I strongly suggest that anyone interested in Feynman Diagrams reads Feynman's book "QED: the strange theory of light and matter". Heck, I suggest that you read it even if your not interested in Feynman Diagrams, it's a fantastic book.
Perry Turner I second that. What a brilliant and suprisingly small book. Leaves you feeling alike a genius (until you try to explain it to someone else lol). You certainly learn a lot about the seemingly impenetrable topic of light and photons.
The man at 0:25 is an excellent communicator. His voice is so calming and clear, and his face is so kind and empathetic. He gives off an auroa of safety and intellect which I love. Extremely attractive and a great quality to have.
+Logan Retamoza I completely agree. His name's Ed Copeland, which is usually mentioned in the video descriptions but isn't in this one, for some reason.
I love the honesty of the first person in the video saying that he could not fully understand it... Only great men have the perspective of their standing!!!
I remember learning of Feynman diagrams from a documentary about six years ago on his life and teachings. What a fantastic man, with an amazing mind and a true, raw passion for science.
+Popo Le'Atheist His main element of genius was his angle of reference. He saw things in a very different way. Check out their video of Feynmann's Safe cracking.
Awesome tabletop diagrams! I love Feynman diagrams; they make me feel like I can almost understand what's going on. The videos of Feynman's Auckland lectures in which he explains and demonstrates them are not to be missed!
Can i just say, yes you are! You've helped so many people love physics, given even more a great understanding of it, and given people hours of entertainment. If i could, i'd name an element after you.
A lot of physics feels like something you could work out if you really tried. Then there is Feynman diagrams. I don't think I'd be able to come up with something like this if I thought about it for a million years
Yeah, like you could come up with relativity, or even Newtonian gravity. Those unique thoughts are only reserved for the most brilliant ones, and trust me, if you are commenting that here you are not one of them.
The first time I was introduced to Feynman Diagrams 40 years ago, I was blown away. One particular diagram caught me by surprise.It describe a particle and an anti-particle producing a photon which emitted an electron. Now that I vaguely understand virtual particles and vacuum quantum fields and the Higgs fields, I can understand why I was surprised, how original his diagrams were. I have no doubt that his diagrams will be key to understand the mysteries of not only dark matter and dark energy, but an unified theory.
Feynman Diagrams come from the Interaction Lagrangian for Quantum Field Theory. The Dirac Lagrangian density is first made Imaginary using the Hermitian Conjugate Operator. From there we get the standard Hamiltonian Density and using the S-matrix we can do a the Wick Expansion to get the propogation terms that satisfies the initial particle state the best. the Feynman Diagram is then in correspondence with the term selected, and then use the Feynman Rules to compute the Probability Amplitude.
Whats funny is that this video was published in June of 2010... The Higgs boson was discovered on 4 July 2012 - 2 years later! Feynman's Diagrams were used to express its existence!
A particle is an excitation of its own field, a photon can jump into existence because the energy in the interaction between the particles generated enough energy to excite the electromagnetic field. This is why light bulbs or fluorescent tubes can generate light from just running electricity through it. Different fields have different energy requirements in order to cause particles to pop into existence, and this is kinda why particle colliders have to get increasingly more powerful.
@puncheex, I might be wrong, but I think that in addition to diagrams discussed here, where particles move forward in time, there are diagrams where some partcles move back in time, coming from the future and moving into the past. I belive this has something to do with the difficulties of accepting the diagrams. Right now, the accepted opinion is that particles don't move backwards in time, but behave "as if" they do.
Wonderful one of my favourites. Feynman has always been my physics hero and have read a lot of books about him and by him, also some amazing lectures he did in New Zealand. For anyone struggling with these concepts i would recommend the New Zealand lectures and the book Genius by James Gleick, the lectures by Feynman because they are derived from his thoughts and Genius because it puts these ideas and the roots of quantum mechanics in context, showing the evolution of his ideas and others. It can be very difficult to understand without a context in my opinion.
In Feynman's view of quantum mechanics particles can move forward and backwards in time. Those that move forward are particles; those that move backwards are their antiparticles with all the opposite attributes: an electron has a negative charge and an electron number of 1, its antiparticle has a postiive charge and an electron number of -1.
I learned how to do Feynman Diagrams in high school... feels melancholy though, as the physics is ridiculously interesting, yet the ideas are devilishly complex. Damned IB HL Physics.
