If the human race were to fall in the universe, would anyone be there to hear it?
“The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us.” ― Bill Watterson
Do you ever wonder if we are alone in the universe?
I certainly do.
There are at least 176 billion, and maybe close to a trillion, galaxies in the observable universe. Between those galaxies there is estimated to be between 10 sextillion (10^22) and 1 septillion stars (10^24). Orbiting around each of those stars it is estimated that they’ll each have on average one or more planets. That is a lot of planets.
Closer to home in our galaxy, the Milky Way, there are estimated to be at least 500 million planets in the habitable zone.
The sheer distances involved are mind-blowing, even if we’re just looking close to home.
At our current level of technology the fastest we could possibly get a satellite to the nearest star (4.2 light-years away) is 19,000 years. Theoretically it might be possible to eventually get this down to 85 years (after 36 years Voyager 1 has barely left our solar system). Unless we discover some radically new physics, the distance is an enormous obstacle.
If we are the only planet in the habitable zone of the Milky Way which harbors life at this point in time then that puts the odds of life existing right now within the habitable zone of the Milky Way at 1 in 500 million (0.0000002%). Therefore 99.9999998% of the other candidate planets would have to be lifeless for us to be alone.
Once you factor in the fact that the universe has been around for about 13.77 billion years and that there are up to a trillion other galaxies in the observable universe, the odds that all these candidate planets (not to mention moons) never harbored life would have to be astronomically high for us to be the only case.
This brings us to a famous equation by Frank Drake called the “Drake Equation” that is a framework for estimating the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy.
Have a look at this great video by TEDEducation that explains the Drake Equation:
Knowing about the sheer size and volume of the universe we’re faced with two insightful probabilities:
- As far as we know, it would be very unlikely that we are the only planet to harbor life in the history of the universe.
- However, as far as we know it is also very unlikely that we are going to be able to communicate with intelligent life anywhere else in the universe unless the human race survives for a very long time.
It seems to me that, at the moment, the biggest missing piece in the puzzle is figuring out how likely life is to come into existence. That’s why our exploration of our own solar system and extreme environments on our planet is so essential to figuring out this mystery.
In summary, I think alien life is very likely to exist, but it is doubtful it will be anything remotely like how it’s portrayed in homocentric science fiction, and the best explanations for current claims of alien visitations are most likely psychological in nature. I’m happy to be convinced otherwise, but as Carl Sagan would say, “extraordinary claims require extraordinary evidence”.
“The only thing that scares me more than space aliens is the idea that there aren’t any space aliens. We can’t be the best that creation has to offer. I pray we’re not all there is. If so, we’re in big trouble.” ― Ellen DeGeneres
[Creative Commons licensed Flickr photo by tgkrause]