What Is the Probability that Alien Life Exists?

Are we alone in the universe? If so, why? If not, where is everybody? Thankfully, math can help us with these astronomically profound questions. Keep on reading to learn all about the probability of extraterrestrial life.

Jason Marshall, PhD,
Episode #295
Alien life probability

Are We Alone?

While the logic of the Drake equation is fairly straightforward, many (or actually most) of the probabilistic factors in this equation are extremely uncertain or even completely unknown. For example, what fraction of planets suitable for life actually give rise to life? We have no idea! What fraction of that life will become intelligent? Or technologically advanced? We have no idea! How long does a technologically advanced civilization exist? Again, we have no idea! Humans have been technologically advanced for about 100 years, but how much longer are we going to stick around? That’s anybody’s guess.

Nonetheless, people have attempted to come up with reasonable approximations to the factors in the Drake equation. As you might expect, different efforts have produced very different estimates—everywhere from one technologically advanced civilization (which is us) up to many millions of independent technologically advanced civilizations in our galaxy.

In truth, until we know more—meaning until we actually find life out there or make some scientific discoveries about the values of the factors in the Drake equation that lead us to believe we are unlikely to find life—this is all just an exercise in probabilistic and back-of-the-envelope thinking. But, to me at least, it’s also a lot of fun. And I genuinely can’t think of anything else that’s more exciting to think about.

Are we alone in the universe? If so, what factors in the Drake equation did life on Earth manage to overcome? And if not, where is everybody else? Just something to think about.

Wrap Up

Okay, that's all the extraterrestrial math we have time for today.

For more fun with math, please check out my book, The Math Dude’s Quick and Dirty Guide to Algebra. Also, remember to become a fan of The Math Dude on Facebook and to follow me on Twitter.

Until next time, this is Jason Marshall with The Math Dude’s Quick and Dirty Tips to Make Math Easier. Thanks for reading, math fans!

Public domain “Wow!” image credit: Big Ear Radio Observatory and North American AstroPhysical Observatory (NAAPO).


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