If anyone needs some more technical details about the diagram, without drowning in them, i suggest Prof. Susskind's lecture on string theory and also the lecture about higgs boson. But for a smooth survey this video is just great. thanks for sharing.
Feynman's way of simplifying complex things. was incredible! I listened to "The Feynman Lectures on Physics" as a 15-year old, and I had no problem understanding everything
Frank R. Haugen Professors generally do explain things in an easy to understand way. That's how they became professors. They know the subject so well, that they can leave out the less important bits and give you the gist of it, and the gist is accurate and simple. If someone didn't understand the whole thing, they would maybe need to include the entirety of a complex subsystem in their explanation, because they don't understand the basic input and output of that system. I.e. if you want to explain string concatenation, you could say 1. This function takes two strings and returns a single string consisting of the two in sequence. or 2. The concatenation function takes an input of two strings, and it creates a new string in memory the size of the combined length of the two input strings, where it first inserts the first string at position 0, and then inserts the second string at the position just after the first string. It then presents this data as a single string. They are both correct, but one of them is easy to understand for its purpose. The other one is only necessary to know about if you do any work near the same level of detail, for instance you need to know how much memory the string concatenation uses.
A nice thing about FDs is that you can read them any other way. If you reverse the time scale a positron is an electron going back in time, for instance.
that diagram is of a slightly different notation to what the guy demonstrates on the table. Time runs from left to right. The interaction is in the middle. Since the positron (e+) is an anti particle, it is by convention drawn with the arrow going backwards in time. Same goes for the anti-quark on the right. This is because charge must be a conserved quantity, and the photon is not a charge carrying boson, so the -1 charge from the electron must leave via the positron, using the reverse arrow.
Sometimes the photon decays back into an electron-positron pair, but their attraction means their velocities are reduced as they move apart. This energy is emitted as a lower-energy photon. Apart from that, the electron-electron repulsion diagram is the electron-positron collision diagram turned sideways. In this sense, a positron is an electron moving backwards in time!
Correct me if I'm wrong but there is one technical inaccuracy in saying that antimatter moves back in time. In quantum field theory we get positive energy solutions (usual particles) and negative energy solutions. Negative energy solutions behave as if they were propagating backward in time. But they are not antiparticles, they are just the "negative-energy particles".
The force is 'apparently' continuous but actually it's actually a discrete force. The image that I carry is the "pig pen" electron is continuously emitting and reabsorbing photons as it moves along. The closer it approaches another electron, the higher the probability that a photon will be exchanged.
@Kargoneth quantum mechanics is difficult to describe, and if you try, it gets confusing. the thing is that electrons constantly emit virtual photons, and if they dont hit anything they never really come into existence. now when two electrons approach each other, some of these virtual photons will hit something, namely the other electron. now they have a real effect, the electrons now exchange real photons, which carry momentum. so the electrons exchange momentum like in a collision.
@Kargoneth also, the feynman diagram of the collision of two electrons is a simplification. actually its one photon going from one electron to the other, and another photon going in the opposite way. but the mathematics allow the simplification, that exchange of a pair of photons is really equivalent to the horizontal wavy line in the diagram. anyway, the photons really dont need to be clever.
Also note that this diagram can exist with a Zo boson instead of the photon which still conserves charge. I prefer Feynmann's original notation to this one. To get it, flip the whole diagram 90 degrees anti clockwise, and then flip the photon another 90 degrees. You can also (like the guy did on the table) tilt the photon upwards to represent the fact that it is not an instantaneous interaction (travels at speed of light or slower) but this is not important and is up to the individual.
Repulsion is an effect which emerges from the diagrams, it isn't assumed going in, or even meaningful when creating a diagram. The video leaves out many things required to actually use a diagram and come out with some numbers. For instance, the junctions in the diagrams are not really representative of an exact location but are taken to represent all possible locations for that junction, which is everywhere and every time. However, some locations and times are far more probable than others.
