Quantum Electrodynamics and Feynman Diagrams
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- Опубліковано 16 тра 2024
- How do we reconcile electromagnetism with quantum physics? How do we describe the interaction between two electrons? What are virtual particles? All these answers in 15 minutes!
0:00 - Introduction
1:27 - Quantum Fields
4:17 - Feynman Diagrams
9:32 - Sum and amplitudes
13:36 - Conclusion
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Alessandro Roussel,
For more info: www.alessandroroussel.com/en
_
To learn more :
en.wikipedia.org/wiki/Quantum...
en.wikipedia.org/wiki/Feynman... - Наука та технологія
this channel is like a crossover between 3blue1brown and pbs spacetime. altogether a better mix of the physics and math
Agreed , well observed
nowadays i'm watching this one before PBS
Don't forget my boy Eugene
This channel is much better than PBS.
@@ethandickson9490 and Arvin Ash
I am a high school physics teacher. I would say this is the best animated video on Feynman diagram I have ever seen on UA-cam. This will certainly be played in my lessons.
This seems way too advanced for highschool, your students are going to become "big brain"😳
@@karotto594 it’s not. It’s part of the syllabus
@-GinPi Gamma Any desserts left is good for me - strawberry in particular. Why is it that these folk with interesting alternative explanations and theories so often seen semi-literate? Curious, that. Old duffer her. If you're going to troll me, at least spell check first :)
This is too easy for high school, I suggest looking at the formulation of the Lagrangian to obtain the Euler-Lagrange equations or imposing the Lorenz gauge condition to reduce the equations to form the QED classical Maxwell equations. This exercise also includes the D'Alembertian operator and the Dirac equation which will undoubtedly be of interest and of use to students nowadays.
Feynman diagrams, that’s how they are known?
The animations are great, as always! And as someone currently studying these topics it's a great overview
I'm glad you liked them !
Can u send the 2D or 3D image of quantum field plz?(example:electron field,up-quark field)
Quantum field in lattice would be helpful
@Science Revolution You should know Quantum is called Quantum because particles at Quantum level don't behave as Classical mechanics. Imagine having to exist at two places at the same time, it defies our common sense and intuition beacuse we know we haven't experienced or see that phenomena with our naked eyes. Everything at quantum level doesn't behave as we expected them to be and the only way for us to understand them is by using mathematical equations and stuffs. That is why theoritical physics exist, just because they are theoritical doesn't mean they are not real.
@Science Revolution You sound like a fool. You decided it was bullshit just because you don't understand it and that is so incredibly ignorant. For the record, quantum field theory has worked just fine in spite of our lack of complete understanding of why tiny things behave the way the do. Without knowledge of quantum field theory, we wouldn't have the computers and/or phones that we are using to post these comments. UA-cam wouldn't have the servers and computers needed to run and maintain this website. We wouldn't even have the internet were it not for our understanding of quantum mechanics. Not only that, if quantum mechanics was bullshit, then none of the science that particle physicists, astrophysicists, or nuclear physicists do would be happening. Oh and also, we wouldn't have the understanding of chemistry that we have without quantum mechanics either. Our current technology would be non-existent if we hadn't figured out what we've already figured out about quantum mechanics. Our unanswered questions about quantum mechanics don't really matter quite that much when what we do understand has allowed us to have what we have now.
As a layman with years of fascination with physics and especially quantum physics, can you verify that I've grasped the content in this video?
Essentially, electrons do not repel each other due to a 'force' as such. Rather, due to superposition, every possible outcome of an interaction between the two electrons exists simultaneously, and the result is the most probable scenario due to amplitude?
Having spent a significant fraction of 35 years getting education in related STEM fields and having read many books or watched many popular science talks with famous people, I have to say you are the first to make it crystal clear.
and he made this video all by himself at 22 years old 🙃
@@ryzikx damn!!!!!
no shade or disrespect intended for the content creator, their contribution is phenomenal :), but i'd like to mention the way our understanding works is somewhat incremental, especially on complex or abstract topics... bits and pieces need to be gathered for the puzzle to 'fall in place'.
