Most Americans when asked if they believe there’s intelligent life somewhere else in the universe will give an enthusiastic yes. They will site that with all the billions of stars in the Milky Way and with the trillion of galaxies in the universe the odds prove there has to be life out there and intelligent life as well. But then there is the Fermi Paradox, or more accurately, the Fermi question. “If there is so much life in the universe, why haven’t we come across it?” Which is a good question since there are over ten to the twenty-fourth stars (that’s a 1 followed by 24 zeros) in the universe. Surely the odds are that other planets with life and civilizations exist, and some day we will find them. Let’s take a second look at those odds.

In his 1980 television series The Cosmos, Carl Sagan made the claim that all that was required for a planet to develop life were two things. It has a stable orbit around a star, and it has liquid water. However, since 1980 the list has grown considerably. Some have increased the number of requirements to over a hundred and fifty. Let’s take a look at some of these and consider the odds of all of them occurring. To make the math easier let’s set the odds for each as one-in-a-thousand. In some cases, it could be less, in others much higher, but let’s keep it simple. So, let’s consider some of the conditions required.

1. The star can’t be too small otherwise planets in the “goldilocks zone” where liquid water is possible would be in tidal lock, like Mercury around our Sun. In such a case one side would be scorching and the other freezing. That planet couldn’t support life. More than likely a star can’t be too large either and has to be a single star (not a binary star system), but we’ll ignore those constraints.
2. The star can’t be too violent. Too many solar flares and radiation will destroy life. So, it needs to be a relatively quiet star such as ours.
3. The system requires rocky worlds in the goldilocks zone rather than gas giants, and many of the exoplanet system have what is referred to as “Hot Jupiters.” Which are gas giants around the goldilocks zone.
4. There needs to be a gas giant orbiting the star to work as a sink for asteroids such as Jupiter in ours. However, this giant can’t be too close, or it will destabilize the orbits of the planets in the goldilocks zone.
5. The planet needs to be large enough and with enough gravity to maintain an atmosphere. At least the size of Earth or Venus. The Moon and Mars are too small as shown by the fact they have little or no atmosphere.
6. The planet needs to have magnet field to prevent solar flares from destroying organic molecules.
7. The planet needs to have tectonic activity constantly recycling the crust to keep carbon-dioxide levels from being too high or too low.
8. It needs to rotate on an axis to allow the Coriolis effect to generate and move clouds, and should have at least a twenty-degree tilt on its axis to aid in seasonal variation.
9. The planet needs to have a large moon that will keep its rotation stable and generate tidal conditions to help maintain life.
10. It must also have oxygen in the atmosphere and the chemical elements for life such as carbon, nitrogen, hydrogen, etc.

These are just a few of the requirements that astrophysicists have generated, and this doesn’t even cover the biochemical requirements such as the oceans having the right pH or salinity.

If we give each one a probability of one in a thousand then the chance of all ten occurring would be the result of multiplying them all together, or one thousand times one thousand times one thousand, and so forth. The final probability of meeting all these conditions is one in ten to thirty (that’s a 1 followed by 30 zeros). In other words, there aren’t enough stars in the universe to find another one with life. In fact, we shouldn’t be here, for we beat the odds, or someone fixed the game.

#Fermi Paradox, #We beat the odds