my friend, tell us the derivations using simple approaches and make us understand these beautiful equations without memorizing them. Thank you, keep up with the videos! 1 Physics Explained YanDrak YanDrak 1 year ago What a great video, keep up the hard work! 7 Physics Explained rbewoor rbewoor 8 months ago Truly brilliant video, explanation, content, everything! Kudos sir! Skives Skives 1 year ago This video has helped me understand a lot that was not really solidified in my mind during my first two years in University. Just by watching this very well put together video, I fell 100% more ready to enter third year. Thank you for this. I have seen all of those equations before, and also used them all in my assignments, so having a refresher on how they were all derived and how they relate really helped me. 1 Physics Explained Edwin9532 Edwin9532 1 year ago I highly enjoy your content. You have something good going on. Keep up the great work, I'm loving all of it. sebastian sebastian 10 months ago I loved this ❤️❤️❤️❤️❤️, sometimes I got lost, but I understood the most essential concept of everything until the end. Just loved it! self studypk self studypk 1 year ago Very simple and mind blowing presentation with a very good start from a question and smooth transition from simple to complex concepts. Addition of explanatory derivations and figures made it more understandable. 1 Physics Explained Kyoto99 Kyoto99 1 year ago Its so mindboggling to me that every field has a minimum quantum that expresses it and carries force but there is no graviton? So either there is a graviton or gravity is a combination of other forces 4 Laurie Laurie 10 months ago Little correction on 24:10. It misses the "lamda" term, and because of it it's not dimentional consistent with Energy units. Great video overall, I'm watching it before taking my QM course, and it's been very helpful!! SmogandBlack SmogandBlack 1 year ago Very very nice: I really appreciated it. One question though: since it seems strange to me that anything (including photons) could propagate into 'nothingness', don't you feel that the Electromagnetic Quantum Field actually is the medium into which photons propagate themselves? Have a nice day and my sincere compliments for the channel 😊, Enrico. 1 Mahmus Mustermann Mahmus Mustermann 1 year ago Thank you for this amazing video! I've never seen such a good explanation of differential equations. Queue Areste Queue Areste 1 year ago I just want to say that your way of explaining things is perfect for my ADHD brain. Thank you, I learned more here than I did in Phys 1, Phys 2, and DiffEQ combined... Robert Hayter Robert Hayter 1 year ago So clearly explained. Amazing how the use of colour helps. Great graphics, too. 1 Physics Explained Ute Fritzkowski Ute Fritzkowski 1 year ago Finally someone explains this in context. Thank you thank you thank you. 3 H. I. H. I. 1 year ago (edited) Exceptional channel! I was "Olympic" (as we say in Europe) in Chemistry and Physics (yep, that nerd in the first row) and still after 40 years I am absolutely fascinated by both. Instantly subscribed. Thank you! 1 Physics Explained fred fred 1 year ago Thanks for this video. I’ve been looking for this explanation for a long time. I have taken undergrad quantum physics. In that course, I realized I have a good idea what a wave is, as I have a nice PDE to describe one, but no idea what a particle is. I’ve asked about it before and it will be like, bosons are particles that don’t collide with each other, but fermions cannot be in the same place at the same time, making me even more confused. 3 zakir hussain zakir hussain 4 days ago My image a particle such as electron is that it is made of yet smaller mass, charge and magnetic particles. These particles are bound together like a water droplet and cannot escape but move randomly at light speed. The parent particle is also surrounded by similar free particles which move with parent particle. Channagiri Jagadish Channagiri Jagadish 3 months ago I love the rigor of this video. It is good to see the math for it is much easier to understand and appreciate...thanks a lot for an excellent video. ali hamad ali hamad 1 year ago I didn't want the video to end. Simply amazing! Pelly Thirteen Pelly Thirteen 10 days ago I've watched many of your excellent video's and I think it is great material to show in a high-school physics class. 