You can observe the same effect by dropping two ice cream sticks or plastic drinking straws along side of each other in a tank of water. When you make some small waves in the water, the 2 are pushed together. The keyword here is _pushed._ The apparent sucking force is the relative absence of waves in the shielded water between the 2.
@@drsjamesserra I think that going to the nano scale or lower the Casimir force becomes more and more powerful, causing anything mechanical to not work as intended. That said there might be applications where the force can help
Hi Sabine! Break a piece of metal in a vacuum, then put the two pieces back together. They vacuum weld. If you get lucky in the shape of the break, the same van der Waals (atomic-scale charge nudging) and metallic bond (delocalized electrons) that hold the metal together internally reactivate across the narrow gap, pulling the pieces back together and making them a single piece again. Given that these are the same forces that make lumps of metal or other materials possible in the first place, there is no need to make the vacuum the final source of the snap-back energy. It is only a return of the energy stored by breaking the metal in the first place. The vacuum wave analysis idea was Bohr’s idea, not Casimir's. There was no need for it since the known internal bonding forces of the plates were already entirely sufficient to explain the attraction effect and, more importantly, to provide precise mathematical limits on how much energy could be stored. Bohr’s far more idealized approach - idealized because, e.g., there is no such thing as a “perfect” plane in grainy atomic matter - unfortunately had the opposite effect. Instead of fully quantifying the forces and energy release in terms of the well-known bonding forces inside material objects, Bohr added a redundant hypothetical energy originating from “the vacuum.” The fact that Bohr’s vacuum energy addition duplicates already well-known internal binding forces is a warning sign. Good old conservation of energy. It's still a great guiding principle! The interesting piece is what you described: Why is vacuum energy between the two nearby plates negative? Unfortunately, it's nothing more than a modeling error. Both metal pieces create Van der Waals and metallic bonding potentials close to their surfaces. If one incorrectly extends these near-surface bonding potentials to infinity, the energy potential between the surfaces necessarily goes negative when the bonds begin to reform. Sabine, I am sorry, and since I'm nothing but a poor, bewildered programmer, I don't expect you to believe me. Nonetheless, for the record, there is no wiggle room for negative gravitational energy in any of this. Bohr did not realize that material objects have bonding fields with positive energy extending slightly beyond their boundaries. By incorrectly presuming a near-field energized vacuum to be a ”pure” vacuum, Bohr wound up with nothing more than an illusion of negative energy vacuums. The actual energy drop when two plates approach closely is always smaller than the bonding potential of their near fields and thus always positive in terms of gravitational energy.
@@leachblah6313, heh, sorry, my self-mocking sometimes makes me come over as a bit more helpless than I am. While I am, indeed, a mere software programmer, I'm also one who speaks physics fluently and is very good at debugging. Physics could use a lot of debugging these days. I did a deep dive on Casimir a year or so ago, but I've been putting off a deeper dive into resolving Casimir's absurd transparency argument. This discussion forced me back into it, and I think I've got a pretty good resolution to the transparency argument. I'll mention my paper here when I feel comfortable with the analysis. I self-publish at Apabistia Press. My only reviewer is me, but since I think most of my ideas are incredibly stupid and don't mind being blunt in telling myself that, it works out.
@@TerryBollinger People with worse ideas than you have published before. The worst they got is just rejection and nothing more. Yours is a bit interesting. It definitely deserves some attention.
@@leachblah6313 thank you, that's much appreciated! I once checked briefly into one of the major journals but lost all interest when I discovered they charged a thousand dollars or so to make an article “open.” I had some interesting email exchanges with the editor. I think he finally realized how (for him, unexpectedly) offensive the pay-to-play meaning of “open” is to someone like me from the open-source software community. I once pretty much annihilated my long-term career to keep one company from destroying open-source software in the US, and I would do it over again in a split second. A friend of mine, whom I neglected to warn of how vicious and unexpected attacks can be on such issues, committed suicide. “Open” is a word that means a lot to me personally, and it's not easy for me to contemplate participating and what I consider a serious misuse of the concept. Also, I still firmly believe that predatory publishing is predatory publishing, even if it's Nature charging $10,000 for the prestige of publishing with them. Pay-to-play never, ever produces good science in the long term. I understand the financial pressures, and I cannot suggest a good alternative, but what is going on now is not the right path.
