@@isodoublet I agree. WHat is the right explanation in your opinion? Maybe just external EM waves exerting pressure on plates? I mean, there is always some that are traveling from around - no need to pop into existence.
That is actually such a good explanation of Hawking radiation. My hat goes off. Hawking radiation can be a maaaassive pain in the arse to explain - and usually to someone who isn't a physicist, it will just never make sense. This video actually makes it make perfect sense. Mike you're a genius.
This is now my favourite "detail" explanation of Hawking Radiation. Tried reading more about it before, but it gets so complicated so quickly there's no chance of really making sense of it... But this, this made a whole lot of sense :)
Thanks for this! I've encounter the Casimir effect before, though usually voiced in terms of electromagnetic waves. It's much clearer when you talk in terms of the virtual particles themselves. The dynamical Casimir effect is a new one for me.
If anyone ever has trouble with understanding concepts in physics, chemistry, philosophy, mathematics, computing, etc., he or she should watch Brady's wonderful videos!
I don't usually comment on videos but I thought typing this out would definitely be worthwile. I'm from a place where you=your test marks..you're gauged on nothing but performances on tests. I'd like to take a moment to thank Brady Haran and the professors at the university of Nottingham for conciliating and kindling the curiosity people like me have in science..people who don't get much time out of academics. The videos are just a few clicks away and are thoroughly informative and lucid. Thank you very much and keep up the good work. :)
2:23 how do they account for the gravitational effects of the two plates??? My naïve assumption is that two objects that close would have a strong gravitational effect on each other
I love physics, but sometimes think I could never be smart enough. To not just watch videos, but to understand it well enough or learn the math well enough to actually do it. I’m grateful to hear explanations that bring a seemingly magic clarity to important concepts. It’s inspiring. It makes me think, yeah, I’m getting this. Maybe there’s a chance I could learn it at a deeper level. Outstanding work, thank you.
Wow, totally love Mike Merrifield. Never heard anyone explain stuff that's complicated enough to be on the fringe of known physics in such an accessible way before.
What an incredible nice video. Nice edited, explained and animated. Though I was more or less familiar with all the processes the video still gave me a lot of joy. I was actually a bit sad that it ended. Good job Brady, Mike and Drew :)
isodoublet elaborate upon your statement, from what I know is that the Casimir effect talks about a force caused by quantum fluctuation (F=π^2 hbar c)/240 d^4 that occurs in electrodynamical vacumm that fluctuates zero point energy fields, these fluctuations are a product of uncertainty principle, what did the professor say that was wrong?
From how the casimir effect was explained, i get the imagine in my head that these photons are trying to press into our dimensions but since we have matter around us, the photons cant get through the sieve(so to speak) since our dimensions here on earth are filled, but in the vacuum, there is nothing blocking the sieve holes. Really interesting things, thats why i love these videos, they really get the imagination firing!
Could this phenomenon have been an important part in shaping our universe during/after the Big Bang when space accelerate faster than the speed of light, particles popping into existence (because of the Casimir Effect) at an unimaginable rate during that acceleration period?
Actually if I've understood things correctly, a significant portion of the particles in the universe were created via this in the first place. When the cosmic inflation ended, the energy of it had to go somewhere and theories suggest that that energy went into the virtual particles that existed at that moment and turned them into real particles.
From what I know, I don't think so. Not in the same way as this. During inflation spacetime itself was expanding insanely fast, but not the particles in spacetime. Not saying that particles didn't get created, but I don't think it's thanks to this.
one interesting consequence of it would be clumps of antimatter and clumps of "ordinary" matter populating the universe, that have no causal interaction between one another because they would have been brought apart by the inflation acceleration. Such an eventuality would leave behind a specific imprint in the cosmic microwave background radiation for instance. Planck data is to this day being studied to test the validity of such models. We may live in a symetric matter / antimatter universe afterall :D
7:30 I remember hearing this at Uni and being determined to think of an experiment that could distinguish acceleration and gravity. I've always wondered about tidal forces - if you're standing on the ground, gravity pulls slightly more strongly on your feet than on your head. Simply because your feet are closer to the Earth's centre of mass. Obviously the difference in gravity is very, very small (1 part in about 10,000,000,000,000 by my rough calculation) but I'd be interested to hear what this does for the equivalence principle because it suggests that one could, theoretically, distinguish a gravity field from acceleration... ...having just written that I think I've just figured out why my "counter-example" is not legit. No doubt Einstein was comparing a *uniform* gravity field with acceleration. Oh well. I'll just get back to my designs for a perpetual motion machine instead..
Well, that's very simple. Bring your own accelerometer , like the kind in a smartphone and start measuring before acceleration and continue after deceleration, then compare with your Earthbound twin. OR Forget the Smartphone and go on a looong circular journey under constant acceleration. When you get back, compare your clock or calendar with your Earthbound twin.
Had a few PM designs back in the day. Prof. Casimir debunked them for me, and warned me not waste my entire life searching :). You can find them on my website for amusement. Still searching though...
Thinking perpetual motion is possible, no matter how small you think the odds are, demonstrates a fundamental misunderstanding of physics as a WHOLE. You need to invest your time in learning all of the fundamentals again before you attempt to pose or answer any questions. Thinking perpetual motion is possible at all and also believing in physics is just like believing in science and religion. Science and religion have direct contradictions to each other that makes their coexistence impossible unless you make logical or moral concessions or you just completely ignore certain conflicts and act like they don't exist. With science you don't have the luxury of being able to ignore or omit the parts that contradict because those things remain true whether you believe it or not, your belief in the matter doesn't change the outcome. Perpetual motion is 100% unequivocally impossible and you'd have to completely disregard some of the most well understood and fundamental build blocks of physics to rationalize the possibility of any system having 100% or higher efficiency. There are plenty of things that are highly efficient and appear to have perpetual motion, but the idea of true perpetual motion is absurd and ignorant.
Usually the pros talk about the eq. Principle that acceleration and gravitation are equivalent at a point. Tidal forces are infact a thing that distinquishes gravitation from acceleration. I find iy easier to see when we think about a very large and very looong object near a massive round body. It is falling towards it, but if the object is long, then it starts to bend (imagine this as the object being longer than the planet's diameter, and the object will start to "hug" the planet by bending to a sircular form, stretching from its far ends). That is another type of a tidal force, and there you can see your spaceship going from straight into a banana-looking shape, and you can say that you are in a Gfield. If the spaceship was just accelerating uniformly, it would stay straight.
In the case of gravity the force is radial ie pulls towards the centre of the Earth. This means that the gravitational force on your left side won't be quite parallel to the force on your right. If you were to hold a weight in each hand, stretch your arms out and drop the weights, the weights would hit the ground slightly closer together than when you released them. Obviously the difference will be tiny and will be masked by masses of other objects in the vicinity. In the case of acceleration the forces will be perfectly parallel on both sides so the weights would hit the ground exactly the same distance apart as when they were released.
So can the Casimir effect be used to explain the phenomenon of interference? I think it would be very usefull to explain the apparent splitting of a particle as it approaches the two apertures. Great work by the way by you guys at Sixty Symbols.....big fan here!
But when Hawking radiation happens and half of the particle-antiparticle pairs fall in the event horizon, why would the antiparticle that decreases the mass of the black hole fall in more often than the regular particle? Shouldn't it statistically be 50-50, in the end neither decreasing or increasing the mass?
Anti particles and particles don't have opposing mass only opposing charge - that's why there's an "energy debt" in the first place as there is technically a net increase of mass (i.e. energy in the universe). Though the mechanics of the theory doesn't exactly work like this the simplest way to explain why the black hole loses mass is that once these twins are split, the one that falls into the black hole has a bountiful amount of energy to interact with to "repay the debt" while the other twin gets to roam the universe as a real particle (without the temporal grim reaper over it's head since the "debt" got repaid in the black hole).
Paulina Jonušaitė And? The antiparticle annihilates something inside the hole and the regular particle doesn't. The regular particle would then increase the mass. DarkenedYeastExtract What I don't get is that it's about particles and antiparticles, yet it doesn't matter which one enters the hole. Of course I assume nothing works the way you'd think inside a black hole, but if I just go by the particle-antiparticle logic, only the antiparticle would end up decreasing the mass of the hole, since it annihilates something within it.
Particles pop into existence, leaving an energy "debt" in their stead. Normally, the "debt" is returned by both particles annihilating again, however, if one of the particles flies away due to extremely warped space-time curvature, the "debt" has to be repaid from other sources, namely, the mass that created the warped curvature. Thus, black hole loses energy and, by extension, mass, because mass *is* energy when speaking about black holes. You seem to think of mass and energy as two separate things, which is just incorrect for black holes. There is no matter or antimatter inside the black hole, that information is completely obliterated, so there is nothing annihilating inside of it either.
I could be totally wrong here but here's what I think of it; If the positive(real) falls in and the negative(anti) remains out, the negative would have to annihilate because it's existence added matter to the black hole. But it can't just vanish. It'd need to pair with a nearby particle, and being as though there are particles being created and annihilated around it constantly, it'd pair with a positive half & annihilate, leaving another anti-particle half there, and would continue to chain until one falls into the black hole, restoring the energy. If that is right then we'd only get "real" photons emitted while over time the black hole reduces in mass to account for the energy released as hawking radiation. Again, could be wrong it's just my interpretation.
