The most accurate thing made... EVER!!!

          What is the definition of a second?  The International Bureau of Weights and Measurements definition of a second is "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom." When you count them, it will be exactly a second. That is how atomic clocks work. They count the 9,129,631,770 periods of radiation and ever thing that comes along with it, making the atomic clock the most accurate thing made by humans... ever. So if you ever need to have the EXACT time... get an atomic clock. It will do the trick. I give all credit to vsause for the information. His youtube channel is grate!!! Also check out asapscience, there videos are equally awesome.