I hope you like the video! A few clarifications: - This video was originally created in 2018, before I studied theoretical physics, which is why the content might not be as precise as the other more recent videos. - Many people are asking how the "playing catch" analogy can explain attraction forces. This is indeed the limit of the analogy. At the quantum scale, virtual particles are really just waves that are spread throughout all space. Therefore they can carry a momentum in any direction, which can have the effect of attracting or repelling particles. - In the stationary wire, many people are asking why the electrons are not contracted since they are moving. They indeed are contracted, but we consider that they were carefully spaced such that, when contracted, the wire has no electric charge. - At the end of the video, electromagnetic waves propagate at the speed of "real photons", and not "virtual photons"
Hi, I'd like to ask you to clarify even better the stationary wire problem. You say that electrons are contracted in such a way that the electric charge is zero when electrons are moving, but claiming so it should imply that when they are not moving they should be even more spaced out (less contracted), which means that the wire has less electron density than proton density in this case. How can the electron density be always the same (resulting in a no electric charged wire) if there is contraction when electrons are moving and no contraction when they're not moving?
For those, who have a question which I had "how did these electrons become 'spaced' just by applying current?", there is a good analogy: car traffic becomes more spaced after traffic lights turn green, because the first car started moving earlier than the second one, the second one earlier than the third one and so on. Just like cars, some electrons are affected by the electric force that creates current earlier than the other ones, since electric force is not immediate and propagates from some point (or multiple points) with the speed of light. And just as I wrote that, another question arose: where do electrons find this 'extra space' if they didn't have it initially? Unlike cars, there is no 'first electron' with empty space in front. Also, electrons on the 'forward front' of electric field propagation start moving earlier than ones in front of them, creating an even denser volume of elecrons which can also play the role just after the current started. I'm confused(
I get the part about the virtual photons repelling electrons, but you didn't make an analogous model for the virtual photons to cause electrons and protons to attract. What causes this attraction?
Every time I asked my professors at college why exactly the electric force (the movement of electrons) produces a magnetic force, none bothered at all to tell me anything and always told me to just accept it. This video finally made me understand how magnetism arises. I am eternally grateful for these videos that come from the best channel on TH-cam. This is pure educational quality.
The fact that it requires Relativity (even if the simplified case of Special Relativity, GR doesn't mix well with QM yet) probably spooked your teachers. Most people, even educated ones, have serious trouble with Relativity, more so at mixing it with Quantum Mechanics, which at the core remains an unsolved problem. Maxwell himself necessarily did not understand the "how" it happens (he inspired Einstein and not the other way around) but only the "what" happens.
@@LuisAldamiz *Special* relativity has been fully integrated with quantim mechanics, it's called Quantum Field Theory. It's only general relativity (the one about gravity) that is problematic with QM.
We've come across the "moving current in a wire" explanation to unifying electric and magnetic fields frequently in textbooks, web pages, forums, etc., and yet nowhere was it presented as simply or intuitively as it was here. Blew us away. Really fantastic job!
I'm an electrician, and theory (D/C Theory, then A/C Theory 1, followed by A/C Theory 2), was part of the required education & class work as an apprentice. Even though I did well in the classes and have a strong understanding of the subject matter, this video (like all your other vids), is so good at explaining complex concepts in a simple and intuitive way, that I now have a broader, deeper, and better understanding of it. Your videos are definitely the best science vids on here. Well done! (And thank you!)
@@kevinflaherty1 so what? You’re jealous of people who pass such high classes that you decide to use the elementary school method of calling them a nerd?
When someone calls you a nerd, they just can’t accept that you may be more intelligent than them. So they find ways to insult you and get more attention for themselves
Modern science isn't correct..... All energy and matter in one simple explanation.... here goes... First we have a radio wave all the way to gamma waves which in turn create hydrogen then from there everything is basically a compound of hydrogen and will decay back to hydrogen before turning back to gamma waves..... There are no free moving electrons within matter.... I use this analogy to simplify it in my mind..... imagine a line of people standing a mile long (each person represents a copper atom in a wire) the first person starts a Mexican wave at one end ( the source ) , as the information propagates along the line ( by exciting each atoms magnetic field ) you would see an continuous wave of the peoples arms transferring the charge/information back and forth but the atoms and electrons don't actually move at all..... Think about it, from the source where electricity is "generated" to the ultimate end use, there's various breaks in chain of that electricity, it goes through controllers, transformers, all sort of components.... the transmission happens because of the magnetic field strength of the atoms in the wire being increased and decreased, not because of an actual "electron" flowing anywhere....
This channel offers some of the best physics explanations I've ever heard and they're so so underrated. When is say underrated I really mean it. How can this channel not have millions of subscribers yet? Damn.
Thank you so much for making me finally understand the basic relationship between the electric and magnetic component of the electromagnetic force - brilliantly illustrated! I can't stress enough, how impactful your videos are. Literally have goosebumps while watching every upload. Thank you so much for what you are doing. By far - and I mean BY FAR - the best educational content of this genre on this platform!
Your videos are among my favorite scientific videos on YT. Every time i see a new upload i immediately cannot help but watch! Thank you for the informative and digestible content!
This is high key the best and most concise complete explanation of electromagnetism I've encountered. I also love that you completely avoided equations of any sort, and just went with a qualitative approach, which makes this video very approachable for anyone. Such a clean video and well-made video!
Your videos are so amazing not only because you illustrate and explain such complex topics in such understandable ways, but also because you bring up ideas that I've never even heard before. For some reason, even among science educators, you connect dots that are always left unconnected by others.
The single cleanest explanation of this phenomenon I've ever seen. Makes sense without the vector calc but can be used to introduce it. This will now be the way I proceed when teaching E&M.
You, sir, are actually amazing. I found you when I was confused about how electromagnetic waves were generated, and just started watching your videos. I went from ugh I have to learn this for my lectures to remembering why I found science so cool. Keep up the good work!!
Interesting that you _started_ with the virtual photon picture and then introduced fields as a way to think about these interactions. Usually we start with the fields and introduce virtual particles as a way to visualize the interactions of the fields.
And that's why I never actually understood how it worked until now (well, I'm not sudenly an expert now). Other explanations take fields as a given and just try to expand on them.
what do you mean field? Because if you mean Quantum Fields (Which the Electromagnetic and Electron Field are) then yes virtual particles are just visualizations of the interactions of the field.
When we learn of macroscopic things feeling electric forces, the electric field is seen as a bookkeeping device: They are the answer to the question "how much force is felt here?, regardless of the charge of a particle to feel it, which may or may not even exist here" Similarly, we can think of elementary particles, as tangible things that move around in understandable ways. When two electrons toss photons to each other, they create a recoil "force". Neat! Again, we build an electric field as a bookkeeping device. Maybe even a quantum electric field. That is a nice intuitive way to understand what is happening. But if I understand it correctly, physicists believe that the fields are more real than the particles, which are the bookkeeping devices. Because that belief fits better with what we know about reality. That might explain it: we want to be thaught in particles, because particles make sense to us, ...but we are thaught in fields by people who see the fields as real, and thus want to explain how the easy-to-understand particles come from them. We stuggle with the shift in perspective. ____________________________________________________________________________ I do not fully understand why fields must be real and not the particles. All below can be wrong and all sorts of ways. But here is what I understand of it: Macroscopic: The electric and magnetic fields can have ripples in them, that travel at the speed of light. This "light" can exist even without charges around at all. So it seems the fields aren't just bookkeeping the effect of charged things that exert force. The circuit of unknownsource-veritasium shows that you don't need charged particles to push on each other through a circuit. The effect of flipping a switch would have to take a light-year long detour to reach a lamp only one meter away, taking a year. But instead, the electromagnetic fields that live everywhere carry the signal to the lamp across the gap in the wire. Long before the edge of the circuit knows that something has changed. In general, I believe there are effects that an electrical circuit cannot predict, because the circuit exists in space, with the wires being close to each other and all that. Quantum: Virtual particles are weird particles. Two electrons tossing photons back and forth is fine, but the analogy breaks for an electron and a proton. When a proton catches a photon from an electron, it recoils towards the electron instead of away, and vice versa, and that is just weird. The relation between energy and lifetime comes from this: the virtual photon has to fly under the radar of heisenbergs uncertainty relation, which is a limit on what we can detect with accuracy and certainty. But why should it fly under the radar? Can't we sometimes see measurable photons being tossed back and forth, in a proper scientific experiment? I believe that charged particles don't glow, unless sped up or down. It is said that virtual photons aren't real photons. They are ripples, perturbations, in the quantum electromagnetic field. When those ripples exceed heisenbergs uncertainty relation, they are seen by detectors. And can thus be called "real" photons. Any other feature -- rippleshaped or not -- can be broken in a sum of smaller ripples, which we can argue are still photons -- ripples --, but they travel under the radar. This helps to calculate what the fields do in an interaction, by looking at scenarios of virtual particles doing what particles do. In theory, we need to mix all scenarios by likelyhood, to know what happens. In practice, we mix only the more likely scenarios as an approximation. Either way: the virtual particle is now the bookkeeping device, and the field is the real thing.