Even though my knowledge is weak in this field it's just a very interesting and fascinating I love to watch these. The idea of hawking radiation is incredible and the genius minds who are finding these outs
I had read about Hawking radiation in his book but could not concieve the idea properly. Your explanation is simple to understand. The picture is clear now. Thank you Prof. Mike.
basically if you know that electron has no energy, you can't exactly tell what time it arrived, hence if there is no electron at all, you can't really tell when
What do we mean when we say that photons can pop in and out of existence if someone isnt noticing them? Bassically what do we mean when we say notice them
When we say we notice them, we might also say we observe them, or we measure them. It means they have an effect. Between two transitions, that is to say between the origin and the end of the existence of a particle, it can be in any state. It can go infinitely many ways, and in some sense it does go all of them. That includes interacting with all kinds of other particles that may or may not be there, as long as the effect at the end is the same. Those other particles the original particle may interact with (or does interact with, depending on your take on things) can be anything, but the more energy they have, the shorter the duration during which they can affect the original particle. They are not measured themselves and as such are considered virtual. And because the sum of the energy between measurements must be zero, all these virtual particles must come with their respective anti-particle. Light is its own anti-particle. All this could be considered a philosophical red herring that originates from the mathematical description, except that the Casimir effect proves that there is more to it. These virtual particles can be made not-virtual. There are other applications that rely on the existence of virtual particles as well. And they are also the explanation for what is Hawking radiation, or in other words: They reconcile GR with thermodynamics. (Which is ironic, because QM (which describes virtual and other particles) and GR are still not reconciled with each other themselves.) Obviously there is more to it than is currently known.
I have a question, ok, virtual particles annihilate in couples in vacuum, where there are no other particles, does this also happen in say, a chamber with no vacuum? I mean, it happens whether there is vacuum or not? If not, why does the presence of matter (gas particles) not allow the creation/annihilation of these virtual particles?
Yes it also happens in a gas or solid. Remember that almost all the space in a gas is empty space. The individual atoms are surrounded by vacuum and inside of them it's almost a perfect vacuum with only a few electrons being very far from the nucleus. Of course one could imagine some of these particles being absorbed by, say, the electrons, but in general they wouldn't even notice the presence of matter.
I see, so, since the annihilation of matter/antimatter takes place everywhere, and as a result, photons are emitted, since the interaction of photon-electrons of matter is unavoidable, can we conclude that matter is constantly receiving energy from the vacuum through the creation of this photons (except of course if the energy of the photon is so low that it can't promote electrons to higher energy states)?
That's a good question. It would seem like the matter should be getting energy for free this way, which obviously isn't the case. Saying that the photons do not have the energy to jump the electrons up to a higher orbit might help explain some, but we would still expect the nuclei to continuously gain energy from the virtual photons. By the way, the photons are not created by matter-antimatter annihilation in this case, but just spontaneously pop into existence because of the uncertainty principle.
Ok, sorry, I put it in the wrong words XD. That is actually the point, thing is, like you already said, I would expect matter to continuously gain energy because of these photon-electron interaction however I agree, that it shouldn't (isn't) happening. And the only way around it is either that they're unable to promote the electrons or that somehow these virtual photons aren't interacting with matter.
This video complements the recent Numberphile videos about the value of the sum of all natural numbers; 1 + 2 + 3 + 4... = -1/12. People were wondering if that result has any meaningful application beyond mathematical trickery. As Professor Merrifield explains here, it is used when calculating the Casimir force. We ignore the part of the calculations that would lead to an infinite amount of energy and "sweep them under the rug", substituting -1/12 instead. Experimental evidence shows that nature agrees with this result, as strange as it is! Excellent excellent video!! :)
So let's imagine two black holes orbiting far ebough they wouldn't merge. Would the hawking radiation of one "feed" the other and viceversa? Could there be a "stable" array of black holes feeding ea other?
i am gonna assume the explanation is way more complicated than this but probably they just do. Maybe they interact with the background radiation or the magnetic field or the higgs field but pretty much they just pop out of nowhere and disappear in a matter of femtoseconds
zach miller you should look into quantum mechanics, and different dimensions, essentially these particles are just going in and out of different dimensions...
zach miller Do you remember when the guy said that when the photon falls into the black hole, it loses mass? Another way you can think of that is by saying that the photon has negative mass and negative energy. When you think of it that way, you realise that virtual particles never violate conservation of energy - when they form, one has positive energy, one has negative energy, and so the total energy sums to zero. As to how and why they form, that's a difficult question, and I probably don't know enough to answer. It's a result of the Uncertainty Principle, as the professor said. The common formulation of the UP follows thusly - the momentum and position of a particle cannot be determined to high precision at the same time. Without a lot of work, the UP can be rearranged to state that, also, the energy and the time interval a particle has existed for cannot be determined to high precision at the same time as well. The vacuum of space - we know exactly how long it has been in existence, at least in theory. 13.75 billion years. Theoretically, we could determine that number to an incredible accuracy. We also know how much energy it has. It's a vacuum, so zero energy. So for the vacuum, we know the time interval and we also know its energy precisely. But by the UP, that's impossible. So one of those two has to be wrong. We aren't wrong about how long its been in existence, so therefore we must be uncertain about its energy. All we know is that it can't have zero energy, because that's too precise a value. This implies that there's energy embedded in the vacuum itself, which we can't measure. I don't know why the particles form, but at least I can tell you where they get their energy from. It's best to stop thinking of the vacuum as a zero energy system. Instead, think of it as the lowest energy state of a system, and by the UP, that lowest energy value is forbidden from being zero. Hope it helped.
+Vai *...essentially these particles are just going in and out of different dimensions...* I just read this and thought, "Hmmmm that sounds an awful lot like pseudo-science to me. Especially since that would be something we cannot observe to be true by any means."
+Yokai Seishinkage He asked where these particles came from so I told him what I knew about it, unfortunately no knowledge is absolute. What makes you think that my statement cannot be observed or tested, you don't have a degree in quantum physics to my knowledge.
I have a question in broken english:) If the photons that being created in the gap between the two plates have shorter wave lengths, doesn't it means that they also have greater energy? as in Hawking radiation? the smaller a black hole and his event horizon is, the more energy being emitted with his photons, and therefore it has a higher temperature? and if so, isn't the fewer (and more energetic) photons between the two plates, somehow balance the pressure that the lower energy photons are causing from the outside, and cancel the force?
If an object was floating completely still in a vacuum would the flashing in of these quantum pairs force some sort of pseudo brownian movement on the object?
I don't think so. If those virtual particles only borrow their energy from the vacuum energy, then their annihilation must not have ANY effect on anything else for the energy conversation to hold true. Because if they interact with anything else, they will lose energy and so give less energy back into the vacuum than they took out of it.
+SkrootNissu Yoctomind There's an experiment that can produce anti-matter and you can see sparks in the air where the anti-matter hits regular matter and gets converted to pure energy
From a pure mechanical viewpoint, these photons are created from the energy of the vibrating plate. This from one side of this duality way of viewing things - and both are correct. So it's merely a roundabout way to get electrons, or any other particle. If you need a lot of photons, use a led lightbulb, easier and cost less. ;)
I have two ways of distinguishing between a gravitational field or a pure accelerating field. 1. In your elevator enclosure have a clock near the ceiling and a second clock near the floor. In a gravitational field they will run at different rates but in an accelerating field they will keep time together. 2. Install two plumb bobs on either side of the elevator enclosure. In a gravitational field there will be an angle between the two lines but in an accelerating field the two lines will hang parallel.
I finally have a good enough understanding of hawking radiation. Always have told myself i knew what it is and I do to some degree. but knowing the casimir effect makes it so much easier to wrap your head around it.
This might be a good question. Can we use the Casimir effect to simulate the event horizon of a black hole ? Per this vid, using a wave guide, physicists were able to move an analog of Casimir plates back and forth at 5% light speed, creating microwave particles ( by preventing some of the virtual particles created in the gap by quantum effects from recombining. Is this analogous or even equivalent to a black hole event horizon and Hawking radiation whose wavelength = the surface area of the hole? If so can it be used to study black hole behavior empirically in the lab? ( L Suskind's talk)
Not really. It would only be useful for studying the casimir effect and breaking particle and antiparticle pairings, but it wouldn't do much else for studying event horizons themselves. Black holes have a similar effect at their event horizons, but the casimir effect doesn't mimic the properties of an event horizon. It's kind of like how a black hole could theoretically have a charge, but studying... I dunno... say a balloon rubbed on a cat wouldn't explain much about what's going on inside a black hole. :P
I would like to know more about the balloon and the cat. I don't think there is any published data on balloons and cats, at least in a refereed journal. Though I may have missed a symposium or two.
I like the way this a bit more detailed than the other black hole videos, I had no idea the evaporation, and chiefly the "popping up" of particles was due to the uncertainty principle.
2:04 What happens if what I want to create corresponds to a time less than the Planck time (5.4*10^-44sec). I guess it is too large to be created ...or not? (shouldn't it be less than the Planck mass=2.17*10^-8 ?)
