Astronomers like to project. Now that sky studies have demonstrated that many other stars out there in our galaxy have planets orbiting around them, the race is on to find the first planet outside our solar system that can support life. Not necessarily life that includes intelligent, sophisticated, sentient beings like us, but any type of life. It may be life based on the carbon atom, as ours is, or based on some other element or molecule. Whatever it is, it’s going to be interesting to see where the first planet is that can support life. And the presence of life on another planet outside our solar system presupposes the presence of life on many other planets in the Milky Way Galaxy. There could be as many as one hundred million planets in our galaxy that have the potential to support life.
But there’s more. The current estimate is that there are at least one hundred billion stars in our galaxy. That’s a 1 followed by 11 zeros. (I’d do the numbers in scientific notation using a 10 to the eleventh power, but as far as I know, Word Press doesn’t support exponents.) If we assume an average of five (5) planets per star, that’s five hundred billion planets. That makes an average of one habitable planet out of every 5000 stars. All of that is possible, although with the data we have now, that’s just an estimate.
There’s still more. Approximately one hundred billion galaxies exist in the observable universe. Every one of those galaxies contains billions of stars, in some cases a hundred billion or more. Let’s assume that the proportion of stars with habitable planets is about the same as ours, that is, one million to one hundred million, depending on the size of the galaxy. Take 10 million as an average. (These numbers are getting huge.) So, if we multiply 10 million stars with habitable planets per galaxy by 100 million galaxies, we get a figure of one quintillion planets that could possibly hold living organisms. That’s a 1 followed by 18 zeros. Can you wrap your mind around that? I have difficulty.
That’s just planets that could conceivably incubate life. Those that hold sentient beings would certainly be a smaller number, perhaps one percent of that, around 10 quadrillion planets. (1+16 zeros) Thus the chances that there is another earth-like planet out there somewhere reaches virtually 100 percent. There could be another you out there. Another me (God save us all.) A fifth Kardashian. Luke Skywalker may really exist (or have existed) in another galaxy far, far away. A planet like Krypton from which Superman came is less likely because the physics of that planet is different from the physics we know of for our universe. But who knows, perhaps the physics of the Andromeda galaxy is different from ours, though it’s unlikely. Is the charge on the electron in a galaxy billions of lightyears away the same as in our galaxy? In any event, the sheer size of the numbers makes anything a science-fiction author can come up with seem almost possible. It staggers the mind and fertilizes the imagination.
Jean-Luc Picard anyone?