It's shorter than a millisecond, shorter than a nanosecond, and even shorter than summers seem when you're a kid—it's the zeptosecond, the unit scientists used to measure the shortest interval of time ever recorded. A zeptosecond is a trillionth of a billionth of a second, or a decimal point followed by 20 zeros and a one, per LiveScience. German researchers say they used zeptoseconds to clock how fast a particle of light moved across a single molecule of hydrogen, NBC reports. The researchers used the PETRA III particle accelerator to knock the two electrons out of the molecule. The light's journey from one electron to the other took 247 zeptoseconds.
"Since we knew the spatial orientation of the hydrogen molecule, we used the interference of the two electron waves to precisely calculate when the photon reached the first and when it reached the second hydrogen atom," said Goethe University researcher Sven Grundmann, co-author of a study published in the journal Science. The researchers said their technique will be useful for more complex experiments looking at "various ultrafast processes." The Independent notes that in 1999, Egyptian chemist Ahmed Zewai won a Nobel Prize with research that used ultrafast lasers to measure how quickly molecules change shape. He used the femtosecond—one millionth of a billionth of a second, which equals a million zeptoseconds. (Read more science stories.)