Ok I have this dilemma about light and gravity, which basically boils down to the question "does light slow down in a gravitational field?" I've always learned three things: 1. Light is affected by gravity 2. Light (in a vacuum) will always travel at the speed of light 3. A gravitational field is equivalent to any other acceleration Based off these three things, if you were to shine a flashlight straight away from the earth's center of mass, it would be pulled back by its gravity and slowed down. However that would contradict the fact that light must always be measured at the speed of light, so it can't slow down. But if it can't slow down how can a black hole stop all light? Doesn't it pull the light trying to escape back down to the center (slowing down the light) I need help lol.
I missed the part about your black hole question. So it's the same idea - mass bends spacetime (called gravity.) Think of this as bending all possible paths you or a particle or a photon could travel down. A black hole is an extreme case of this - at the event horizon, all possible paths bend inward. The black hole has bent spacetime so much that even the paths leading directly away from it end up pulled forward instead. So light still travels at c even in a black hole. But there is no way for it to go out because there is no such thing as out anymore. All paths inside the event horizon lead to the singularity.
+ForeverOfTheStars The black hole doesn't slow the light down. It can bend light but also it can change the wave length of the light. Think of it like the Doppler effect. When light is emitted from very close to the horizon of a black hole then it will appear to have a much longer wave length once it escapes the vicinity of the black hole. So blue light will appear more red. Eventually at the horizon light emitted would have an infinite wave length and hence a zero energy. This all ignore quantum effects though, which makes things a little more interesting.
ForeverOfTheStars think about like light doesn't slow down but the path In which it's traveling if warped in away so that light seems to move slower. It's hard to explain over the phone but whatever Light follows the curvature of space time, if the curvature of space time is warped by gravity then the path in which light travels through is warped, think about like this, say you have to walk x distance this takes time y, if x distance is distorted or warped in a wavey like way then you have to travel the same x distance but now since it's distorted instead of being a straight path it's takes y+z time where z is the prolonged time due to the path being distorted, same behavior for light if say light travels x distance and it takes time y if it's straight path is distorted by gravity then it's the same amount of distance and speed but the time (y) is prolonged by a certain amount depending on the how much space time curves.
How does the virtual particle falling into the BH from the EH cause it to lose mass? Can that be understood simply? I would expect the virtual photon that falls in to have a positive energy, as well as the one that escapes.
Could the mathematics of Quantum mechanics represents the physics of ‘time’ with the future unfolding photon by photon with each new photon electron coupling or dipole moment?
Brady, I have a pressing concern. I found it interesting this video came about right around the same time as the -1/12 Gold Nugget video on numberphile, because in this video Merrifield says around 4:00 "you end up with an infinite mass, but we have a process through which we can normalize those infinities to finite quantities". Was he talking about the same process as adding the integers (1 + 2 + 3...)? It was stated that that result was used in physics? I'd love for you to follow up on this!
I know. He actually does a really good job of explaining things, but it's hard to keep up with it sometimes. I had a lecturer like this in my freshman chemistry class way back when. It was kind of a maddening experience.
i just watch physics videos on youtube - i'm not an expert at all. that's an interesting thought but my understanding is that this casimir effect produces photons which are mass-less particles. Dark matter is a source of unknown gravity in the universe implying that the cause of dark matter has a mass. then again e=mc^2 says mass and energy are interchangeable so what do i know?
+Melodic Guitar Rock/Metal GuiltyGearRockYou Yes, that is true, and they also exist incredibly briefly. This prevents it from entangling with even nearby particles, and dark matter operates at an extremely long range, from what I gather anyways.
I'm a bit skeptical to how all this actually leads to the black hole "evaporating" .. I mean.. i still don't see HOW the black hole actually loses mass, other than "It has to lose mass, because the energy have to come from somewhere". I mean, why can't black whole rip apart virtual particle pairs, generating a form of zero-point energy, or "dark energy". Energy that comes out of nowhere and "shouldn't" be there. That's because it's the leftover from broken virtual particle pairs. I mean.. I'm sure there's a lot of smarter people that know's a lot more about science than me.. But i would like some better explanation how the black hole LOSES mass by sucking in virtual particles.. that would make me a lot happier.
Okey.. Now I feel stupid .. I did a bit of research and found the quite obvious explanation that The anti-particle that were sucked into the black hole, sending it's lone, ex-paired ex-virtual particle partner to fly through the galaxy as a real particle in the form of hawking radiation, would simply annihilate with a particle in the black hole's singularity, and thus making it lose mass. Quite obvious actually, and that's why i feel so stupid.. But… It still doesn't answer some questions.. like.. how come ONLY the anti-particle is sucked in and not the other way around? Why isn't it completely random which one from the virtual-particle-pair that's being sucked in.. I mean, the only difference between a particle and it's anti-particle is it's electric charge. So why does that have effect which of the two particles in the pair is being sucked into the black hole? And also, when a particle and an anti-particle annihilate, they create pure energy in the form of photos (that travels in the speed of light), and since whatever is inside the event horizon has to go Faster than the speed of light to escape, (something that is impossible) means that the energy Still can't Leave to black hole. So I still don't see where the loss off mass comes in.. So I still don't understand the basis for the claim that black holes evaporate.
Dahxelb The mass of a black hole will increase whether an electron or positron enters it. When an electron/positron pair (or any other matter/antimatter particles) come into existance just outside the event horizon and just one of the pair falls in, the black hole increases by the mass of that particle but the mass is also reduced by the energy required to separate that particle pair so there is a net loss of mass to the black hole. To summarize:- Electron/positron pair comes into existance electron falls into black hole, positron flies away. Universe now has gained the mass of one positron. Black hole has gained the mass of one electron but lost the mass of separating the electron positron pair which will be eqivalent to the mass of two electrons so the black hole has effectively lost the mass of one electron.
bob s Thank you for trying to explain. But it still doesn't explain exactly how something with mass actually leave the black hole. The energy that separates the particle pair comes from the black holes gravitational pull. And gravity doesn't "lose" energy just because something is pulled by it.
Dahxelb Nothing actually leaves the black hole, the particle that "leaves" (Hawkings radiation) originates just outside the event horizon. Mass and energy are equivalent (e=mc^2). The energy to separate the pair must come from somewhere.
Dahxelb I agree with you in that it doesn't make sense at least to us. All these people say that it takes energy to separate them but I see the world as you in that gravity doesn't lose energy by pulling. My guess is that the problem lies in the fact that we (no one really) don't know how to link quantum mechanics with gravity. It was mentioned in the video. That there is something that is missing in the puzzle.
3:29 How do you measure this force? Does it move? Then there's an free increase in energy, unless it's countered by negative energy (whatever that means) when the plates stop.
Thank you so much for another excellent explanation of a complex idea. I find your videos always leave me with greater knowledge and a better understanding of the topic at hand. If only I had been fortunate enough to have had such excellent instructors in school, instead of the disappointed intellectuals with poor communication skills that I had in the 70's my life my well have turned out differently with my pursuing education instead of grabbing an axe and going to work. Thumbs up for teachers who love to teach and share the knowledge that they have with anyone wanting to learn what they are offering. Thumbs down for those teaching for any other reason.
chasem007ify The Casimir effect is measurable with boson force carrying particles like photons that are the boson particles of the electromagnetic field. These bosons have no mass, so an infinite amount of them can exist in the exact same space at the same time. A blue whale is made of fermion particles, that have mass and are matter particles, only one fermion particle can be in the same space at the same time. The Casimir is a quantum sub-atomic effect that thankfully does not measurably happen to us or blue whales.
If you create a pair of particles, they have to annihilate themselves in a brief time. If you separate them before that happens, they can’t annihilate. Have you just created real matter?
Haha....black holes are like people.....if left to our own devices, just existing burns energy and we would lose weight from just breathing and our hearts beating over a long time....but most of us actually gain weight because of the process called stuffing our faces with food xD
Is there a place, or group working on the same discussion? I have ideas relating to making vacuume spaces that could be manipulated for the sake of energy conversion. Specifically using the casimir effect for a dial or tuning device to make the energy represent as usable electricity and provide a one way valve of environments that forces conversion.
It's a correct description. Scientists use the word "theory" in a way that's much closer to the colloquial meaning of theory than the one you've been told is the "scientific definition of theory".
avicenna the definition of a scientific theory is correct, but when scientists are talking (especially to the lay person, but even among themselves) then they will often use the colloquial form of the word just like everybody else does
No, it isn't. Scientists don't have a special snowflake ivory tower definition of "theory". They use it just like everybody else, when talking to themselves or to the public. This top-down enforcement of "theory" as necessarily having evidence behind it is not based on any kind of fact.
"es the word theory does have a very specific scientific definition and use, are you a creationist? " Nope, I'm a physicist and I see the usage of the word in person every day. This fiction that the word somehow means the current pinnacle of scientific understanding seems in fact to have been invented to combat creationists, but the correct response to creationism is not to say "evolution is a theory so shut up stop asking questions", but rather to give the evidence in support of it.
A question (from a complete layman in the subject) Since these forces are so tiny, how do you know for sure that the force pushing the plates together are actually a result of this Casimir Effect and not just a gravitational pull between the plates themselves?
If it's been reported (and presumably confirmed and peer reviewed), the it's safe to assume they took all other forces into account. No dea how they would measure it though.