@@leachblah6313, again, thanks. If you have a specific collaboration suggestion, please let me know directly. I'm not hard to find. However, for my current goals, rapid self-publishing with little concern for audience width - I already have better depth than you might expect - works better than excruciating slow external review cycles. That's especially true since much of what I'm doing is better understood as solution-space scouting.
I would like, but how i understand it the casimir effect should not happen. Hard to make a video explaining something nobody can and goes against our understanding of physics.
the vacuum between the plates contains waves of only a certain size, so that the distance between the plates is a multiple of the wavelength. therefore, there is less energy between the plates than outside. By the way, the magnitude of this effect was calculated thanks to the great Indian mathematician Ramanujan.
What is the scientific consensus on using the negative energy in the Casimir effect as the negative energy required in the Alcubierre warp drive? A long time ago I was on a science message board and someone did the math (which was over my head...) and he determined that you'd have to have plates no larger than one atom thick. And then came along graphene and I've wondered ever since.
We just don't know enough about the vacuum/quantum gravity to definitively answer these questions yet. Unfortunately the Alcubierre drive isn't physically feasible as it stands at the moment.
The potential energy arising from the combined electronegativity of the molecules in the materials can contribute to the overall interaction between the plates, leading to the observed attractive force in the Casimir effect.
I suspect the plates simply can't be too light, as in that case they would no longer effectively shield the space between them (i.e. they would become too translucent). The overall effective energy would be the volume-weighted average of the 'negative' space in between the plates, and the plates themselves - and would always come out positive.
Yes indeed I had been thinking the same. However, while this might be the case in practice for sure, I do not see any way why this would have to be fundamentally so. If it was, that would also be interesting because it would require a so-far unknown relation between geometry and the constants of nature.
@@SabineHossenfelder: There is a case where I would argue that the mass of the plates becomes a trivial bit of minutea: when one of the plates is in orbit around the other. Is there a scale at which the Casimir effect disappears, or does it contribute in some (miniscule) fashion to dark energy?
I though it was because of virtual particles coming into existence outside of the plate striking the outside of plate and the plates causing a void between the plates.
That is what Sabine means by „different vacuum“. Quantumfluctuations are virtual particles and the conditions in between the plates allow fewer virtual particles to exist (because of their wavelength). There is also a non quantum explanation via Van der Waals forces and it is producing valid results aswell.
I thought it was sort of like hawking radiation in which the plates act as a sort of horizon for the particles involved to escape annihilation, but then I remembered that hawking radiation exists by virtue of drawing energy from the black hole, so it should be the total energy state would be zero not negative.
Sounds like wringing- when two very flat surfaces adhere to each other like high quality thickness gauges. One way to eliminate the possibility of the cause of adhesion being the vacuum of the absence of air, would to place the two plates in a perfect vacuum. The vacuum of space wouldn't work with two pieces of metal since they would become welded together. Which causes me to wonder if this welding is caused by the Casimir effect.
@Berend-ov8of this tablet I'm responding to your comment with adheres to a painted metal cabinet I place it on regularly. It doesn't sit perfectly flat, because the lense sticks out a millimeter or two, so I think that rules out suction as the cause for adherence. Being a tablet, I would think the case would be made out of a material that provides shielding as well as antistatic properties leading me to believe that it has something to do with the close approximation of electrons in both surfaces.
I've heard many physicists argue that over all, there is no negative energy involved at all, because the "negative" value between the plates is only negative *relative* to the vacuum energy outside the plates. Maybe there's a strong argument that disproves this point, but maybe this negative energy value effectively just means that there's less vacuum energy between the plates than outside, without ever violating the positive-energy condition. Idk.
now i have a stupid question: are we sure about it not just being an effect related to the atomes of the plates? the plates are very close together, so couldn´t it be just (at least partial) some sort of attraction between the atoms of both plates?
