How to Disguise a Helium Atom as a Hydrogen Atom

Donald Fleming of the University of British Columbia in Vancouver, Canada, and colleagues managed to disguise a helium atom as a hydrogen atom byreplacing one of its orbiting electrons with a muon, which is far heavier than an electron. Because it is so heavy, the muon sits 200 times closer to the helium nucleus than the electron it replaces and cancels out one of the nucleus's positive charges. The remaining electron then behaves as if it were orbiting a nucleus with just one positive ch...