Because we can calculate how much gravity there should be and we can incorporate that in the calculations. What you bring up is a very good point that is often missed by pseudo-scientists: You got to isolate what you're trying to measure in an experiment. Experimental science is all about finding out how we can maximize the signal to noise ratio. The signal is what we're trying to measure and the noise is everything else that is skewing the results. Even in the video: The squid thing that was supercooled that he mentioned. Supercooling cools down stuff so much that materials start behaving in a very clean and predictable way. Barely any thermal energy, no electrical resistance etc etc. All that stuff is basically noise that we can remove by supercooling it. Excellent question :) I hope my answer clears it a bit up.
CASIMIR FORCE:- Increases as the inverse fourth power of the plate surface gap & it stops when the plates come into contact. The surfaces have to be electrically conductive ~ there is no Casimir force between ceramic [or other non-conducting] plates. GRAVITATIONAL FORCE:- Between two objects does not depend on the gap between the surfaces of the objects ~ it depends on the masses of the objects & the separation between their CENTRES OF GRAVITY [CoG]. It increases as the inverse second power of the CoG gap. The gravitational force does not care what the objects are made of ~ all that matters is their masses. DIFFERENCE IN STRENGTH:- At a gap of 10 nm [100x size of an atom] the Casimir effect produces the equivalent of 1 atmosphere of pressure. This is far far stronger than gravity by a crazy amount
When measuring the casimir effect, how do you distinguish between the photon 'pressure' and inter-atomic forces between the two plates? How big is this pressure?
TheGreatSnoozer The gap is far too large for the weak & strong interactions to have an effect. Inter-atomic forces are at around the femtometre scale [10^-15 metres] e.g diameter of a proton is appro 1.7fm. Casimir experiments are performed at typically a gap of 10 nanometres [10^-9 metres] which is 100 larger than the size of a whole atom.
A very good question -- indeed, it has been argued that the Casimir effect can be explained by such "conventional" forces rather than the virtual particle effects discussed here. I think the jury is still to some extent out, but this explanation has the stronger backing.
I do have a question. Judging by this video, The Casimir effect looks scalable - the amount of produced photons is directly correlated to the acceleration. Respectively, the Hawking radiation scales with the mass of the black hole. However, certainly the area of the event horizon must be a limiting factor (equivalent of the volume of the space, confined by the plates). If this is correct - how do the effect of the area and the effect of the gravity scale, compared to each other? In other words - do larger black holes evaporate faster or slower than small ones?
i think it's the opposite, you see a massive black has an event horison whose gravitational pull is weaker than lets say a microscopic one. i don't think it's proprtional to the volume but the intensity of the grav-pull of the event horison
Relative to their size a large black hole is much slower than a small black hole. Microscopic black holes (if they exist) are supposed to evaporate almost instantly.
Particles seem to highlight a type of, analog flow of a dense form of space itself. Where you would expect to see crests of two opposing flows ,wether it's at a peak or trough , coinciding particles would be found.
@ 0:25 I don't mean to be that guy, but in order to measure the energy wouldn't you want the wavelength of the photon, and not the amplitude? For that matter, how does one even measure the amplitude of a single photon?
i dont get the hawking radiation. if a virtual photon escapes into black hole and this makes black hole less massive but when negative particle escapes to the black hole doest it make black hole more massive than before? if it is then why this process doesnt evens out?
the flow of spacetime makes the ingoing particle have a negative frequency as viewed from outside. this is like a negative mass. it is very strange since we don't see negative frequencies very often, if ever
does this have any practical application? Could we create out of nothing and eliminate that amount of materia ? Its a very extrange question, but, could you "transform" trash to gold if they have the same mass?
If one were to travel at the speed of light, one would be able to travel between two crests of a photon's wavelength, and in that frame of reference the wavelength will have stretched out to infinity. Infinite wavelength means zero energy. A change in velocity would result in said photon revealing itself. Matter can't travel at the speed of light, but there are reference frames so arbitrarily close to the speed of light that the wavelength of the photon is stretched out to be larger than the universe. We could be surrounded by such long-wavelength photons, and only when we change speed are we able to see those photons as they are blue-shifted into detection. Because one wasn't expecting a photon, one might think it spontaneously popped into existence.
yup, i'd even think that what you say is mandatory since dt dE = h, low energy virtual photons would last a long time and this makes them pretty much real photons.
Best explanation I've ever heard of Hawking Radiation. No sarcasm -- before this vid, I never understood WHAT was making a black hole (i.e., something that traps everything forever) actually release something.
I knew I had heard about the 2011 dynamic Casimir experiment before. It was done by people from my university (Chalmers in Gothenburg, Sweden), and I've talked to people involved. Back then I didn't really grasp what the effect really was, but nonetheless it's really quite cool.
Sixty Symbols When he says shoveling the infinities under a rug at 4:25 Is he talking about the same kind of infinite sums that numberphile is discussing in this video: Million Dollar Math Problem - Numberphile The ones with the Riemann Zeta function and that 1+2+3+4+... = -1/12 ? I would be immensely interested in the answer!! Please can someone help me?
How is energy conserved in the case of the usual Casimir effect? The negative energy density between the plates is reduced as the plates come together but where does this energy go? Into the plates?
This has been useful content. I am/was watching in 2021, having already audited "What's Up With Muons", and "Betelgeuse Might Explode (in the next 150,000 Years)" this afternoon. Most engaging.
Great explanation overall, but did he misspeak at 8:58 when he said the particle falling into the black hole causes its mass to decrease? Isn't it in fact the particle flying away that causes the black hole's mass to decrease?
Could the Casimir Effect not better be explained by something like the electrons in these metal plates interacting? Maybe a subatomic particle not yet considered like the graviton? Rather than nonexistent particles temporarily existing? (Or is it that they always exist, just in a high dimension, and this is them traveling across our one of many "3D space" as they go about their 4D orbits?)
The background radiation of the universe has currently a lot more energy than the temperature of the Hawking radiation. Thus the black holes are passively increasing in mass.
Great explanation. I have a question . Why does the energy density between the plates in Casimir effect has to be negative ?? This has made hawking infer that Casimir effect can prove warping of space time in negative direction!
This is the best explanation I've ever heard for Hawking radiation.
Also the best (i.e. simplest and most correct) explanation of the Casimir effect I've ever heard.
Hi, sorry I'm late, but both explanation are wrong.
isodoublet shut up and leave
@@isodoublet I agree. WHat is the right explanation in your opinion?
Maybe just external EM waves exerting pressure on plates? I mean, there is always some that are traveling from around - no need to pop into existence.
It's actually the only decent one I've ever heard.
This man is a genius. He explains it sooooo simple and nice
Right? Incredible
...somebody has never seen, heard nor read Feynman, Walter Lewin, Judith Grabiner, Eric Kandel...
@@crackakilla2506Some of us probably have, but that doesn't diminish this man's didactic skills in any way :)
@@BackflipBeaver ty for the new word!
@Pink Pyramids chill
8:32 "it is then doomed ...... To wander the universe as a real particle"
How I'm feeling
I think I understand how you feel.
That is actually such a good explanation of Hawking radiation. My hat goes off.
Hawking radiation can be a maaaassive pain in the arse to explain - and usually to someone who isn't a physicist, it will just never make sense. This video actually makes it make perfect sense. Mike you're a genius.
Sounds great
This is now my favourite "detail" explanation of Hawking Radiation. Tried reading more about it before, but it gets so complicated so quickly there's no chance of really making sense of it... But this, this made a whole lot of sense :)
Agree!
Thanks for this! I've encounter the Casimir effect before, though usually voiced in terms of electromagnetic waves. It's much clearer when you talk in terms of the virtual particles themselves. The dynamical Casimir effect is a new one for me.
yeah im sure they are pulled together not pushed. they are attracted to each other. they are of the same element.
Love the simplicity of his dialogue.
If anyone ever has trouble with understanding concepts in physics, chemistry, philosophy, mathematics, computing, etc., he or she should watch Brady's wonderful videos!
I don't usually comment on videos but I thought typing this out would definitely be worthwile.
I'm from a place where you=your test marks..you're gauged on nothing but performances on tests.
I'd like to take a moment to thank Brady Haran and the professors at the university of Nottingham for conciliating and kindling the curiosity people like me have in science..people who don't get much time out of academics.
The videos are just a few clicks away and are thoroughly informative and lucid.
Thank you very much and keep up the good work. :)
2:23 how do they account for the gravitational effects of the two plates??? My naïve assumption is that two objects that close would have a strong gravitational effect on each other
This is one of my favorite Sixty Symbols videos for all time and it's caused me to think about so many things.
that's great!
+Sixty Symbols why only the anti partical falls inside the black hole and not the partical?
+Amit r Could be the other way round - nothing is stopping that.
+NuclearCraft Mod sorry, what?
Amit r It isn't always the anti-particle that falls into the black hole - it can sometimes be the particle.
I love physics, but sometimes think I could never be smart enough. To not just watch videos, but to understand it well enough or learn the math well enough to actually do it.
I’m grateful to hear explanations that bring a seemingly magic clarity to important concepts. It’s inspiring. It makes me think, yeah, I’m getting this. Maybe there’s a chance I could learn it at a deeper level.
