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do anyone know how this they did it?
They didn't actually levitate anything, they're theorists and this is a theoretical paper. They used the fact that if a certain type of new and interesting material (called a
metamaterial) was placed between the plates that normally get pushed together by the Casimir effect, the material would have the effect of changing the rule in between those plates a bit. As the authors put it:
"A transformation medium performs an active coordinate transformation: electromagnetism in physical space, including the effect of the medium, is equivalent to electromagnetism in transformed coordinates where space appears to be empty."Let me give you an imperfect analogy to see what this means. Suppose you're having a garage sale and you're trying to get rid of some old autographed baseball cards. The value of those cards will depend on who comes browsing through them. They might be worth a fair amount to fans of the particular player who autographed them, a bit less to someone who just enjoys baseball or baseball card-collecting, and usually only in the absence of anybody whatsoever are they worth less than the paper stock they're printed on. That is, often things (or rules) depend on the particular surroundings--the "medium." But suppose for some reason the crowd--the medium--at your garage sale turned out to be a bunch of baseball-haters. The value of your cards would be nil, just as if nobody was there at all because, of course, these people won't want to buy them.
We could say this particular medium--the crowd of baseball-haters--has the effect of transforming the rules governing the value of your cards so that they act as if the garage sale appears empty of people. It isn't, there are people there. But the particular group of people (medium) is such that the value of your cards is determined by the same rules as if nobody was there at all.
I don't know if that helped at all but in this levitation effect the special metamaterial acts like the baseball-haters. That is, it makes the rules of electromagnetism (like the rules for assigning value to your cards) act as we're in empty space (i.e. nobody's around) and not in a situation where a material is sandwiched between two plates. The overall effect of making electromagnetism act as if it's playing in empty space is to take the standard attraction of the Casimir effect and make it repulsive. But the special metamaterial has to be stuck in there to "reset the dial," so to speak, to empty space.
Weak analogy, I know, but they're not really my thing.
Edited by Startraveler, 07 August 2007 - 08:11 PM.