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British Scientists Reverse Casimir Effect
An anonymous reader writes "The Telegraph reports that Scientists at the University of St. Andrews have developed a technique to cause the Casimir effect to repel instead of attract. This discovery could lead to near frictionless machines or in theory even levitation."
Gasp, that means we will have to repel one of the laws of seance.
I'm not a big fan of knitwear at the best of times.
At the bottom of the
The BBC are slightly more useful at http://news.bbc.co.uk/1/hi/scotland/edinburgh_and_ east/6932283.stm - they say it's a "friction reducing lens". Still doesn't give us a lot to go on, but it's a start!
Depends how you look at it - pessimists will see the lower atom being depressed ;)
So was it only me that heard Sir Alec Guinness read that line out?
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"Goodness me, how unlike the FBI to abuse the trust of the American public." -- The Onion
What is this? a spelling contest or a discussion about a new scientific discovery?
/. is populated purely by obsessive pedants with nothing better to do.
Sheesh. Anybody would think
oh..
Try checking out the University website - it had much more information about the science of the discovery:
http://www.st-andrews.ac.uk/~ulf/levitation.html
Pity they have a photo of Syndrome and his Zero-Point Energy device as an example at the top. Doesn't help anyone to take them seriously surely.
Thanks for the link - the Wikipedia article explains the effect and says that for materials with certain electromagnetic properties and configurations, the Casimir effect might result in a repulsive force instead of an attractive. Looks like somebody demonstrated that. Still, there's a long way from this to a macroscopic levitation system...
I assume it involves a cat with a piece of buttered toast strapped to its back...
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This wasn't enough for me, so I wandered over to Wikipedia:
The only changes to the Wikipedia article lately have been a link to this article, which is sort of meta. Wikipedia linking to an article plagiarizing from, of all places, Wikipedia. Cute, but also a little sad.
Against stupidity the Gods themselves contend in vain.
I am a physicist, but these subjects are often beyond me. Still, let me try a short explanation. This seems, to me, rather an important discovery.
The Casimir effect happens when you get two surfaces very nearly touching. Virtual particles emerge on the other side of the surfaces and force them together. Virtual particles being, well, virtual -- very short-lived and low-energy -- this effect only occurs when the surfaces are very, very close to one another.
What's intriguing about the Casimir effect is that it is extracting work from the zero point energy of the universe, the base energy field of empty space. (Yes, even a total vacuum contains virtual particles, and thus some energy.) It is not immediately obvious how to make this useful, however, if the only way to tap into the zero point energy is to destructively sandwich two expensive materials together.
Reversing the Casimir effect is brilliant. By placing a perfect lens between the two materials, the virtual particles create a repulsive force. This could, as stated, create a levitation effect by preventing the surfaces from ever touching. 'Levitation' is a strong word, though. It'll 'levitate' a nanometer or so above the other surface, which is only good for reducing the friction between them to zero. So 'frictionless surfaces' is probably the keyword we should be using here.
I'm intrigued because it would seem to be easier to generate power from the zero point energy with a repulsive effect than an attractive one. So this could also be the first step toward a zero point energy generator -- free energy. What will they think of next...
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I have a masters in physics, and although im not an expert in these things, i believe i have a better working knowledge than parent.
:-) .
In the quantum description of the electromagnetic field, there is no such thing as uniformly zero field - even in completely empty space, there are oscilations in the field spread over all modes (ie. wavelengths). It can be compared to an ocean or pond in stormy weather where there will allways be *some* waves.
Now, if we have a geometry consisting of two flat opposing plates, only certain wavelengths corresponding to the distance between the plates will be allowed. Thus by increasing or decreasing the distance between the plates, we can deside which zero-point wavelengths will be allowed, and it is such that the situation where the plates are very close are energetically favorable, hence we will see the two plates attract each other and this is known as the casimir force which has been measured many times in the experiment. Its important to realize that its not charges on the plates which are doing the work - everything is kept charge neutral. Its vacuum doing work
(by manipulating the geometry of the plates, inserting lences, etc. its then theoretically possible to make the plates repel instead, which is what the article is about)
Anyway. My point is. This is not like nuclear chain reactions. The experimental conditions under which you see these effects are extreme (as in: the truck on the street or the cellphone in the assistants pocket will ruin it). Its a neat discovery, but the doom and gloom is completely uncalled for.
