The Chameleon in the Vacuum Chamber A new proposal for an experiment that could test the presence of a fifth force with unprecedented precision. It still amazes me that everything I see is made up of only some few dozen particles and four interactions. For all we know. But maybe this isn’t all there is? Physicists have been speculating for a while now that our universe needs a fifth fundamental force, one responsible for the phenomenon of dark energy, to maintain the observed expansion rate. Although this idea has been around for more than a decade, it has turned...