(it has helped me w/ being patient w/ myself, hope it helps someone else too)
My man, your animations interact perfectly with your explanations making very conceptually difficult subjects easy to understand.
Keep up the good work, we believe in you
Thank you 🙏
Can u send the 2D or 3D image of quantum field plz?(example:electron field,up-quark field)
@Science Revolution иди поспи
@@ScienceClicEN U are one of the most greatest animators dude keep goin my man ... can you try doing vids on quantum computing ?
i really love how some parts of your videos are easy enough to get you interested (eg the animations), but also informative enough for you to come back to the video with more knowledge and still learn something new. and the more complex the topic is, the more times you can rewatch the video! honestly amazing
-2 -1 0
Your accent and your voice are honestly unbelievably satisfying
You guys keep knocking it out of the park! Amazing description, with no fluff. I've been consuming popular physics media for decades, and this is some of the best!
🙏
Can u send the 2D or 3D image of quantum field plz?(example:electron field,up-quark field)
@Science Revolution You do know that quantum computers are real right?
@Science Revolution A discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents, is the definition of quantum, but I'm pretty sure that's not what you're asking? Why do you think it is BS, do you have a real reason or do you just think that everyone is out to get you?
@Science Revolution Okay, let me get this straight, you responded to my question of why you think it is BS with "copy and paste BS?". Are you saying that all scrabble games and boggle games are fake because they use a dictionary same as how my response to your question asking what quantum is was wrong because I told you exactly what quantum is? I could have wasted your time and mine by making up my own definition that wouldn't be correct, and wouldn't provide a useful answer.
Copy and Paste, YES
BS, NO
You are a gifted scientist, but also an artist. Rare combination of animator and physicist. Here is my praise for this gift:
You are destined for sparking a virtual qft and physics interest, much like the elegance found among the particles in our universe which you've animated so creatively. This video, as well the previous ones, serve to rekindle an interest in learning new physics that I never could grasp. Awe-inspiring content. Quantum Art.
🎨
it's absolutely awesome how you squeeze such complex matter into 15 minutes.
so what I'm getting is that there's an infinitesimally small chance of me just falling through my chair.
I failed physics while in High School. I wish you were my high school physics teacher back then.
he wouldnt have helped you.
This is a higher level of physics that you can study after highschool
@@professorfrog7181 QM 1 is even tougher than this video. QM deals with advanced equations
@@professorfrog7181 Hey, can you please tell me the fundamental notions that you mentioned in your comment? I'm in grade 9, so could you please tell the only ones necessary to understand this video full?
@@zamilhoquesiddique3249 not OP but honestly it would be hard to point them out concretely, one by one. I think of you keep going and watch and read more of more material you'll slowly be able to connect together everything and build a more comprehensive understand and a broader picture of everything. At least that's what I did personally.
After an year or so I thought I understood most things now but in reality I'd just become more familiar with them and my understanding was not even half of all there was to understand. So that's also important to keep in mind, that if you're a beginner no matter how you feel in the moment, your understanding almost certainly, is wholly incomplete. Why I stress this, is because two of my friends who previously were interested in this kind of physics left after just a surface level understanding thinking they've understood most stuff (which probably represents the majority of people)
You still amaze me everytime on how much better you explain complex theories and topics than basically everyone else. Hope you never stop :)
As a theoretical physics major, I cried for this video.
I'm there with you bud. Sometimes you are so close to understanding something and a video like this can sometimes help to make it 'click' together.
Also idk what that other dude is on his high horse about, went off on some tangent. If there is anything I dislike its people who gatekeep physics.
@@ferp.2078 Gamma is spewing jargon that he thinks makes sense but, in fact, is bumbling on about simple things in a way that tries to pass them off as complex and insightful. Just another "UA-cam physicist" that thinks he knows what he is talking about, but in fact make little sense at all.
