Somewhere along the line, someone figured that you could actually put time into a bottle. To be technical, it was more of a bowl than a bottle. The clepsydra (or water clock) was one of the earliest forms of timekeeping discovered to date (aside from the sundial), and was surprisingly accurate. Water clocks are any timepiece in which time is measured by the regulated flow of liquid into (or out of) a vessel where the amount is then measured. Over the millennia that these time pieces were used, accuracy was improved through modifications to include gears, escapement mechanisms, and water wheels. Eventually, the development of the European pendulum clock replaced the clepsydra as the most accurate means of timekeeping.
While mechanical pendulum clocks still exist today, it did not stop humanity from striving to achieve even more accurate means of timekeeping. Accuracy to the minute within a 24 hour period was just not good enough. In response, clever scientists cut a quartz crystal in a certain way and made it vibrate (oscillate) at a desired frequency. A circuit, also supplying power to the crystal, was incorporated to count the number of oscillations and translate it into recordable time that is accurate within 10 to 20 seconds per year.
Quartz clocks are a mainstay toady. They are comprised of many analog clocks and watches in many homes (or on wrists). But once again, humanity was not satisfied with this level of accuracy. Hence, in 1949, we entered the atomic age (as far as clocks are concerned) with the development of the first Atomic clock. Mind you, the first atomic clock was not even as accurate as a quartz movement at that time, but it did serve as proof that timekeeping could be maintained on the atomic level. This accuracy was quickly refined to 10−9 seconds per day shortly thereafter. Due to its accuracy, some governments actually broadcast a radio signal which carries atomic time updates to movements that are designed specifically to receive these radio signals (referred to as Atomic Time movements). In fact, government use of the Atomic clock has even helped scientists to determine that time in space actually moves slightly faster than time on Earth (proving that time travel forward into the future, in a manner of speaking, is actually conceivable).
To look back at how humanity has advanced timekeeping is incredible to conceive. It seems like yet another instance where something out of a Science Fiction magazine or book has become a reality. In the last 300 years alone, improvements to timekeeping have advanced leaps and bounds. It almost makes me wonder how much more accuracy humanity will strive to achieve in the next 100 years alone. By then, the concept of the water clock may well be a matter of “water under the bridge”…