Outstanding work, thank you.
Wow, totally love Mike Merrifield. Never heard anyone explain stuff that's complicated enough to be on the fringe of known physics in such an accessible way before.
What an incredible nice video. Nice edited, explained and animated. Though I was more or less familiar with all the processes the video still gave me a lot of joy. I was actually a bit sad that it ended. Good job Brady, Mike and Drew :)
he speaks very good.. and in detail.. excellent
because he is a professor and lecturer
bertazoid lol
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>< And he's a dapper man. A true gentleman of the people.
I love how complicated the subject is, yet it's explained in a very simple way
This explanation of Hawking Radiation makes it much easier to understand than the initial reports about it.
It's also wrong though.
isodoublet elaborate upon your statement, from what I know is that the Casimir effect talks about a force caused by quantum fluctuation (F=π^2 hbar c)/240 d^4 that occurs in electrodynamical vacumm that fluctuates zero point energy fields, these fluctuations are a product of uncertainty principle, what did the professor say that was wrong?
From how the casimir effect was explained, i get the imagine in my head that these photons are trying to press into our dimensions but since we have matter around us, the photons cant get through the sieve(so to speak) since our dimensions here on earth are filled, but in the vacuum, there is nothing blocking the sieve holes. Really interesting things, thats why i love these videos, they really get the imagination firing!
Could this phenomenon have been an important part in shaping our universe during/after the Big Bang when space accelerate faster than the speed of light, particles popping into existence (because of the Casimir Effect) at an unimaginable rate during that acceleration period?
Accelerate faster than the speed of light? You're comparing two different nominal measurements, acceleration and velocity.
That was what I thought... maybe some smart intelligent friendly person could answer this question?
Actually if I've understood things correctly, a significant portion of the particles in the universe were created via this in the first place. When the cosmic inflation ended, the energy of it had to go somewhere and theories suggest that that energy went into the virtual particles that existed at that moment and turned them into real particles.
From what I know, I don't think so. Not in the same way as this. During inflation spacetime itself was expanding insanely fast, but not the particles in spacetime. Not saying that particles didn't get created, but I don't think it's thanks to this.
one interesting consequence of it would be clumps of antimatter and clumps of "ordinary" matter populating the universe, that have no causal interaction between one another because they would have been brought apart by the inflation acceleration. Such an eventuality would leave behind a specific imprint in the cosmic microwave background radiation for instance. Planck data is to this day being studied to test the validity of such models. We may live in a symetric matter / antimatter universe afterall :D
Brady's presence facilitates an interaction that helps me to feel like I'm the one in the room. Also, Prof Merrifield is awesome!
7:30
I remember hearing this at Uni and being determined to think of an experiment that could distinguish acceleration and gravity.
I've always wondered about tidal forces - if you're standing on the ground, gravity pulls slightly more strongly on your feet than on your head. Simply because your feet are closer to the Earth's centre of mass. Obviously the difference in gravity is very, very small (1 part in about 10,000,000,000,000 by my rough calculation) but I'd be interested to hear what this does for the equivalence principle because it suggests that one could, theoretically, distinguish a gravity field from acceleration...
...having just written that I think I've just figured out why my "counter-example" is not legit. No doubt Einstein was comparing a *uniform* gravity field with acceleration.
Oh well. I'll just get back to my designs for a perpetual motion machine instead..
Well, that's very simple. Bring your own accelerometer , like the kind in a smartphone and start measuring before acceleration and continue after deceleration, then compare with your Earthbound twin.
OR
Forget the Smartphone and go on a looong circular journey under constant acceleration. When you get back, compare your clock or calendar with your Earthbound twin.
Had a few PM designs back in the day. Prof. Casimir debunked them for me, and warned me not waste my entire life searching :).
You can find them on my website for amusement. Still searching though...
Thinking perpetual motion is possible, no matter how small you think the odds are, demonstrates a fundamental misunderstanding of physics as a WHOLE. You need to invest your time in learning all of the fundamentals again before you attempt to pose or answer any questions. Thinking perpetual motion is possible at all and also believing in physics is just like believing in science and religion. Science and religion have direct contradictions to each other that makes their coexistence impossible unless you make logical or moral concessions or you just completely ignore certain conflicts and act like they don't exist. With science you don't have the luxury of being able to ignore or omit the parts that contradict because those things remain true whether you believe it or not, your belief in the matter doesn't change the outcome. Perpetual motion is 100% unequivocally impossible and you'd have to completely disregard some of the most well understood and fundamental build blocks of physics to rationalize the possibility of any system having 100% or higher efficiency. There are plenty of things that are highly efficient and appear to have perpetual motion, but the idea of true perpetual motion is absurd and ignorant.
Usually the pros talk about the eq. Principle that acceleration and gravitation are equivalent at a point. Tidal forces are infact a thing that distinquishes gravitation from acceleration. I find iy easier to see when we think about a very large and very looong object near a massive round body. It is falling towards it, but if the object is long, then it starts to bend (imagine this as the object being longer than the planet's diameter, and the object will start to "hug" the planet by bending to a sircular form, stretching from its far ends). That is another type of a tidal force, and there you can see your spaceship going from straight into a banana-looking shape, and you can say that you are in a Gfield. If the spaceship was just accelerating uniformly, it would stay straight.
In the case of gravity the force is radial ie pulls towards the centre of the Earth. This means that the gravitational force on your left side won't be quite parallel to the force on your right. If you were to hold a weight in each hand, stretch your arms out and drop the weights, the weights would hit the ground slightly closer together than when you released them. Obviously the difference will be tiny and will be masked by masses of other objects in the vicinity.
In the case of acceleration the forces will be perfectly parallel on both sides so the weights would hit the ground exactly the same distance apart as when they were released.
It's incredible that these advanced concepts can be explained with such clarity! Amazing.
So can the Casimir effect be used to explain the phenomenon of interference? I think it would be very usefull to explain the apparent splitting of a particle as it approaches the two apertures.
Great work by the way by you guys at Sixty Symbols.....big fan here!
This guy is a really good teacher. He manages to explain some very difficult concepts in simple terms.
i never understood Hawking radiation until now. Great way of explaining
The clearest explanation of the Casimir effect I found. So beautiful.
But when Hawking radiation happens and half of the particle-antiparticle pairs fall in the event horizon, why would the antiparticle that decreases the mass of the black hole fall in more often than the regular particle? Shouldn't it statistically be 50-50, in the end neither decreasing or increasing the mass?
Uhm... both particles and antiparticles have a positive mass.
Anti particles and particles don't have opposing mass only opposing charge - that's why there's an "energy debt" in the first place as there is technically a net increase of mass (i.e. energy in the universe). Though the mechanics of the theory doesn't exactly work like this the simplest way to explain why the black hole loses mass is that once these twins are split, the one that falls into the black hole has a bountiful amount of energy to interact with to "repay the debt" while the other twin gets to roam the universe as a real particle (without the temporal grim reaper over it's head since the "debt" got repaid in the black hole).
Paulina Jonušaitė And? The antiparticle annihilates something inside the hole and the regular particle doesn't. The regular particle would then increase the mass.
DarkenedYeastExtract What I don't get is that it's about particles and antiparticles, yet it doesn't matter which one enters the hole. Of course I assume nothing works the way you'd think inside a black hole, but if I just go by the particle-antiparticle logic, only the antiparticle would end up decreasing the mass of the hole, since it annihilates something within it.
Particles pop into existence, leaving an energy "debt" in their stead. Normally, the "debt" is returned by both particles annihilating again, however, if one of the particles flies away due to extremely warped space-time curvature, the "debt" has to be repaid from other sources, namely, the mass that created the warped curvature. Thus, black hole loses energy and, by extension, mass, because mass *is* energy when speaking about black holes.
You seem to think of mass and energy as two separate things, which is just incorrect for black holes. There is no matter or antimatter inside the black hole, that information is completely obliterated, so there is nothing annihilating inside of it either.
I could be totally wrong here but here's what I think of it;
If the positive(real) falls in and the negative(anti) remains out, the negative would have to annihilate because it's existence added matter to the black hole. But it can't just vanish.
It'd need to pair with a nearby particle, and being as though there are particles being created and annihilated around it constantly, it'd pair with a positive half & annihilate, leaving another anti-particle half there, and would continue to chain until one falls into the black hole, restoring the energy.
If that is right then we'd only get "real" photons emitted while over time the black hole reduces in mass to account for the energy released as hawking radiation.
Again, could be wrong it's just my interpretation.
Even though my knowledge is weak in this field it's just a very interesting and fascinating I love to watch these. The idea of hawking radiation is incredible and the genius minds who are finding these outs
The energy caliper at 0:27 should be horizontal rather than vertical :D
I had read about Hawking radiation in his book but could not concieve the idea properly. Your explanation is simple to understand. The picture is clear now. Thank you Prof. Mike.
basically if you know that electron has no energy, you can't exactly tell what time it arrived, hence if there is no electron at all, you can't really tell when
Best explain explanation for Hawking radiation I've ever seen on UA-cam.
What do we mean when we say that photons can pop in and out of existence if someone isnt noticing them? Bassically what do we mean when we say notice them
When we say we notice them, we might also say we observe them, or we measure them. It means they have an effect.
