Frank Drake is (note the “is,” Drake is still very much with us) an astronomer and astrophysicist who helped grow radio astronomy through the 20th century. When Fermi asked his version of The Question, Drake was an student at Cornell, where he was soon to graduate and serve a stint as an electronics officer in the Navy. Drake was, and is, an eminently practical guy, as much engineer as scientist, but he had one big interest that made his colleagues roll their eyes — aliens. After hearing a lecture from Russian scientist Otto Struve, Drake became obsessed with the idea of extraterrestrial life. And he never got over it.

This obsession didn’t exactly hurt Drake’s career. He was instrumental in converting the giant radio dish at Arecibo, Puerto Rico into an instrument for astronomy. He worked with a guy named Carl Sagan to create the plaque mounted on the side of the Pioneer probe. And in between he wrote dozens of influential papers, not a few books, and was a professor of astronomy at his alma mater for decades.

In 1961, Drake was one of the hosts for the first international scientific conference on the possibility of extraterrestrial life. Specifically, Drake was interested in how many alien civilizations might be out there who could chat with us over the radio. For that event, Drake produced a string of letters that defined an equation. And it look like this:

N = R * x f p x N e x f 1 x f i x fc x L

For the non-mathematically inclined, that may look a bit daunting. It’s not. What Drake is suggesting with this equation is that it’s really just a matter how how many stars there are in the galaxy, then how many of those stars have planets, and how many of those planets are capable of sustaining life, and so on. That big ‘L’ at the right side of the equation? That’s Drake’s term for how long a civilization capable of being detected hangs around. Remember that. We’ll come back to it.

The equation that Drake produced sounds very much like York’s description of Fermi’s thoughts after breaking into the conversation with his “Where are they?” question. And just as with what came to be called the Fermi Paradox, the Drake Equation really has no answer. You can fill in the values of the equation with numbers that make life exceedingly rare. Or you can crank out values that should have us neck deep in alien visitors. Neither Fermi nor Drake had a way to actually populate the variables of this equation with real numbers, so while it was a fascinating mental exercise … it was just a mental exercise.

But these days we have some real numbers to stick in those letters. Based on the work of probes like NASA’s just-retired Kepler Telescope, current estimates suggest that there are could be 40 billion Earth-sized planets hanging around the Milky Way. 40 billion. With a ‘b.’ And many of these planets exist within the “Goldilocks zone” around their parent stars. That is, the place where water can exist as a liquid.

It’s safe to say that the numbers we’ve determined for the first three values of the Drake Equation are bigger than those Drake used in 1961. In particular, that value up there represented as f p , which is the “portion of stars that have planets” looks like very close to 100 percent. So, in the words of a smart guy … where are they?

The answer has to be in the other parts of the equation; the places where we can’t yet fill in the values. Over the decades since Drake, those missing numbers—and the details of how they might be determined—have gotten some serious poking. And it’s led to a new term.

In 1996, economist Robin Hanson coined the term “The Great Filter.” Hanson, a professor at George Mason, and an adherent of “prediction markets,” put together several themes related to Fermi and Drake when putting together his approach. Paraphrasing his original thesis, we can see that there are good reasons to expect a large number of alien civilizations based on the number of stars and planets. But clearly there are not a large number of alien civilizations. In fact all the evidence we have suggests that there are exactly none.

To account for this startling result, there has to be something in the steps between having a planet where life could occur, and having an advanced civilization, that is so hard, such a difficult barrier to exceed, that it’s very, very … very, very. Very. Very rare for that barrier to be breached. Something out there — a Great Filter — stands between planets that could bear life, and those that produce intelligent civilizations.

People have had objections to this idea. Maybe aliens abide by the Prime Directive and they all leave primitive upstarts to their lonesome. Or maybe they’re homebodies who just don’t wanna go on an interstellar walkabout. And besides, it really is a long, long way between the stars.

Sorry, but none of those objections really cuts it. You don’t need 10,000,000 alien civilizations to have us tripping over old warp cores and wrappers from Phaser Burger. You just need one. For any of the “maybe they’re just quiet” objections to work, it would require that every single civilization that developed, regardless of the conditions in which it developed, would independently and uniformly determine that they would be quiet homebodies. No one, not a single Klingon Musk or Darth Bezos could ever get the idea of venturing out to colonize or launching self replicating probes. That answer seems much, much less likely than what the evidence suggests: There is no one out there.

Really, when you put the Great Filter together with Fermi’s question, there seem to be only two possible outcomes.

Answer One: Intelligent life is a fluke.