@@jarredgrant1 Yeah but they talked about Gallileo in the same way "thinks he knows what he is talking about, but in fact make little sense at all" etc.
@@alwaysdisputin9930 I mean, all the guy said was "changing the position of a mass in a gravitationally bound system alters the angular momentum" but he said it in 100 words and in a very confusing way. He just wants to sound profound.
@@alwaysdisputin9930 also, he never finished a full thought. He got halfway through saying something as if he was leading up to something and then just stopped. Basically, "yeah but don't forget that the angular momentum of the system is altered!" Which doesn't link what he's saying with the original comment. So, again, makes no sense at all.
Few times am I genuinely impressed by an explanation that is truly informative, visual, and summarizes much that others fail to clarify. In other words, all these years and you've shown me what a Feynman diagram is in rich variety what no one else has every done via video or writing, that I've come across.
As an architect who is curious about physics, I’m grateful of your creations: the combination of visualization graphic, your music, your voice and especially your own way of explaining. Thank you.
It would be impossible for me to express how thankful I am for your beautifully-animated and clear explanations of these ideas. Thank you.
This is, by far, the best explanation of QED and Feynman diagrams I have ever seen.
I was hoping you'd mention the fine structure coupling constant as an explanation of why we can neglect higher order diagrams (perhaps also why "higher order" is intuitive language). This could lead into a nice future video explaining the computational differences between QED and QCD, where the coupling constant is much larger so we cannot neglect the higher order diagrams.
Seconded, an explanation of QCD fundamentals in a similar style would be fantastic!
I'm necroposting but I agree. Mentioning that more complex diagrams are orders of magnitude less likely to occur and naturally give rise to the simple diagrams nearly completely describing the overall behavior would have made a nice conclusion to his layer overlapping animation and the general "repulsion" we experience
I'm happy there is now an english version of this channel. I watch both, because I have the feeling that although both have the same information, I get a fuller understanding than if I were to watch only one of them...
Please keep doing what you're doing! Through your videos, I am learning things that I never had any idea about before, and even if I'd looked into it (and I do like science), I probably wouldn't have understood nearly as well as with your videos. You are opening up a new world to people like me! Thank you!
This week I had a Quantum Mechanics 2 exam. That was basically quantum field theory. I actually had enough of it. But when Sciene-Clic makes a video. Good summary of the principle of QFT.
@-GinΠΓ Τάο wat
@-GinΠΓ Τάο What are you ever trying to say? Of course, the complexity of every consecutive science is much bigger. Physics is very complex, and imagine the complexity of chemistry that is based in physics, biology that is based in chemistry... That is why medical doctors have to spend 10 years learning about a specific part of one type of animal, Homo Sapiens, to get a degree. And what is that "Nature is the Universal purpose"? You are putting some teleological meaning to Nature? There is no purpose, some think that evolution has a purpose, but that is wrong. No purpose, only adaptation to the environment.
@-GinΠΓ Τάο You are talking in general, or you are insulting me? I actually teach something, and I have a Master's degree, but if you think that I am stupid without knowing anything about me, such ad hominem attacks speak only about the person who does that.
@-GinΠΓ Τάο You should make difference between stupidity and ignorance. Ignorance can be cured, stupidity can't, that is why in the time when we have so much info under our fingers there are flat-Earthers, anti-vaxxers, and many who think that 20 videos on youtube are equal to 200 years of medical science, or 200 years of physics.
@-GinΠΓ Τάο I am not impressed with your simplistic explanations and incredible hubris which is an indication that you are under the Dunning-Kruger effect. Maybe my degree is not impressive for you, but it is impressive enough for people that matter.
Grow up, and try to learn, I know it is hard, but that is the only way, and stop thinking that you are something special.
Absolutly astonishing! I admire your talent of understanding so complex theories and producing so detailed and understandable animations noone else on UA-cam could do that.