@@nielskorpel8860 you cannot detect them because they are pure nonsense. Photon exchanged between proton and electron has negative momentum for proton and positive momentum for electron. Another problem is - why does any field even exist? If it were for virtual particles to exist, you could imagine how in uniform electric field one pair of electron-positon popping out of nothingness, creating a circle, and then disappear. Not a big problem, but inside said circle, electric forces of the field are balanced out by formentioned particles. You create a "bubble" with no force at all. Now go on with as many bubbles you like, and whole field disappears! It's absurd, because there is no virtual photon or electron, but quantum field. And all the sudden it all makes sense.
@@Etrexum Actually, that's a far more accurate picture. The virtual particles are just oscilation in the underlying field. Oscilation caused by the real electron themselves. Nothing more.
This is one of the most deeply impactful videos I've ever watched, believe it or not. Absolute legend. 2 in the morning I realize I want to understand how nuclear reactors work (and expand from there into every fundamental aspect of electricity) and this was my starting point, how electromagnetic fields work and anything around it.
People need to understand that these descriptions are models. Models that can be worked with because they are mathematically correct. But nobody knows what these interactions really look like in reality. But all the more impressive I find this channel and the author, who really manages to present the phenomena of physics vividly. I learned years ago: "If someone can't explain something to you easily, then he hasn't understood it himself".
@@DrDeuteron Then what in the hell is a virtual photon ??? A photon that both repels and attracts ? Why would two same charges make possible fror them to appear ??? Also when you say something exists for such a short time it actually DOESN'T exist I'd say you got some nonsense on your hands .
@@alokinzna that's a good question. So in Quantum Electrodynamic (QED), one considers scattering amplitudes. E.g: Moeller scattering (e-e- --> e-e-) or Bhabha scattering (e-e+ --> e-e+), which differ by repulsion vs. attraction. In QED, the Feynman path integral says the EM/electron field takes all possible configuration between initial an final states...which is not solvable exactly. Instead, on considers "perturbation theory", and you approximate the exact solution with a power series in powers of the fine structure constant (alpha). The first term (called "tree level") has a configuration that is the exchange of a so-called virtual photon. That is what a virtual photon is. A term in a power series expansion of QED amplitude. At this level, repulsion or attraction isn't really a thing. If you look up Moeller and Bhabha scattering on wikepdia, they work out the amplitudes in QED, and you will see they depend on (iq)^2 with q = -e or q = +e as needed, and then to get a probability you square the magnitude of the complex amplitude, so the sign just disappears....nevertheless it works. Moreover, in Feynman diagrams, energy and momentum are conserved at all points in the diagram, so the virtual photon can have very unusual kinematics. For instance, for two electron scattering back-to-back in head on collision, the photon has zero energy buy large momentum. That means the mass squared in negative. weird for a photon. Meanwhile in electron positron annihilation in the same kinematics, the photon as huge energy and zero momentum...so it is at rest. Weird for a photon. Basically: the virtual photon can have negative, positive, or zero energy or momentum...so it repels if it needs to repel, and attracts if it needs to attract. So with that, virtual photons are just mathematical things that approximate quantum field configurations. It sounds like BS, but when you use them to calculate "the electron g-factor", experiment and theory agree to 13 (or 14) digits...which is the most accurate and precise calculation in ALL of science. It represents decades of theoretical and experimental work by hundreds (or more) people, and it is remarkable.
@@DrDeuteron You know this is sorta strange . When talking about gravity you can at least come across the terms Higgs field or Higgs boson . How is it that getting the details of magnetism is this difficult and obscure ? Is this a case where we have the detailed description in the form of math as to what is happening but don't know REALLY what is happening ?
@gohangoku3447 uff bro, so theoretical models for describing certain properties, processes, etc. of reality, conveyed through mathematically describtions, are actually just models? Wow, that's incredible? Thank you for explaining the most trivial aspect of this video and all of (natural) science
I never clicked so fast in a notification This is btw, and I mean literally, the B E S T visualization and explanation for both the electric field, but also for how virtual particles are supposed to carry force, simply amazing, bravo!
Amazing video. I understood how the virtual photon picture, with the recoil, can explain a repulsive force. But I find it hard to understand how the virtual photon explanation applies to an attractive force between opposite charges. By the time the video speaks about attraction between opposite charges, the virtual photon picture no longer makes an appearance.
@@elpak it looked like the attraction was depicted by two virtual photons being emitted simultaneously by the electron and proton, and then meeting in the middle. But yeah no intuitive explanation was given for the electromagnetic attraction as it relates to that illustration.
@@ScienceClicEN Modern science isn't correct..... All energy and matter in one simple explanation.... here goes... First we have a radio wave all the way to gamma waves which in turn create hydrogen then from there everything is basically a compound of hydrogen and will decay back to hydrogen before turning back to gamma waves..... There are no free moving electrons within matter.... I use this analogy to simplify it in my mind..... imagine a line of people standing a mile long (each person represents a copper atom in a wire) the first person starts a Mexican wave at one end ( the source ) , as the information propagates along the line ( by exciting each atoms magnetic field ) you would see an continuous wave of the peoples arms transferring the charge/information back and forth but the atoms and electrons don't actually move at all..... Think about it, from the source where electricity is "generated" to the ultimate end use, there's various breaks in chain of that electricity, it goes through controllers, transformers, all sort of components.... the transmission happens because of the magnetic field strength of the atoms in the wire being increased and decreased, not because of an actual "electron" flowing anywhere....
I teach for a living and this is one of the best short, non technical explanations I have seen. I loved how you picked up the story with virtual photons and also explained the relativistic origin of the effect on the moving charge. One question though! @5.29: the electrons in the wire are moving while the apple is stationary. Why isn't there a relativistic contraction effect there? Shouldn't we expect the moving electrons to appear "more dense" to the apple as they pass by, thus the apple experiences a force? This is the same basic argument which is used later in the video (moving apple, "slow" electrons, "faster" protons).
if the apple is perceived as still, the direction of motion of the wire is leftwards. The protons move leftwards in the direction of motion because the wire is moving leftwards. These similar motions add onto each other out and net leftward motion is greater. Therefore, wrt. to the stationary apple, protons move faster. Increased speed wrt to the stationary apple is what causes the contraction, as per special relativity. In contrast, the electrons move rightwards, opposite to the direction of motion because the wire is moving leftwards. These contrasting motions try to cancel each other out and net rightward motion is smaller. Therefore, wrt. to the stationary apple, electrons move slower. Decrease in speed wrt to stationary apple is what causes the expansion, as per special relativity. You can compare the change in resultant speed of both particles @6:57. Hope this helps!!
