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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."
Isn't it "repel" rather than "repeal"?
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Gasp, that means we will have to repel one of the laws of seance.
How says science cannot be uplifting.... literally.
This could be put to immediate use in the USA, where much bad legislation needs to be repealed and they need to attract fewer blockheads to a career in politics.
Rich And Stupid is not so bad as Working For Rich And Stupid.
I'm not a big fan of knitwear at the best of times.
At the bottom of the
It's "repel" as in "the body odor of submitter repels women worldwide", as opposed (heh) to repeal, which means, "to remove or reverse a law".
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!
So was it only me that heard Sir Alec Guinness read that line out?
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The discovery is not to be belittled, but both the article and the poster somehow forget to mention that the "levitation" which is talked about is on the order of nanometers (check the Wikipedia article on the Casimir effect). Far from the kinds of stuff you see stage magicians do.
"Goodness me, how unlike the FBI to abuse the trust of the American public." -- The Onion
Now, Leonhardt and Philbin have calculated that the Casimir force between two conducting plates can turn from being attractive to repulsive if a "perfect" lens is sandwiched between them. A perfect lens can focus an image with a resolution that is not restricted by the wavelength of light. Such a lens could be made from a metamaterial made of artificial structures that are engineered to have negative index of refraction -- which means that the metamaterial bends light in the opposite direction to an ordinary material.
According to the researchers, the negative-index metamaterial is able to modify the zero-point oscillations in the gap between the surfaces, reversing the direction of the Casimir force. Indeed, the researchers believe that this repulsive force is strong enough to levitate an aluminium mirror that is 500nm thick, causing it to hover above a perfect lens placed over a conducting plate. Since the Casimir force acts on the length scale of nanomachines, manipulating it could be important for future applications of nanotechnology. To summarize, nothing has been built yet. It's possible that it could be built, though you'd have to make a "perfect" lens in the tiny space between the two plates. Unfortunately, every "perfect" lens I've heard of tends to be wavelength-specific and relatively large (compared to the gap the Casimir effect requires). It may be that these are just engineering hurdles, but it may also be physically impossible to pull off.
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..
"dry glue" effect that enables a gecko to walk across a ceiling.
"Spider-pig, Spider-pig,
Does whatever a Spider-pig does."
-- Boycott Shell
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.
It's a "lift" you insensitive clod...
Quantum levitation by left-handed metamaterials
Ulf Leonhardt and Thomas Philbin
Provisionally scheduled for August 2007
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...
A humorous page about these British scientists' work by St Andrews physics Professor Leonhardt explains their work on Casimir "levitation".
--
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1. Invent/discover something cool
2. Tell everyone about it
3. ???? 4. NO Profit
It's sad to say that here in the UK we never learn and have a long and distinguished history of brilliant research followed by total fumbling of the ball and making no money out of the discoveries whatsoever.
I want a list of atrocities done in your name - Recoil
The thelegraph is supposed to be one of the more serious british dailies. So heaven help us all if this is what they pass off as a science story.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
I did not know this guy => http://en.wikipedia.org/wiki/Casimir_(dinosaur) had a physics degree.
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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Given the distance over which the force operates, it doesn't sound like you can use this to levitate large items. Surface roughness is measured in micro-meters and the force operates over nano-meters. http://en.wikipedia.org/wiki/Roughness
A standard solution for a 'frictionless bearing' is an air bearing. http://en.wikipedia.org/wiki/Air_bearing
The utility of this work seems limited to very small things.
"It's a tarp!" -- Dyslexic Admiral Ackbar
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.
I've already patented using this technology on skateboard decks, and no, Back to the Future doesn't count as prior art! I didn't get the idea from there at all!
which is totally what she said
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.
Well, it appears it's in the process of trying to revoke the law of gravity
which is totally what she said
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?
Only works with live cats. The cost of feeding and care for the cats makes this uneconomical. ;-)
"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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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?
It's all well and good until you have to take the cat down for maintenance. Have you ever seen a cat that's been wrapped in wire, strapped to a piece of buttered toast, and spun for 3 days? Let's just say it's not happy.
Actually, the cat will freeze in midair suspended on its side, because in that case, the direction of spin that requires the least work to get the cat/toast to the correct position are in opposite directions with an equal magnitude. So, sadly, it will hit static equilibrium, so you'll just have a crazy floating cat, not a crazy floating power-generating cat.
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Or maybe this discovery that works by means of 'a "perfect" lens with a negative index of refraction' is somehow related to their work on the invisibility cloak, which is based on metamaterials with a negative refraction index.
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.
Don't worry, that's a cyclic effect that primarily appears when posting AC. In your case, it's probably just your sinuses. No need to go off on a tangent. Have a slice of pie and call me in the morning. I'm sure you're feel radiant by then.
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Why the hell did this get modded down? I think this is an insightful point.. he is right.
I used to post AC when doing this, but it's just Slashdot. I don't give a shit about my karma anymore. Mod me down all you want.
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