1 Physics Explained Professor Sandwich Professor Sandwich 1 year ago Any chance you could do a video on why the magnetic force is perpendicular to a moving charge? I am having trouble wrapping my head around the interaction. 1 Francis Zerbib Francis Zerbib 1 year ago Wonderful video. Your videos should all be part of the physics courses around the world. You explain clearly with the most charming English accent. A pleasure to learn physics with you. Thank you very much. Francis from Israel 4 Physics Explained Keith Staines Keith Staines 1 year ago This is an amazing explanation, thank you. Can you go on from here to explain virtual particles? 1 MisterLau MisterLau 10 months ago Good review of the concepts. It's great to refresh them. Great job. i think it is not suitable for everyone though, but for those who have a good grasp of the physics and maths on which this model is based on. Like when you say "constraint forces". Only if I already know analytical mechanics and Lagrange & Hamilton, I could follow your explanation. Fine for me, thank you very much. I'm going to check other videos of yours. Bernard C Bernard C 1 year ago Wonderful. Please keep these videos coming. What about the equations of Maxwell, ultra violet catastrophe and Planck, Einstein’s photoelectric equation, de Broglie, Heisenberg, Schrödinger, Dirac, Einstein’s general theory of relativity! 1 Eşref Eşkinat Eşref Eşkinat 1 year ago Excellent videos. I have learnt a great deal from them. Keep it up please. Thank you. 1 Physics Explained 3V0 3V0 9 months ago The Ultraviolet Catastrophe was a fantastic video. There was just so much information that I needed to know before hand in order for me to begin to understand it. Hopefully this video will be a little more my pace of understanding. If not, oh well. Cheers! Physics Explained iMentor iMentor 1 year ago I am reading radiation chemistry, where I have to study energy and particle interaction. This video of yours is helpful. 26 M0lecular Ep1phany M0lecular Ep1phany 1 year ago This is absolutely beautiful. Thank you, this is a tremendous service. 2 Physics Explained Robert Robert 1 year ago Hi, I have really enjoyed your videos. I’ve just been wondering about radiant heat and light and what electromagnetic radiation is. What happens to an electromagnetic radiation over long distances? Does a wave of EMR weaken depending on how far it has traveled? Is visibility of a distant star more about its size relative to the field of vision than about any changes in the light wave? From what I understand the laws of space and time don’t apply to EMR? What laws do apply? What about particles that decay like those you mentioned when sunlight first hits the atmosphere? Why do those decay? Is it because they encounter matter? Can I say that matter things subject to time and space can change EMR? Sorry for the stream of questions from an amateur but the one about distance is my main question. edwardjcoad edwardjcoad 1 year ago Bravo!! Again, an awesome video. Concise, fluid and calm. Keep them coming! This level of physics isn't significantly beyond school physics (loved the "every child learns at school" comment) so why aren't we exposing "children" to this?? We should confuse them somewhat as it is likely to be their successful final state of understanding of Physcis! Davor Senković Davor Senković 1 year ago All they ever taught us were disconnected dots. This finally connected everything. Remarkable, thank you! Hadi Hadi 1 year ago Absolute star for this explanation. Thank you. I have a little problem with the quantization of energy of a free particle. after we solve the Schrodinger equation for this type of particle, we learn that the energy is continuous for this type of particle. So why do we think firstly the energy is quantized? Able One Able One 1 year ago Brilliant! Excellent presentation! 