April 26, 2017

Humanity Was Here

Under ceaseless skies…

Photo by author.

Astronomy forces us to think big. And not just big in terms of gazillions of miles of distance, but also in terms of time. The stars in the Milky Way galaxy, for example, are swirling around the galactic core to the tune of one orbit every quarter of a billion years – but the constellations you see from you backyard tonight looked pretty much the same on the day you were born, and won’t have changed much come the day that you die. We’re privileged to share this little corner of time and space together, for sure. But nothing lasts forever, and humanity too will literally have its day in the Sun. How will things play out? It’s a fun thought experiment that’s both exhilarating and depressing. Want to put a major downer on the mood at the next public star party? Tell ‘em that our Sun too will one day, billions of years from now, expand into a red giant star, probably incinerating the Earth. But humans won’t have to worry about that far of date with destiny, as the increasingly luminous Sun will first boil off our oceans about a billion years from now. But humankind won’t stagnate in the meantime. In the span of a billion years, we’ll either have gone extinct (the fate of most species) or have evolved into something else.

Maybe we’ll have taken evolution into our own hands, and moved out into the galaxy. Certainly, the extinction path is the most depressing one to contemplate, though I often wonder just what the thoughts and life of the very last human would be like. Certainly, they’d at least have a mother, who would be destined to die before them. Life would also be fairly rough for the last human on Earth, or wherever humanity had gone off to as the species dwindled to nothing. Would they have an inkling of their rich heritage, our music, our literature, our discoveries and dreams?

Likewise, you can imagine what wondrous forms of life evolution will produce in that final era, as life tries its very best to make due with dwindling resources, especially the lack of water. What would be the tipping point, where the planet becomes inhospitable for even the hardiest of life?

Would subterranean bacteria survive up to (and maybe through) the final death throes of Sol? Of course, our radio messages will continue to traverse the cosmos. On Earth, buildings, cities and structures will eventually be subducted under the continents, though our satellites in geosynchronous orbits will remain stable for hundreds of millions of years.

And spacecraft such as the twin Pioneers and Voyagers I and II and New Horizons will circle the galaxy, a mute testament to a curious group of primates that once sent artifacts to the stars…  all a moot point, perhaps, on a sunny Friday morning. At least our star will stay stable for our lifetime, and those end days aren’t for us to witness, as the drama of humanity plays on.

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