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In today's world, many things are shorter and shorter. Scientists have just something incredibly short. They the shortest unit of time ever measured. It is a zeptosecond. This is a tiny, tiny, tiny fraction of one second. It a trillionth of a billionth of a second. This is a decimal point by 20 zeros and then a 1. The scientists atomic physics at the Goethe University in Germany. They used special high-tech equipment to measure how long it a photon to cross a hydrogen molecule. The scientists said it took 247 zeptoseconds for this to . This is too small for the human eye to see, and the time it takes is too fast for humans to .

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

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