@@chad7928 I actually meant the case where both wire+apple are stationary! So, protons stationary wrt apple. So from the point of view of the apple, stationary protons and moving electrons should make the electrons appear "denser" in the wire relative to the protons, no?
Great as always. Man, a few years ago I posted on a few science forums trying to understand what magnetic fields actually are. This video underlines that the responders had no idea what they were talking about, but they were extremely confident nonetheless. It was frustrating, and it's refreshing to get this with so much clarity. You have a knack for clear thinking about fundamentals.
@@ab8jeh nah these type of videos give the sense how things are actually layered and related to eachother. The content isn't meant to really be remembered but rather is a tool for interpretation; such that the content you eventually do have to remember can be remembered and understood easier
oh wow! this is a perfect explanation! the first time I have ever finally understood what magnetism actually is, and I'm 40. this should be mandatory viewing in any science class. amazing work, thank you so much for this! another pre example is your video on QFT
Caro Alessandro, Consultando il tuo sito personale ho scoperto che sei anche un po' Italiano e che abbiamo quasi la stessa età. Ti stimavo già da prima ovviamente, ma questo mi permette di esprimere tutta la mia ammirazione nella lingua che più mi è familiare. Questo tuo incredibile, minuzioso lavoro sta dando frutti in tutto il mondo che neanche riesci a immaginare, e i frutti più grandi devono ancora nascere. Grazie infinite, davvero. - Un umile ingegnere appassionato di fisica
I once built a mostly wooden generator for a physics extra credit project in 2016.. Made my own solenoid (x2), bought a horseshoe magnet, made a pully mechanism to spin the magnet against my 2 solenoids.. A friend helped me set up my resistor and light to a breadboard, and I just now figured out how it actually worked. I essentially memorized that a change in the magnetic field would induce a current within the wires, but I never understood it until now.. thanks for the video!!
I always am looking forward to new ScienceClic English videos. They are the highest quality science education videos available anywhere on the internet and I am so grateful for all the time and effort that obviously goes into them. Thank you thank you thank you!
Protons emits photons. Whereas electrons absorb photons. This phenomenon creates a momentum within the proton and electron and thus they attract each other
What an amazing time we live in. 1. There are brilliant people that understand these complex topics and are willing to make cool videos. 2. Animation software has evolved to easily illustrate these concepts. 3. Finally, TH-cam for distributing this content to the masses anytime, anywhere.
Your channel is really really great because I had almost lost touch in Electric and Magnetism but this entire video really helped me to summarize almost all theoretical points that once I learnt during class 12th days! 💖
I dont think there are many videos on youtube that explain both the exchange of virtual particles and how magnetism is a consequence of special relativity. Even those that do usually leave out permanent magnets. You really covered all bases here. 👍 Some criticism: It was apparent how repulsion between like charges works but i didnt really understand how two particles could attract each other by exchanging photons. Ive heard that some particle physicists believe that magnetic monopoles do exist after all. It would be interesting to hear how that could work.
I agree, regarding: "It was apparent how repulsion between like charges works but i didnt really understand how two particles could attract each other by exchanging photons." It seems the explanation of attraction was neglected, as the motivation of throwing the ball from the intro doesn't seem to neatly map onto an exchange of photons between opposite charges, it begs further discussion. Also, regarding Maxwell's second equation-it's not a fundamental law that the equation equals zero, but rather the value was set to zero as a choice to reject the magnetic monopole. Dirac has some things to say about this: en.wikipedia.org/wiki/Magnetic_monopole#Dirac_string -- I'm not quite as optimistic about their existence, but they are not categorically forbidden under the theory and equations of electromagnetism (kind of the opposite).
@@Alex-nb7on I was also troubled, and was looking for a critical comment among the flurry of unbridle praise. But I think the implication is buried between the lines that _virtual_ particles are able to be endowed with the property of negative momentum. Since virtual photons are nothing but constructs arising from the field, and not particles _at all,_ they escape the prescription that they must necessarily have mass, and even a _proscription_ that they cannot have a negative mass.
Search "magnetic monopoles and PBS spacetime" here on youtube if you haven't done so by now. They have a great video on the topic of monopoles and how quantum mechanics suggests that they might be possible (despite classical theory indicating otherwise).
last comment but this was honestly exactly what I was looking for. Sometimes when doing exercises I'm just using the formulas but I felt like I needed a more intuitive understanding to really know what I'm actually calculating. Thank you so much, this explanation was simply brilliant!
I kind of lost it halfway, why does the apple not experience a pull towards the electrons when it's motionless? Shouldn't it be that by the presented logic, electrons are moving and so they are more condensed than the protons (which are not), and so there are more of them => more pull? Also, we got an intuitive explanation on why certain particles can repel each other (ball being passed around in space as our virtual photon), but what intuitive explanation is there for attraction?
For your first question, we suppose that the wire is neutrally charged in the initial frame of reference. This means that there would be slightly less electrons than protons in the wire, such that, when the electrons move, they get contracted exactly the right amount to compensate the protons. For your second question, there is indeed no good image that I know of to picture attraction by virtual particles. One analogy I like to use it to imagine that the two people are not exchanging a ball but rather a boomerang : they throw the boomerang towards the exterior, which pushes them back closer to each other.
In the stationary reference frame, where only the electrons are moving, it is supposed that the electrons and protons are equally dense in the wire. That's the setup for the thought experiment. It's a little confusing because he first showed the electrons as motionless as well, but the setup is really that they are in motion and equally dense as the protons.
Because the wire at rest is electrically neutral. We can just measure this. You can try to think about what happens when you turn on the current that ensures this but that gets _really_ complicated. The upshot is that the wire is neutral before you turn on the current and once the current is stable, but not necessarily while the current builds up. I think ScienceClic have a video where they mention a boomerang analogy. Instead of throwing a ball at each other, they throw a boomerang away from each other which then travels around and hits the other particle from the other side, each time imparting momentum that pushes them together. Otherwise you just sort of have to accept that virtual particles can have negative momentum.
Really appreciate new video of the deeper dive of the Electromagnetic field! Question: the exchange of virtual photons can explain the same type of particles repel each other, but how does it explains the opposite particles attract each other?
I am not a physicist but as I understand it virtual particles have no requirement to be created before absorbed (so it will travel back in time). So when its taken before created then it can create attraction.
I had the same question. The Virtual Photon seems to be an abstraction to try to explain electric forces en.wikipedia.org/wiki/Virtual_photon Virtual Photons with negative energy causes attraction ... but IMHO is kinda hand-wavy
I have watched a lot of explainers about electromagnetic force, but this video is very well explained, and excellent visuals! More videos on quantum physics and elementary particles physics please!
Would you believe that I was just checking your channel in months and saying "damn they disappeared". This channel's visualization style was copied by many channels btw! Edit: I think I never heard this intuition as an explanation for electromagnetic repulsion. What a gem! But can it explain attraction too? I guess I should finish the video before I comment LOL
This video was crazy! I've always learnt the basic electronic concepts but never could find or understand how it actually worked? this simplified everything....about how things actually happen. Thanks a lot!
7:36 The Magnetic Force So why isn't the apple attracted when it is motionless? From the apples frame of reference this means the electrons are moving faster than the protons and are contracted and should be more condensed together than the slower moving protons ( in the wire) Basically, why isnt the opposite true when the apple is at rest relative to the wire?
Because this is all garbage suedo science. Absolute rott. Gobbledygook. Only the feeble minded go " oooo so thats how it works " I hope he clapped his hands to wake his audience up at the end. What a joke.
He explains it very well in the video. They cancel each other out until movement is introduced. It's right there in the video. Were you not paying attention?
1:00 but the speed of ball isn’t scaling so doesn’t that mean that after some throws both people will achieve speed greater than the ball so ball will never get to person?
Very good question! That's where the analogy ends, because the ball is in reality a photon moving at the speed of light, and which therefore is impossible to move faster even after accelerating for an infinitely long time.
