How To Read Feynman Diagrams

This is how to get your head around Feynman Diagrams. Get your free trial of MegellanTV here try.magellantv.com/domainofsc...
A Feynman diagram is a picture of what happens when particles interact with each other. I in this video I explain what you need to know to understand Feynman diagrams, show you what all the particles in the standard model are, as well as which lines we use to represent them. And the general rules the fundamental particles follow as well as which particles take part in interactions via the fundamental forces.
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[@domainofscience]

Hey this is a re-uploaded version of this video as the first one contained a couple of errors which I wanted to fix. Hopefully this is basically free of errors now, but let me know if you spot anything. Also what do you think of the funny bits? Yay or nooo?

[@AwkwardTalent]

gotta get the cheese collection right, I understand

[@Happy_Abe]

Definite yay

[@lorrat4210]

Defenetly yay but I also like the more serious style. Maby you can use both depending on the topic of the video. Also I realy likes the sience round ups. I would love one about last year.

[@Ivarius321]

I really do not like the funny bits. One of the reasons I liked your channel was because it was so technical and in depth. Most people seem to like it though, so you should probably keep them in, but make them a bit less frequent please.

[@xBris]

Definitely not a fan of the "humour" bits. It doesn't really feel all that natural and therefore kind of kills the enjoyment of watching one of your videos - at least for me.

[@bengoody595]

Good afternoon sir! When you started off by saying you`re going to teach me how to read Feynman diagrams i paused your video, chuckled and said to myself .. "You can try" ... BUT i have to confess you made me understand. When i got towards the end and you proposed the specific question "what force is mediating this interaction" .. Gluon - Strong Force!

[@domainofscience]

Brilliant! :D

[@Schmuckimaster]

The last diagram looks like a strong proton-nucleon interaction. So basically what makes nuclei stick together. The down and up quark exchange can be viewd as an exchange of a virtual pion. So its more a "remnant" strong interaction, since its not directly transferred via gluons. Great video! Edit: typo

[@SirArthurTheGreat]

What do you mean by remnant strong interaction?

[@Schmuckimaster]

​@@SirArthurTheGreat The strong force is mediated by the exchange of gluons. So all hadrons are bound system of the strong force and the composites (quarks) carry a color charge and can hence directly exchange gluons. Nucleons on the other hands are already made up from quarks and are neutral in terms of color charge. So nucleons cannot exchange gluons to bind together into nuclei. But instead they exchange color neutral pions as a force carrier. These pions arise as kind of residual effect of the inner dynamics of the nucleon. Very similar to the Van der Waals forces between electrically neutral atoms and molecules. For more information check out this paragraph: en.wikipedia.org/wiki/Nuclear_force#The_nuclear_force_as_a_residual_of_the_strong_force

[@jorgepeterbarton]

It confuses the heck with me reading the arrow of antiparticles in reverse. But down is -1/3, pion is down -1/3-2/3 antiup or -1. Subtract -1 to -1/3 is an up quark which is +2/3. Add -1 to the up 2/3 to make 1/3, an up quark. And the gluons stick it all together. But why, i guess thats your explanation of how nuclei are bonded but why do neutrons and protons swap?

[@Schmuckimaster]

@@jorgepeterbarton Not sure if I understand your question correctly, but in the example the proton and neutron swap since the exchange a pi^-, which has a negative charge. Due to the pion exchange one valence quark in the proton and neutron changes its flavour and hence the proton becomes a neutron and vice verca.

[@paulbelfrage]

So this is the interaction that binds the protons and neutrons in an atom? The interaction that makes the most of the mass?

[@EventHorizon511]

8:00 probably the nicest "zoomed in" depiction of the residual strong force I've seen.

[@CraftyF0X]

If Iam right you are right too :D

[@cvoges12]

en.wikipedia.org/wiki/Strong_interaction#/media/File:Nuclear_Force_anim_smaller.gif Then you'll love this one.