I could, but there is not enough space here. Feynman imagined a particle staring at one point in space-time travelling to another point and imagined the particle taking all possible paths between them. For each path he worked out a quantity called the ``action'' , A, and divided it by Plank's constant. From the sum over all paths of exp(iA/hbar) he could work out the probability of an event happening. His approach gives ordinary quantum mechanics as taught to students. But it gives lots more.
there are various rules which need to be conserved, it's similar to momentum in that the production of a muon and antimuon, charge will be conserved (both will be 0 or both will be +1 -1) and the 'lepton' number (amount of 'electron-esque' molecules) will be conserved at +1 -1 being 0, producing two baryons of +1 -1 conserving the baryon number sorry if you don't understand that, it's the best I can do I'm afraid :p
"Do you have any Idea what would cause a particle to emit a cloud of photons? " It's a consequence of the uncertainty principle. You can never determine a particle's kinetic energy with 100% precision, it is always fluctuating. But, due to the conservation of mass/energy total mass/energy must remain the same. That means for each downward fluctuation in the particle's mass/energy it must emit a photon and eventually that photon will collide back with the electron and repay the "energy debt".
Antiparticles are positive energy solutions, and they are obtained by acting with charge conjugation operator on the negative-energy solutions. So, antiparticles move forward in time, as usual particles.
If you see the diagram of the Feynmann diagram on wikipedia, an electron annihilates a positron to release a photon which then produces a quark, antiquark and later a gluon. The thing I don't understand is the direction of the arrow on the positron and the anti-quark. Why does it oppose the direction of time? Or does the direction simply indicate the value of the positron (i.e. negative value)? and not the direction of movement.
Maybe I am not understanding this correctly. Repulsion is a continuous force, that strengthens as two particles get closer. So there cannot simply be one photon in the quantum mechanical process because there needs to be an acceleration, not just an impulse at a certain distance. Is there a near infinite stream of "photons" being emitted at all times, with more hitting as they get closer?
Didn't they use Feynman diagram to determine what particles to collide in order to elicit a Higgs boson? (And where to look for it.) Am I understanding that correctly?
When the particles come close one another, a photon is emitted, which then pushes the particles apart without them touching; does this mean that light has mass? That light can actually effect something by means of a force?
Bowleyium would not sound good, and Rogerium sounds rude. Perhaps Martynium Polyakoffium would be better. I hope to do another 60symbols video this week to entertain and inform you about momentum, or if you prefer an element how about momentumium? Thank you for your kind comments.
The diagram at 1:12 seems incorrect (if I understand the concept correctly). Either e- is interacting with q- and resulting in e+, q, etc.; in which case the particle directions are correct, but the representation of time should be vertical, flowing from top to bottom. Or it is representing an electron colliding with an anti-electron, creating energy, resulting the formation of q-, q, etc. Which means time is represented correctly, but e+ and q- need to switch directions (seems most likely).
@Kargoneth third comment... and if you want to know more about these virtual particles, how long they can exist and how far they can move, you need heisenbergs uncertainty principle. you cannot exactly tell where an electron is, due to heisenbergs uncertainty principle you get a volume where the electron will most likely be, and thats the volume that is filled by those virtual photons surrounding the electron. they cannot violate the principle so they cannot be anywhere else.
@mcmurder3 unless you're doing it wrong. If a truck destined south is going north, it doesn't matter how fast the truck is going. (infinite plane uniform density)
Back when I was in high school - or rather, its equivalent - we did basic quantum mechanics, including QED (and QCD, wave-particle duality, et cetera).
I had a professor who is a bit like that, when ever I asked him about any new findings in physics he says I'm too old to understand (or I'm retired) it's your turn to explain to me :)
What determines the energy of the photon in an interaction. In the case of two particles scattering, does the momentum of both particles change like a macroscopic elastic collision?
"The particle is whizzing along in time, but it says 'ooh I don't feel very nice, I feel a bit naked so I'll dress myself' so then we'll have one of those going along there" I never thought I'd learn about science by analogy of a camp subatomic particle
@djd904 Photons have zero rest mass. However, they do have energy. And energy and mass are essentially the same thing. So if an electron emits a photon it losses some energy and therefore it losses some mass.
BTW, I was trying to understand relativity, if we think the movement of particle in 2 dimensions(1 for time) at speed of C and C is the limit speed we accept that, when particle starts moving on space dimension, it have to lose speed in time dimension to keep the length total vector of space-time movement at C. I still dont get it, I get it mechanically and mathematically, but not intuitively enough.