I've never heard of a virtual foton before! Came here to look for some intuitive EM knowledge before my test tomorrow and left with cool physics knowledge
My mind is blown. This stuff has always been fascinating to me, but I never quite understood details like what allows EM waves to propagate. I'm glad I can finally say I understand it better, thanks to your channel! Never stop making videos!
Mind blown, wish i had this truly exceptional way of understanding the concepts of physics. You're blessed. Keep up the good work. We highly appreciate it.
Great video. I liked the starting example on how repulsion worked. It would have been great if another example of attraction was included. How do the virtual photons help pull two particles (electron and a photon) together. In a bigger example, how does a magnet pull another object towards it? I always wondered about this.
The virtuality of virtual photons does not lie in their fleeting evanescent existence _as particles._ They are not particles at all. Their virtuality is in that they are imposter-artifacts in the field that temporally behave with real particles as though they were the real deal. It's the difference between a dollar bill and a check for one dollar. They can thus have peculiar properties such as no momentum, or even negative momentum (=they can behave like a 1-dollar IOU... just the opposite sense of a dollar) As long as the latter doesn't bugger-up the particle's otherwise photon- _like_ attributes with respect to the other actors in the interaction, yes, it can exert a yank, instead of a yeet before it disappears. Because it is not a real particle, it doesn't have to have real mass, and can seem to defy Newton.
I get the momentum of exchanging virtual photons could be said to represent repulsion. Then what causes attraction? How can you explain exchanging a negative and positive virtual photon, giving each particle momentum in the same direction? You would think the electron would still get repelled, like it did when it exchanged in the same exact way with another electron. Same goes with the proton, the momentum explanation totally breaks down here. The electron can do the very same action and go in two opposite directions depending on the other particle.
This is the best video I've found so far explaining this phenomenon! Explaining the Virtual Particles first made me understand this way better for some reason :)
I love all of your videos, but I'm still really confused as to how virtual photons can lead to forces of attraction. Repulsion makes intuitive sense, but I just can't get my head around the attraction. Can someone help me out?
But wait, when the apple is at rest ,from the apple's frame of reference the protons are at rest and the electron are moving then , the electron will be shrink and there will be more electron than protons from the apple's reference, then the wire will be negatively charged and attract the apple🍎.🤔
no way ive spent months trying to understand this concept and now i understand it in 14min43seconds. Insane. The color thing helps sooo much thank you (i just started physics 3 and never took the time to completely understand E field and B field laws and concepts)
wow. i had a calculus teacher that could break down the math and make it easy to understand, and this video is just like that. being able to explain the complex simply is the greatest
Thank you for the great video! However, isn't the reasoning for the energy of virtual photons the wrong way round? If vp have to travel a short distance between two close electrons, they CAN have a higher energy, but why should they? Why don't they move on further? Isn't it rather a kind of diluted or stretched out energy if vps are force to cover or bridge a greater distance between electrones? Short: the travel distance rather determines the energy instead of the energy determining the range. No idea what that means physically, but it seems more logical in the analogy used (if this is close enough to reality enyways)
Yes there is indeed a caveat with this pop-science approach, one should keep in mind that this image with virtual photons is just an analogy, but what really underlies all this are the maths of quantum electrodynamics. As you noticed, it is difficult (and not very judicious anyway) to determine the cause/effect relationship between how far and how energetic a virtual photon can travel/be.
Just wanted to know, how does special relativity affect the electrons when they are moving in the wire? i.e. When the apple is stationary, wouldn't the movement of the electrons cause length contraction relative to stationary observers? This would mean that the apple should be attracted to the wire, due to the increased density of negative charges. Perhaps there is a subtle point here that I'm not able to grasp.
Yes, this is exactly what I am wondering about. It should not matter what is moving against what. All movement are relative therefore it seems to me that stationary positively charged apple should be attracted to wire with flowing electricity by imbalance of forces in the same manner as moving charged apple. Any explanation what I get wrong?
@@balabuyew I think the explanation for this is that due to the sheer number of particles involved, summing the extremely small contribution of each one results in a significant overall effect. Though, I'm not too sure about the details, electric current is measured in Coulombs/sec, meaning that given even a small drift velocity, the number of particles moving past a given point in the wire is quite significant: approximately the equivalent of 6.242 x 10^18 electrons per second.
Without a doubt this is best channle...teach us with example..bro..that apple and wire example and then adding special relativity you easily teach us one of the most mind twisting facts...thank you thank you thank you
I hope you like the video! A few clarifications:
- This video was originally created in 2018, before I studied theoretical physics, which is why the content might not be as precise as the other more recent videos.
- Many people are asking how the "playing catch" analogy can explain attraction forces. This is indeed the limit of the analogy. At the quantum scale, virtual particles are really just waves that are spread throughout all space. Therefore they can carry a momentum in any direction, which can have the effect of attracting or repelling particles.
- In the stationary wire, many people are asking why the electrons are not contracted since they are moving. They indeed are contracted, but we consider that they were carefully spaced such that, when contracted, the wire has no electric charge.
- At the end of the video, electromagnetic waves propagate at the speed of "real photons", and not "virtual photons"
Oh Thanks a lot for these clarifications! I just got this video in my recommendation. Glad to see it :)
Hi, I'd like to ask you to clarify even better the stationary wire problem. You say that electrons are contracted in such a way that the electric charge is zero when electrons are moving, but claiming so it should imply that when they are not moving they should be even more spaced out (less contracted), which means that the wire has less electron density than proton density in this case. How can the electron density be always the same (resulting in a no electric charged wire) if there is contraction when electrons are moving and no contraction when they're not moving?
For those, who have a question which I had "how did these electrons become 'spaced' just by applying current?", there is a good analogy: car traffic becomes more spaced after traffic lights turn green, because the first car started moving earlier than the second one, the second one earlier than the third one and so on. Just like cars, some electrons are affected by the electric force that creates current earlier than the other ones, since electric force is not immediate and propagates from some point (or multiple points) with the speed of light.
And just as I wrote that, another question arose: where do electrons find this 'extra space' if they didn't have it initially? Unlike cars, there is no 'first electron' with empty space in front. Also, electrons on the 'forward front' of electric field propagation start moving earlier than ones in front of them, creating an even denser volume of elecrons which can also play the role just after the current started. I'm confused(
thanks for clarifications, for the atractive forces I was thinking if they were sharing somehow virtual photons with negative mass/momentum hahahaha.
I get the part about the virtual photons repelling electrons, but you didn't make an analogous model for the virtual photons to cause electrons and protons to attract.
What causes this attraction?
Every time I asked my professors at college why exactly the electric force (the movement of electrons) produces a magnetic force, none bothered at all to tell me anything and always told me to just accept it. This video finally made me understand how magnetism arises.
I am eternally grateful for these videos that come from the best channel on TH-cam. This is pure educational quality.
the real question is why does the magnetic force equation look like the Coriolis force equation?
The fact that it requires Relativity (even if the simplified case of Special Relativity, GR doesn't mix well with QM yet) probably spooked your teachers. Most people, even educated ones, have serious trouble with Relativity, more so at mixing it with Quantum Mechanics, which at the core remains an unsolved problem. Maxwell himself necessarily did not understand the "how" it happens (he inspired Einstein and not the other way around) but only the "what" happens.
@@LuisAldamiz *Special* relativity has been fully integrated with quantim mechanics, it's called Quantum Field Theory. It's only general relativity (the one about gravity) that is problematic with QM.
Fun fact, it was Feynman who was the 1st to describe this phenomena using SR
@@Ecl1psed276 exactly. Dirac combined SP and Quantum Mechanics.
When a free TH-cam video explains better than paid University and tuition cources
in uni you learn to ask the right questions.
We've come across the "moving current in a wire" explanation to unifying electric and magnetic fields frequently in textbooks, web pages, forums, etc., and yet nowhere was it presented as simply or intuitively as it was here. Blew us away. Really fantastic job!
good to see you here. Love your channel too
Thanks a lot!