5 Gahan Chattopadhyay Gahan Chattopadhyay 6 months ago This video is not just a video man, it's a treasure. I mean, I was screaming with every revelation that this guy was making as if I was watching football or Takeshi's Castle. I will never forget this video, absolutely brilliant and beautiful. Loved it. 1 Physics Explained nmgreg11 nmgreg11 1 year ago Simply beautiful. Thank You! 10 Physics Explained Jonathan Jonathan 5 months ago Amazing - this was exactly what I was looking for. Zach Steiner Zach Steiner 11 months ago I love physics, but I can sometimes find the underlaying math a bit boring. You simply took the boring part out! Your video is really well done! Rishikesh Wagh Rishikesh Wagh 1 year ago Thank you for providing such brilliant explanations for such fundamental tropics! And that too for free! Can't thank you enough 1 Physics Explained Adam Reis Adam Reis 1 year ago Hello! I loved the video, but I couldn't get a point. How does the quantum framework do not violate the 2nd law of thermodynamics since the harmonic oscillator is always in motion, given it has a minimum frequency and consequently a constant minimum energy? Udit Sharma Udit Sharma 1 year ago (edited) This is very informative video. Liked it, the way you explained was great. Is there a way of getting the slides/pdf used ? Rafael Quirino Rafael Quirino 1 year ago (edited) Best physics video i've ever seen. Mind boggling! 3 Augmented Martini Augmented Martini 1 year ago As a musician, I'm familiar with the term "quantize" but never realized it was related to "quantum" (albeit related to tempo rather than amplitude). Squirrel ASMR Squirrel ASMR 1 year ago I might have to pause once or twice to figure a few things out 😜 but this is very nicely presented and the visuals and narration are very relaxitng. 1 Tom Potter Tom Potter 3 weeks ago Good job. I like it you kept it simple. Now the fun thing is to find out if the thing that's called quantum fields has anything to do with SpaceTime fabric... In other words what is a quantum field in terms of relations to other fields and what is it made of etc that'll be fun to find out. 1 Brian Juel Pedersen Brian Juel Pedersen 1 year ago Needs more equations. But...seriously: very well thought out and very clearly presented. pablovirus pablovirus 3 weeks ago Finally a video that actually explains the math in a bit more detail than all the useless physics infotaiment out there. Thank you 2 Physics Explained Michael Bishop Michael Bishop 1 year ago Its a bit of a shame that some of the darker expressions he writes are so hard to read on my screen, with the black background. That said, this man's pedagogical technique is without peer, and he deserves to be paid well. 6 Lachie Hanrahan Lachie Hanrahan 1 year ago Outstanding video, Great level of detail and explanation. Please make more content teefkay2 teefkay2 1 year ago Best, & most succinct, explanation that I’ve ever seen. Sincere Thanks 1 Physics Explained Discourse Manifold Discourse Manifold 1 year ago Please never stop bringing out such amazing knowledgeable videos. You're just amazing. Superb.. 1 Physics Explained Lyall Taylor Lyall Taylor 1 year ago My main takeaway from this video is i wish i was smart enough to fully appreciate just how good this explanation is. J C J C 10 months ago C'mon Google, give this channel some exposure... it truly deserves it! 2 M.R Wakawaka M.R Wakawaka 1 year ago Very exciting stuff! Best channel on the platform confirmed. 4 Diabolical Jazz Diabolical Jazz 1 year ago A lot of this video was over my head, honestly, but I think by the end I did come away with a deeper misunderstanding of relativistic fields and quantum theory, so good work! Veg Ahimsa Veg Ahimsa 1 year ago ~370 years of discovery > ~37 years of education and learning > ~37 - ~3.7 days of preparation or 37 hours of video editing > 37 minute compressed video How many hours of prep and production for this masterpiece? 4 Physics Explained An Old Man and his HPV An Old Man and his HPV 1 year ago What a great video! Having the math makes it so much easier to grasp. Ring that bell. yanga bavuma yanga bavuma 7 months ago I think this is the best physics video I've ever seen. Thank you guys. Instant subscribe. 