New Study Finds the Proton to be Surprisingly Light

Imagine hefting a liter of water in your hands. That's a kilogram of weight. Divide that by a billion, and you've got a quantity called a microgram--a thousandth of a single milligram. Divide thatamount by a billion, and you've got a femtogram--which it's almost impossible to get an intuitive sense for.But divide by a billion yet again, you've got roughly the mass of a single proton--and that's what scientists have measured with unprecedented precision in a surprising new experiment at the Max P...