Your channel hits exactly my sweet spot in terms of difficulty of material
This is really really really excellent. I very much appreciated that you allow pauses for my brain to process information between the animation and the explanation. I have always wanted to know more about this field.
This is the best explanation of Feynman diagram on internet.
Wow, this absolutely blew my mind. The explanation of the probabilities and the amplitudes was one of the clearest and best I have ever seen.
About a month ago, I watched this video for the first time. And I'm back. This video really opened up so much to me that I never knew. You illustrate this so well and bring up things that I haven't heard elsewhere, even though I've looked. Things like the nature of the actual fields, how all Feynman diagrams and their amplitudes are added up to come up with a final probability of the movement of electrons, anti-particles seeming to move backwards in time, and more...these were so eye-opening to me! Thank you again!
One of best videos I've seen on the topic. Very impressed.
outstandingly well explained, thank you
This channel is amaze-balls:
1. Great summary explanations -not too complicated, not too simple
2. Great graphics and representations
3. Great connections between branches of science
I accidentally came across this channel and boy am I enjoying this. Thank you for explaining complex theories in a very simple and concise way.
Damn, it feels like the previous video came out yesterday and now there is a new one!
It is such an incredible topic! I always wanted to see it ♥️
These vids are so well put together and make perfect sense, also I love the way it's taught in these videos since the abstractions, math etc is spoken of not as the cause of the phenomenon but as a description of a real, physical thing.
The narration on these is really good. Always the conclusion with the music is so fitting excellent job and strangely moving
*Wish we were taught physics in high school like this*
This is an amazing channel.
This video is a beautiful simplification. Keep up the great work
Thanks!
The best explanation I have seen so far. What a genius!
I think this is the best physics channel online today. You explained three things in this video alone better than I have seen before.
Those Feynman diagrams would make a good tshirt pattern.
That yoink photon blew my mind, never thought such a thing could exist. Albeit Transiently
'Albeit Transiently' was Albert Einstein's school nickname, did you know that fact that I just made up? Old UK duffer here, enjoying the science :)
@@tim40gabby25 lmao
I love how quantum theory makes me see things in a deep different way, making me ask what is real, and if asking such a question makes sense in the first place
Man, your explanations, as well as visualizations are just... uhhhngh. HUGELY talanted
These are the best made explainer videos on UA-cam I've ever watched. Amazing work.
Your videos are insane! Keep up the amazing work!
Thanks :)
Well done video, thanks!
These videos turn science into an art form.
I am just left mind blown after every one of your videos. You explain things in such an intuitive way. I come back to rewatch your videos all the time, just because they are so captivating to watch.
Love your videos. Please can you make a video about magnetic and electric fields, while exploring Maxwell equations. Thank you!
Amazing video again...👍
Thank you very much for helping me to understand QED.
Would you please make a video about the Re-normalization?
The place in your QFT video where you described how electromagnetic repulsion represents the superposition of all possible interactions blew my mind. It's great to see you treat just that concept here in more detail.
It doesn't matter how good the animations, voice, sounds and author's understanding of topic are, because it's even more frightening more simple explanation more difficult to understand the complexity of the place we are living.
Great job, Alessandro!
This is beautiful, as always!
Thanks !
I would love a video series about the mathematics of QFT !
Wow this is an incredibly enlightening video. Of all the hours of videos I have seen in trying to understand the fabric of reality, this has been the most informative.
I love the excellent PACING of this video. Those little breaths that give it all a moment to sink in. Thank you.
Your videos have my favorite visual representations for these ideas! I dream of a full-team collaboration between yall and PBS space-time, on any mechanism in the standard model or relativity!
As many know, the "color" analogies used for complex phase-space in QED, as well as for gluon colors in QCD is a compelling narrative to delineate linear amplitudes from modal phases for many charge concepts in physics. But, would you consider making a side-by-side animation where the rainbow diagrams (going from 2:40 to 3:53) are juxtaposed with a grayscale diagram, where the "color" of the rainbow is replaced by a spectrum of thick-to-thin textures?