@@erinm9445 Very true, but I would fall out of my chair laughing if one day, a scientist came out and reported "sorry, sorry, it was just atoms and gravity doing things we hadn't predicted. The RU-vidrs win today".
The scientists did think of this and the Casimir force can be explained by the varying electric field inside the atoms of both plates, that create attractive Van-der-Waals forces, which pull the plates together. But this doesn't disprove the more fundamental model, that involves vacuum fluctuations. There's actually a big debate, whether vacuum fluctuations are real and many physicists claim that the Casimir effect proves they are real. But since the Casimir effect can also be explained by Van-der-Waals forces, many other physicists claim, the Casimir effect doesn't prove anything about vacuum fluctuations. There are other experiments though, that do suggest the existence of vacuum fluctuations, and if they exist, they should be seen as the more fundamental theory to explain the Casimir effect (rather than Van-der-Waals forces, which would then arise from vacuum fluctuations).
We do not even know if the overall charge of the universe is zero; symmetry is not really a proof of the net amount being zero. The only thing we know is: positive charge + negative charge of Electron and Proton restoring the sum of overall charge of the particles back to the average. Like waves in the ocean have heights and lows, the total amount of water is not required to be zero. All we can measure is the deviation from the average when negative charge experiences a displacement from the positive charge.
If you read the wikipedia page on the Casimir effect, you can see how the computation uses zeta-function regularisation to compute ζ(−3) = -1/120. Compare that to the standard Ramanujan summation which is ζ(−1) = -1/12.
@@rahantr1Since you asked for a video I also assumed you didn't know where to look for information. They weren't being condescending they were simply referring to where you can find information
From possible explanations I've heard, instead of it being an actual negative energy, it's a reduction in the underlying quantum field strength. So not really negative energy, just a lower energy region than outside of the plates. Kind is like when people describe a vacuum as "negative pressure" which isn't a real thing, they just measured a "negative" gauge pressure.
Ye well if we not wanna adjust the unnderstanding of gravity and radiation on large scale vs small scale we gonna dwindle arround. Maybe casimir effect is just gravity between objects. Obscured by the other huge fields surrounding a planet.
Casimir effect! Really famous in physical chemistry circles. As this effect is used to describe weak interactions, someone should do the experiment with two sheets of graphene.
I always thought that electrons spinning around atom nucleolus (at least that is how electrons used to be portrayed - like planets round a sun) might gradually sync-up very very slightly between plates ... e.g. two plates -one on the left one on right. Then over nanoseconds the electrons on the left plate move left as the elections on the right plate move left. As the electrons on the left move right the electrons on the right move right so each side electron are fractionally closer to the opposing plates positive center as they rotate causing a slight attraction. Not all electrons all the time but enough syncing between to cause some attraction
It appears to be where the new physics is hiding in plain view. If you view particle physics its an attribute of unknown particle interactions. If its all about waveform interaction then its again unknown interactions. We will spend another 100 years stuck in the same uncertainty.
Any uncharged surface sufficiently close to another will finally attract due to molecular forces caused by the polarization of molecules in close proximity. This effect is theorized for such things as gauge blocks and Gecko's feet. No quantum vacuum needed.
On first hearing this I recall the very moment I was introduced to this. 2003 in New Scientist, a sunny day in Melbourn. I acepted the explination of twenty years ago. I am excited this is being thought through again. Thankyou.
The arguments about the Casimir effect? There are several. One is whether it's actually a quantum field theory effect or not. Another one is whether this negative energy is real, or whether that's some sort of mathematical artefact. The third one is whether, if it's real, that negative energy would anti-gravitate.
Okay, I'm a simple guy, so I think in simple terms. Metal plates have electrons that randomly move around. As they do, the plates become polarized. The dipole moment of a plate randomly changes. Those random changes of the polarization of one plate affect polarization of the other plate in such a way that the plates attract each other. In other words, Casimir force between the plates has the same origin as the van der Waals force between neutral atoms.
It's actually more along the lines of - only particular standing waves can exist between the plates as they have to complete a half cycle exactly. Waves outside the plates have no such limitation. So there are more of them, and the overall energy outside the plates is therefore higher than that between them.
