字幕列表 影片播放 列印英文字幕 Okay, Well, I could tell you one of two things to tell you the standard sort of classical view of what a vacuum is. But for me, that's not so interesting. I'd rather tell you that sort of non standard quantum mechanical view of the vacuum, because we, you know, we typically think of vacuum being something quite dull place with not much going on quantum mechanically, nothing could be further from the truth. Essentially, the vacuum is extremely lively. Place. Yeah, vacuums. Pretty straightforward, isn't it? It's where there's nothing there. There are no particles. You can't breathe in a vacuum. You. Many of us have seen the experiments where you take a route of a out of a jar and you see there's a flame and the flame gradually guards, because first of all of the oxygen is taken out. So you're you're extracting something out from a body on. Eventually, when there's nothing left, that's the vacuum until you go to the world of the quantum and it seems to just blow up in your face. This vacuum with vacuum in quantum theory isn't quite like that, indeed that in quantum theory, the vacuum doesn't have any particles that you and I detect. That's so that's common. That's still the same. But But it does have, is what you call virtual particles. These air particles, which, because quantum mechanics, works on principle of uncertainty, these particles can pop up into existence and then disappear again over a very short period of time. I mean, the way I like to picture it is if you go seem I'm a celebrity. Get me out of here. These guys, they sort of have these sort of Taub's of full of eels and snakes all wriggling around like and they always have to get any or something for many. And well, that's sort of picture of all these eels and snakes. Wriggling around is actually how you would pick to the vacuum quantum. Mechanically, it's that lively. So the reason it's so lively is what's happening is you get these particles and anti particles. They literally pop into existence and then pop out of existence again, and it happens continuously on all points in space within that vacuum. So it's kind of like this is continuous sort of hive of activity where particles are going in and out of the vacuum popping into existence and then going out of existence again. We it's been tested, but the the idea that these particles are there has been tested. It was originally devised by a number of eminent physicist people like pulled Iraq and Richard Feinman Schwing. I had the idea that there were these things that could pop up into the vacuum. So you have that you start up, if you like with nothing, and then you think it is, there's no particles there. And then these things are popping up and disappearing again. Use the vacuum and energy. We know it gives the vacuuming, and you've actually tested this experimentally. This only noticed the cosmic effect. Will you take two parallel plates in a vacuum Very close together if you think classically know thinks it happened. But quantum mechanically, because of this black humanity on this vacuum energy is sort of affected by how far apart these plates are. That gives you a force between the plates and actually it's being observed that the plates actually moved together. So we actually really have experiment. We tested this vacuum. Energy is a real thing that it's very a way in which we do characterize the vacuum now that it has this energy, this inherent energy is there that our universe has a vacuum energy. If what I think is a vacuum is, in fact, receiving massive part was popping into an out of existence wanted us of that human behave like a vacuum. Why does a jar crumple when I cycled particles out of it? Why aren't these virtual products still striking the inside of the vessel in keeping the vessel inflated? And things like that the virtual particles that present don't produce forces that are strong enough to overcome those kind of pressures that you're talking about? They are. They're they're all around us. If the world of quantum electrodynamics is correct and our understanding of the quantum world is correct everywhere around is there are virtual particles being created and annihilated all the time. And in fact, some people actually believe that it's the presence of these. This force, this kind of Kazimir is an energy you can associate with. It got like a Kazemi of energy. It's called some people believe that that is accounting for the expansion of the whole universe. It's called the cosmological constant, and so it's having a huge effect on large scales. But on small scales, it turns out the actual contribution of these in any small region is actually relatively small, and so it's not big enough to effect the kind of process that you just have just been describing. So if you took everything else in the universe, everything you thought you saw, all the planets, all the stars, all the dark matter, there's still something left over. And that's the vacuum energy. One of the great mysteries of physics is that the vacuum energy that we see that way we think is out there is only very, very small. The density is very low. They radically we expected, that stated very high. And we really don't understand why it's like that. Can you create a super vacuum where even virtual particles don't exist? That would be a super duper vacuum, just a super vacuum. I'm no, I don't think so, because any process quantum quantum mechanics can care any on any scale at any time. At any temperature, quantum fluctuations can occur. There's there's nothing to stop them, And so because the Cana care, they will care over some time period that something will occur. And so you will get these fluctuations popping up. I'm not. I'm not aware of any situation where I can actually suppress the fluctuations themselves.