I imagine a visual aid that depicts a low-energy red color expressed by a thinly-textured space, transitioning to a thickly-textured space for high-energy blue colors - flowing through "R-G-B" space for electrons, and "R-B-G" space for positrons would be like flowing through thin-to-thick or thick-to-thin grayscale textures respectively.
I think this would both help people with standard color vision transcend the color analogy by seeing an alternate but equal expression for quantum phase, as well as expand the accessibility of the color analogy for people with alternate color perception.
Your animations are sooo cool
Your explaanations are also great
thanks for electrons existence
Lol copied 3blue 1 Brown's name and renamed
@@averycuriousclumpofatom2159 ya and space time s too lol
Can u send the 2D or 3D image of quantum field plz?(example:electron field,up-quark field)
I have consumed science media for the layman for as long as I can remember. This is absolutely top-tier among some truly excellent competitors. Thank you!
Thank you so much for this explanation, it's very useful and clear.
what triggers particles to emit a photon? It just decides like "hey I feel like I want to emit a photon... why not?"
Yeah, actually. it's like every instant there's a chance of emmiting a photon, the universe then sums up all the possible outcomes according to that probability.
Although different than the topic of this video, particles (say, an excited electron in an atom) can be triggered to emit a photon (i.e. fluorescence via spontanous emission), initiated by a perturbation from the fluctuating vacuum. Granted, this is a real photon and not a virtual one. And QED deals directly with the vacuum fields, so it still leaves the question of what triggers the virtual interaction amongst the fields..I suppose it really comes down to a probability game as the above commenter noted.
It both decides to emit it and to not, for each second the electron does both, and for each emition the photon is emited in all possible direction and decides to emit electron positron pairs or not at the same time, superposition is the answer
Feynmann diagrams do not try to answer this question, you could try to give a meaning but is more honest just to say that we dont understand the reason if there is a reason in the human understanding of what a reason is
As already stated it's based on probability which increases based on the energy state the electron is in if it's in a high energy state it has a higher probability of emitting a photon which will cause it to fall to a lower energy state due to conservation.
If it's in a low energy state it has a lower probability etc.
incredible
Thanks for making these i rewatch them all the time. Highly underrated.
I cannot thank you enough for this video. Youve told a very exciting story with mathematical precision. This video should be required watching for humanity. Thank you!
greatest channel in the world
🙏
Feynman was a genius!!!
The momentum of the 'wave' pulling them together!!! Mind blown! Finally an explanation that I can grasp.
Your videos are the height of my day. Thank you!
Minor criticism here. At 9:16 you say that virtual particles although intermediary are essential to consider them. This isn’t true. Non perturbation QFT (Also known as lattice QFT) does not use virtual particles at all to do calculations. Otherwise, great vid!
But lattice doesn't work with weakly coupled abelian theories like QED, right? Or at least it gives inconsistent results, both numerical and theoretical for small coupling constants if I recall correctly (I could be wrong, it's been some years since I read this subject). That's why it is used mainly to approach QCD and other strong coupled non abelian theories.
Also if you want an analytical results you need to consider the full expansion to a given order so you would need all virtual particles.
So Intuitively you can claim anything!
The quality of animations and content in these videos is a game changer! Looking forward to new work!!
Very informative, very intuitive, and very well animated. Thank you.
@ScienceClic Wow, thank you for explaining something so complex, so well, that it could be quickly and visually understood.
I have just a BSME, and mechanical things seem intuitive,,, atomic/electrical/optic& quantum things previously seemed less intuitive, so this is great, with excellent, logical animations!