Between two transitions, that is to say between the origin and the end of the existence of a particle, it can be in any state. It can go infinitely many ways, and in some sense it does go all of them. That includes interacting with all kinds of other particles that may or may not be there, as long as the effect at the end is the same.
Those other particles the original particle may interact with (or does interact with, depending on your take on things) can be anything, but the more energy they have, the shorter the duration during which they can affect the original particle. They are not measured themselves and as such are considered virtual. And because the sum of the energy between measurements must be zero, all these virtual particles must come with their respective anti-particle. Light is its own anti-particle.
All this could be considered a philosophical red herring that originates from the mathematical description, except that the Casimir effect proves that there is more to it. These virtual particles can be made not-virtual. There are other applications that rely on the existence of virtual particles as well. And they are also the explanation for what is Hawking radiation, or in other words: They reconcile GR with thermodynamics. (Which is ironic, because QM (which describes virtual and other particles) and GR are still not reconciled with each other themselves.)
Obviously there is more to it than is currently known.
I've heard plenty of explanations of Hawking Radiation and this was probably the best one yet!
I have a question, ok, virtual particles annihilate in couples in vacuum, where there are no other particles, does this also happen in say, a chamber with no vacuum? I mean, it happens whether there is vacuum or not? If not, why does the presence of matter (gas particles) not allow the creation/annihilation of these virtual particles?
Yes it also happens in a gas or solid. Remember that almost all the space in a gas is empty space. The individual atoms are surrounded by vacuum and inside of them it's almost a perfect vacuum with only a few electrons being very far from the nucleus. Of course one could imagine some of these particles being absorbed by, say, the electrons, but in general they wouldn't even notice the presence of matter.
I see, so, since the annihilation of matter/antimatter takes place everywhere, and as a result, photons are emitted, since the interaction of photon-electrons of matter is unavoidable, can we conclude that matter is constantly receiving energy from the vacuum through the creation of this photons (except of course if the energy of the photon is so low that it can't promote electrons to higher energy states)?
That's a good question. It would seem like the matter should be getting energy for free this way, which obviously isn't the case. Saying that the photons do not have the energy to jump the electrons up to a higher orbit might help explain some, but we would still expect the nuclei to continuously gain energy from the virtual photons.
By the way, the photons are not created by matter-antimatter annihilation in this case, but just spontaneously pop into existence because of the uncertainty principle.
Ok, sorry, I put it in the wrong words XD. That is actually the point, thing is, like you already said, I would expect matter to continuously gain energy because of these photon-electron interaction however I agree, that it shouldn't (isn't) happening. And the only way around it is either that they're unable to promote the electrons or that somehow these virtual photons aren't interacting with matter.
Yes it will be interesting to know the answer to this. I will try asking some physicists.
This video complements the recent Numberphile videos about the value of the sum of all natural numbers; 1 + 2 + 3 + 4... = -1/12. People were wondering if that result has any meaningful application beyond mathematical trickery. As Professor Merrifield explains here, it is used when calculating the Casimir force. We ignore the part of the calculations that would lead to an infinite amount of energy and "sweep them under the rug", substituting -1/12 instead. Experimental evidence shows that nature agrees with this result, as strange as it is! Excellent excellent video!! :)
Very interesting! Thank you!
So let's imagine two black holes orbiting far ebough they wouldn't merge. Would the hawking radiation of one "feed" the other and viceversa? Could there be a "stable" array of black holes feeding ea other?
how exactly do these photons appear? i want to ask where they come from but that doesnt seem like the right question.
i am gonna assume the explanation is way more complicated than this but probably they just do. Maybe they interact with the background radiation or the magnetic field or the higgs field but pretty much they just pop out of nowhere and disappear in a matter of femtoseconds
zach miller you should look into quantum mechanics, and different dimensions, essentially these particles are just going in and out of different dimensions...
zach miller Do you remember when the guy said that when the photon falls into the black hole, it loses mass? Another way you can think of that is by saying that the photon has negative mass and negative energy. When you think of it that way, you realise that virtual particles never violate conservation of energy - when they form, one has positive energy, one has negative energy, and so the total energy sums to zero.
As to how and why they form, that's a difficult question, and I probably don't know enough to answer. It's a result of the Uncertainty Principle, as the professor said.
The common formulation of the UP follows thusly - the momentum and position of a particle cannot be determined to high precision at the same time. Without a lot of work, the UP can be rearranged to state that, also, the energy and the time interval a particle has existed for cannot be determined to high precision at the same time as well.
The vacuum of space - we know exactly how long it has been in existence, at least in theory. 13.75 billion years. Theoretically, we could determine that number to an incredible accuracy. We also know how much energy it has. It's a vacuum, so zero energy.
So for the vacuum, we know the time interval and we also know its energy precisely. But by the UP, that's impossible. So one of those two has to be wrong. We aren't wrong about how long its been in existence, so therefore we must be uncertain about its energy. All we know is that it can't have zero energy, because that's too precise a value. This implies that there's energy embedded in the vacuum itself, which we can't measure.
I don't know why the particles form, but at least I can tell you where they get their energy from. It's best to stop thinking of the vacuum as a zero energy system. Instead, think of it as the lowest energy state of a system, and by the UP, that lowest energy value is forbidden from being zero.
Hope it helped.
+Vai *...essentially these particles are just going in and out of different dimensions...*
I just read this and thought, "Hmmmm that sounds an awful lot like pseudo-science to me. Especially since that would be something we cannot observe to be true by any means."
+Yokai Seishinkage He asked where these particles came from so I told him what I knew about it, unfortunately no knowledge is absolute. What makes you think that my statement cannot be observed or tested, you don't have a degree in quantum physics to my knowledge.
This is far and away the best explanation of Hawking Radiation I've ever heard.
3:53 maybe the mass is only -1/12 maybe? ;)
Maybe the mass is 1/0? ( ͡° ͜ʖ ͡°)
Ramanujams identity won't work. Mass isn't negative
No.
I have a question in broken english:)
If the photons that being created in the gap between the two plates have shorter wave lengths, doesn't it means that they also have greater energy? as in Hawking radiation? the smaller a black hole and his event horizon is, the more energy being emitted with his photons, and therefore it has a higher temperature? and if so, isn't the fewer (and more energetic) photons between the two plates, somehow balance the pressure that the lower energy photons are causing from the outside, and cancel the force?
If an object was floating completely still in a vacuum would the flashing in of these quantum pairs force some sort of pseudo brownian movement on the object?
yes, but the effect would only be noticeable if the object was very very small.
I am wondering this too. I think it must do, these tiny forces would become imbalanced for a short period before naturally balancing.
I don't think so. If those virtual particles only borrow their energy from the vacuum energy, then their annihilation must not have ANY effect on anything else for the energy conversation to hold true.
Because if they interact with anything else, they will lose energy and so give less energy back into the vacuum than they took out of it.
Regigigity yes and the geometry of said object can effect the ways in which it behaves, but the effect overall is so miniscule.
3:07 how would someone explain conservation of energy in this case....does plate loses equivalent amount of mass?
Maybe it will be a future way to create lots of anti-particles, the vibrating plate thingy.
+SkrootNissu Yoctomind There's an experiment that can produce anti-matter and you can see sparks in the air where the anti-matter hits regular matter and gets converted to pure energy
+lawlerzwtf
Sounds like a cool way a space ship engine could work. The Vibrator Engine!
From a pure mechanical viewpoint, these photons are created from the energy of the vibrating plate.
This from one side of this duality way of viewing things - and both are correct.
So it's merely a roundabout way to get electrons, or any other particle.
If you need a lot of photons, use a led lightbulb, easier and cost less. ;)
I have two ways of distinguishing between a gravitational field or a pure accelerating field.
1. In your elevator enclosure have a clock near the ceiling and a second clock near the floor. In a gravitational field they will run at different rates but in an accelerating field they will keep time together.
2. Install two plumb bobs on either side of the elevator enclosure. In a gravitational field there will be an angle between the two lines but in an accelerating field the two lines will hang parallel.
Best explanation of Hawking Radiation ever! :-)
I finally have a good enough understanding of hawking radiation.
Always have told myself i knew what it is and I do to some degree. but knowing the casimir effect makes it so much easier to wrap your head around it.
This might be a good question.
Can we use the Casimir effect to simulate the event horizon of a black hole ? Per this vid, using a wave guide, physicists were able to move an analog of Casimir plates back and forth at 5% light speed, creating microwave particles ( by preventing some of the virtual particles created in the gap by quantum effects from recombining. Is this analogous or even equivalent to a black hole event horizon and Hawking radiation whose wavelength = the surface area of the hole? If so can it be used to study black hole behavior empirically in the lab? ( L Suskind's talk)
Not really. It would only be useful for studying the casimir effect and breaking particle and antiparticle pairings, but it wouldn't do much else for studying event horizons themselves. Black holes have a similar effect at their event horizons, but the casimir effect doesn't mimic the properties of an event horizon. It's kind of like how a black hole could theoretically have a charge, but studying... I dunno... say a balloon rubbed on a cat wouldn't explain much about what's going on inside a black hole. :P
I would like to know more about the balloon and the cat.
I don't think there is any published data on balloons and cats, at least in a refereed journal. Though I may have missed a symposium or two.