1 Physics Explained MindlessTurtle MindlessTurtle 1 year ago Great video. Connecting mathematical expressions to make sense of the world completely fits with that quote at the end. Kinda funny how the aether was replaced with dark energy. Guess the quantum guys wised up and replaced real experiments with thought experiments to not end up as failures like Michelson and Morley. Abdulkader AlSalhi Abdulkader AlSalhi 11 months ago Well done, a very illuminating video. The simplification and presentation are very good. Thanks for your effort. SosiKokeilu SosiKokeilu 1 year ago So far interesting, I'd disagree with the spring charting though, springs have a lot of forces acting on it that would make that sine wave slowly oscillate back to zero line. :P Berke Tozlu Berke Tozlu 1 year ago I am just taking wave physics course this semester and this video literally summed up everything I learned and taught even more 4 Physics Explained A yo A yo 7 months ago 14:16 "Let us calculate the energy uncertainty in our oscillator by replacing x with Δx and p with Δp in the classical energy expression." ΔE ≥ ℏ²/8m(Δx)² + ½mω²(Δx)² I cannot figure out how you mathematically arrived at this inequality. How do you merge Heisenberg's Uncertainty Principle: ΔxΔp ≥ ℏ/2 with the classical energy expression: Eₜₒₜₐₗ = p²/2m + ½kx² ? Can anyone show me some intermediary steps? My attempts to merge the inequality & equation have only resulted in sadness... catfooddogfood catfooddogfood 1 year ago Thank you so much for this. Any chance of a pdf printout? Video was great, just feel that I would benefit from working through it at a slower pace on paper. ff00005 ff00005 1 year ago It's been some time since I delved this deep, but never did anyone explain it to me with that broad a picture in mind. Good job :D eso eso 1 year ago No words to describe this kind of content is exactly why nature invented fields of information in the first place How to Visualize Quantum Field Theory 189,408 viewsAug 31, 2020 7.1K DISLIKE SHARE DOWNLOAD CLIP SAVE ZAP Physics 12.4K subscribers Quantum field theory has made incredible advancements in physics and technology possible and is arguably the most successful theory in all of physics. But what exactly is it? How can we visualize a quantum field theory? Let's run some simulations to see how we can interpret this complicated subject in a simple way! Link to github repository: https://github.com/ZAPPhysics/QFT_Sims If you do cool things with the code, let me know in the comments! I would love to see it! Music credit: 'Low Frequency Music' Track Name: 'Good Day' Music By: Low Frequency Music @ https://soundcloud.com/user-551516820 License for commercial use: Creative Commons Attribution 3.0 Unported "Share Alike" (CC BY-SA 3.0) License. Music promoted by NCM https://goo.gl/fh3rEJ @ https://www.LoFi-HipHop.com LAKEY INSPIRED Track Names: "WARM NIGHTS" Music By: LAKEY INSPIRED Official SoundCloud https://soundcloud.com/lakeyinspired Official YouTube Channel: https://www.youtube.com/channel/UCOmy... License for commercial use: Creative Commons Attribution 3.0 Unported "Share Alike" (CC BY-SA 3.0) https://creativecommons.org/licenses/... Music promoted by: Chill Out Records @ https://goo.gl/fh3rEJ www.ChillOutMedia.com / www.LoFi-HipHop.com 'Homie Cat' ● Track Name: 'Sweet In Bitter,' 'Childhood Imagination' ● Official "Homie Cat" SoundCloud HERE - https://soundcloud.com/homie-cat/ ● Official "Homie Cat" Instagram HERE - https://www.instagram.com/homiecatbeats/ ● DOWNLOAD @ https://www.chilloutmedia.com/download License for commercial use: Creative Commons Attribution 4.0 Unported "Share Alike" (CC BY-SA 4.0) License. ● Music promoted by NCM https://goo.gl/fh3rEJ @ https://www.LoFi-HipHop.com "Who I Want To Be" Track Name: "My Favorite Song Is Your Heartbeat" • Snapchat - https://soundcloud.com/who-i-want-to-be • SoundCloud - https://soundcloud.com/who-i-want-to-be • Music released by: Chill Out Records https://goo.gl/fh3rEJ License: Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) • See More @ https://www.LoFi-HipHop.com 306 Comments rongmaw lin Add a comment... ZAP Physics Pinned by ZAP Physics ZAP Physics 1 year ago This one was a ton of fun to make! If you want to play with the code or read about the math behind the animations, check out the git: https://github.com/ZAPPhysics/QFT_Sims 67 brotherhood of steel paladin brotherhood of steel paladin 1 year ago you know... you're a classic example of "I learned this better on youtube then I did in class" 111 Pretty Much Physics Pretty Much Physics 1 year ago Amazing visualization! Really well done :D 70 Le YASEP Le YASEP 1 year ago This is an outstanding demonstration of a step-by-step emergence of behaviour from discrete elements, thanks for your work ! Oh, and sharing the code is the cake on the other cake :-D 13 Physics Rules-Roels Physics Physics Rules-Roels Physics 1 year ago Great video. It would also be nice to see this kind of simulations for 2D fields instead of rings. Thanks for your great work !! 