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

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

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