Even with all the crazy costumes, it's hard to keep track of the super-villain activity in Gotham City -- especially when you have a shape-shifter like Clayface running about. He can take the form of anybody: a bank teller, Bruce Wayne, you name it. He adapts his physical appearance to fit his environment, making him a rather crafty adversary.
Particle physicists have their own Clayface in the form of chameleon particles. So far, we can only speculate on these peculiar bosons that may or may not be powering the expansion of the universe. Scientists first predicted their existence in 2003 as a possible explanation for all that mysterious dark energy that makes up 70 percent of our universe [source: Johnston].Like criminal shape-shifters, the chameleon particles adjust their properties to fit their local environment. For example, if a chameleon particle hangs out here on Earth, where the matter density is high, it would exhibit high mass, too, but its matter interactions would be very weak and short-range.
But that's here on Earth. Out in the void of space, chameleon particles would exhibit low mass and react strongly with matter over great distances. In theory, these speculative particles could be pushing the universe apart in what we call cosmic inflation.
Not surprisingly, chameleon particles would be rather difficult to detect here on Earth. We'd have to go out into deep, empty space to register their presence.
Still, physicists have a number of high-tech detection schemes up their sleeves, and the search continues for the elusive chameleon.
And so the Dark Knight returns once more to his underground Bat Cave and physicists vanish as well, to manage their underground particle colliders.