No, the process you are imaging is a ball beign tossed ? Because it is not that. Just think about the photon as the agent who pass the information about the position of the particles. If the photon was carrying momentum to the other particle the way you thougth, then how could particles wth different atrract each other ?
It depends on the energy of elextron and positron. In the Quantum field theory it can be only one photon but the possibilities are two or more. If they have high kinetic energy they can produce mesons or netrino... (sorry for my english I don't speak this languague very well :/)
Something thats not mentioned here (and probably for good reason) is that in the electron and positron collision the line drawn for the positron is pointing backwards with regard to the time axis. Ill just leave that fact here to boggle your minds.
Since positron-electron annihilation mostly results in two 511keV anti-parallel photon emissions, isn't the bit at 3:45 misleading? I don't deal with Feynman diagrams, but I do deal with the anti-parallel emissions in mt research (modelling in positron emission tomography). I should go and check this myself, but just thought I'd make this comment.
A wee bit confused with this one, at the start it said when the get close but never collide it moves of equidistant to each other, then on the other breathe it says when they collide it moves this way, if there is no potential then it won't move,if there is potential then it move to the greater potential, flow will only flow if the potential is there, therefore this Therom is liking riding a bike in a ballon in space,are you peddling or is the potential moving the pedals? Wait there is no potential in space is there?
@BSZanatsu Rocket engines work by expelling propellant mass at stupendous speed and thus pushing the engine in the opposite direction in accordance with Newton's 3rd law and all that.
So... I'm in year 9, about to start my IGCSE course in science, and I know a considerable amount of particle physics and quantum physics. I just want to know, are these things really taught in higher level studies and, in that case am I giving myself a head start or doing something that may not have any proper implication to my studies?
i dont understand. you say you are doing particle physics but you want to skip doing feynman diagrams because . . . you might not need it? You shouldn't be doing particle physics unless you love it and that means of course you want to study the feynman diagrams. The only people who use feynman diagrams are those who actually study particle physics at a graduate level or above, so no you probably don't need it.
I strongly suggest that anyone interested in Feynman Diagrams reads Feynman's book "QED: the strange theory of light and matter". Heck, I suggest that you read it even if your not interested in Feynman Diagrams, it's a fantastic book.
Perry Turner I second that. What a brilliant and suprisingly small book. Leaves you feeling alike a genius (until you try to explain it to someone else lol). You certainly learn a lot about the seemingly impenetrable topic of light and photons.
+Perry Turner
Thanks :)
Will read.
On top of this, the QED lectures from the 70s are on UA-cam and are amazing.
somsoc I didn't realize that! Gonna go find those now.
he was a fine man.
The man at 0:25 is an excellent communicator. His voice is so calming and clear, and his face is so kind and empathetic.
He gives off an auroa of safety and intellect which I love. Extremely attractive and a great quality to have.
+Logan Retamoza I completely agree. His name's Ed Copeland, which is usually mentioned in the video descriptions but isn't in this one, for some reason.
Isn't it amazing that humans can study and understand concepts this complex? These videos completely blow me away.
I love the honesty of the first person in the video saying that he could not fully understand it... Only great men have the perspective of their standing!!!
I remember learning of Feynman diagrams from a documentary about six years ago on his life and teachings. What a fantastic man, with an amazing mind and a true, raw passion for science.
+Popo Le'Atheist
His main element of genius was his angle of reference. He saw things in a very different way. Check out their video of Feynmann's Safe cracking.
I'm not a physicist, after high-school was afraid of it and because of this lectures I'm addicted to it. Thanks a lot to all who contribute!
np
Awesome tabletop diagrams! I love Feynman diagrams; they make me feel like I can almost understand what's going on. The videos of Feynman's Auckland lectures in which he explains and demonstrates them are not to be missed!
Can i just say, yes you are! You've helped so many people love physics, given even more a great understanding of it, and given people hours of entertainment. If i could, i'd name an element after you.
I had a hard time understanding this ...
Richard Feynman Surely You're Joking, Mr. Feynman!
That's funny because I'm reading that book now! It's awesome! RayJan Richard Feynman
Nobody understands this.
@@khellil2 amazing!
A lot of physics feels like something you could work out if you really tried. Then there is Feynman diagrams. I don't think I'd be able to come up with something like this if I thought about it for a million years
Yeah, like you could come up with relativity, or even Newtonian gravity. Those unique thoughts are only reserved for the most brilliant ones, and trust me, if you are commenting that here you are not one of them.