@@IanM-id8or yours is of course the standard explanation. But the phenomenon @MrKarpovy describes needs to be accounted for also for the uniqueness of the Casimir effect to stand out.
@@IanM-id8orto add on this, those waves mean less virtual particles pop into existence between the plates, than outside the plates. This is how I believe that there isn't negative energy, it's just that empty space isn't truely empty.
@@wb3904 Now imagine these plates in true empty space devoid of any gravity and em waves but the waves and gravity created by the 2 plates. You think they not gonna be attracted at even greater distance?
Well, in practice we can't do it (the Casimir energy density is super tiny). However, in principle that should be possible and I don't know anything that would forbid it. That's what makes this problem so weird!
"Uncharged" perhaps statically, but dynamically, probably is charged via exposure to electro-magnetic waves. I suspect both plates are acting as antennae's, but I know nothing about this, Sabine, other than what you point out in this short. Very interesting! -John (from Arizona)
This may be a clue for warp generation. Someone needs to put multiple plates togeter, start them in staggered compression in different frequencies, and observe what happens.
I heard from guy at the pizza shop; It correlates to magnetism. The "pressure" is the differential of compressed spacetime between the plates. As the plates get closer the space and time between the pates is reduced relative to the outside of the plates.
I think magnetic waves pass more easily through metal. They can alter the magnetic wave pattern. Maybe it has something to do with atom alignment or magnets.
How thin can we make the plates? At some point, deforming metal into a foil results in something too flimsy to be a plate. Can we reinforce the plate somehow? A truss design out of nano-tubes? Maybe need a vaccuum, as air molecules or dust might puncture the foil. Thus a bottom limit of thickness is that if we need to test pressure differences, then ambient pressure can't break the foil. idk.
We can make foils as thin as a single gold atom, though they would need to be thicker. In theory we can make graphene sheets one carbon atom thick much stronger than gold, and you could put tensions on the side and release any charges. So you could have a graphene sheet held on opposing sides juxtaposes to another sheet held orthogonally oriented to the first by two opposing sides. If you made a large container at say earth sun L2 then you can remove differential gravity, you could get the plates close. But graphene sheets, despite their large area are quantum structures, I should clarify, there are molecular orbitals on graphene which have wave like properties that cover a significant area of the sheet. So for instances at small distances (2 cm) graphene acts as a superconductor. Thus there is quantum uncertainty, a rather lot, about the position of electrons on the graphene sheet (or even if they are on the graphene sheet, but that’s another issue). So you still have to maintain a statistical distance between the sheets. Also Aromatic rings like to stack, right, they are wave functions, so the problem if you get the electrons close enough to resonate the sheets might just collapse. I’m not sure what happens in a vacuum, but in water they like to stack.
No, for one thing, the calculation has nothing to do with gravity. But maybe more confusingly, whether the force is attractive or repulsive depends on the geometry. Eg, for a sphere it would be repulsive.Also, on the more practical side, people are actually using the Casmir Effect to *measure* gravity! (By balancing the forces.
Yeah you're never going to have an instrument come back and say it measured "negative energy". I think this is just illustrating that we don't understand the vacuum very well.
Well, it's definitely originating from the time that Philips was more than just a bunch of factories, the theory was born there.. (Natuurkundig Laboratorium der N. V. Philips' Gloeilampenfabrieken, Eindhoven, Netherlands ;)
I don’t know anything, but the affect of the physical objects on spacetime, wouldn’t the concept suggest that something like a Casimir “attraction” would have to exist at some scale?
It would be nice to see a comment on Casimir v.s. Van der Waal effects ... i mean we know what the common explanations to the respective effects are but ...we don't have a real, deep "Sabinsplanation"
My own take is it is the latter. Like potentials, it is the relative difference that is important. The kicker though is that this energy density should contribute to the stress-energy tensor in GR. Hence, at what point is the vacuum not contributing a positive value to the stress-energy tensor. That is why Sabine has sleepless nights wondering how modified the vacuum must be before antigravity becomes a thing or not.