But it’s a quantum ball.. right? My brain tickles.
Just experienced, That was extraordinary.
Anyone good at physics here❓
How does this not have more views?? Literally the best video on electromagnetism I've EVER seen.
Wow, this is exactly the stuff I couldn't wrap my head around until now. Thanks so much for this!
Very glad you liked the explanation! Thank you very much for your support!
I'm not tired to repeat this every time. This is the best channel ever created on youtube. Absolutely brilliant!
The best science channel
Agreed it's in a nutshell on steroids!
Indeed
It's not even close
Hands down
But worst video in their catalogue
never have i seen such simplicity and comprehensiveness combined into a single animated video about EM theory
I'm an electrician, and theory (D/C Theory, then A/C Theory 1, followed by A/C Theory 2), was part of the required education & class work as an apprentice. Even though I did well in the classes and have a strong understanding of the subject matter, this video (like all your other vids), is so good at explaining complex concepts in a simple and intuitive way, that I now have a broader, deeper, and better understanding of it. Your videos are definitely the best science vids on here. Well done! (And thank you!)
@B.L.A. “those of us with formal education” 🤓
@@kevinflaherty1 so what? You’re jealous of people who pass such high classes that you decide to use the elementary school method of calling them a nerd?
When someone calls you a nerd, they just can’t accept that you may be more intelligent than them. So they find ways to insult you and get more attention for themselves
@@kevinflaherty1
cry harder ignoramus :)
Modern science isn't correct.....
All energy and matter in one simple explanation.... here goes...
First we have a radio wave all the way to gamma waves which in turn create hydrogen then from there everything is basically a compound of hydrogen and will decay back to hydrogen before turning back to gamma waves.....
There are no free moving electrons within matter....
I use this analogy to simplify it in my mind..... imagine a line of people standing a mile long (each person represents a copper atom in a wire) the first person starts a Mexican wave at one end ( the source ) , as the information propagates along the line ( by exciting each atoms magnetic field ) you would see an continuous wave of the peoples arms transferring the charge/information back and forth but the atoms and electrons don't actually move at all.....
Think about it, from the source where electricity is "generated" to the ultimate end use, there's various breaks in chain of that electricity, it goes through controllers, transformers, all sort of components.... the transmission happens because of the magnetic field strength of the atoms in the wire being increased and decreased, not because of an actual "electron" flowing anywhere....
This channel offers some of the best physics explanations I've ever heard and they're so so underrated. When is say underrated I really mean it. How can this channel not have millions of subscribers yet? Damn.
Thank you so much for making me finally understand the basic relationship between the electric and magnetic component of the electromagnetic force - brilliantly illustrated!
I can't stress enough, how impactful your videos are. Literally have goosebumps while watching every upload. Thank you so much for what you are doing. By far - and I mean BY FAR - the best educational content of this genre on this platform!
suhlas :)
Shadilay
KKK
25+ years of trying to understand this and this guy gets it through in less than 10 mins. Damn it, best science channel ever!!!
Your videos are among my favorite scientific videos on YT. Every time i see a new upload i immediately cannot help but watch! Thank you for the informative and digestible content!
Same
same
very much the same. He seem to cover conventionel topics, but from a new angle, which somehow also makes it easier to understand
You just logically united all of the last 3 units in my Grade 12 physics course. Thank you.
This is high key the best and most concise complete explanation of electromagnetism I've encountered. I also love that you completely avoided equations of any sort, and just went with a qualitative approach, which makes this video very approachable for anyone. Such a clean video and well-made video!
yeah, fully concur, until you understand the mechanics , any equation won´t make sense
@@absolute___zero Well said brother. Just mugging up formulae without proper Intuition and Visualization is not true learning.
Your videos are so amazing not only because you illustrate and explain such complex topics in such understandable ways, but also because you bring up ideas that I've never even heard before. For some reason, even among science educators, you connect dots that are always left unconnected by others.
The amazing thing is the author is 24 year old, and my feeling he has an understanding of Physics that is often superior to many Physics professors.
The single cleanest explanation of this phenomenon I've ever seen. Makes sense without the vector calc but can be used to introduce it. This will now be the way I proceed when teaching E&M.
You, sir, are actually amazing. I found you when I was confused about how electromagnetic waves were generated, and just started watching your videos. I went from ugh I have to learn this for my lectures to remembering why I found science so cool. Keep up the good work!!
What I love about this channel is that it's able to explain physical phenomena in a digestible way without sacrificing the accuracy of the science.
Something main professors should learn from
This was the best educational video I've ever seen and it blew my mind 5 times.
Interesting that you _started_ with the virtual photon picture and then introduced fields as a way to think about these interactions.
Usually we start with the fields and introduce virtual particles as a way to visualize the interactions of the fields.
And that's why I never actually understood how it worked until now (well, I'm not sudenly an expert now). Other explanations take fields as a given and just try to expand on them.
what do you mean field? Because if you mean Quantum Fields (Which the Electromagnetic and Electron Field are) then yes virtual particles are just visualizations of the interactions of the field.
When we learn of macroscopic things feeling electric forces, the electric field is seen as a bookkeeping device:
They are the answer to the question "how much force is felt here?, regardless of the charge of a particle to feel it, which may or may not even exist here"
Similarly, we can think of elementary particles, as tangible things that move around in understandable ways.
When two electrons toss photons to each other, they create a recoil "force". Neat!
Again, we build an electric field as a bookkeeping device. Maybe even a quantum electric field.
That is a nice intuitive way to understand what is happening. But if I understand it correctly, physicists believe that the fields are more real than the particles, which are the bookkeeping devices. Because that belief fits better with what we know about reality.
That might explain it:
we want to be thaught in particles, because particles make sense to us,
...but we are thaught in fields by people who see the fields as real, and thus want to explain how the easy-to-understand particles come from them.
We stuggle with the shift in perspective.
____________________________________________________________________________
I do not fully understand why fields must be real and not the particles. All below can be wrong and all sorts of ways. But here is what I understand of it:
Macroscopic: The electric and magnetic fields can have ripples in them, that travel at the speed of light. This "light" can exist even without charges around at all. So it seems the fields aren't just bookkeeping the effect of charged things that exert force.
The circuit of unknownsource-veritasium shows that you don't need charged particles to push on each other through a circuit. The effect of flipping a switch would have to take a light-year long detour to reach a lamp only one meter away, taking a year. But instead, the electromagnetic fields that live everywhere carry the signal to the lamp across the gap in the wire. Long before the edge of the circuit knows that something has changed.
In general, I believe there are effects that an electrical circuit cannot predict, because the circuit exists in space, with the wires being close to each other and all that.
Quantum: Virtual particles are weird particles. Two electrons tossing photons back and forth is fine, but the analogy breaks for an electron and a proton. When a proton catches a photon from an electron, it recoils towards the electron instead of away, and vice versa, and that is just weird. The relation between energy and lifetime comes from this: the virtual photon has to fly under the radar of heisenbergs uncertainty relation, which is a limit on what we can detect with accuracy and certainty. But why should it fly under the radar? Can't we sometimes see measurable photons being tossed back and forth, in a proper scientific experiment? I believe that charged particles don't glow, unless sped up or down.
It is said that virtual photons aren't real photons. They are ripples, perturbations, in the quantum electromagnetic field. When those ripples exceed heisenbergs uncertainty relation, they are seen by detectors. And can thus be called "real" photons. Any other feature -- rippleshaped or not -- can be broken in a sum of smaller ripples, which we can argue are still photons -- ripples --, but they travel under the radar. This helps to calculate what the fields do in an interaction, by looking at scenarios of virtual particles doing what particles do. In theory, we need to mix all scenarios by likelyhood, to know what happens. In practice, we mix only the more likely scenarios as an approximation. Either way: the virtual particle is now the bookkeeping device, and the field is the real thing.