7 IM Flór IM Flór 1 year ago Thanks a lot! I'm used to this theory from books but seeing how you applied this knowledge (e.g. propagators) in your code is really exciting. Keep it up!! 8 Erik Panzer Erik Panzer 2 months ago Very helpful, thank you! I wonder if this can be extended to show how fields interact and the role of bosons virtual and otherwise. Another case might show how two particles repel each other. 2 M M M M 1 year ago mind-blowing! really amazing work, thanks for uploading 26 ZAP Physics Vaibhav Vaibhav 1 year ago (edited) Thanks for making this, having code and resources to look at makes this video that much more amazing! A series surrounding this would definitely be interesting. I'm sure the algorithm will roll 20s for you someday in the future! 3 Tibra Ali Tibra Ali 2 months ago Amazing video. I like how you don’t get bogged down in mysterious statements about how QFT is the marriage of special relativity and quantum mechanics. I think more physical intuition is to be had from the condensed matter point of view. 1 G3 McK G3 McK 11 months ago Very nice. It's cool the way "particles" emerge from a continuous field. I'm looking forward to seeing how you add relativity to this model. Also, since it's circular, I wonder if rather than imposing quantization "arbitrarily", you would get it by fixing a single node to zero, which my intuition says would create reflections and standing waves, and get the antisymmetric wavefunctions of fermions by fixing another point to 1, possibly representing the singularity at the big bang, and an anti-singularity at the "big rip" at the end of time. Deep Bayes Deep Bayes 1 year ago One of the best vids I have seen so far on the topic. Thanks. 50 Pandagoggles Pandagoggles 2 months ago This was amazingly well-explained and clear, excellent work! 1 Manlio Lo Giudice Manlio Lo Giudice 1 year ago Excellent video, simple, clear. I really appreciate this kind of videos and i do appreciate you are also making the code available to others. You really are giving added value to the Internet. Thanks 1 Brendan Murphy Brendan Murphy 1 year ago Very nicely done. I haven’t seen things presented in this way before and it certainly gives a nice perspective. 3 RBK STUDIOS RBK STUDIOS 1 year ago Nice I want to see a whole series about this How did you get the million dollar list? It was so cool. I I didn't know that P vs NP is there too PS: I don't see a speed changing option in this video. Just to point out you know. Have I said it already that I want more content on these 9 bob bob 2 months ago Very good video! I am taking qft right now and this touched on everything we’ve done so far but Noether’s theorem. Thanks for making this. xenmaster0 xenmaster0 4 months ago Outstanding. Really fine visualization that makes the math come alive. Bravo! Road to 200 Million Road to 200 Million 1 year ago This finally helped me visualize anything quantum related after so many articles and videos failed and it is the best simplification of something complicated I have ever seen 1 folwr folwr 1 year ago Hi there! Nice simulation. I missed however some interpretation at the end. I will try to sketch my picture of it: Since the end result of the classical and quantum field simulation are sort of visually identical, despite the completely different calculation, it seems to come down to interpretation of the ‘particles’ (localized sound waves versus phonons). So I wondered what the difference would be. You mentioned that in the quantum field description the energy quantum has a 50% of being in the top particle and 50% of being in the bottom particle, instead of half of the energy being in the top and half of it being in the bottom. But it seems that there is no real distinction between the evolution of the two systems as long as you do not interact with them. In the first simulation you assume to have two classical waves propagating around the circle, each carying half of the energy in the system. They could be detected individually by an observer. It is possible to harvest an arbitrary amount of energy from the sytem by interacting with one of the particles, even without disturbing the other particle. In the quantum