We all have some sense of time, whether the agonies of waiting or amazingly fast moments of excitement. But, most of us rarely reflect much on where those senses and sensibilities come from.
Humans began measuring time so long ago that there is no clear beginning to when and how the concept emerged.
Obviously early humans observed the daily rituals of sun up and sun down and the rise and fall of the moon. Gradually, people began to calculate the intervals and attach what we call numbers to those events.
It was not as if anyone ever discovered a universal element of time that dictated those passages. If that had happened some of our concepts of time might well have evolved differently. But, as Einstein proved, time itself is relative.
For example, today we think that the time since Jesus was on earth was a LONG time ago. If you were told that that long period of time (about 2000 years) was only one tiny part in 2,000,000 years (quicker than an eye blink) since the beginnings of planet Earth, you would probably have a hard time grasping the meaning of that metric in human terms. Still, it does seem like a long time.
To many humans alive today, JFK's death 50 years ago seems like ancient history. The 150 years since Lincoln's Gettysburg address seems so long ago that few grasp its nearness and timeliness today.
People 80 years old today have been alive for more than one-third of the life of the United States. For someone that age, it's hard to believe. (Younger readers will simply have to trust me.)
A light year is the distance light travels in a year (at a velocity of 186,282.4 miles per second, or some 461 million miles per hour).
One might say, "How on earth are we supposed to think about time and distances like that?" In human terms such scales are unfathomable- and a lot of our potential theoretical destinations are thousands or millions of light years away.
So, if we want to begin to think seriously about exoplanet exploration, will we have to go back to square one and rethink our basic concepts of time and distance and perhaps reengineer the human species -at least for some of us--for indefinite life?
Some of the fundamental measurements of time, distance and direction, such as 360 degrees in a circle could possibly have been other numbers, such as 3600. But the concepts of those fundamentals are fixed, and universal. (To get around this apparent limitation, some physicists are now positing the existence of maybe billions of additional universes!). And, up to now, these fundamentals, our system of time and distances as we need them here on mother earth, have served us pretty well.
In earlier times, different places and regions kept their own time schedules somewhat the way we have time zones today. Then Greenwich, England became the base marker of global time and chronometers (the forerunners of individual clocks) as recently as a couple of hundred years ago. And, now with the Internet, though it may be darker or lighter in different places every day, we really are in one time zone globally--which is NOW!
What all this adds up to is this: since time is basically a human construct to fit the needs of humans as we grow and evolve, it stands to reason that we can and should rethink and try to adapt our ideas and use of time into something that will be more useful in the coming age of the Universe.