According to The Times of India, in 2010 a group of German physicists claimed “to have measured the shortest-ever time interval by discovering the tiniest duration an electron takes to leave the atom.”
The scientists found that “when light is absorbed by atoms, the electrons become excited and get ejected from the atom if the photons carry sufficient energy.” However, when electrons are separated from atoms there is a time delay of 20 attoseconds, “which they claim is the shortest time interval measured to date.”
Reasonably, it is a bit difficult for us to wrap our heads around such a short interval of time, so consider this: one attosecond is one billionth of one billionth of a second. It can be written as 1 as, 0.000000000000000001 seconds, 10-18 seconds, or described as one quintillionth of a second. Still fuzzy?
To really help us envision this length of time, the BBC News painted this picture: “If 100 attoseconds is stretched so that it lasts one second, one second would last 300 million years on the same scale.”