[@gfconstantino]

7:37 - The last Feynman Diagram depicts an Strong nuclear interaction between an Neutron (comprised of Up-Down-Down Quarks) and an Proton (comprised of Up-Down-Up quarks). In this quantum process, the initial Neutron (bottom-left of the Time-Space (TS) graph; T is Y-axis and Space is X-axis) is transformed into an Proton (upper-left of the TS graph) and the initial Proton (bottom-right of the TS graph) is transformed into an Neutron (upper-right of the TS graph). The gluons are always made of pairs (Color-G and anticolor-B or -Red, or Color-R and anticolor-G or -Color- B...). So the gluons (Strong force gauge bósons) change the individual color-charge of the quarks inside an NUCLEON - PROTON or NEUTRON, (in an dynamic; never-ending manner); BUT is by the process of creation and annihilation of PIONS (in this case, symbol-Pi -1; made always by a pair of quark anti-quark (both FERMIONS) and depicted as crossed solid lines), drawn in the MIDDLE of the TS graph as crossed lines that makes possible for different NUCLEONS to BE HELD TOGETHER by the STRONG NUCLEAR INTERACTIONS...(in this case by the STRONG RESIDUAL NUCLEAR INTERACTION)! GREAT VíDEO DoS! For more details: kzbin.info/www/bejne/fKC1ZJunasdor6c kzbin.info/www/bejne/n3q6hYWtf9GlfdE

[@felicityc]

i hate when i get time backwards

[@JeremyCoppin]

What like US time format mm:ss:hh ? 😉

[@Fizikakaalda]

Dear, Dominic Thank you for this amazing topic It really drives me towards Quantum Physics. As a high school student,I am very grateful to you Dominic

[@dunglvht]

keep it up mate, it's going to be hard if you want to follow the path of a theorist. But if study hard enough, you will like it

[@Fizikakaalda]

Thank you I surely will

[@rakshnaanachiyarsuresh1217]

I know quantum physics is an addictive field.

[@SomeGuy-ne3yl]

@@rakshnaanachiyarsuresh1217 attractive* hehe

[@augayoupvis7797]

​@@SomeGuy-ne3yl More like BOTH

[@abhishalsharma1628]

Explained so interestingly and simply only within 9 minutes. That's really appreciating

[@RC32Smiths01]

Thank you for working on the corrections. Really great video!

[@xXYourShadowDaniXx]

Love the art, animations, and inclusion of every particle in the standard model, very cool

[@vynneve]

I read that as "antimation" been trying to understand feynman diagrams for a tad too long 😂

[@zyansheep]

"That's all photons, _they're wiggly_ "

[@saintburnsy2468]

Have you uploaded the second part to this? Can't wait to learn more! You're doing great work m8

[@camellkachour4112]

I feel impressed by these incredible guys who do a lot of efforts to try to explain us deep ideas of Physics. Big Thank You Very Much !

[@robertschlesinger1342]

Excellent video. Very interesting, informative and worthwhile video. A must see for everyone interested in science, and most everyone not particularly interested in science. Many thanks.

[@manavnaik1607]

Lw becoming one of my fav science channels for your realistic approaches.

[@FCPSjdmahoney]

Using this today to start my lesson on particle physics with my higher level IB physics students. Thank you so much! Even my husband enjoyed it!

[@theghost-killer0_1]

Thank you, you saved my time.

[@gravimagswnforce9123]

Great! very well explained! thank you so much for the knowledge!👍

[@Ciencillamente]

2:02 This is just the best explanation of the standard model ever!

[@mactavish6236]

Thanks Dominic Sir...... Great Video!!

[@mdmem3521]

Wow, so easy to understand ^^ great work

[@Yekemcar]

Thank you sooo much for this video, and to make me update with new version of Physics. Since I finished my school !

[@PiXeLSn1p3r]

Welcome back! :D

[@raghdaelraaie9335]

I thought I'll give up on passing Elementary Particles course till I watched this video, which also cracked me up! XD Thank you so much ! Don't stop!

[@vladmedvedev8290]

Very great video! Thank you)

[@thaybo999]

best explanation ever!

[@warrenarnold]

Seemed scary, I was hesitant but this now is the best thing i have ever seen. Animat ok ng thr diagrams makes everything different

[@philip7468]

Really enjoy the humour, bit over the top in places, nevertheless 11/10 would watch again.

[@kugaththeplaguefather6332]

man give this man 1M subs

[@hamadaag5659]

at 7:39 the reaction is mediated by the strong force (cus gluons) and it describes an up quark (bottom right) spontaneously turning into: an anti-up quark + down quark, turning into a down quark. At the same exact time a down quark (bottom left) interacts with the anti-up quark + down quark, turning into an up quark. This can be thought of as: u (bottom right) --> anti-u + d + d (top right) and d (bottom left)+ d + anti-u --> u (top left) happening at the same time, each on its own breaks conservation laws but when put together: u + d --> u + d it obeys those laws, and its almost as if the up and down quarks "switched places" You can also rewrite the equations, substituting (d + anti-up) with (negative pion): u (from bottom right) --> negative pion + d (top right) and d (from bottom left) + negative pion --> u (top right) both happening simultaneously. If you, dear fellow commenter, want to derive this yourself, you can write the feynman diagrams starting from the bottom right up quark ending with the top right down quark, and the same starting from the bottom left down quark ending with the top left up quark. Then you can combine the two feynman diagrams and you'll see the common pion arise between the two.

