Researchers have measured what is now the shortest time ever – 247 zeptoseconds. It is the amount of time it takes for a photon to get from one side of a hydrogen atom to the other side. A zeptosecond is a trillionth of a billionth of a second. In somewhat more understandable terms, “there are as many zeptoseconds in one second as there are seconds in 2,500 times the age of the universe, which is about 13.8 billion years old.”
How did they get this measurement? They bombarded hydrogen gas with X-ray light. As the X-ray photons hit the hydrogen atoms, it ejected one electron and then another. These two electrons caused a wave in the gas, spreading out like ripples in a pond. Since they each started a wave pattern, the patterns overlapped and created an interference pattern. Had the electrons been ejected at the same time, the pattern would have been symmetrical around the center of the H2 molecule; however, the electron waves were slightly off from one another, and the time lag was what gave the researchers the 247 zeptoseconds measurement.
All of this was done using a reaction microscope, and the results were published in Science.
“Zeptosecond birth time delay in molecular photoionization,” Sven Grundmann et al., 2020 Oct 16, Science