I am always blown away by the quality of these videos.
The first time I was introduced to Feynman Diagrams 40 years ago, I was blown away. One particular diagram caught me by surprise.It describe a particle and an anti-particle producing a photon which emitted an electron. Now that I vaguely understand virtual particles and vacuum quantum fields and the Higgs fields, I can understand why I was surprised, how original his diagrams were. I have no doubt that his diagrams will be key to understand the mysteries of not only dark matter and dark energy, but an unified theory.
Amazing we used these last year of high school. How something complicated can be explained in simple andbeautiful diagrams is amazing!
Feynman Diagrams come from the Interaction Lagrangian for Quantum Field Theory. The Dirac Lagrangian density is first made Imaginary using the Hermitian Conjugate Operator. From there we get the standard Hamiltonian Density and using the S-matrix we can do a the Wick Expansion to get the propogation terms that satisfies the initial particle state the best. the Feynman Diagram is then in correspondence with the term selected, and then use the Feynman Rules to compute the Probability Amplitude.
Whats funny is that this video was published in June of 2010... The Higgs boson was discovered on 4 July 2012
- 2 years later! Feynman's Diagrams were used to express its existence!
A particle is an excitation of its own field, a photon can jump into existence because the energy in the interaction between the particles generated enough energy to excite the electromagnetic field. This is why light bulbs or fluorescent tubes can generate light from just running electricity through it. Different fields have different energy requirements in order to cause particles to pop into existence, and this is kinda why particle colliders have to get increasingly more powerful.
@puncheex, I might be wrong, but I think that in addition to diagrams discussed here, where particles move forward in time, there are diagrams where some partcles move back in time, coming from the future and moving into the past.
I belive this has something to do with the difficulties of accepting the diagrams.
Right now, the accepted opinion is that particles don't move backwards in time, but behave "as if" they do.
Wonderful one of my favourites. Feynman has always been my physics hero and have read a lot of books about him and by him, also some amazing lectures he did in New Zealand. For anyone struggling with these concepts i would recommend the New Zealand lectures and the book Genius by James Gleick, the lectures by Feynman because they are derived from his thoughts and Genius because it puts these ideas and the roots of quantum mechanics in context, showing the evolution of his ideas and others. It can be very difficult to understand without a context in my opinion.
In Feynman's view of quantum mechanics particles can move forward and backwards in time. Those that move forward are particles; those that move backwards are their antiparticles with all the opposite attributes: an electron has a negative charge and an electron number of 1, its antiparticle has a postiive charge and an electron number of -1.
i am doing this is AS physics at the moment and this helped me so much, thank you.
I learned how to do Feynman Diagrams in high school... feels melancholy though, as the physics is ridiculously interesting, yet the ideas are devilishly complex. Damned IB HL Physics.
All science is
If you've found a science that is simple then it's probably an arts subject :P
omg im doing IB physics rn!!!
@@xoxoxoxoxoxoxo6921 lol why didnt u do a level
I’m doing topic 7 right now, and I’m actually loving it
If anyone needs some more technical details about the diagram, without drowning in them, i suggest Prof. Susskind's lecture on string theory and also the lecture about higgs boson. But for a smooth survey this video is just great. thanks for sharing.
why is it even though i don't understand a word, I still find these videos fascinating?
Feynman's way of simplifying complex things. was incredible!
I listened to "The Feynman Lectures on Physics" as a 15-year old, and I had no problem understanding everything
wow, you must be such a genious
Angelo Zamudio I wish. He was a great teacher, and I just curious about physics. The actual mathematics of the physics is beyond me :-(
Frank R. Haugen Professors generally do explain things in an easy to understand way. That's how they became professors. They know the subject so well, that they can leave out the less important bits and give you the gist of it, and the gist is accurate and simple. If someone didn't understand the whole thing, they would maybe need to include the entirety of a complex subsystem in their explanation, because they don't understand the basic input and output of that system.
I.e. if you want to explain string concatenation, you could say
1. This function takes two strings and returns a single string consisting of the two in sequence.
or
2. The concatenation function takes an input of two strings, and it creates a new string in memory the size of the combined length of the two input strings, where it first inserts the first string at position 0, and then inserts the second string at the position just after the first string. It then presents this data as a single string.
