Paragraph 2
In 1999, Ahmed Zewail, an Egyptian
won the Nobel Prize in Chemistry for measuring the
at which molecules change their
. He found that one femtosecond equals 0.000000000000001
. This is a decimal point followed by 14 zeros and then a 1, or a millionth of a
of one second. The zeptosecond measures things in terms of the speed of
. It is difficult for the human
to understand these measurements. One
is a thousandth of one second. This is the time for a neuron in the
brain to fire. One nanosecond is one billionth of one second. The shortest unit of time it may be
to measure is one Planck. This is a decimal point followed by 44 zeros and a 1.