[@khilorn]

Ngl that poster you made is the best diagram of the standard model I've seen. At least from an outsiders perspective

[@megamanx466]

Thanks for explaining this topic and sprinkling a little brevity on/in it! 😅

[@orialtman6176]

I don't know quantum physics, but from what you described in the video: The last feynman diagram looks like a neutron and a proton exchanging and up quark for a down quark, turning the proton into a neutron and the neutron into a proton? The gluons involved makes it a strong force interaction?

[@adhritgulati6794]

I think yes

[@domainofscience]

Bingo!

[@aryanbajaj4337]

I also don't know mu h about quantum physics but for I know charge of up and down quark So charge of gluon came as 4/3 And charge of that orange* down quark came -5/3 But gluon isn't supposed to have charge I am able to understand this is strong force interaction But I also know charge is conserved

[@aryanbajaj4337]

@@domainofscience please help me

[@aviadshimalkovski7711]

@@aryanbajaj4337 If I'm correct, the gluon didn't change the charge in the system. The yellow down change his movement because of the gluon "discharge" (as in the electrons and photon in the beginning) and then it happened again with another gluon. The first gluon became an up quark and anti up (charged add up to 0) and then the anti up and other up became the second gluon. So not charge was added to the system or taken from it. Hope I help a little!

[@CarolynFahm]

Brilliant!

[@Naman...123]

Thank u so much 😀😀

[@evifnoskcaj]

The passion, jokes, and sarcasm in this video make it thoroughly enjoyable and informative. Love it!

[@JohnRay1969]

I don't know anything about quantum physics but I would listen to anything you wanted to talk at length about.

[@dosomething3]

Amazingly enough I did not suffer information overload

[@chrissaffran7655]

The funny bits let you get really technical while keeping the material accessible, so I say keep them in!

[@kittybecker-smits154]

Abdolutely fascinating 👌🙌🎀🐺

[@kagannasuhbeyoglu]

Thanks a lot DoS👍

[@maxwellinsihirlilambas9029]

Kral altyazı koyabilir misin

[@kagannasuhbeyoglu]

@@maxwellinsihirlilambas9029 keşke o yeterlilikte olsamda çevirip koysam Maxwell. Üzgünüm :(

[@TheTastyPancake]

Crazy quality stuff

[@VincenzoTilotta]

Nice colors 😊

[@xBris]

Well, you're definitely not a comedian. But the physics is solid.

[@zyansheep]

He'll get better with time... hopfully...

[@domainofscience]

@@zyansheep This made me chuckle. Can you do the jokes from now on?

[@zyansheep]

@@domainofscience Sure I can! I'm the proud owner of 1.4k reddit karma! That's a lot right? Right....? _oh god what have I been doing with my time_

[@domainofscience]

Fair point. In my defence, making physics funny is probably not the easiest kind of comedy.

[@bradyelich2745]

@@domainofscience You need Lee Mack. He knows nothing about physics, but lots about comedy.

[@Marinealver]

I got a question. How do we measure time when the flow of time is know to be relevant to the velocity and not exactly a linear variable? Also thank you for the fundamental model. It always seemed to me that the standard model was missing half of it.

[@bhupindersinghnagi2827]

What if I reverse the direction of time for beta emission? Do I only need to change directions of the arrows or do I also need to swap the positions of the neutron and the proton?

[@Aartistha1998]

Love you😆❤️

[@shmeef279]

you should make videos on the map of relativity and the map of classical physics

[@navjotsinghdhiber3454]

Very cool

[@spacemonkey1071]

Hey man do you offer like a poster bundle to get all of them at a reduced price? I wanna cover my bedroom in a science map wallpaper

[@austinalderete2730]

But how do you recover the path integral from a set of Feynman diagrams? Or the converse too?

[@cccircuit8296]

I would really appreciate it if you made a poster for all medical fields if you are so inclined. Regardless I appreciate all of your videos.

[@pradyuniyer7508]

Thank you for revising the concept. We were taught this around the age of 10 and there us gonna be a test about this in our school after summer (im 14 now)

[@user-jf2bq9su6m]

who the hell teaches 10 year olds mandatory particle physics

[@jaw0449]

I'm in 2nd semester of a (graduate) QFT course and we're using "Quantum Field Theory and the Standard Model" by Schwartz...any opinion on it?