field case you inject one quantum of energy in the system that creates two propagating waves, but you can only harvest the whole quantum by interacting with one of the ‘particles’, destroying both of them at the same time, even if they are miles apart! At least according to the Copenhagen interpretation (and others). In the many worlds interpretation you somehow split off a world branch when interacting with one of the ‘particles’. The other ‘particle’ lives happily in a diffent world that is forever out of reach. Both interpretations are hard to swallow, but that seems to be the conundrum of QM or QFT. I wonder how the QFT simulation would look like when you would have more than one quantum to play with? I assume you have to specify the chance for having one quantum and the chance for having two quanta in each point of the ring? 6 Wizard Wizard 1 year ago Thanks for making this, it was great to hear this complementing perspective while reading a QFT textbook. 2 Jarof Clay Jarof Clay 2 months ago This is one I’ll keep coming back to. It closes some gaps of understanding books left out. What would this look like if it was 3d like an electron orbiting a nucleus? Would it be a fuzzy sphere with a small bump moving on rhe surface randomly? I would guess it would take a lot more computing power to code that as well. mbrv mbrv 10 months ago Awsome video ! Makes some concepts really clear and more intuitive! Great job !! Cesar Omiste Cesar Omiste 2 months ago The harmonic oscillators (HO) connected together in a circle (closed string) is a great visualization of how QFT works. You can imagine extending this to a 2D plane of HO joined together to show how a fluctuation may travel through the field (system of HOs) thus revealing the familiar particle representation. Andrew Jones Andrew Jones 1 month ago A great intuitive explanation of a non-intuative topic!! Well done! J L J L 1 year ago I seen some videos about QFT and it was not very clear how exactly particles are viewed as field excitation, so I glad I saw this :) I hope more people in future will ask themself same question and with some luck end up here :) 1 Antony Kolarov Antony Kolarov 1 year ago (edited) Great work! Congratulations! Although I find a big mystery here. According to the Uncertainty principle ∆x.∆p ≧ ћ/2, if the particle has a known position, its moment goes towards infinity and the position becomes undefined. In the classical quantum mechanics that's related to the non-commuting position and momentum operators. In QFT that's given (somehow) by the non-commuting field operator φ and the momentum operator and momentum operator of the particle: [φ(x),π(y)]=iδ(x-y). Thus we could not know the field amplitude and momentum simultaneously and that would introduce the quantum uncertainty. The particle cannot be localized and their energy cannot be known precisely. To me, that part is somehow missing or is too much hidden in your video. Maybe You can create a next slightly improved version? 1 Leeroy Jenkins Leeroy Jenkins 1 year ago This is incredibly well explained MK Uis MK Uis 1 year ago In the continuous case the two look exactly the same, but I'm sure they are not, can you explain a bit more their differences? (no uncertainty but with continuous energy level vs discrete energy level but with uncertainty?) Syed Masud Ali Syed Masud Ali 1 year ago Great explanation and a very nice work indeed. Thanks a lot for the efforts. Best wishes... 1 ron Chad ron Chad 2 weeks ago Beautifully explained and demonstrated. WintersRampage WintersRampage 1 year ago Really nice way to visualise periodic boundary conditions of a finite spring by a ring of oscillators!, I’m doing a (many body non rel) qft couses atm and this really helped seeing where particles come from, rather than just creation operators! Iliyan Bobev Iliyan Bobev 1 month ago How would this work in higher number of dimensions? Would we need to introduce momentum to keep the location probability along a single path, rather than smearing in all directions? Walid A Jalil Walid A Jalil 9 months ago (edited) Excellent video. I just subscribed to your channel. Also appreciate that you uploaded this to your GitHub repository. I'm still skeptical of just how far the ""infinite number of coupled quantum harmonic oscillators""-analogy holds up when discussing QFT. Either way, great video :) Cheers, Walid 1 Sergei Gladchenko Sergei Gladchenko 1 year ago Thanks for the video! How did you set the interaction between the separate harmonics oscillators? What's the form of this potentials? Leon Jiang Leon Jiang 1 year ago Does each particle have its own field in QFT? Can each oscillator take on different levels of energy(multiple of the discrete chunk)? if so, do they show up as different particles when trying to observe classically? 