There are certain concepts that the human mind has a hard time comprehending, due to limitations in our perspective. I'll write about a couple of them today.
First, we don't like to dwell on distances on an interstellar (or even worse, intergalactic) scale, because they make us seem small and insignificant in the grand scheme of things. Last week, there was a news story about how the European space agency had discovered a new planet that was the most "earth-like" of any found to date. This planet orbits a relatively nearby red star that is about 120 trillion miles away from us. Read that number again: 120 trillion miles. That's about 20.5 light years away. A light year is the distance that it takes light to travel in one year at 186, 282 miles per second. The light from that star now reaching our telescopes started in 1986. Indeed, when you look at the night sky, all of the light from the stars that you see originated years ago; even the closest nearby stars are more than 4 light years away. Many of the stars you see are much farther away; you may be looking at starlight that originated hundreds or even thousands of years ago. And of course, you may be looking at stars that are no longer there at all; when we see the light from a star "going nova", we are seeing light from a star that died many years ago.
Another concept that we can only feel around the edges is time. Not just the current hour and minute, but deep time, distant time, time far beyond that of a human lifespan. My grandmother turned 90 years old a couple of days ago. That seems like a very long time, and on the human scale, it is. Most people don't live that long, so anything that happened 90 years ago is very long ago indeed.
I grew up in St. Joseph, Missouri, and the Kansas City metropolitan area. Those cities were settled in the mid-1800s, so anything that was from that time seemed "old" to me. Then, when I went in the Army, I went to Massachusetts for a training school. I spent some time playing tourist in Boston, a city that was 350 years old or so, and that seemed very old. I prowled the historic sites, looked at the worn tombstones in the old cemeteries, visited Paul Revere's house and the Old North Church and Bunker Hill, and I thought I had a grasp of what "old" really was. Then, for my first duty assignment, I went to Augsburg, Germany -- A city that was founded by the Romans in 15 B.C. All of a sudden, my point of reference for "old" was again recalibrated. When I visited Rome a few years later, walked through the ruins of the Forum and the Colosseum, and then went and saw the ruins of Pompeii, I once again had to reassess what "old" really was. And visits to the Egyptian Museum in Berlin and last year's trip to Fort Lauderdale to see the Treasures of Tutankhamen exhibition just pushed "old" back a little farther.
But even those ancient things were only a few thousand years old. Every day, however, we walk around on a planet that has been here for over four billion years. The land where you are sitting hasn't been here that long, of course. It's almost certain that at some point in the past several million years, it was under the ocean, and at some point in the next several million years, it will almost certainly be again. The continental plates drift and shift and bump into each other. Mountain ranges are pushed up and then worn away by the forces of erosion. Ice sheets form and melt away as the climate cools and warms. This has happened for eons and will continue to do so. We have the illusion that we exist in stasis, that things are as they always have been and as they always should remain. This is, of course, only an illusion. But we can only really comprehend the kind of changes that take place within a human lifespan. Years, even decades, we understand. Centuries, millenia... We don't. Our existence is too brief for that to happen. And it's uncomfortable to think about how ephemeral and inconsequential that existence really is. A hundred years from now, will anyone remember anything that you or I have accomplished? Or will it be like the Shelley poem: "Look on my works, ye mighty, and despair."
