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# Scientist Is Pretty Sure Aliens Will Be Bear-Sized

In a thought experiment that demonstrates how science can be as fantastical as religion or magic, a mad scientist named Fergus Simpson from the University of Barcelona is publishing a paper in the journal arXiv that uses a mathematical approach to determine the population and body size of alien races. According to Live Science, who read and understood the paper (I didn’t, because I’m a dummy), those aliens will probably be bear-sized.

Simpson uses a branch of math called Bayesian statistics, and starts with the assumption that, within a galaxy as big as ours, there’s got to be other planets with Earth-like conditions, and those planets are likely to have life. But then comes the crazy stretch: based on what we know about Earth’s life, what can we know about the supposed life on other planets? Obviously, we cannot “know” anything, since we haven’t discovered said life. But here’s what Simpson concludes, according to the abstract:

If the range of habitable radii is sufficiently broad, most inhabited planets are likely to be closer in size to Mars than the Earth. Furthermore, since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300kg. Primitive life-forms are a pre-requisite for advanced life, and so the planets which host them must trace at least the same volume of parameter space. Our conclusions are therefore not restricted to the search for intelligent life, but may be of significance when surveying exoplanets for atmospheric biomarkers.

Live Science has an analogy that I would summarize as being like, “the most people live in China, but the median population is closer to, like, Spain’s population, so most aliens live on planets the size of Spain, I guess.” The hypothesis seems to be that Earth is the median size for an inhabited planet.

The details of the math are less important to me than the fact that a guy who works at an actual university is publishing a scientific article in a Cornell-affiliated journal where he claims to have figured out that aliens weigh 692 lbs, roughly the size of an average brown bear. Obviously this is an insane conclusion, because the size of aliens will be impossible to know until we meet them, but maybe Fergus Simpson is right. Maybe when a flying saucer lands and a grizzly walks out, Fergus will be there like, “I told you!”

Head over to Live Science if you want to make sense of it and then come back here and tell me what a dummy I am.

(Image: Bucky Turco/ANIMALNewYork)