ANALYSIS: Has Kepler Discovered an Alien Megastructure?
"The properties of your country, and your football club, are unlikely to be a fair reflection of most other countries and most other clubs," Simpson wrote on a website explaining the research, The Big Alien Theory. The punchline? When it comes to aliens, the "average" size (he says) is likely to be roughly 310 kilograms, or 683 pounds. That's about the mass of a polar bear.
To come up with this figure, first Simpson surveyed Earth's range of species and made a few observations. Species that are larger physically will have lower population densities (think, insects vs. whales). Given that everything in the universe is subject to the laws of thermodynamics - meaning, larger species consume more energy - this is probably a common theme across the universe.
How Aliens Can Find Us (and Vice Versa)
Some aliens may be very energy-efficient or live in very different environments than ours, but Simpson argues we aren't looking at the outliers. We are thinking about the average alien. Simpson then compared a typical human with the range of species of Earth. Turns out on Earth, we are slightly below average. The polar bear is more typical - and that's likely where the average alien's size would lie.