It’s long been theorized that the first detection of extraterrestrial intelligence will come from radio waves. But it’s possible that what’s out there may go well beyond what anyone has dreamed to look for until now. (Danielle Futselaar)

The Drake Equation Is Broken; Here’s How To Fix It

In the aftermath of everything we’ve learned about what’s in the Universe, we can make much better estimates of how many alien civilizations are out there.

Ethan Siegel
Starts With A Bang!
10 min readApr 12, 2018

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In 1961, scientist Frank Drake wrote down a simple-looking equation for estimating the number of active, technologically-advanced, communicating civilizations in the Milky Way. From first principles, there was no good way to simply estimate a number, but Drake had the brilliant idea of writing down a large number of parameters that could be estimated, which you would then multiply together. If your numbers were accurate, you’d arrive at an accurate figure for the number of technologically advanced civilizations that humanity could communicate with, within our own galaxy, at any given moment. It’s a brilliant idea in concept, but one that’s become less and less useful as we’ve learned more about our Universe. As it stands today, the Drake equation is broken, but we know enough about the Universe to construct an even better framework.

The possibilities of having another inhabited world in our Milky Way are incredible and tantalizing, but if we want to know whether it’s real or not, we absolutely have to get the science right. (Wikimedia Commons user Lucianomendez)

The Drake equation, to be specific, said that the number of civilizations (N) we have at any given time within our galaxy, is equal to the product of seven different unknown quantities from astronomy, geology, biology, and anthropology, each of which build off of the previous element. They are:

  1. R_∗, the average rate of star formation,
  2. f_p, the fraction of stars with planets,
  3. n_e the average number stars-with-planets that have one that could support life,
  4. f_l, the fraction of those planets that developed life,
  5. f_i, the fraction of life-bearing planets that developed intelligent life,
  6. f_c, the fraction of these intelligence-having planets that are technologically communicative across interstellar space, and
  7. L, the length of time such a civilization can broadcast-or-listen.

Multiply these numbers all together, in theory, and that will give you the number of…

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Ethan Siegel
Starts With A Bang!

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.