| Date | Text | |
|---|---|---|
24 Aug 1997
Largest prime number |
Largest prime number In 1997, Gordon Spence discovered the largest known prime number, 2^2976221 - 1, the 36th known Mersenne prime number. It took his 100-MHz Pentium PC fifteen days to prove it. At 895,932 digits in length, if printed out the number would stretch for 1.4 miles or if spoken 8 hours a day would take 28 days to complete. |
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24 Aug 1997
Louis Essen |
death Louis Essen Died 24 Aug 1997 at age 88 (born 6 Sep 1908). English physicist who invented the quartz crystal ring clock and the first practical atomic clock. These devices were capable of measuring time more accurately than any previous clocks. He built a cesium-beam atomic clock, a device that ultimately changed the way time is measured. Each chemical element and compound absorbs and emits electromagnetic radiation at its own characteristic frequencies. These resonances are inherently stable over time and space. The cesium atom's natural frequency was formally recognized as the new international unit of time in 1967: the second was defined as exactly 9,192,631,770 oscillations or cycles of the cesium atom's resonant frequency, replacing the old second defined in terms of the Earth's motion. |
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