No, the OP was right. They're repealing attraction. Don't know why they took so long, Slashdotters repealed attraction years ago.
I hate printers.
I hereby theorize that cramming peanuts into your arsehole will cause levitation.
There, now that I've officially theorized this, I can say, "In theory, cramming peanuts into your arsehole will cause levitation." and it's perfectly true.
FTA: "The force is due to neither electrical charge or gravity, for example, but the fluctuations in all-pervasive energy fields in the intervening empty space between the objects and is one reason atoms stick together, also explaining a "dry glue" effect that enables a gecko to walk across a ceiling." ... and now that scientists have figured out how to reverse the Casimir effect, this will soon enable geckos to walk on the floor.
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That would repel from the floor, but not from another cat with another slice of buttered toast strapped to its back (which is what this can potentially do).
From what I remember of the buttered toast cat, doesn't it end up spinning just above the floor as the cat tries to land feet-first and the toast tries to land butter-side down? If so then why is no-one wrapping these cats in wire, putting them between magnets and throwing them off surfaces en-mass to generate electricity while they spin?
From the researcher's point of view:
Step 3 doesn't have to involve selling technology.
"What happens if all the molecules in your body suddenly repels eachother?"
Okay, that's a good safety tip. Don't cross the streams!
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I assure you, Ladies and Gentlemen of the audience, this gigantic crate is levitating! Between it and the stage are entire nanometers of magic.
- The Amazina Llama
The Casimir effect is very wierd indeed. If you take two metal plates and put them close together in a vacuum they will attract one another VERY weakly. The effect is caused by fluctuations in the electric charge of the vacuum. Think of it a little like sea level. On average if you measure sea level lots of times you wil get "0" for the height but if you measure it just once the height you get will depend on the tide and the size of any waves. The same is true for a vacuum. Look at a particular volume of space and measure the electric charge. On average you will get zero but for a particular moment in time it may be non-zero.
Ok so far but how do we get an attractive force? Well it turns out that charge must be conserved so if one region of space has a small positive charge at one instant a neighbouring area must have a small negative charge (in quantum terms we say that we pair produce and virtual electron-positron pair) thuse we have a dipole. Now remember the two conductors? Well the one nearest the positive charge will have the electrons in the conductor attracted to it and being a conductor they will move towards it giving the conductor a net negative charge. The opposite will happen in the conductor nearest the negative charged area of space.
So now we have, instantaneously, a conductor with a negative charge and one with a positive charge...so they attract one another. this is the Casimir effect. If you stop to think about it is is VERY strange because it means that two metal plates in vacuum, with no externally applied fields will attract...so you have to ask yourself what exactly is doing the work i.e. where is the energy coming from to move these plates?
I'm not a condensed matter guy so I must admit I don't quite understand why this effect is so important to them. I understood that in molecules it was known as Van der Waal forces and due to periodic dipoles occuring in molecules in much the same way it does ina vacuum. Only, because there is a real electric field, the effect is much larger. So if there are any condensed matter people out there perhaps they would like to explain why it is Casimir and not Van der Waals that is important? or is it just because they have the same origin the name Van Der Waals has been dropped?
>>> the whole world is not American you know
That depends on who is defining "world".
Here's the paper, courtesy of arXiv:
http://www.arxiv.org/abs/quant-ph/0608115
It should be noted that this work is purely theoretical. What they have done is show that there is a much more physically realizable way to way a repulsive Casimir effect than the previous schemes, using a material with negative refraction over some range of important frequencies (this is a similar problem as making a cloaking device, but with a harder range of the spectrum). In practice, the effect would be small and the material hard to make, but the idea is interesting.