Season 17, Episode 55: Drake, Seager and Oluseyi – Are We Alone in the Universe?

Hey StarTalkians! Episode 55 of season 17 was a Cosmic Queries edition with astrophysicist Dr. Hakeem Oluseyi. While discussing his new book Why Do We Exist, Dr. Oluseyi mentions his “Oluseyi equation”:

Why Do We Exist with Hakeem Oluseyi - StarTalk Radio

(from 12:30)

Neil immediately compares it to the famous Drake equation. And despite key differences, their goals are ultimately the same. But that goal might not be what you’re thinking.

The Drake Equation Explained

Frank Drake’s equation was proposed in 1961, when the Search for Extraterrestrial Intelligence (SETI) was just getting started. It’s largely composed of a series of probabilities multiplied together.

The equation is for N, the number of civilizations in the Milky Way we may be able to communicate with. It depends on:

• The rate of star formation in the galaxy

• The fraction of stars suitable for life

• The fraction of stars with planets

• The number of planets per system that could support life

• The fraction of these that develop life

• The fraction of that life which is intelligent

• The fraction of intelligent life with the technology and desire to communicate

• How long such a civilization lasts

Dr. Oluseyi points out that this is outdated. We now know, for instance, that basically every star hosts planets. The equation is clearly geared towards the goals of SETI, with a focus on radio communication across space.

Speculation vs. Science

The Drake equation is largely speculative. How can we possibly determine the fraction of planets that develop intelligent life? It was intended more as a conversation-starter than it was a genuine piece of science [2]. The results depend strongly on how optimistic you are about these unknown questions.

Seager’s Variant and the Oluseyi Equation

Dr. Oluseyi mentions Sara Seager’s version. She switches the focus on radio signals for a more modern, grounded focus on life creating a “signature gas” which can be picked up by spectroscopy.

Dr. Oluseyi’s equation from his new book continues this tradition, focusing instead on the presence of multi-cellular life. He describes it as combining the probability of “just right” stars, “just right” planets and whether life actually occurs.

All of these – from Drake to Oluseyi – have a shared goal: to promote discussion of the search for alien life. It’s more about sparking thought than it is getting a solid number.