1 İlker O İlker O 1 year ago Video went perfectly until you introduced discreet energy levels and probability at the same time. Would be much better if you introduced discreetness and showed its effects and then introduced probability and gave us a sense of how the probability is calculated. We went from "ok here are connected dots with springs" to "things are discreet in a way that we dont know and there is a magic proability" all the intuition went away. 11 Mustafa Ashry Mustafa Ashry 1 year ago (edited) A master piece! Please continue making it GodBlessYou2008 GodBlessYou2008 1 year ago (edited) could you please make more of the example? I need a little bit more examples to intuitively imagine quantum field, especially together with the formula of quantum field which is a liner combination of many creation/annihilation operators multiplied by the corresponding wave functions respectively. Thanks! 1 Michael Hutton Michael Hutton 1 year ago Nice animations and lovely explanation of the concepts. I'll browse the code with interest. Nice one. A A A A 11 months ago I have a question, we need to have oscillators in advance(point like particles which you add more number of them to the circle) to make the wave. My question is why we say particles will emerge from fields ?! 1 Abhishek Roy Abhishek Roy 9 months ago Truly a great video! keep up the great work! 1 tmlen845 tmlen845 1 year ago (edited) does it also work if there is a 2D or 3D mesh of masses connected by strings? would a particle stay contained in a point and travel in a straight line? 1 Wulfaz Wlkwos Wulfaz Wlkwos 1 year ago If you have not done it, I think it would be brilliant to take famous equations in physics (Maxwell, Schrodinger,etc.)and explain the Math symbols and what they say in an intuitive way. 4 Tomasz W Tomasz W 7 months ago Finally wrapped my head around it!! Thank you so much!! Johnny Utah Johnny Utah 1 year ago Great video. Many thanks for putting it together David Jones David Jones 1 year ago But how does the particle get from one side to the other side, faster than the speed of light, if you decide to remove one of the vibrating particles? Michal Grňo Michal Grňo 1 year ago It's been a nice video, but I don't see how the introduced concepts tie to the maths of QFT. It would be awesome to see a sequel that would tie the concepts of QFT (field operators, annihilation&creation operators, Fock spaces) to this visual analogy! 4 Adonai Blackwood Adonai Blackwood 1 year ago Amazing topic & information! Wonderful video & explanation too! Thanks so much! Sub'd & Shared! 1 Ralph Dratman Ralph Dratman 1 year ago Very helpful. Thank you! Amr Aref Amr Aref 1 month ago It is really a great video, the animation is really nice thanks for uploading The Neutral Container The Neutral Container 9 months ago Most intuitive video on the topic I've seen to date <3 David Freeborn David Freeborn 1 year ago Intuitively, I find it hard to see why the energy disperses less as N increases. Are there any good intuitions about why that happens? 7 The Bright Side of Mathematics The Bright Side of Mathematics 1 year ago Really nice visualisation! I like it :) 1 Jeremy Hofmann Jeremy Hofmann 2 months ago So does the fact that there were two “particles” represent the concept of entanglement? Suman Dey Suman Dey 1 year ago I learned this concept from the Classical Mechanics book by Goldstein for classical fields.. thanks for your nice explanation... 