@@nielskorpel8860 you cannot detect them because they are pure nonsense. Photon exchanged between proton and electron has negative momentum for proton and positive momentum for electron.
Another problem is - why does any field even exist? If it were for virtual particles to exist, you could imagine how in uniform electric field one pair of electron-positon popping out of nothingness, creating a circle, and then disappear. Not a big problem, but inside said circle, electric forces of the field are balanced out by formentioned particles. You create a "bubble" with no force at all. Now go on with as many bubbles you like, and whole field disappears!
It's absurd, because there is no virtual photon or electron, but quantum field. And all the sudden it all makes sense.
@@Etrexum Actually, that's a far more accurate picture. The virtual particles are just oscilation in the underlying field. Oscilation caused by the real electron themselves. Nothing more.
This is one of the most deeply impactful videos I've ever watched, believe it or not. Absolute legend. 2 in the morning I realize I want to understand how nuclear reactors work (and expand from there into every fundamental aspect of electricity) and this was my starting point, how electromagnetic fields work and anything around it.
People need to understand that these descriptions are models. Models that can be worked with because they are mathematically correct. But nobody knows what these interactions really look like in reality.
But all the more impressive I find this channel and the author, who really manages to present the phenomena of physics vividly.
I learned years ago: "If someone can't explain something to you easily, then he hasn't understood it himself".
they look like the math says they look like
@@DrDeuteron Then what in the hell is a virtual photon ???
A photon that both repels and attracts ?
Why would two same charges make possible fror them to appear ???
Also when you say something exists for such a short time it actually DOESN'T exist I'd say you got some nonsense on your hands .
@@alokinzna that's a good question. So in Quantum Electrodynamic (QED), one considers scattering amplitudes. E.g: Moeller scattering (e-e- --> e-e-) or Bhabha scattering (e-e+ --> e-e+), which differ by repulsion vs. attraction.
In QED, the Feynman path integral says the EM/electron field takes all possible configuration between initial an final states...which is not solvable exactly.
Instead, on considers "perturbation theory", and you approximate the exact solution with a power series in powers of the fine structure constant (alpha). The first term (called "tree level") has a configuration that is the exchange of a so-called virtual photon.
That is what a virtual photon is. A term in a power series expansion of QED amplitude.
At this level, repulsion or attraction isn't really a thing. If you look up Moeller and Bhabha scattering on wikepdia, they work out the amplitudes in QED, and you will see they depend on (iq)^2 with q = -e or q = +e as needed, and then to get a probability you square the magnitude of the complex amplitude, so the sign just disappears....nevertheless it works.
Moreover, in Feynman diagrams, energy and momentum are conserved at all points in the diagram, so the virtual photon can have very unusual kinematics.
For instance, for two electron scattering back-to-back in head on collision, the photon has zero energy buy large momentum. That means the mass squared in negative. weird for a photon.
Meanwhile in electron positron annihilation in the same kinematics, the photon as huge energy and zero momentum...so it is at rest. Weird for a photon.
Basically: the virtual photon can have negative, positive, or zero energy or momentum...so it repels if it needs to repel, and attracts if it needs to attract.
So with that, virtual photons are just mathematical things that approximate quantum field configurations.
It sounds like BS, but when you use them to calculate "the electron g-factor", experiment and theory agree to 13 (or 14) digits...which is the most accurate and precise calculation in ALL of science. It represents decades of theoretical and experimental work by hundreds (or more) people, and it is remarkable.
@@DrDeuteron You know this is sorta strange .
When talking about gravity you can at least come across the terms Higgs field or Higgs boson .
How is it that getting the details of magnetism is this difficult and obscure ?
Is this a case where we have the detailed description in the form of math as to what is happening but don't know REALLY what is happening ?
@gohangoku3447 uff bro, so theoretical models for describing certain properties, processes, etc. of reality, conveyed through mathematically describtions, are actually just models? Wow, that's incredible? Thank you for explaining the most trivial aspect of this video and all of (natural) science
This channel is soooo underrated
I never clicked so fast in a notification
This is btw, and I mean literally, the B E S T visualization and explanation for both the electric field, but also for how virtual particles are supposed to carry force, simply amazing, bravo!
Thank you so much, glad you liked it!
Amazing video. I understood how the virtual photon picture, with the recoil, can explain a repulsive force.
But I find it hard to understand how the virtual photon explanation applies to an attractive force between opposite charges.
By the time the video speaks about attraction between opposite charges, the virtual photon picture no longer makes an appearance.
@@elpak it looked like the attraction was depicted by two virtual photons being emitted simultaneously by the electron and proton, and then meeting in the middle. But yeah no intuitive explanation was given for the electromagnetic attraction as it relates to that illustration.
@@ScienceClicEN Modern science isn't correct.....
All energy and matter in one simple explanation.... here goes...
First we have a radio wave all the way to gamma waves which in turn create hydrogen then from there everything is basically a compound of hydrogen and will decay back to hydrogen before turning back to gamma waves.....
There are no free moving electrons within matter....
I use this analogy to simplify it in my mind..... imagine a line of people standing a mile long (each person represents a copper atom in a wire) the first person starts a Mexican wave at one end ( the source ) , as the information propagates along the line ( by exciting each atoms magnetic field ) you would see an continuous wave of the peoples arms transferring the charge/information back and forth but the atoms and electrons don't actually move at all.....
Think about it, from the source where electricity is "generated" to the ultimate end use, there's various breaks in chain of that electricity, it goes through controllers, transformers, all sort of components.... the transmission happens because of the magnetic field strength of the atoms in the wire being increased and decreased, not because of an actual "electron" flowing anywhere....
This video tells the story of a whole semester in short. Loved it!👍
I teach for a living and this is one of the best short, non technical explanations I have seen. I loved how you picked up the story with virtual photons and also explained the relativistic origin of the effect on the moving charge. One question though! @5.29: the electrons in the wire are moving while the apple is stationary. Why isn't there a relativistic contraction effect there? Shouldn't we expect the moving electrons to appear "more dense" to the apple as they pass by, thus the apple experiences a force? This is the same basic argument which is used later in the video (moving apple, "slow" electrons, "faster" protons).
if the apple is perceived as still, the direction of motion of the wire is leftwards.
The protons move leftwards in the direction of motion because the wire is moving leftwards. These similar motions add onto each other out and net leftward motion is greater. Therefore, wrt. to the stationary apple, protons move faster. Increased speed wrt to the stationary apple is what causes the contraction, as per special relativity.
In contrast, the electrons move rightwards, opposite to the direction of motion because the wire is moving leftwards. These contrasting motions try to cancel each other out and net rightward motion is smaller. Therefore, wrt. to the stationary apple, electrons move slower. Decrease in speed wrt to stationary apple is what causes the expansion, as per special relativity.
You can compare the change in resultant speed of both particles @6:57. Hope this helps!!
@@chad7928 I actually meant the case where both wire+apple are stationary! So, protons stationary wrt apple. So from the point of view of the apple, stationary protons and moving electrons should make the electrons appear "denser" in the wire relative to the protons, no?
You won't get your answer from clowns.
EXACTLY the question I have as well. Please if you found an answer share it, I need to know this! 🥺
‘The Best Channel’ of Science. Literally, Science Clic and Arvin Ash are the only two channels I watch of science. Both are ‘The Best’. ❤️❤️❤️
The best description of where charge originates I've heard
Great as always. Man, a few years ago I posted on a few science forums trying to understand what magnetic fields actually are. This video underlines that the responders had no idea what they were talking about, but they were extremely confident nonetheless. It was frustrating, and it's refreshing to get this with so much clarity. You have a knack for clear thinking about fundamentals.
That's some mind-bending concepts to think about 😮👍🏼
You deserve more recognition your videos and their visuals are easily one of the best scientific and educational channels on yt
Wow. Just, wow. Never seen such an intuitive explanation on the relation between special relativity and electromagnetism. ♡
Your one of the most underrated channels on this app, the clarity of the information you explain is unbelievable. Keep it up!