They are both correct, but one of them is easy to understand for its purpose. The other one is only necessary to know about if you do any work near the same level of detail, for instance you need to know how much memory the string concatenation uses.
"listened to"? i don't know where you can listen to them because the Feynman Lectures are a book series.
johnx4224 Audio books maybe?
A nice thing about FDs is that you can read them any other way. If you reverse the time scale a positron is an electron going back in time, for instance.
that diagram is of a slightly different notation to what the guy demonstrates on the table. Time runs from left to right. The interaction is in the middle. Since the positron (e+) is an anti particle, it is by convention drawn with the arrow going backwards in time. Same goes for the anti-quark on the right. This is because charge must be a conserved quantity, and the photon is not a charge carrying boson, so the -1 charge from the electron must leave via the positron, using the reverse arrow.
Is it true that Richard Feynman called it "The Diagram"?
I really love this comment for all of its philosophical glory.
Yes because he didn’t believe in names
Sometimes the photon decays back into an electron-positron pair, but their attraction means their velocities are reduced as they move apart. This energy is emitted as a lower-energy photon. Apart from that, the electron-electron repulsion diagram is the electron-positron collision diagram turned sideways. In this sense, a positron is an electron moving backwards in time!
Correct me if I'm wrong but there is one technical inaccuracy in saying that antimatter moves back in time. In quantum field theory we get positive energy solutions (usual particles) and negative energy solutions. Negative energy solutions behave as if they were propagating backward in time. But they are not antiparticles, they are just the "negative-energy particles".
The force is 'apparently' continuous but actually it's actually a discrete force.
The image that I carry is the "pig pen" electron is continuously emitting and reabsorbing photons as it moves along. The closer it approaches another electron, the higher the probability that a photon will be exchanged.
@Kargoneth
quantum mechanics is difficult to describe, and if you try, it gets confusing. the thing is that electrons constantly emit virtual photons, and if they dont hit anything they never really come into existence. now when two electrons approach each other, some of these virtual photons will hit something, namely the other electron. now they have a real effect, the electrons now exchange real photons, which carry momentum. so the electrons exchange momentum like in a collision.
I'm suppose to be doing my trig pre-cal homework, and this is what I'm watching :D
@Kargoneth
also, the feynman diagram of the collision of two electrons is a simplification. actually its one photon going from one electron to the other, and another photon going in the opposite way. but the mathematics allow the simplification, that exchange of a pair of photons is really equivalent to the horizontal wavy line in the diagram.
anyway, the photons really dont need to be clever.
Feynman was a magician.... He was the greatest of them all. Salute to him
Also note that this diagram can exist with a Zo boson instead of the photon which still conserves charge. I prefer Feynmann's original notation to this one. To get it, flip the whole diagram 90 degrees anti clockwise, and then flip the photon another 90 degrees. You can also (like the guy did on the table) tilt the photon upwards to represent the fact that it is not an instantaneous interaction (travels at speed of light or slower) but this is not important and is up to the individual.
Repulsion is an effect which emerges from the diagrams, it isn't assumed going in, or even meaningful when creating a diagram.
The video leaves out many things required to actually use a diagram and come out with some numbers. For instance, the junctions in the diagrams are not really representative of an exact location but are taken to represent all possible locations for that junction, which is everywhere and every time. However, some locations and times are far more probable than others.
I love these videos, the comments can be just as interesting.
I could, but there is not enough space here.
Feynman imagined a particle staring at one point in space-time travelling to another point and imagined the particle taking all possible paths between them. For each path he worked out a quantity called the ``action'' , A, and divided it by Plank's constant. From the sum over all paths of exp(iA/hbar) he could work out the probability of an event happening. His approach gives ordinary quantum mechanics as taught to students. But it gives lots more.
there are various rules which need to be conserved, it's similar to momentum in that the production of a muon and antimuon, charge will be conserved (both will be 0 or both will be +1 -1) and the 'lepton' number (amount of 'electron-esque' molecules) will be conserved at +1 -1 being 0, producing two baryons of +1 -1 conserving the baryon number
sorry if you don't understand that, it's the best I can do I'm afraid :p
Your syntax is exceptional.
Thank you so much. I am not a scientist. You explained this so well that I understood it.