I like the way this a bit more detailed than the other black hole videos, I had no idea the evaporation, and chiefly the "popping up" of particles was due to the uncertainty principle.
did anyone else see that bud beind the house at 2:08
2:04 What happens if what I want to create corresponds to a time less than the Planck time (5.4*10^-44sec). I guess it is too large to be created ...or not? (shouldn't it be less than the Planck mass=2.17*10^-8 ?)
Ok I have this dilemma about light and gravity, which basically boils down to the question "does light slow down in a gravitational field?"
I've always learned three things:
1. Light is affected by gravity
2. Light (in a vacuum) will always travel at the speed of light
3. A gravitational field is equivalent to any other acceleration
Based off these three things, if you were to shine a flashlight straight away from the earth's center of mass, it would be pulled back by its gravity and slowed down. However that would contradict the fact that light must always be measured at the speed of light, so it can't slow down. But if it can't slow down how can a black hole stop all light? Doesn't it pull the light trying to escape back down to the center (slowing down the light) I need help lol.
I missed the part about your black hole question. So it's the same idea - mass bends spacetime (called gravity.) Think of this as bending all possible paths you or a particle or a photon could travel down. A black hole is an extreme case of this - at the event horizon, all possible paths bend inward. The black hole has bent spacetime so much that even the paths leading directly away from it end up pulled forward instead. So light still travels at c even in a black hole. But there is no way for it to go out because there is no such thing as out anymore. All paths inside the event horizon lead to the singularity.
+ForeverOfTheStars The black hole doesn't slow the light down. It can bend light but also it can change the wave length of the light. Think of it like the Doppler effect. When light is emitted from very close to the horizon of a black hole then it will appear to have a much longer wave length once it escapes the vicinity of the black hole. So blue light will appear more red. Eventually at the horizon light emitted would have an infinite wave length and hence a zero energy. This all ignore quantum effects though, which makes things a little more interesting.
+ForeverOfTheStars Gravitational redshifting is the answer you are looking for :)
Kevin Falls yep this effect is called Einstein shift, essentially it is the redshift of wavelengths due to gravitational radiation.
ForeverOfTheStars think about like light doesn't slow down but the path In which it's traveling if warped in away so that light seems to move slower. It's hard to explain over the phone but whatever
Light follows the curvature of space time, if the curvature of space time is warped by gravity then the path in which light travels through is warped, think about like this, say you have to walk x distance this takes time y, if x distance is distorted or warped in a wavey like way then you have to travel the same x distance but now since it's distorted instead of being a straight path it's takes y+z time where z is the prolonged time due to the path being distorted, same behavior for light if say light travels x distance and it takes time y if it's straight path is distorted by gravity then it's the same amount of distance and speed but the time (y) is prolonged by a certain amount depending on the how much space time curves.
How does the virtual particle falling into the BH from the EH cause it to lose mass? Can that be understood simply? I would expect the virtual photon that falls in to have a positive energy, as well as the one that escapes.
Could the mathematics of Quantum mechanics represents the physics of ‘time’ with the future unfolding photon by photon with each new photon electron coupling or dipole moment?
Don't mind if I do (nom nom). Now, did you have an actual argument?
No.
Brady, I have a pressing concern. I found it interesting this video came about right around the same time as the -1/12 Gold Nugget video on numberphile, because in this video Merrifield says around 4:00 "you end up with an infinite mass, but we have a process through which we can normalize those infinities to finite quantities".
Was he talking about the same process as adding the integers (1 + 2 + 3...)? It was stated that that result was used in physics? I'd love for you to follow up on this!
That strange feeling when view count raises from 124 views to 287. Is Sixty Symbols become so unpopular? ;)
This is one of best vids yet.. Thank you Brady and Prof
Professor Merrifield talks so godamn fast.
I know. He actually does a really good job of explaining things, but it's hard to keep up with it sometimes. I had a lecturer like this in my freshman chemistry class way back when. It was kind of a maddening experience.
All you have to do is click the three dots upper right corner and slow him down.
So clear and simple, I love listening to Feynman, Susskind, Don Lincoln, etc... I just added Mike Merrifield to my search list :)
Has the appearance of matter everywhere nothing to do with the dark matter we've searching for?
i just watch physics videos on youtube - i'm not an expert at all.
that's an interesting thought but my understanding is that this casimir effect produces photons which are mass-less particles. Dark matter is a source of unknown gravity in the universe implying that the cause of dark matter has a mass.
then again e=mc^2 says mass and energy are interchangeable so what do i know?
***** it can also produces particals with mass like a proton, but the chances are way less than for a photon...
+Melodic Guitar Rock/Metal GuiltyGearRockYou Yes, that is true, and they also exist incredibly briefly. This prevents it from entangling with even nearby particles, and dark matter operates at an extremely long range, from what I gather anyways.
They actualy DO interact with nearby objects, as was shown in the plate experiment.
Melodic Guitar Rock/Metal GuiltyGearRockYou
I barely speach english, but I understand everything with you guys. Hi from Argentina
I'm a bit skeptical to how all this actually leads to the black hole "evaporating" .. I mean.. i still don't see HOW the black hole actually loses mass, other than "It has to lose mass, because the energy have to come from somewhere".
I mean, why can't black whole rip apart virtual particle pairs, generating a form of zero-point energy, or "dark energy". Energy that comes out of nowhere and "shouldn't" be there. That's because it's the leftover from broken virtual particle pairs.
I mean.. I'm sure there's a lot of smarter people that know's a lot more about science than me.. But i would like some better explanation how the black hole LOSES mass by sucking in virtual particles.. that would make me a lot happier.
Okey.. Now I feel stupid .. I did a bit of research and found the quite obvious explanation that The anti-particle that were sucked into the black hole, sending it's lone, ex-paired ex-virtual particle partner to fly through the galaxy as a real particle in the form of hawking radiation, would simply annihilate with a particle in the black hole's singularity, and thus making it lose mass.
Quite obvious actually, and that's why i feel so stupid.. But…
It still doesn't answer some questions.. like.. how come ONLY the anti-particle is sucked in and not the other way around? Why isn't it completely random which one from the virtual-particle-pair that's being sucked in.. I mean, the only difference between a particle and it's anti-particle is it's electric charge. So why does that have effect which of the two particles in the pair is being sucked into the black hole? And also, when a particle and an anti-particle annihilate, they create pure energy in the form of photos (that travels in the speed of light), and since whatever is inside the event horizon has to go Faster than the speed of light to escape, (something that is impossible) means that the energy Still can't Leave to black hole. So I still don't see where the loss off mass comes in.. So I still don't understand the basis for the claim that black holes evaporate.
Dahxelb
The mass of a black hole will increase whether an electron or positron enters it. When an electron/positron pair (or any other matter/antimatter particles) come into existance just outside the event horizon and just one of the pair falls in, the black hole increases by the mass of that particle but the mass is also reduced by the energy required to separate that particle pair so there is a net loss of mass to the black hole.
To summarize:-
Electron/positron pair comes into existance
electron falls into black hole, positron flies away.
Universe now has gained the mass of one positron.
Black hole has gained the mass of one electron but lost the mass of separating the electron positron pair which will be eqivalent to the mass of two electrons so the black hole has effectively lost the mass of one electron.
bob s Thank you for trying to explain. But it still doesn't explain exactly how something with mass actually leave the black hole. The energy that separates the particle pair comes from the black holes gravitational pull. And gravity doesn't "lose" energy just because something is pulled by it.
Dahxelb
Nothing actually leaves the black hole, the particle that "leaves" (Hawkings radiation) originates just outside the event horizon.
Mass and energy are equivalent (e=mc^2). The energy to separate the pair must come from somewhere.
Dahxelb I agree with you in that it doesn't make sense at least to us. All these people say that it takes energy to separate them but I see the world as you in that gravity doesn't lose energy by pulling. My guess is that the problem lies in the fact that we (no one really) don't know how to link quantum mechanics with gravity. It was mentioned in the video. That there is something that is missing in the puzzle.
This is so brilliant. Exactly the type of thing that gets people into physics.
what kind of sorcery is this? :D
it's just regular Deep Magicks
I read The brief history of time. Was tough one to make much send out of. This explanation is great. Thanks
that was fucking brilliant.
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ಠ_ರೃ s
>< c\_/ Yes. Yes it was.
3:29 How do you measure this force? Does it move? Then there's an free increase in energy, unless it's countered by negative energy (whatever that means) when the plates stop.
Okay, so the vacuum has infinite potential energy that can be unleashed if you move plates really fast. Bloody hell !
Thank you so much for another excellent explanation of a complex idea. I find your videos always leave me with greater knowledge and a better understanding of the topic at hand. If only I had been fortunate enough to have had such excellent instructors in school, instead of the disappointed intellectuals with poor communication skills that I had in the 70's my life my well have turned out differently with my pursuing education instead of grabbing an axe and going to work. Thumbs up for teachers who love to teach and share the knowledge that they have with anyone wanting to learn what they are offering. Thumbs down for those teaching for any other reason.
so a blue whale could appear for an infinitesimal amount of time and then just disappear
chasem007ify The Casimir effect is measurable with boson force carrying particles like photons that are the boson particles of the electromagnetic field. These bosons have no mass, so an infinite amount of them can exist in the exact same space at the same time. A blue whale is made of fermion particles, that have mass and are matter particles, only one fermion particle can be in the same space at the same time. The Casimir is a quantum sub-atomic effect that thankfully does not measurably happen to us or blue whales.
