as
attosecond
Timeexact by definition
The attosecond is 10⁻¹⁸ of a second, an exact SI prefix on the base unit. It is the timescale of electron motion: an electron takes roughly 150 attoseconds to circle a hydrogen atom once, and attosecond laser pulses are the tool that made electron dynamics observable at all.
| 1 as | 1.0000000e-18 s |
Where the unit came from
The 2023 Nobel Prize in Physics went to Agostini, Krausz and L'Huillier for generating attosecond pulses. To put the unit in scale, there are as many attoseconds in one second as there have been seconds in about 32 billion years.
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