[@michaeldeklerk268]

Hi, in this video you promised a followup video on the LAWs. I cannot seem to find it?

[@trambakphysik7]

At 6:22, how is the photon aligned at an angle, it should be parallel to the space axis right?

[@hazemyoussef8898]

The last Feynman diagram shows a down quark changed its colour charge and direction by the momentum of the emitted gluon . This gluon decayed into up quark and anti up quark then the up quark change the first nutron into proton then the anti up quark join the up quark from the other proton to make a gluon that changes the direction and the colour charge of the first down quark which changed the second proton into nutron

[@rebecadorantescarvajal8838]

"Hopefully they tell you, and if they don't, then they're bad people" nomames HAHAHAHAH such a nice nice channel!! Greetings from Mexico! :)

[@bbbl67]

8:00 That looks like a neutron and proton exchanging positions via a pion exchange? The force at work here is the residual nuclear force.

[@michaelemmenegger3576]

I have no idea what you are talking about 😂but this video is just great!!

[@chaoslord8918]

I'm gonna say it's a strong force interaction (gluons carry the strong force at 3:14), and it appears to be a neutron becoming a proton and a proton becoming a neutron in tandem. I seem to remember in one of your videos that neutrons are less stable than protons, so I assume the initial driving force is the left neutron's potential to decay into a proton. This is shown with the down-quark emitting the gluon (as it gets attracted to the proton on the right, I'm guessing). That gluon then splits into an up-quark and anti-up-quark (obeying the laws of conservation of something?). That up-quark goes back with his buddies to become a proton, and the anti-up-quark gets attracted to an up-quark in the other proton, they annihilate and become a gluon, in the opposite process of what created the anti-up-quark in the first place. All the while, we got this down-quark moving toward this proton, probably missing it's gluon energy, then here this gluon comes, just in time to put it all together into a neutron. Seeing as how this is protons and neutrons, I can only assume this takes place in the nuclei of atoms.

[@adityamane4182]

Suggest me a good self study book for studying particle physics. Should contain basics.

[@Paul-ty1bv]

I love your videos!

[@151balance]

Is it fission? Or particle collision in an accelerator?

[@thepitts42]

In the first animation, when the electrons collided you showed one moving away before the other. Is that really what happens? I'm relatively new to quantum physics and will be watching most, if not all, of your videos, so if this question is answered in one of them, please link it.

[@user-zp4nb8ku9o]

Youre so funny love your work

[@gubbi4547]

1:43 "time on the y -axis is the most common way of..." My teachers, text book and the test: ...no...

[@robbiewilliamson9783]

That axes joke was top-tier

[@aarongrant1184]

So if antimatter goes backwards in time and exchanges with a particle of matter, does anti matter change the course of time? say like a potential future from when in time the antimatter came from?

[@impossibur]

3:29 The feeling in our hearts when we look deep into the eyes of a loved one He: Looks right into my eyes Me: 😳

[@Panthera-Uncia]

😉

[@shilpadesai8031]

No.

[@psltmtir]

@@shilpadesai8031 ?

[@joshdheda8776]

can anti-particles be detected? do they really move backwards in time? if so, can we use them to send messages to the past?

[@MuhammadHanif-bx4pb]

8:01 looks like a proton and neutron hitting each other ? and there's some gluon keeping those 2 particle in place am I right ?

[@Rayne-jx6sl]

Hey, when the down quark turns into an up quark and the up quark turns into a down quark, is the electrical charge of the quarks transferred by w-w+ bosons? Also, after the up quark turns into a down quark and the up quark turns into a down quark, where do the electric charges come from? Does w- w+ come from bosons or is it a phenomenon arising from the nature of quarks?

[@timless5157]

Hi - I'm thinking that the diagram is n+p elastic scattering where the n & p exchange into each other. I'm not a theoretical physicist (I'm a Medical Physicist); but it appears that the standard model rules and particles keep increasing. This reminds me of the past Earth-centered model of the universe, where epicycles upon epicycles must be added to make it work. We do not have enough understanding of the universe to make it work either. Cheers! - Tim

[@JAUNEtheLOCKE]

Here from the short! :))

[@RickClark58]

Photon Kitty! 😀 Good vid.

[@ultramadscientist]

Is it the strong force holding a proton and neutron together in the nucleus through a strong force interaction but in doing so they technically swap places?

