0TIME
Time is quantity. It can measure by clocks. Sundials were used in accent periods, but in modern period clocktower is made up it measures time by using gravity. The advance clock uses the caesium atom to accurately measure the energy emitted by electrons to jump back higher to lower energy levels of sell.
Modern understanding of time is an event happening in space. Space and time are merged called space-time. Einstein thought experiment concluded that space-time combines into a single quantity.
More about time is arrows of time is similar to the increase in entropy of the universe. Time moves only one direction only past to future there is no present, that why its called present.
Next topic is VELOCITY.