Maybe life is much more rare, much more unlikely, than our theories would suggest. All the substances required to create life seem common enough, and there are all those planets. But maybe there’s a step we don’t understand. Or maybe life is common, but it’s the development of complex life that’s rare. Maybe if we get out there, will find that our galaxy is really the Slimy Way, filled with planets overrun with the simplest forms of life, and nothing else. Or maybe it’s intelligence. Or technology — a lot of creatures on Earth, on both land and sea, seem to have reached the simple tool-using stage, but maybe getting from pointy stick to pointy stick with stone attached is just much, much harder than it looks. We don’t know which step, but one of the steps between “having a planet that appears suitable for life” and “having a technological civilization” may be a near impossible move.

This, by the way, is the Good Answer. The answer you should really, really hope is true. This is the answer that says “Yes, there is a Great Filter that stands in the way of developing a technological civilization, but we have passed that filter. The universe—the lonely, empty universe—is at our feet!”

Answer Two: Intelligent life is a disaster.

This the less good answer. The answer that says “Yes, there is a Great Filter out there … and it’s in our future.” What’s particularly bad about this is that everything would suggest that it’s in our immediate future. Because given not too much longer to hang around, this little group of monkeys is likely to escape and start being the sort of interstellar pest who would build a McDonald’s franchise on someone else’s moon … if there was anyone else.

Here’s what makes this excessively worrisome: We have no reason to think that developing intelligent life is all that hard. After all, in the one example we know of it all worked out. We know that in our Solar System, there are three planets that are at least somewhat “Earth like” and somewhat near the habitable zone. Of those, one developed life. That one went on to pass every other proposed bottleneck of the Filter theory. So as far as we can tell … it’s not that hard.

Answer two says that sure, intelligence may be as common as sand, but holding onto a technological civilization isn’t just hard, it’s essentially impossible. There are very good reasons to believe this is the correct answer.

It’s not just that since 1970, we’ve managed to kill off 60 percent of Earth’s animal life (yes, with caveats). It’s not just that humans and the things we eat now account for 96 percent of all the biomass on the planet—meaning that every Blue Whale, Mountain Gorilla, and African Elephant is left to squeeze into that last 4 percent. It’s not even that we’ve now driven our planet straight out of the climate zone where it has existed since our civilization originated. Although … yes, it could be any of those things. It may be that every intelligent civilization is simply not intelligent enough to not utterly foul its own nest.

Or it could be a matter of expanding access. A kind of malignant form of the freedom of information promoted by the Internet, and our laws, and … me, among a few billion others. Think about it this way: How many people on the planet have the ability right now to start a thermonuclear war? If you started tallying up leaders of nuclear-armed nations, you’re badly underestimating the problem.

Consider this event from 1983. On September 26 of that year, the Cold War was at its least cold. The United States and the Soviet Union were moving missiles around the globe, Ronald Reagan was talking “Star Wars,” and the United States was engaged in operations that were purposely designed to test the limits of Soviet airspace (and patience) by trotting nuclear bombers right up to the line.

So when the Soviet nuclear early-warning system lit up to announce the launch of multiple Minutemen ICBMs from the United States, there was every reason to believe that it was the real deal. Nuclear Armageddon was scant minutes away. But a Soviet officer named Stanislav Yevgrafovich Petrov correctly determined—guessed, is more like it—that the report was in error. He did not order the required retaliatory strike. When you go to bed tonight, say a little thank you prayer to Mr. Petrov.

There are thousands of people, from submarine commanders to software engineers, who have in their hands not just their own life, but that of our entire civilization. You don’t just have to worry about Kim Jong Un. You have to worry about the maintenance tech who installs Kim’s light bulbs. Now multiply that issue by genetic engineering. And nanotechnology. And AI.

We are reaching a period when the number of people who have it in their capacity to initiate a civilization-ending event may be as great as the number of people in that civilization. To survive is going to require that we meet the impossible task of behaving responsibly and sensibly, every one of us, all the time, day in and day out, for as long as we want that ‘L’ in the Drake Equation to go on.

After the first nuclear bomb was developed, there was talk of “putting the genie back in the bottle.” That never happened. We also can’t return any of these new genies, or any of the others whose bottles will soon wash up on our shores. We have to deal with them. Or die.

All that can be done is to consider these issues with the gravity that they deserve. To understand that we walk a knife edge every day. To embrace the idea that we have to educate every person on the Earth in both the opportunities our technology presents, and threats we must endure.

And there is one thing you can do about it that will have an immediate effect.

You can vote.