Maybe We Haven't Found Aliens Yet Because They're Trapped on Their Planets

The fact that we have yet to uncover any evidence of alien life has frustrated plenty a scientist, to say the least. There are enough hypotheses to explain why we haven't met E.T. to last a lifetime — but they just keep getting more and more fun. A 2018 study on the matter is no exception.

Gravity Got Ya Down?

Like a grounded penguin hopelessly flapping its wings to take flight — that's what aliens are. That's according to a April 2018 study, anyway. Independent astrophysicist Michael Hippke, who is affiliated with the Sonneberg Observatory in Germany, writes in his research that intelligent alien life living on super-Earths somewhere out there in space may just be having a really hard time getting off their home planets. As in, they're trapped. While a 2017 study suggested maybe aliens are trapped beneath a thick layer of ice, this one answers the Fermi paradox by saying aliens may be trapped by gravity.

As Hippke explains in his paper, "Many rocky exoplanets are heavier and larger than the Earth, and have higher surface gravity. This makes space-flight on these worlds very challenging, because the required fuel mass for a given payload is an exponential function of planetary surface gravity." With such strong gravity, an incredibly powerful rocket would be necessary to even get off the ground. Chemical rockets couldn't do it, but something like nuclear propulsion might.

Don't Underestimate

Not so fast. Senior Astronomer for the SETI Institute Seth Shostak has a few issues with Hippke's trapped idea. He writes for NBC News that, sure, aliens on super-Earths with an extra dose of gravity weighing them down would have a harder time getting into the air. But not that much harder of a time — nothing impossible, anyway. "Some of Hippke's calculations seem to be in error, leading him to overestimate the challenges to space programs on super-Earths," he writes. "But even if stronger gravity delayed the inhabitants of these worlds from getting off their planet by 50 or 100 years, you have to ask: so what? Does that bump in the road matter more than the fact that the larger size of their planet would delay the laying of telegraph cables from one continent to another, or that long-distance transport would be slower, simply because the distances would be — well — longer?"

In fact, Shostak argues, being on a super-Earth could actually be positive for such a civilization. "More gravity would mean a thicker atmosphere, which might speed the development of aviation. Greater acreage might bring a wider diversity of animals, possibly producing intelligence sooner than happened on Earth. And one could expect more abundant natural resources on an oversized world." Without aliens on our doorsteps detailing every challenge they've faced to reach us, we can't really know for sure. But for the time being, says Shostak, "I would hesitate to judge the worth of our planet, or anyone else's, by the size of its rockets."

Want to keep searching for aliens? Check out Shostak's book "Confessions of an Alien Hunter: A Scientist's Search for Extraterrestrial Intelligence." We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.

Written by Joanie Faletto May 17, 2018

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