3 Keshav J Keshav J 8 months ago (edited) Nice and simple explantion . Just graduated 12 th , I would really love if you can give me some tips on how to get started with QTF ( I only have basic knowledge of physics but the subject really interest me ) Lucas Baldo Lucas Baldo 2 months ago (edited) What model did you use for your phonons on the second part of the video? In the infinite N limit they seem to have perfectly defined trajectories, which shouldn't be possible for quantum particles because of the uncertainty principle... a finite trail should be developed. Otherwise great video 👍 Fernando Hood Fernando Hood 1 year ago Brilliant demonstration of how some can seemingly appear from nothing. Shakhter Siren' Shakhter Siren' 1 month ago Aren't the phonons actually simmetric? Seems like a positive energy flux goes one way and it's negative counterpart goes the other way. As their energies are opposite, not the charge, they can be thought of as one going forward andbthe other backwards in time, or more commonly interpreted as charge and used as a model for pair production Jari Kosonen Jari Kosonen 1 year ago (edited) I would guess it has been hard to put all that together, but also even more hard to apply it to make some device. Making a device with existing theory is of course better than making the theory as well... Its great it can be visualized, but what if I could just 'zoom in' to real atoms and view different fields and forces there and including time axis. Then if something like 26-dimensional space is needed for numbers to crunch it is nothing one could perfectly visualize. Of course the equations would run anything without questions. Dialectical Monist Dialectical Monist 2 months ago My God. Are you kidding me? This is the best physics video I have EVER seen. I feel like I understand it better than ever. Eichelonen Eichelonen 1 year ago Quantised does actually not re,ate to “the number of particles”, it’s a discrete distribution of energy with the (h.v) as the smallest possible energy chunk,. It makes it confusing for newbies but it’s cool! Tyler Sanderson Tyler Sanderson 1 year ago (edited) How does this extend to the 2D or 3D case? It seems like energy would spread out in a circle rather than a single point "particle" 2 Entenkommando Entenkommando 6 months ago These two particles rotating in opposite direction look like the explanation of how one unit of energy has to form both matter and anti-matter. Bob Aldo Bob Aldo 1 year ago (edited) Is there anything in the universe that is actually continuous? Serious question. I know that quantum fields are said to fill the entire universe. Are they somehow "continuous", or is that just a human-scale way of visualizing them? 1 Ryan Perrin Ryan Perrin 1 month ago This is a great conceptual motivation for QFT Jim Beaver Jim Beaver 1 year ago Fantastic explanation and visualization. Thanks 1 Chris Barry Chris Barry 2 months ago I wish he made examples showing how this turned into actual particles that make up an atom. Like the different fields moving to make an atom MICHAEL Collins MICHAEL Collins 2 months ago Superb effort and explanation 👏👏👏 Brihaspati Angiras Brihaspati Angiras 9 months ago That was really good explanation.... thanks man Hossain Pezeshki Hossain Pezeshki 1 year ago Thank you for sharing the knowledge. Andrew MacRae Andrew MacRae 1 year ago Awesome description, great video! Frank Reashore Frank Reashore 2 months ago Amazing video. Huge thanks. Mauricio Furlan Mauricio Furlan 2 months ago Poderia terem colocado legendas em portugues Parsa Oveisi Parsa Oveisi 1 month ago Good job dude! Keep it up! Theo0x89 Theo0x89 1 year ago I'm not sure I understand what's happening here. Doesn't the limit N→∞ correspond to quantum field theory, which doesn't have a discrete set of oscillators but still a delocalization of probability for particles over time? If this is correct, then why do the probabilities do not smear out? 2 chintan jani chintan jani 1 year ago This was awesome. Thanks! 1 P Stenzel P Stenzel 1 year ago Okay, so in the classical represantation the masses are coupled by those imaginary springs and they are the cause for the difference in density right? But how are the quantic oscillators linked? Do they just transfer their chunks of energy to its neighbours? And which neighbour gets the energy chunk when its the smallest piece? Dénes Tandary Dénes Tandary 1 year ago This material is marvellous. And a special thanks for the links below. Moritz M Moritz M 2 months ago Awesome work! Tenzin Lundrup Tenzin Lundrup 7 months ago I looked at the .pdf of your algebra. At the end you say that the probability density K(y) has to be between 0 and 1. However only its integral w.r.t. y should equal unity. Are the singularities of K(y) integrable?