All this under 15 minutes, what a brilliant video!
why does this make so much more sense than it did in school
It's very well presented, but next week it will be gone from our minds. Somehow reading a book works better for remembering this stuff!
@@ab8jeh nah these type of videos give the sense how things are actually layered and related to eachother. The content isn't meant to really be remembered but rather is a tool for interpretation; such that the content you eventually do have to remember can be remembered and understood easier
Because it's wrong.
this was astonishingly good. the relativity origins of magnetism was a head-tripping section
oh wow! this is a perfect explanation! the first time I have ever finally understood what magnetism actually is, and I'm 40. this should be mandatory viewing in any science class. amazing work, thank you so much for this!
another pre example is your video on QFT
I always had such a tough time comprehending EM - this FINALLY clarifies things for me. Clear explanations, nice and slow.
These are the best science videos on TH-cam, thank you so much for making these with such attention to detail.
Caro Alessandro,
Consultando il tuo sito personale ho scoperto che sei anche un po' Italiano e che abbiamo quasi la stessa età. Ti stimavo già da prima ovviamente, ma questo mi permette di esprimere tutta la mia ammirazione nella lingua che più mi è familiare. Questo tuo incredibile, minuzioso lavoro sta dando frutti in tutto il mondo che neanche riesci a immaginare, e i frutti più grandi devono ancora nascere. Grazie infinite, davvero.
- Un umile ingegnere appassionato di fisica
Glad to see a new video. I really appreciate them, worth the long waiting time! 🙌
Very glad you like them!
Fab video. On ice, standing facing away from each other, throwing a boomerang away from the catcher would cause both to move closer. Bit convoluted :)
Phenomenal! As a physics student in university you’ve blown my mind, no one ever took the time to give me such explanations
nice video from underrated channel
I once built a mostly wooden generator for a physics extra credit project in 2016.. Made my own solenoid (x2), bought a horseshoe magnet, made a pully mechanism to spin the magnet against my 2 solenoids.. A friend helped me set up my resistor and light to a breadboard, and I just now figured out how it actually worked. I essentially memorized that a change in the magnetic field would induce a current within the wires, but I never understood it until now.. thanks for the video!!
I always am looking forward to new ScienceClic English videos. They are the highest quality science education videos available anywhere on the internet and I am so grateful for all the time and effort that obviously goes into them. Thank you thank you thank you!
Your videos are most underrated brother thanks a lot noone can understand better than you
This channel takes these amazing complex ideas and without dumbing it down simplify it in digestible ways. Thanks for all the hard work y’all
Dude, these are the coolest videos on yt
I am just feeling very frustrated why I am checking your channel so late 😕 hands down bro this is so good!!
I understand this mathematically but this video FINALLY showed me how that works in a physical context! Lifesaver.
If a proton and an electron exchange virtual photons, then why do they attract each other? Two electrons are repelled by the same exchange.
Protons emits photons. Whereas electrons absorb photons. This phenomenon creates a momentum within the proton and electron and thus they attract each other
Virtual particles don’t exist, they just could exist that’s what important for this analogy to help people understand
@@OviMitra-f8owhat I think you don't understand this😅
What an amazing time we live in. 1. There are brilliant people that understand these complex topics and are willing to make cool videos. 2. Animation software has evolved to easily illustrate these concepts. 3. Finally, TH-cam for distributing this content to the masses anytime, anywhere.
Your channel is really really great because I had almost lost touch in Electric and Magnetism but this entire video really helped me to summarize almost all theoretical points that once I learnt during class 12th days! 💖
I have been searching all over the Web for such explanation....but finally.. this is the answer to my questions..thank a lot
I dont think there are many videos on youtube that explain both the exchange of virtual particles and how magnetism is a consequence of special relativity. Even those that do usually leave out permanent magnets. You really covered all bases here. 👍
Some criticism:
It was apparent how repulsion between like charges works but i didnt really understand how two particles could attract each other by exchanging photons.
Ive heard that some particle physicists believe that magnetic monopoles do exist after all. It would be interesting to hear how that could work.
I agree, regarding: "It was apparent how repulsion between like charges works but i didnt really understand how two particles could attract each other by exchanging photons." It seems the explanation of attraction was neglected, as the motivation of throwing the ball from the intro doesn't seem to neatly map onto an exchange of photons between opposite charges, it begs further discussion. Also, regarding Maxwell's second equation-it's not a fundamental law that the equation equals zero, but rather the value was set to zero as a choice to reject the magnetic monopole. Dirac has some things to say about this: en.wikipedia.org/wiki/Magnetic_monopole#Dirac_string -- I'm not quite as optimistic about their existence, but they are not categorically forbidden under the theory and equations of electromagnetism (kind of the opposite).
@@Alex-nb7on
I was also troubled, and was looking for a critical comment among the flurry of unbridle praise. But I think the implication is buried between the lines that _virtual_ particles are able to be endowed with the property of negative momentum. Since virtual photons are nothing but constructs arising from the field, and not particles _at all,_ they escape the prescription that they must necessarily have mass, and even a _proscription_ that they cannot have a negative mass.
Search "magnetic monopoles and PBS spacetime" here on youtube if you haven't done so by now. They have a great video on the topic of monopoles and how quantum mechanics suggests that they might be possible (despite classical theory indicating otherwise).
The best video on basics of electromagnetism I've ever seen.
This makes so much sense! I have a deeper understanding and really appreciate this video
last comment but this was honestly exactly what I was looking for. Sometimes when doing exercises I'm just using the formulas but I felt like I needed a more intuitive understanding to really know what I'm actually calculating. Thank you so much, this explanation was simply brilliant!
I kind of lost it halfway, why does the apple not experience a pull towards the electrons when it's motionless? Shouldn't it be that by the presented logic, electrons are moving and so they are more condensed than the protons (which are not), and so there are more of them => more pull?
Also, we got an intuitive explanation on why certain particles can repel each other (ball being passed around in space as our virtual photon), but what intuitive explanation is there for attraction?
For your first question, we suppose that the wire is neutrally charged in the initial frame of reference. This means that there would be slightly less electrons than protons in the wire, such that, when the electrons move, they get contracted exactly the right amount to compensate the protons.
For your second question, there is indeed no good image that I know of to picture attraction by virtual particles. One analogy I like to use it to imagine that the two people are not exchanging a ball but rather a boomerang : they throw the boomerang towards the exterior, which pushes them back closer to each other.
In the stationary reference frame, where only the electrons are moving, it is supposed that the electrons and protons are equally dense in the wire. That's the setup for the thought experiment. It's a little confusing because he first showed the electrons as motionless as well, but the setup is really that they are in motion and equally dense as the protons.
Because the wire at rest is electrically neutral. We can just measure this.
You can try to think about what happens when you turn on the current that ensures this but that gets _really_ complicated. The upshot is that the wire is neutral before you turn on the current and once the current is stable, but not necessarily while the current builds up.
I think ScienceClic have a video where they mention a boomerang analogy. Instead of throwing a ball at each other, they throw a boomerang away from each other which then travels around and hits the other particle from the other side, each time imparting momentum that pushes them together.
Otherwise you just sort of have to accept that virtual particles can have negative momentum.
@@ScienceClicEN Gotcha! That helps, thanks for replying, and thanks for the jaw droppingly mind-bending content you deliver with every video!
Thanks for teaching multiple concepts in one video
Really appreciate new video of the deeper dive of the Electromagnetic field! Question: the exchange of virtual photons can explain the same type of particles repel each other, but how does it explains the opposite particles attract each other?
I am not a physicist but as I understand it virtual particles have no requirement to be created before absorbed (so it will travel back in time). So when its taken before created then it can create attraction.
