Using an two types of lasers, researchers measured the ejection of helium electrons with previously unheard of precision, measuring the minuscule amount of time it takes for the electron to be ejected after the photon strike; a zeptosecond; .000000000000000000001 of a second; a trillionth of a billionth of a second. Meet the Zeptosecond, the Smallest Slice of Time Yet Recorded | Smart News | Smithsonian Magazine