Humans have been on the lookout for aliens since the birth of modern astronomy, and with all the hype surrounding water on other worlds and the kinds of potentially habitable exoplanets we’re discovering, you would think we would have finally found signs of extraterrestrial life, right? Well, a new paper suggests the reason we haven’t found aliens yet is because life on Earth simply started much too soon.
In a study to be published in the Journal of Cosmology and Astroparticle, a team of Harvard and Oxford University astronomers has formulated a new model predicting the probability of life elsewhere in the universe, and they hypothesize that if life can emerge on worlds that exist in planetary systems with stars less powerful than our sun, then perhaps extraterrestrial life will be much more common in the future.
Depending on who you talk to, the fact that life exists on Earth is either a miracle within a miracle, or simply one of many instances of a universe that is potentially teeming with organisms on all kinds of worlds. In either case, because we only have Earth as a standard for what a habitable world probably looks like, it follows that we would also look for planetary systems with stars similar to our sun — not too hot, not too cold, not too big, and not too small.
The vast majority of stars in the universe, however, are smaller and weaker than our yellow sun. Red dwarf stars are one variety of low mass stars that make up 80 to 90 percent of the stars in our own Milky Way galaxy. They’re dimmer than the sun, but more and more research predicts they could encourage the formation of habitable planets as moons as easily as bigger stars.
More critically, red dwarfs can live for up to a thousand times longer than sun-like stars. This means with enough time, they could encourage the evolution of habitable traits on orbiting planets, and foster the characteristics needed to allow life to spring on these worlds.
Life on Earth may have evolved faster simply because our star is bigger and brighter. A red dwarf might simply need more time — trillions of years maybe — and this explains why we haven’t found other life yet.
The other explanation, of course, is that red dwarfs simply prevent habitable environments from growing. The only way to really determine if this is true is to study red dwarfs and other low mass stars more directly.
This new paper certainly isn’t the first effort to peg a probability to the discovery of extraterrestrials. A new update to the famed Drake Equation was a boon to E.T. optimists and predicted an extremely high increase in the odds aliens — intelligent aliens, mind you — exist. Another study suggests we should concentrate on investigating multi-planet systems, since they could theoretically exchange life with one-another via meteors. And yet another study focused around the mediocrity principle says we only have to wait 1,500 years before aliens make contact with us. Oh, and there’s one more study that suggests maybe we haven’t found aliens because they’re all dead. Womp, womp.
Photos via Christine Pulliam/CfA