@meekmoe there is no mistake there. It shows interraction of electron and positron which then produse quarq and antiquarq. Sorry for bad english
"Do you have any Idea what would cause a particle to emit a cloud of photons? "
It's a consequence of the uncertainty principle.
You can never determine a particle's kinetic energy with 100% precision, it is always fluctuating. But, due to the conservation of mass/energy total mass/energy must remain the same. That means for each downward fluctuation in the particle's mass/energy it must emit a photon and eventually that photon will collide back with the electron and repay the "energy debt".
Antiparticles are positive energy solutions, and they are obtained by acting with charge conjugation operator on the negative-energy solutions. So, antiparticles move forward in time, as usual particles.
Understanding how little you know, it the beginning of true wisdom.
If you see the diagram of the Feynmann diagram on wikipedia, an electron annihilates a positron to release a photon which then produces a quark, antiquark and later a gluon. The thing I don't understand is the direction of the arrow on the positron and the anti-quark. Why does it oppose the direction of time? Or does the direction simply indicate the value of the positron (i.e. negative value)? and not the direction of movement.
That is an exceptional example of a fragment.
Maybe I am not understanding this correctly. Repulsion is a continuous force, that strengthens as two particles get closer. So there cannot simply be one photon in the quantum mechanical process because there needs to be an acceleration, not just an impulse at a certain distance. Is there a near infinite stream of "photons" being emitted at all times, with more hitting as they get closer?
Didn't they use Feynman diagram to determine what particles to collide in order to elicit a Higgs boson? (And where to look for it.) Am I understanding that correctly?
And you were undoubtedly learning more.
I like the fact that both professors tried to use ANALOGIES to explain the concept.
When the particles come close one another, a photon is emitted, which then pushes the particles apart without them touching; does this mean that light has mass? That light can actually effect something by means of a force?
I saw Feynman diagramms in my physics book, but there was no explenation what they mean. Not that I'll ever use them but I needed this:D
Bowleyium would not sound good, and Rogerium sounds rude. Perhaps Martynium Polyakoffium would be better.
I hope to do another 60symbols video this week to entertain and inform you about momentum, or if you prefer an element how about momentumium?
Thank you for your kind comments.
Particles go in, particles go out.
You can't explain that!
vote for the pixiedust party. we will make a whole bunch of shiny new hospitals, and reduce the debt and uh taxes, at the same time, uh somehow.
These must but O'reily's Diagrams
Bread goes in, toast comes out, but where does the bread go?
Felony Videos Ironically, it makes sense :)))
@@FelonyVideos The bread could take many different routes, and we can calculate the probability of those routes.
The diagram at 1:12 seems incorrect (if I understand the concept correctly). Either e- is interacting with q- and resulting in e+, q, etc.; in which case the particle directions are correct, but the representation of time should be vertical, flowing from top to bottom. Or it is representing an electron colliding with an anti-electron, creating energy, resulting the formation of q-, q, etc. Which means time is represented correctly, but e+ and q- need to switch directions (seems most likely).
@Kargoneth
third comment...
and if you want to know more about these virtual particles, how long they can exist and how far they can move, you need heisenbergs uncertainty principle. you cannot exactly tell where an electron is, due to heisenbergs uncertainty principle you get a volume where the electron will most likely be, and thats the volume that is filled by those virtual photons surrounding the electron. they cannot violate the principle so they cannot be anywhere else.
@mcmurder3 unless you're doing it wrong. If a truck destined south is going north, it doesn't matter how fast the truck is going. (infinite plane uniform density)
2, so that momentum can be conserved. The two photons are of equal energy, and move in opposite directions.
Back when I was in high school - or rather, its equivalent - we did basic quantum mechanics, including QED (and QCD, wave-particle duality, et cetera).
I had a professor who is a bit like that, when ever I asked him about any new findings in physics he says I'm too old to understand (or I'm retired) it's your turn to explain to me :)
What determines the energy of the photon in an interaction. In the case of two particles scattering, does the momentum of both particles change like a macroscopic elastic collision?
if periodic table of videos' crew and sixty symbols' crew did a collab video I'm sure it would be EPIC
Hey, it was one of these things that stumped Sheldon (and Leonard et al) in the PMS vs AA episode of the Big Bang Theory. Fun fun.
