It’s one of the great questions of our age: Are we alone in the universe? A long line of films—from Contact to Close Encounters of the Third Kind to the latest entry, Arrival—have explored whether intelligent life is somewhere out there in the cosmos and wondered what would happen if, or when, we finally come face-to-face with it.

Speaking from his home in Gloucestershire, England, Miller explains why the TESS project could finally tell us if there is life elsewhere in the universe, how comedy and science connect, and why we will need a new Rosetta Stone to interpret alien messages.

You write in your book that we are living through one of the most extraordinary revolutions in the history of science—the growing belief that we are not alone.

When I was studying at university, we weren’t even sure if there were planets around other stars or whether the solar system might be a one-off. But for the last few decades we have been on this extraordinary voyage where we’ve found thousands of planets around other stars. Strangely, we started looking for planets a long way out because of the technology we had at the time. Now we are starting to look at the stars closest to our own.

Recently, there was an exciting discovery that the very nearest star to us, a red dwarf, has got a planet called Proxima b. Not only that, but the planet is the right distance from that star to have liquid water on its surface. We think liquid water is very important for life. So, right on our doorstep, the conditions might be right for life.

Life Could Exist on Mars Thanks to Methane According to geobiologist Jeff Marlow, anywhere on Earth we find liquid water and enough energy, we find life. So the best way to find it on Mars might be to consider what early life on Earth looked like.

A lot of the new thinking about the possibility of alien life-forms comes not from space but from deep in the ocean. Tell us about extremophiles.

This is an incredible story. Since the early 1960s we’ve been finding these living things, often single cells, in conditions we thought impossible for life to survive. One of the first places they were found was in Yellowstone Park, in hot springs of up to 90 degrees Celsius. That’s altered our thinking on alien life-forms. We have found bacterial life on the inside of nuclear power stations, in the upper atmosphere, and in rocks deep within the Earth. That means there’s more real estate for life out in the galaxy.

It also means we have to rethink where we fit in the spectrum of life. We now believe life on Earth started in hot, volcanic springs at the bottom of the ocean. What I love about that is that it makes you rethink the whole idea of what an extremophile is. When you think about it, we’re the extremophiles, sitting here having a conversation, breathing in oxygen, at absurdly low temperatures compared to how life first stared out. And we’re not even in water! We are an extraordinary, hyper-organized colony of bacteria that started its evolutionary journey in scalding hot, alkaline water in the bottom of some primordial ocean. In other words, one of your ancestors is a rock! [Laughs]

Comedy and space are not words that are usually linked. You have to tell us your favorite space joke.

How many ears has Capt. Kirk got? The answer is three: the left ear, the right ear, and the final front ear. [Laughs] Actually, the link between comedy and space is pretty strong. Science is a skeptical pursuit, and so is comedy. There’s a fantastic tradition of combining science and comedy, from Douglas Adams to Monty Python. Think of Eric Idle’s songs about the universe and evolution. On my TV show, we have always done sketches on global warming. A man’s looking out the window, it’s raining, and he says to his wife, “Look at that! It’s dripping out there. So much for global warming, eh?” [Laughs]

View Images Organisms discovered in hot springs in Yellowstone National Park have expanded our understanding of where life can flourish. Photograph by Michael Nichols, Nat Geo Image Collection

Stephen Hawking believes we should not attempt to contact alien civilizations. What’s his thinking? And do you agree?

His position is a little harder to interpret than that. He’s a great supporter of the Breakthrough Listen project, this idea that we should put proper funding into searching the nearest million stars to see if there are signs of life. His point, generally speaking, is that when two civilizations come into contact, the civilization that’s not so technologically advanced doesn’t come off too well. His example is that it didn’t work out too well for North American Indians when they met Western settlers. I don’t agree [with his position on contacting alien civilizations]. I can’t say there’s not a risk. But what we stand to gain far outweighs the risk.

If we receive a message from outer space, we may not be able to understand it. How can Egyptian hieroglyphics help us with that conundrum?

We owe the deciphering of the hieroglyphs to Napoleon, who decided to annex Egypt and took with him some of the brightest philosophers and scientists of the age. But the hieroglyphs were an incredibly difficult thing to crack. What did a picture of a bee mean? Did that mean a bee, or the concept of being stung, or did it stand for a phonetic sound?

The breakthrough came when Napoleonic troops were dismantling an old fort at the port of Rosetta and found this stone with three different inscriptions. One was in hieroglyphs, another in ancient Greek, and the other in an intermediate form of Egyptian writing. It became known as the Rosetta Stone and was one of the ways we managed to crack Egyptian hieroglyphs.

We won’t have a Rosetta Stone when we receive our alien message, so it will be a very hard thing to translate. People have come up with clever ideas about how you might create a Rosetta Stone, how you might compose a message to send to an alien which contained something within it the aliens would also have within their culture, like mathematics or the ratio of the electron to the proton.

One thing we’ve learned is that the more information and language you have, the more chance you have of decoding it. The problem with sending just a short message, such as those attached to the Pioneer and Voyager spacecraft, is that there’s very little information in them. That’s why some experts, like Seth Shostak, the head of SETI, have come up with the idea of sending the Internet. The Internet is the most honest reflection of who we are as a species. Cats licking lollipops, a hundred recipes for American pancakes, the whole thing! [Laughs] We are not these superintelligent beings we’ve tried to present ourselves as in previous messages.

View Images This image of galaxy cluster Abell 2744 shows some of the youngest galaxies ever detected in space. Photograph by NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

In 2017, NASA will launch the Transiting Exoplanet Survey Satellite (TESS). What is it—and what’s its mission?

We’re finally looking at the planets nearest to us. To begin with, we weren’t really sure any stars had planets. So we put up the Kepler space telescope and focused it on a very dense portion of the star field in a region of our own galaxy a long way away. The amazing thing about Kepler was that it found most of the stars have planets!

TESS, which will launch in 2017, will be looking at the very nearest stars. It may even be possible to look at the light coming from the atmosphere of those stars and tell what gases are in those atmospheres. When you look at Earth and see all this oxygen, you’d think there’s something strange going on. Oxygen is an incredibly reactive gas. What’s that doing in mass quantities in an atmosphere? It will be those kinds of signals that we’ll look for when we look at the atmospheres of other planets.

You know what the last question has to be: Are the aliens really coming?

Within the next ten years we’ll know whether the nearest Earth-like planets to us have got life on them. That has enormous implications for us as a species. Once we find life out there, you have to think that other intelligent life-forms and civilizations exist as well.

At the moment we are in this extraordinary position that our planet may be the only thing in the entire universe with life. So we would be taking a closer step to one of two extraordinary results: that we are the only life-form in the universe or that we are not alone. Either will be species defining. It will change the whole way we view ourselves: religion, politics, our individual psyches, everything.

One of these two possibilities has to be true. It’s just us—or we are not alone.

This interview was edited for length and clarity.