Time does not exist. The universe is an infinite array of cause and effect deployed in the present moment. But is it that simple? The foundation of all timekeeping on Earth was a subdivision of periods based around the astronomical regularities of the Sun and Moon. The ancient Egyptians and other ancient civilizations tracked the Sun with obelisks and variants on the sundial. “Water clocks” were also used in much the same way as the hourglass to track time. A major element to modern timekeeping also stemmed from an ancient culture. The Sumerians implemented a “sexagesimal” or base-60 method of telling time. This was because the numeral 60 can be evenly broken down into finer and finer segments. And so, as technology grew more and more advanced, time could be calculated with increasing synchronized precision. Pendulums and vibrating quartz gave way to atomic clocks. While having scientific applications (with divisions of time as small as a femtosecond, one quadrillionth of a second), atomic clocks tell time by sensing the change in energy states of cesium atoms, among other elements. The precisely calculated time is transmitted via radio signals from a worldwide network of atomic clocks to owners of so-called radio clocks. So that is the normal deployment of time in ordinary reality. But scientists have concluded that time would do some really strange things in spaceships traveling close to the speed of light and in the proximity of a black hole. In both circumstances, different forms of a phenomenon known as time dilation come into play. In the spaceship, time speeds up because the higher speed you travel, the faster time moves. So, relative to Earth’s time, one year could pass on board the ship, while ten years will pass on Earth. Near a black hole, because of the prodigious amount of gravitational pull, time slows down relative to Earth. –By Michael Isenbek