Being exceptional is an exception, to the exceptionalists
"The particle is whizzing along in time, but it says 'ooh I don't feel very nice, I feel a bit naked so I'll dress myself' so then we'll have one of those going along there"
I never thought I'd learn about science by analogy of a camp subatomic particle
@djd904
Photons have zero rest mass.
However, they do have energy. And energy and mass are essentially the same thing. So if an electron emits a photon it losses some energy and therefore it losses some mass.
What an exceptional sentence fragment!
Feynman was an absolute legend.
BTW, I was trying to understand relativity, if we think the movement of particle in 2 dimensions(1 for time) at speed of C and C is the limit speed we accept that, when particle starts moving on space dimension, it have to lose speed in time dimension to keep the length total vector of space-time movement at C. I still dont get it, I get it mechanically and mathematically, but not intuitively enough.
Another great lesson learned from Sixty Symbols, thanks guys!!!
That was an exceptional complete sentence.
How do you draw diagram for particles with attractive interaction, such as proton to electron?
is it related to a PET scan because positron reacts with the electron and then it produces a gamma ray ?
It's also learning,but in a much better and fun way.
I bought richard feynmans lectures on geometrical optics , clever fellow .
No, the process you are imaging is a ball beign tossed ? Because it is not that. Just think about the photon as the agent who pass the information about the position of the particles.
If the photon was carrying momentum to the other particle the way you thougth, then how could particles wth different atrract each other ?
It depends on the energy of elextron and positron. In the Quantum field theory it can be only one photon but the possibilities are two or more. If they have high kinetic energy they can produce mesons or netrino... (sorry for my english I don't speak this languague very well :/)
Something thats not mentioned here (and probably for good reason) is that in the electron and positron collision the line drawn for the positron is pointing backwards with regard to the time axis.
Ill just leave that fact here to boggle your minds.
I would love it if they added one of those "extrmely complicated diagrams" to the video. Wouldl like to see one.
No your English is very good!! I am an English teacher as well as a physicist, where are you from?
Since positron-electron annihilation mostly results in two 511keV anti-parallel photon emissions, isn't the bit at 3:45 misleading? I don't deal with Feynman diagrams, but I do deal with the anti-parallel emissions in mt research (modelling in positron emission tomography).
I should go and check this myself, but just thought I'd make this comment.
Electrons are so tiny tiny... How often do they collide or come near enough to be called a collision 💥
A very nice explanation of a difficult concept, well done!
So when the particles move closer or further apart in the feynman diagrams does that represent them coming closer together in space?
Yes
Why does the energy released in the electron/antielectron reaction decay into other particles?
Great for A-level physics!! Thanks
Particles go in, particles go out. You can't explain that! (Well, I guess you can, to an extent.)
Nice video!
Feynman was a brilliant man
A wee bit confused with this one, at the start it said when the get close but never collide it moves of equidistant to each other, then on the other breathe it says when they collide it moves this way, if there is no potential then it won't move,if there is potential then it move to the greater potential, flow will only flow if the potential is there, therefore this Therom is liking riding a bike in a ballon in space,are you peddling or is the potential moving the pedals? Wait there is no potential in space is there?
@BSZanatsu Rocket engines work by expelling propellant mass at stupendous speed and thus pushing the engine in the opposite direction in accordance with Newton's 3rd law and all that.
Great visual discription.
Great Introduction!
So... I'm in year 9, about to start my IGCSE course in science, and I know a considerable amount of particle physics and quantum physics. I just want to know, are these things really taught in higher level studies and, in that case am I giving myself a head start or doing something that may not have any proper implication to my studies?
i dont understand. you say you are doing particle physics but you want to skip doing feynman diagrams because . . . you might not need it? You shouldn't be doing particle physics unless you love it and that means of course you want to study the feynman diagrams. The only people who use feynman diagrams are those who actually study particle physics at a graduate level or above, so no you probably don't need it.
I love this channel. Thank you for posting.
@MisterGibs Thanks for the responce. I should have known that.. heh.
Do you have any Idea what would cause a particle to emit a cloud of photons?
This is one of the videos where I feel like I need a full physics class for.
@bherkert They do "collab", its called Nottingham university.
Wouldn't the results vary if your wire spools don't have equal amounts of wire on them?
2:30 Where does the photon come from when it's emitted? It can't just jump into existence, can it? Could someone explain, please?