On the left, the equation considers the average (mean) expected number of origin-of-life events for a given planet. To get there, it takes into account the number of potential “building blocks” for life on the planet, the average number of building blocks needed to create a living system, the availability of those building blocks during a given time and the probability of that assembly happening during that time.

On Earth, building blocks for life take the form of amino acids, lipids and certain essential metals. Somewhere else, though, an entirely different set of ingredients could create enough complexity to form life — the equation doesn’t assume any specific set is necessary.

“We’re being kind of sneaky,” Scharf said. “I think it’s one of the beautiful things about it: If you write the equation this way, you don’t necessarily have to worry about all the fine, fine details, but what you do do is, you start to break open the factors that you might be able to put some numbers to.”