What is time? I’ve seen a few posts on the internet lately about “time.” Questions have been raised about whether time exists or not, and what it is, and if there is any substance to it. Some have suggested that time does not exist, that it is a figment of our imagination, or that we just made it up to satisfy our interest in measuring the interval between events.
Time, if it exists at all, is measured by artificial means. We here on Earth use the rotation of our planet around its axis, the rotation of the planet around the sun, and the rotation of the moon around the planet, and suitably divided into segments based on ancient ways and methods to measure intervals between events. Hours, minutes, seconds simply give us easily identifiable time segments to use. A lecture lasts an hour. A semester is four months. Whiskey takes twenty-one years to age. (Or whatever.) You work from 9 to 5. A light year is the distance light travels in one year. When I worked in a virology lab, I might incubate some experiment at 37°C for a half-hour. Or an hour. Or overnight. We’ve simplified the measuring of intervals to our practical use. But it must be strongly emphasized that “time” and the interval are not the same.
But I maintain that time does exist. It has to. Take those intervals. There are zillions of them, many—like those experiments of mine in the lab—man-made, but many naturally occurring. If time didn’t exist, we wouldn’t exist. The big bang that took place some 14+ billion years ago took time. The expansion of the universe was fast, so fast we couldn’t measure it even if we had been there at the time. But it did take time. A nanosecond is still a unit of time, albeit very short. Now, when we look at stars, including our sun, we know a lot about the nuclear reactions taking place within the core of those stars that produce the light and heat that drive the star and maintain its existence. Those nuclear reactions are fast, no doubt, but they do take time. That light, especially from our sun, takes a certain interval to reach us here on Earth (8 minutes and 20 seconds). It still takes time. Time exists within the space between events. All our measurements are not time, they are simply a way of cataloging it and relating it to other intervals. Measurement is not time. Time is the interval. Time makes the interval. Without that interval the universe could not exist because all those beginnings and ends would exist at the same time, and there would be no interval for all those vast number of reactions to take place. The universe would start and stop in one short, immeasurable amount of—you guessed it—time. The big bang could not exist without time. Time exists within that interval. It is time that makes that interval real.
Now that I’ve thoroughly confused you, what time is it?