Ok here is a very off the charts idea. I have always wondered that the "Expansion of the Universe" is dependent on the mass of the object/area modifies the expansion rate....more mass=greater expansion per unit time. If this is reality then the mass of the vacuum between the plates would be less than the mass of the vacuum outside the plates thereby having the universal expansion between the plates being less and to us that would look like the plates are being pushed together
I've seen an experiment where two dense objects are left on a frictionless pivot and their gravitational attraction slowly pulls them together over a period of days. Don't plates have a natural gravitational attraction?
I think that's the Bernoulli effect, lower pressure between the ships due to the faster current there. I don't think that's relevant here because there is no fluid flow.
Hello Sabine! I love your videos, thank you❤ But if I am allowed to give some advice: I don't think shorts fit your kind of public. We are not lazy, we can handle long videos😂 And short videos are too short for us, they convey to little information...Keep it up❤
it is a form of vdw force at play, the evidence for vacuum fluctuations beeing the cause is dubious at best since it doesmt even have a real derivation unlike the explaination via vdw
Simple experiment to test this: instead of using two plates, use two cylinders. The cylinders should be made of conductive foil one inside the other placed closely enough that plates at that distance would demonstrate the Casimir effect. The air in the closed chamber should be pumped out The cylinders should be discharged/grounded, and then the ground should be removed. Then Lasers can be pointed at the outside cylinder and reflect back-and-forth off the inside cylinder to detect deformation. The amount of deformation can be used to calculate the force of the Casimir effect. The circumference of the cylinders can gradually be reduced until the central cylinder has a diameter, smaller than the width at which the Casimir effect is normally observed between two flat plates. Since the wave lengths allowed inside the central cylinder will be less than the wavelengths normally allowed on the opposite side of one of the flat plates used when the Casimir effect is normally tested, we should be able to determine the degree to which quantum fluctuations restricted by wave length can influence the attraction between the surfaces.
Wouldn’t we expect them to come together?? Seems like there’s aplenty of possible explanations like gravity, magnetic moments aligning, maybe charges of the plates are generally equal but on smaller scales there are charge patterns or even EM structures. In the surface, it doesn’t seem like external factors would be needed to explain the behaviour.
I can generate more negative energy than that, and I can store it. You will never know how close and far this is to something usable out of this effect.
The vacuum between the plates contains waves of only a certain size, so that the distance between the plates is a multiple of the wavelength. therefore, there is less energy between the plates than outside. By the way, the magnitude of this effect was calculated thanks to the great Indian mathematician Ramanujan.
Understanding lots of all these unexplained things will possibly learn us to travel at lightspeed, but I'm afraid we're not intelligent enough to be able to put that puzzle together?
If the overall traits of materials were different than they are, would the trivial traits differ in other ways from the dominant traits? That sounds like this question, but it also sounds nonsensical.
🌊🌊⛴⛴🌊🌊 I've only heard Casimir effect just stuck two boats together because they have waves pushing them from every direction except appart because there are no waves between them once they are together
How coherent is the medium - vacuum in this case - over the surounding volume ? What coherent medium units of the vacuum medium can "hand over" the "pressure" over any distance ? Do these medium units exist long enough to hand over and carry the "pressure" up until the surface of the plate ? Because if these "appearances" do not last long enough how can they build a "pressure " over a distance longer than their "appearance" radius ? deducted from this could it mean the " pressure" can only exist right on the border of the surface in the "radius" of the "appearance" since " appearances" do not last long enough to carry the "presure" over more than one "appearance" distance, because they allegedly fluctuate ? or is it something else ?
Why isnt this just a factor of the electromagnetic flux field... If we know these are conductive plates, then when brought together they should induce the flux in each other and thus a pull on each other.... Effect is small since the magnetic effect of the uncharged electromagnetic fieldof the metal is expected to be the action of the free electrons present in the metal.... Just as when we overcharge the effect with a charge...
If the gravity would be weak enough one plate could be pulled up by another. The energy for putting it down again needs to come from somewhere. I heard many fun stories about how useful this effect could be to get free energy. But it's not useful for that. The plates attract each other until they collide and you need to put the energy back in to divide those plates.
