Article of the Day: “Are We Alone In The Universe?”

If you’ve been reading Letters Blogatory for a while, you know that I am an enthusiast for astronomy and cosmology. I have often surprised people by saying that I hope we do not discover extraterrestrial life, especially simple extraterrestrial life. I get the same reaction I get when I tell people that it is illegal to use, possess, or sell marijuana anywhere in the United States. In this month’s Commentary, astrophysicist Ethan Siegel has an article that bears on my point even though he doesn’t draw the same conclusion.

In the mid-20th century, physicist Enrico Fermi asked, “where is everyone?” That was a laconic way of saying that there are millions of myriads of stars in our galaxy and millions of myriads of galaxies in the universe. The numbers are so large that we should expect there to be lots of civilizations all around us. Our own experience tells us that you don’t need to be fabulously advanced in technology to send out electromagnetic radiation that can be detected across the vast distances of space, given enough time. So where is everyone?

Today we use the Drake Equation to try to formalize Fermi’s intuition. The equation looks like this:

N = R* * fp * ne * f1 * fi * fc * L

Where N is the number of civilizations in our galaxy, R* is the average rate of star formation in the galaxy, fp is the fraction of stars with planets, ne is the fraction of planets that could support life, f1 is the fraction of those planets that actually do develop life, fi is the fraction of those planets that develop intelligent life, fc is the fraction of those planets that develop high technology, and L is the length of time a civilization is detectable from afar. We know a lot now about the number of stars in the galaxy, how many of them are the kind of stars that could support life like us, and how many planets an average star of the right type has. So if we have not encountered intelligent life, and with some caveats that I’ll mention in a moment, we can say that either f1, fi, or fc is very small, or in other words, that it is very hard for life to arise at all, or very hard for intelligent life to evolve from simple life. Or else maybe L is very small, and technological civilization rarely if ever lasts long.

Now, if we discover simple extraterrestrial life in our own solar system—if we dig up a microbe on Mars or find bacteria in a thimbleful of water from Europa—or if we detect the chemical signatures of life using our increasingly excellent techniques for observing exoplanets and their atmospheres, then we will know that it is not difficult for simple life to arise, and the lack of extraterrestrial civilizations that we observe will mean either that it is difficult for advanced life to develop from simple life or that advanced civilizations do not last long. I’m no evolutionary biologist, but it seems to my inexpert understanding that intelligent life is an inevitable consequence of the development of life, given enough time. So it seems to me that if we find that simple life is common, the logical conclusion to draw from the absence of extraterrestrial civilizations that we observe is that technological civilization does not last long when it arises. And so I will feel better about the prospects for the human future if life is very rare, or even if it is unique to the Earth. It’s just math!

The caveats: maybe ET is out there but doesn’t want to be found. Maybe we have met ET but are not smart enough to realize it. And so forth. I nevertheless will continue to say I hope we never meet ET.

5 responses to “Article of the Day: “Are We Alone In The Universe?””

  1. The word of the day is “abiogenesis.”

  2. Antonio Di Stefano

    Back when we were visiting the moon and interest was high for space travel and ETs, a science professor at California State University in San Francisco offered a lecture-presentation with video, charts and all , that led to the inexorable conclusion that “We are effectively quarantined on Earth, and all this talk about leaving our solar system to find another home is simply delusion.The numbers simply do not lie” And he had plenty numbers to show. I think he may have made an exception for the Moon and Mars, but without any native life there. A boy with Ebola crossed into Uganda in the last 24 hours, and panic ensues. Can you imagine an ET stopping by and shaking your hands.
    I found my view more in line with the a message in the 1991 movie: The Final Approach. The other-worldly psychiatrist coaxes a deceased test pilot to think of the form of intelligence we call God as a scientist. This god-scientist has a huge laboratory the size of the universe in which to gather empirical evidence about life.; and has setup an ideal test environment, like a Petri dish, the size of the Earth. In this environment he is doing serious work to determine how to populate the universe.

    The same way that Ebola deaths are not in vain as someone always survives and provides a remedy, so our life experience though restricted to this planet is not in vain. While it seems unlikely we shall ever come face to face with an ET, we can try to intuit how a god-scientist is likely to transmit life to other worlds in the universe.
    Live long and prosper.

  3. Antonio Di Stefano

    A book that gives some plausible reasons why we should not wish to meet aliens or alien worlds is Solaris by Stanislaw Lem. After that you can choose to see the two movies based on the book.

    1. You’ve got good taste in science fiction, Antonio!

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