[@FelixMBlume]

The first part of the sentence is right. Yes, the strong force holds the nucleus together. No, they don't "swap places". There is ofc other forces in play though, so it's not the only force inside of a nucleus

[@vu4y3fo846y]

I'm doing good thank you

[@domainofscience]

Good to hear

[@filippo6157]

In the first example, how can I tell from which electrons the photon is coming?

[@jvcmarc]

the jokes are a bit more than expected. but the content is great! love your videos

[@loki7237]

Strong force they dude behind this interaction as gluons are being seen and involves closely kept nucleons.

[@MrBenjie1992]

Yeah what direction the time space gap closes as when ignited that's OK quite fast but not enough control

[@hhshum1238]

great, as a social science student, learning it for no reason at all.

[@adamforster3036]

Hi all I can't seem to find the next video in the series; the one about the conservation rules. If someone could point me in the right direction would be much appreciated

[@RedHair651]

Aw, I hope you didn’t miss out on many views by reuploading

[@mostrum195]

got my physics final exams today 😎 thanks for the video

[@taranmellacheruvu2504]

Question: Why would drawing Feynman diagrams with time going up be the most common way? In physics, time is usually the independent variable (going horizontally) and position is the dependent variable (going vertically) so why would they switch it in this one instance? I don’t know enough about this, so it might not be just one instance and I probably don’t have enough info to assert this. I just don’t understand why basic depictions wouldn’t be homogenous across all of physics.

[@qop8188]

Sir which software use to make your video please tell me sir

[@maheyshramesh3244]

I use a range of Adobe software to make my videos: Photoshop and Illustrator for the art, After Effects for the animation and Premiere to edit everything together..............it's on his website. link in the description

[@kugaththeplaguefather6332]

On 7:25 how do I know that the neutron ain't colliding with the proton?

[@comik300]

KZbin won't open dftba links for me

[@mlunin7926]

At 5 50 in the top left there is a depiction of a weak interaction, but I am confused to as why the exchange particle is W- boson and not a W+ boson, as the diagram seems to depict a beta + decay

[@user-jf2bq9su6m]

it’s an interaction that can be found in supernovae: an electron and a proton combine to form a neutron and an electron neutrino in a sort of reverse beta decay. the electron is giving up its charge in the form of w- turning it into an electron neutrino, which then neutralises the proton’s charge to make a neutron.

[@louisrobitaille5810]

7:30 Question: What is the diagram depicting and which force is mediating this interaction? The fact that the arrows at the top point in opposite directions kinda puzzle me, but I'd say it's the formation of deuterium through the strong nuclear force. I'm 99% sure the strong force is responsible for this interaction, but only 5% sure about what the diagram is actually showing 🥲.

[@gluonic]

7:35 the strong force in an atom nucleus (between a neutron and a proton)

[@gwenturo9550]

I frickin love all the physics! 7:35 God I hope I'm not wrong about this... Was so hard to not look at comments before writing this lol Looks to me like the strong force bringing a proton and neutron together to make a hydrogen nuclei?

[@SwordQuake2]

Soo any explanation on the 7:28-7:41 diagram?

[@arnaldosantoro6812]

3:09 "every single human experience" -> also hearing and touching?

[@rudhraveena2638]

8:09 is the answer gluons

[@johndoh1000]

7:33 I actually took the time to parse out what was going on in this model and it was in this moment where I exclaimed "I'm starting to comprehend quantum mechanics! Holy Sh**!"

[@schmetterling4477]

Except that you don't. These diagrams do not represent quantum mechanics. They represent one particular way to solve its equations.

[@lucxidmusxic2098]

So do photons vibrate forwards and backwards in time As well as forwards and backwards in space?

[@lucxidmusxic2098]

All photons are traveling in a brand new direction at every spacetime-space

[@ginobinoy4998]

When you're so early, you don't know what to say.

[@gaminghunt5837]

I hate trends.

[@TheMixxon2]

apparently not early enough, since if you were early enough that means you would have watched the first upload with errors, and while making a comment here 4 minutes after this video was uploaded, you would have said something about seeing the first upload of this video

[@gaminghunt5837]

@@TheMixxon2 he re-uploaded.

[@TheMixxon2]

@@gaminghunt5837 why are you say it as if I don't know that ? have you like read what I said ? I think it explicitly shows that I am and was more than aware that this was a re-upload :)

[@gaminghunt5837]

@@TheMixxon2 whoa! I was just fooling around.