M-31 Andromeda from Astronomy Picture of the Day 1/24/2008
Copyright © 2009 by Ralph Couey
Written content only
Like millions of others, I often look to the night sky, fascinated by the possibilities of what lies out there. However, at times I also find myself idly wondering whether in that sky there might be someone else standing on another planet some impossibly long distance away looking back.
The latest estimate for the size of the known universe is around 150 billion light years across, containing somewhere between 100 billion and 500 billion galaxies, each probably containing between 200 billion to 400 billion stars. Certainly amongst that blizzard of zeroes, there has to be at least one other intelligent technological civilization.
In short, do I believe there are other intelligent species in the universe?
Do I think we’re being visited by aliens in flying saucers?
The physical laws of the universe, as we know them, make interstellar journeys impossible, impractical, and even pointless. The speed of light, warp drive notwithstanding is a barrier impossible to cross. Any physical object, be it human or molecule, converts to pure energy at the speed of light. Not a bad way to travel, all things considered. But understand that there’s no way to be reassembled at the end of that journey.
We could travel very close to the speed of light, but physics makes it pointless.
Scientists studying the behavior of subatomic particles in an accelerator, discovered that as they approached the speed of light, their rate of decay slowed tremendously. That remarkable find led to an understanding called “time dilation.” What that means, essentially, is that if you were on a starship that was traveling at 90% of the speed of light, time for you would slow down enormously, while back home, clocks would continue to tick along at their normal rate. Dr. Carl Sagan in his ground-breaking program “Cosmos” said that time dilation would make a round trip to the center of our Milky Way galaxy doable within a human lifetime.
Such a ship could make that trip, a distance of about 50,000 light years, in about 42 years, as time would be measured aboard the ship. That’s assuming the crew would survive the hard radiation, asteroids, million-degree clouds of gas, and each other. Unfortunately, for those of us left behind subject to the clocks here on earth, about 60,000 years would have passed, the time that separates modern humans from Neanderthals. Even if our intrepid explorers survived the trip, their return would become an encounter between two completely alien cultures.
Of course, that’s assuming there would still be life on earth. Asteroids, comets, gamma-ray bursts, super volcanoes, climate change, and what we could do to each other are all very real possibilities that would cause the end of life as we know it.
Homo sapiens is not the first dominant species on this planet, and almost certainly won’t be the last.
Even if the possibility of contact with another species existed, I don't necessarily think restricting humanity to the local neighborhood a bad thing. Until we learn to get along peacefully with each other, we really have no business bothering anybody else.
This doesn’t mean we should stop the exploration of space. Our own solar system holds enough unsolved mysteries to keep us enthralled for centuries. Despite six manned visits to the moon, it remains an enigma. The other planets, and the moons that circle them, are a googolplex of questions humans don’t yet know how to ask. Beyond them lie the Kuiper Belt and the Oort Cloud, containing comets that hold the secrets to the very beginnings of time. That kind of effort lies within our foreseeable technological capabilities.
Romantic dreams die the hardest deaths and despite the inescapably hard facts of science, dream of “first contact” will linger on. We will probably never know for sure if anyone else is out there. But that uncertainty is part of the romance. It is what sends us out on clear nights to contemplate the universe.
And for that, all we really need is the night sky, our eyes, and a willingness to dream.