I know, it's a hitchhiker's guide to the galaxy reference
chasem007ify LOL I should see that show.
chasem007ify well, 42.
Not so much because of this but that is possible if there is an infinite multiverse thanks to quantum mechanics.
Outstanding Explanation Mike.. I love Physics because it is simple.. Scientists like him have always inspired me !!
Minus 301 club :)
If you create a pair of particles, they have to annihilate themselves in a brief time. If you separate them before that happens, they can’t annihilate. Have you just created real matter?
Haha....black holes are like people.....if left to our own devices, just existing burns energy and we would lose weight from just breathing and our hearts beating over a long time....but most of us actually gain weight because of the process called stuffing our faces with food xD
Is there a place, or group working on the same discussion?
I have ideas relating to making vacuume spaces that could be manipulated for the sake of energy conversion. Specifically using the casimir effect for a dial or tuning device to make the energy represent as usable electricity and provide a one way valve of environments that forces conversion.
Please stop saying "just a theory"
It's a correct description. Scientists use the word "theory" in a way that's much closer to the colloquial meaning of theory than the one you've been told is the "scientific definition of theory".
avicenna the definition of a scientific theory is correct, but when scientists are talking (especially to the lay person, but even among themselves) then they will often use the colloquial form of the word just like everybody else does
No, it isn't. Scientists don't have a special snowflake ivory tower definition of "theory". They use it just like everybody else, when talking to themselves or to the public. This top-down enforcement of "theory" as necessarily having evidence behind it is not based on any kind of fact.
"es the word theory does have a very specific scientific definition and use, are you a creationist? "
Nope, I'm a physicist and I see the usage of the word in person every day.
This fiction that the word somehow means the current pinnacle of scientific understanding seems in fact to have been invented to combat creationists, but the correct response to creationism is not to say "evolution is a theory so shut up stop asking questions", but rather to give the evidence in support of it.
"a game theory'
A question (from a complete layman in the subject)
Since these forces are so tiny, how do you know for sure that the force pushing the plates together are actually a result of this Casimir Effect and not just a gravitational pull between the plates themselves?
If it's been reported (and presumably confirmed and peer reviewed), the it's safe to assume they took all other forces into account. No dea how they would measure it though.
Because we can calculate how much gravity there should be and we can incorporate that in the calculations. What you bring up is a very good point that is often missed by pseudo-scientists: You got to isolate what you're trying to measure in an experiment. Experimental science is all about finding out how we can maximize the signal to noise ratio. The signal is what we're trying to measure and the noise is everything else that is skewing the results.
Even in the video: The squid thing that was supercooled that he mentioned. Supercooling cools down stuff so much that materials start behaving in a very clean and predictable way. Barely any thermal energy, no electrical resistance etc etc. All that stuff is basically noise that we can remove by supercooling it.
Excellent question :) I hope my answer clears it a bit up.
CASIMIR FORCE:- Increases as the inverse fourth power of the plate surface gap & it stops when the plates come into contact. The surfaces have to be electrically conductive ~ there is no Casimir force between ceramic [or other non-conducting] plates.
GRAVITATIONAL FORCE:- Between two objects does not depend on the gap between the surfaces of the objects ~ it depends on the masses of the objects & the separation between their CENTRES OF GRAVITY [CoG]. It increases as the inverse second power of the CoG gap. The gravitational force does not care what the objects are made of ~ all that matters is their masses.
DIFFERENCE IN STRENGTH:- At a gap of 10 nm [100x size of an atom] the Casimir effect produces the equivalent of 1 atmosphere of pressure. This is far far stronger than gravity by a crazy amount
When measuring the casimir effect, how do you distinguish between the photon 'pressure' and inter-atomic forces between the two plates? How big is this pressure?
TheGreatSnoozer The gap is far too large for the weak & strong interactions to have an effect. Inter-atomic forces are at around the femtometre scale [10^-15 metres] e.g diameter of a proton is appro 1.7fm. Casimir experiments are performed at typically a gap of 10 nanometres [10^-9 metres] which is 100 larger than the size of a whole atom.
A very good question -- indeed, it has been argued that the Casimir effect can be explained by such "conventional" forces rather than the virtual particle effects discussed here. I think the jury is still to some extent out, but this explanation has the stronger backing.
I do have a question.
Judging by this video, The Casimir effect looks scalable - the amount of produced photons is directly correlated to the acceleration. Respectively, the Hawking radiation scales with the mass of the black hole.
However, certainly the area of the event horizon must be a limiting factor (equivalent of the volume of the space, confined by the plates).
If this is correct - how do the effect of the area and the effect of the gravity scale, compared to each other? In other words - do larger black holes evaporate faster or slower than small ones?
i think it's the opposite, you see a massive black has an event horison whose gravitational pull is weaker than lets say a microscopic one. i don't think it's proprtional to the volume but the intensity of the grav-pull of the event horison
Relative to their size a large black hole is much slower than a small black hole. Microscopic black holes (if they exist) are supposed to evaporate almost instantly.
It's took me a while to finally understand why black holes lose mass and this video helped me doit. Thanks!
Particles seem to highlight a type of, analog flow of a dense form of space itself. Where you would expect to see crests of two opposing flows ,wether it's at a peak or trough , coinciding particles would be found.
@ 0:25 I don't mean to be that guy, but in order to measure the energy wouldn't you want the wavelength of the photon, and not the amplitude? For that matter, how does one even measure the amplitude of a single photon?
i dont get the hawking radiation. if a virtual photon escapes into black hole and this makes black hole less massive but when negative particle escapes to the black hole doest it make black hole more massive than before? if it is then why this process doesnt evens out?
the flow of spacetime makes the ingoing particle have a negative frequency as viewed from outside. this is like a negative mass. it is very strange since we don't see negative frequencies very often, if ever
Can the Casimir effect explain gravity in an infinite universe for example or a very very very big one?
does this have any practical application?
Could we create out of nothing and eliminate that amount of materia ?
Its a very extrange question, but, could you "transform" trash to gold if they have the same mass?
If one were to travel at the speed of light, one would be able to travel between two crests of a photon's wavelength, and in that frame of reference the wavelength will have stretched out to infinity. Infinite wavelength means zero energy. A change in velocity would result in said photon revealing itself. Matter can't travel at the speed of light, but there are reference frames so arbitrarily close to the speed of light that the wavelength of the photon is stretched out to be larger than the universe. We could be surrounded by such long-wavelength photons, and only when we change speed are we able to see those photons as they are blue-shifted into detection. Because one wasn't expecting a photon, one might think it spontaneously popped into existence.
yup, i'd even think that what you say is mandatory since dt dE = h, low energy virtual photons would last a long time and this makes them pretty much real photons.
Best explanation I've ever heard of Hawking Radiation. No sarcasm -- before this vid, I never understood WHAT was making a black hole (i.e., something that traps everything forever) actually release something.
I knew I had heard about the 2011 dynamic Casimir experiment before. It was done by people from my university (Chalmers in Gothenburg, Sweden), and I've talked to people involved. Back then I didn't really grasp what the effect really was, but nonetheless it's really quite cool.
Wow. I have never had this explained in a way in which I understood it so well. Thanks.
Sixty Symbols
When he says shoveling the infinities under a rug at 4:25
Is he talking about the same kind of infinite sums that numberphile is discussing in this video:
Million Dollar Math Problem - Numberphile
The ones with the Riemann Zeta function
and that 1+2+3+4+... = -1/12 ?
I would be immensely interested in the answer!! Please can someone help me?
How is energy conserved in the case of the usual Casimir effect? The negative energy density between the plates is reduced as the plates come together but where does this energy go? Into the plates?
Vacuum.
No where?
The displacement of the plates takes work.
Do the virtual particles create drag?? If you push a marble in outer space, would they slow it down a bit?
Very nice explanation for Casimir force! Thank you very much for this video.
This has been useful content. I am/was watching in 2021, having already audited "What's Up With Muons", and "Betelgeuse Might Explode (in the next 150,000 Years)" this afternoon. Most engaging.
Great explanation overall, but did he misspeak at 8:58 when he said the particle falling into the black hole causes its mass to decrease? Isn't it in fact the particle flying away that causes the black hole's mass to decrease?
both are required due to conservation of energy
Could the Casimir Effect not better be explained by something like the electrons in these metal plates interacting? Maybe a subatomic particle not yet considered like the graviton? Rather than nonexistent particles temporarily existing? (Or is it that they always exist, just in a high dimension, and this is them traveling across our one of many "3D space" as they go about their 4D orbits?)
The background radiation of the universe has currently a lot more energy than the temperature of the Hawking radiation. Thus the black holes are passively increasing in mass.
0s4x.... I watch the old videos over again so the same topics covered by different minds from different viewpoints is still fascinating to me!
Great explanation. I have a question . Why does the energy density between the plates in Casimir effect has to be negative ?? This has made hawking infer that Casimir effect can prove warping of space time in negative direction!
it is negative compared to outside the plates