Science & Technology

# Scientists Have a Depressing New Answer for Why We Haven't Met Aliens — But Elon Musk Isn't Fazed

If you want to figure out where the aliens are, first you've got to come up with a reasonable estimate for how many of them there might be. That's why the Fermi paradox and the Drake equation go hand in hand. Now, a new paper casts some doubt on the latter, making the solution to the former sound a little less exciting (if you were as excited about aliens as we were). Still, some notable spacefarers say that an empty universe is nothing but good news.

## Alone Again, Extraterrestrially

Just as a quick refresher, the Drake equation is a formula invented in 1961 by Dr. Frank Drake to estimate the likelihood of encountering an alien civilization through astronomical means. It goes like this (sing along if you know the words): N = R* ∗ fp ∗ ne ∗ fl ∗ fi ∗ fc ∗ L. In that equation, N is the number of alien civilizations emitting detectable electromagnetic signals, and the numbers you multiply to get N are elements like the number of stars created per year, the number of stars with planetary bodies, the fraction of planets with conditions suitable for life, the fraction of intelligent life forms that develop the ability and desire to broadcast into space, and finally, L, the average lifetime of a civilization after it has begun sending out those signals. You can read more about it here, but the major takeaway should be that N is an estimate — we're making our best guesses for all of those numbers.

Although it technically came first, the Fermi paradox naturally follows from the Drake equation — scientists have crunched the numbers time and time again, and while the particulars have changed, the estimates for how many civilizations that are out there have remained high. So where are all the aliens? That's the essence of the Fermi paradox. But according to a new paper by Anders Sandberg, Eric Drexler, and Toby Ord of Oxford's Future of Humanity Institute, we shouldn't be calling it the Fermi paradox at all. We should be calling it the Fermi observation.

There's one factor that gets consistently left out of Drake equation formulations, the scientists say, and that's our level of certainty. Sure, we might have a better idea of how many stars in the galaxy have planets orbiting their habitable zones (almost all of them), but even then, there's a lot of uncertainty. When it comes to guessing whether a planet with simple life forms will ever develop more complex species, well, we still have only a sample size of one. That's just the start. We should be calculating our certainty for each of these factors as we run the equation — and when we do, we'll find that we can say virtually nothing for sure.

## Into the Abyss

According to the team's modified calculations, there is a 53 to 99.6 percent chance that we are the only space-bound species in the galaxy and a 39 to 85 percent chance that we are the only one in the entire universe. You might say to yourself that even these numbers are based entirely on speculation (and you'd be right to do so), but to the authors, that's not the point. They just wanted to point out that the "paradox" is no such thing if you factor in certainty — but that that's no reason to stop the search for extraterrestrial life.

Furthermore, it can be seen as good news. Remember how the L part of the equation stood for the lifetime of the species? Well, one disturbing possible answer to the paradox is that alien civilizations might very rarely, if ever, survive after they have developed the technology to broadcast to the stars. And that's not a good sign for us here on Earth since we've just barely developed that technology on the time scale of the universe. But if there's no paradox, then there's no countdown timer from when we get the tech and when we go kaput.

It's good news on another front as well, according to those of us looking for interplanetary real estate to snatch up. As Elon Musk said on Twitter in response to the news, "This is why we must preserve the light of consciousness by becoming a spacefaring civilization & extending life to other planets." And in another response, "As individuals, we will all die in [the] blink of an eye on a galactic timescale. What can live on for [a] long time is civilization. Those who first go to other planets will face far more risk of death & hardship than those who stay. Over time, space travel will be safe & open to all." It's a fair point and a noble goal — but we're going to wait to be those first spacefarers until there's something more appealing than a Martian homestead on the market.

Fermi's is just one of science's many paradoxes. In Jim Al-Khalili's "Paradox: The Nine Greatest Enigmas in Physics," the author explores everything from a footrace between Achilles and a tortoise to a pair of identical astronaut twins who are decades apart in age. 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.

Clue #5: My daughter and I both won a nobel prize.