The shortest unit of time is the time it takes a light particle to cross a hydrogen molecule. The record time for that event is 247 zeptoseconds. What is a zeptosecond, you ask? Prepare yourselves, cause this is a mouthful. A zeptosecond is a trillionth of a billionth of a second. To put it simply, it’s a decimal point followed by 20 zeros and a one at the end. Yep, that small!
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