I ask also: does the fact the Ben Franklin and others got the electron flow direction backwards and we keep that mistake currently(no pun intended), i.e. are forced to call charge negative (e-), [cause I know this complicates my understanding of diodes]... What I'm getting at is; that "negative", as when used for numberlines has the idea of debt or lack of something, whereas charge positive and charge negative are just two different real things, and electron flow(vs conventional flow) models for circuits seems to help the intuition to match the actual happenings,,, just curious if there is an alternate/better way to think about "charge"
that moment when the music changes always makes me hyper focus 😂
This music is so incredibly awesome that you play I hope you never stop using it because it helps me learn because it's just so incredible to have playing in the background while I'm thinking
Amazingly elegant explanation. Bravo.
Is it possible that electrons would actually attract for a brief period of time, since there is a small chance of it happening?
Yes as long as the momentum and total charge is conserved. For example, If u have two electrons initially moving eastward, and one emits a photon to the northeast and the other to the southeast, then they can indeed attract each other
attraction or repulsion is not a concept in ee-->ee scattering. If you label the electrons e_L and e_R (for left and right) and they scatter to e_U and e_D (for up and down), and you draw an attraction like trajectory, there is a problem: irl, the e_U is going to be a mixture of e_L and e_R, and likewise for e_D, and the trajectory with the final state electrons swapped is going to look like repulsion. Both occur in super-position. (it's called t-channel and u-channel, and it was not discussed in this video).
My god where did this channel come from?
14:55 This is so fascinating that it gives me goosebumps. Great video! Wonderful topic!
I never thought I'd understand any quantum physics, but somehow you've done it. You've taught something about quantum physics that I've actually understood, after only like 3 hours of watching your videos. Absolutely amazing, I never thought I'd find physics cooler than chemistry but I do now. I've found a new special interest and her name is physics :)
I think I’ve struck gold. I know I have.
Does this mean there is a small chance two electrons actually attract each other instead of repelling?
Yes.
Yes and it happens all the time. The repel is much more frequent, thought. The overall impression is they are repelling in general
how could you even tell, since the electrons do not retain their particle labels[1] in scattering?
[1] ab-->ab can not be distinguished from ab->ba
@@DrDeuteron That would depend on whether the electrons have the same spin or not.
I love this so much! You’ve such a great way of explaining things clearly through your speech, and visually through a clever combination of 2d and 3d examples. Great work!
You show that elegant, simple (yet complete) explanations can help clear up lifetimes of mass confusion.
“If you can't explain it to a six year old, you don't understand it yourself.”
― Albert Einstein
I don't think you can explain most physics to 6yo without losing most of the information. This is what pop media does and the theory is interpreted as wrong. Also the quote was by feynman ig. This video had a lot of things which a 6yo wouldn't know.
Ya maby 13 year old . Point is articulating a concept as simple as possible, which is what feynman did with his diagram
Simply the best explanation, no one not even close as good as you in visual explanation!
Genius video with remarkable visuals. Superb!
The best depiction of QED I’ve ever seen. Keep up the good work!
These videos are insanely well made
This finally goes into depth the charge of electron, positron, and quantum field. thank you!!
The way you present the theories is amazing. It helps me visualize those theories easier. I would love if you made a series of "Group theory" and its applications.
It's great to have these videos that go deeper. Keep them coming thanks!
Thanks for this great video and all the effort behind it!
Wow. The videos on this channel are shockingly good at explaining these concepts for a lay-audience. Please keep up the good work.
Glad you like the channel!
Wow !!! The way that the interaction between the electrons was explained is very intriguing!! Amazing work
I really love your videos, you make my random interest in physics palatable and I love being able to learn more. Thank you!
I am studying electrical engineering. I had a quantum physics class. Passed it with a pretty good grade. Understood almost all phenomena, aside from why two of the same charge repel from eacother. I just thought it was a given thing that we can’t prove. This video made me understand this very simple concept if a very beautiful way. Thank you.
Excellent presentation. I am a retired Physics teacher who taught the subject for 33 years, and appreciate the simplicity with which the topic is introduced at an elementary level.
What a brilliant and crystal clear explanation.
you deserve more viewers and subscribers as a Physics hobbyst... this is gold.