I had the same question. The Virtual Photon seems to be an abstraction to try to explain electric forces en.wikipedia.org/wiki/Virtual_photon
Virtual Photons with negative energy causes attraction ... but IMHO is kinda hand-wavy
I have watched a lot of explainers about electromagnetic force, but this video is very well explained, and excellent visuals! More videos on quantum physics and elementary particles physics please!
Would you believe that I was just checking your channel in months and saying "damn they disappeared". This channel's visualization style was copied by many channels btw!
Edit: I think I never heard this intuition as an explanation for electromagnetic repulsion. What a gem! But can it explain attraction too? I guess I should finish the video before I comment LOL
This video was crazy! I've always learnt the basic electronic concepts but never could find or understand how it actually worked? this simplified everything....about how things actually happen. Thanks a lot!
Physics: study about motion of apples
One of the best videos about electromagnetism
7:36 The Magnetic Force
So why isn't the apple attracted when it is motionless?
From the apples frame of reference this means the electrons are moving faster than the protons and are contracted and should be more condensed together than the slower moving protons
( in the wire)
Basically, why isnt the opposite true when the apple is at rest relative to the wire?
Because this is all garbage suedo science. Absolute rott. Gobbledygook. Only the feeble minded go " oooo so thats how it works "
I hope he clapped his hands to wake his audience up at the end.
What a joke.
He explains it very well in the video. They cancel each other out until movement is introduced. It's right there in the video. Were you not paying attention?
Good question..
This is what i searched for .Thankyou so much........
1:00 but the speed of ball isn’t scaling so doesn’t that mean that after some throws both people will achieve speed greater than the ball so ball will never get to person?
Very good question! That's where the analogy ends, because the ball is in reality a photon moving at the speed of light, and which therefore is impossible to move faster even after accelerating for an infinitely long time.
I've never heard of a virtual foton before! Came here to look for some intuitive EM knowledge before my test tomorrow and left with cool physics knowledge
My mind is blown. This stuff has always been fascinating to me, but I never quite understood details like what allows EM waves to propagate. I'm glad I can finally say I understand it better, thanks to your channel! Never stop making videos!
Mind blown, wish i had this truly exceptional way of understanding the concepts of physics. You're blessed. Keep up the good work. We highly appreciate it.
Great video. I liked the starting example on how repulsion worked. It would have been great if another example of attraction was included. How do the virtual photons help pull two particles (electron and a photon) together. In a bigger example, how does a magnet pull another object towards it? I always wondered about this.
The virtuality of virtual photons does not lie in their fleeting evanescent existence _as particles._ They are not particles at all. Their virtuality is in that they are imposter-artifacts in the field that temporally behave with real particles as though they were the real deal. It's the difference between a dollar bill and a check for one dollar. They can thus have peculiar properties such as no momentum, or even negative momentum (=they can behave like a 1-dollar IOU... just the opposite sense of a dollar)
As long as the latter doesn't bugger-up the particle's otherwise photon- _like_ attributes with respect to the other actors in the interaction, yes, it can exert a yank, instead of a yeet before it disappears.
Because it is not a real particle, it doesn't have to have real mass, and can seem to defy Newton.
Io non avevo mai capito da cosa deriva il magnetismo, e finalmente ho capito a cosa serve lo spin delle cariche elettriche.
Infinitamente grazie.
I get the momentum of exchanging virtual photons could be said to represent repulsion. Then what causes attraction? How can you explain exchanging a negative and positive virtual photon, giving each particle momentum in the same direction? You would think the electron would still get repelled, like it did when it exchanged in the same exact way with another electron. Same goes with the proton, the momentum explanation totally breaks down here. The electron can do the very same action and go in two opposite directions depending on the other particle.
I have the same doubt
This is the best video I've found so far explaining this phenomenon! Explaining the Virtual Particles first made me understand this way better for some reason :)
I love all of your videos, but I'm still really confused as to how virtual photons can lead to forces of attraction.
Repulsion makes intuitive sense, but I just can't get my head around the attraction.
Can someone help me out?
I was wondering that too.
@@moukafaslouka4796 hopefully someone in the know will pop into this comment thread in the near future :D
Clear, short with no unnecessary hype. Great content
But wait, when the apple is at rest ,from the apple's frame of reference the protons are at rest and the electron are moving then , the electron will be shrink and there will be more electron than protons from the apple's reference, then the wire will be negatively charged and attract the apple🍎.🤔
your channel is a gift to humanity
Keep up the excellent content!
no way ive spent months trying to understand this concept and now i understand it in 14min43seconds. Insane. The color thing helps sooo much thank you (i just started physics 3 and never took the time to completely understand E field and B field laws and concepts)
this is what school DIDN'T teach us.
School does teach this
School tried to teach you this and you didnt listen.
@@BonurChamp ratio 💀💀
I have never seen so much physics being explained so well
Imagine if Magneto took notes… He’d be OP
I only wish this video had existed when I was studying for my exams. This is the best explanation I've ever seen
Hes da rollie pollie ollie, hes small and smart and round
wow. i had a calculus teacher that could break down the math and make it easy to understand, and this video is just like that.
being able to explain the complex simply is the greatest
Thank you for the great video! However, isn't the reasoning for the energy of virtual photons the wrong way round? If vp have to travel a short distance between two close electrons, they CAN have a higher energy, but why should they? Why don't they move on further? Isn't it rather a kind of diluted or stretched out energy if vps are force to cover or bridge a greater distance between electrones?
Short: the travel distance rather determines the energy instead of the energy determining the range.
No idea what that means physically, but it seems more logical in the analogy used (if this is close enough to reality enyways)
Yes there is indeed a caveat with this pop-science approach, one should keep in mind that this image with virtual photons is just an analogy, but what really underlies all this are the maths of quantum electrodynamics. As you noticed, it is difficult (and not very judicious anyway) to determine the cause/effect relationship between how far and how energetic a virtual photon can travel/be.
@@ScienceClicEN How electron knows in which direction it should fire a "virtual photon"?
Your science channel is my favorite !!! ❤️🥰. The music behind it especially gives me infinite motivation to keep watching forever!
Just wanted to know, how does special relativity affect the electrons when they are moving in the wire? i.e. When the apple is stationary, wouldn't the movement of the electrons cause length contraction relative to stationary observers? This would mean that the apple should be attracted to the wire, due to the increased density of negative charges. Perhaps there is a subtle point here that I'm not able to grasp.
Good question, don't get it either...
Agree. Also, electrons speed in a wire is around 10 centimeters per hour. Not enough for any relativistic effect.
Yes, this is exactly what I am wondering about. It should not matter what is moving against what. All movement are relative therefore it seems to me that stationary positively charged apple should be attracted to wire with flowing electricity by imbalance of forces in the same manner as moving charged apple. Any explanation what I get wrong?
@@balabuyew I think the explanation for this is that due to the sheer number of particles involved, summing the extremely small contribution of each one results in a significant overall effect. Though, I'm not too sure about the details, electric current is measured in Coulombs/sec, meaning that given even a small drift velocity, the number of particles moving past a given point in the wire is quite significant: approximately the equivalent of 6.242 x 10^18 electrons per second.
Finally some peeps are questioning this garbage !
So Thankful ! I finally got answers to my qns which were unanswered since I started learning about electromagnetic theory.
50% of watermelon is water....the other 50 is melon
No dude without the fructose (solids of watermelon) and its water together makes watermelon they separately can't be called as watermelon. 😅😅
@@SachinKumar-gq3qz
water
Melon
2 halves
😂😂😂 hilarious
@@NIKITA-v4z5j hi nikita
Human is 40 % Hu and 60% Man !
Such a genius explanation in only 14 minutes...thanks a lot... May be the best video available on TH-cam on this topic...
Your starter slide is super bright White. Can you use a darker color? The rest of your video and animation is a lot darker
Without a doubt this is best channle...teach us with example..bro..that apple and wire example and then adding special relativity you easily teach us one of the most mind twisting facts...thank you thank you thank you
Never seen a better explanation with basics