The Department of Defense just released a new report to Congress: There are no aliens.
By aliens, I don’t mean illegal immigrants. I mean alien aliens. As in, from another planet.
I hate to disappoint all you Star Wars fans, but there is no cool intergalactic bar with dozens of weird intelligent life forms from different planets.
You will understand why if you read a book call “Rare Earth,” one of those rare books that fundamentally changes the way one thinks about the universe. The critically acclaimed book was first published in the year 2000 by a couple of astrophysics professors at the University of Washington.
I came across the book by happenstance. I had always wondered why we only see the one side of the moon. The moon rotates on its axis in exactly the same amount of time it takes to revolve around the Earth. A Google search to find the answer led me to this book.
The answer has to do with the fact that the moon and the Earth are more like sister planets caused by a great collision during the birth of our solar system. The huge gravitational pull on each other causes the synchronicity of the moon’s rotation.
This tidbit of science found its way into “Rare Earth” because this is one of dozens of improbable events necessary for life as we know it to evolve on Earth. Without the pull of our huge moon, the Earth’s rotation would begin to synchronize with its revolution around the sun. One side of the Earth would be scorching hot. The other side incredibly cold. Life could not exist.
As far as we know, there are 10 septillion stars in the universe. That is 10 to the 23rd power. In other words, 10 times 10, 23 times. That’s a lot.
But in “Rare Earth,” the authors document at least 23 unique events that had to occur before advanced life on Earth could develop. If you have 23 such preconditions - and each precondition is less likely than one out of 10 - then the probability of another Earth is one-tenth to the 23rd power - 10 septillion.
Many of the mandatory preconditions for advanced life on Earth were much less probable than one in 10. In a nutshell, we are probably alone in the universe.
The authors of “Rare Earth” are scientists. There is not an iota of religion in the book. The authors argue that simple organisms such as single-celled bacteria are probably quite common throughout the universe. More complex organisms are - by their very nature - more sensitive to ecological disruption that can wipe them out. Very few places in the universe can provide a billion years of evolutionary calm.
For instance, our Milky Way galaxy is unusually hospitable for life. Most galaxies are more compact, meaning a higher density of stars. More stars means more nearby exploding stars called supernovas. One supernova within a few million light years will “sterilize” all life with its gamma rays. In addition, in most galaxies, stars are so closely packed together that the stars affect each others’ gravitational pull, preventing the kind of stable orbits necessary for life to evolve.
If the Earth was any closer to the sun, its rotation would synchronize with the sun. So not only is our huge moon necessary, but the Earth must be in an exceedingly narrow window of distance to the sun.
Not only that, but the chemical composition of our sun, which contains numerous heavy elements, is rare. Then factor in the existence of Jupiter, which because of its near-sun size, deflects and absorbs the thousands of asteroids which could sterilize advanced life. If Jupiter were any bigger, it would prevent Earth from having a stable orbit. If it were any smaller, it would not deflect asteroids. The odds of this precise balance greatly exceed one in 10.
Without plate tectonics and a unique set of elements and atmospheric events, the Earth would be far too cold or hot for advanced life. No other planet in the solar system has either. The list of improbable events is long.
Why, despite all our advanced equipment probing the depths of space, have we found no signals that indicate the existence of intelligent life outside of Earth?
The authors compute the odds roughly by looking at the stars in the Milky Way galaxy times the fraction of earth-like stars times the fraction of stars with planets times the fraction of planets within a star’s habitable zone times the fraction of habitable planets where life arises times the fraction of planets inhabited by intelligent beings times the percentage of a planet’s lifetime that is marked by the presence of a communicative civilization.
Their conclusion? We haven’t made contact because nobody else is out there. The odds are too great.
This is quite a shock to someone like me who grew up with Star Wars and Star Trek. I just assumed Jabba the Hutt was out there somewhere. In fact, the real science indicates we are alone in a universe that exploded out of what Big Bang physicists describe as “infinite singularity” - nothingness, as best we can understand.
How interesting that all our knowledge and science just brings us back to Genesis.
