Are we alone in the universe? We're close to finding out | Lisa Kaltenegger

0:06You're listening to TED Talks Daily, where we bring you new ideas to spark your curiosity every day. I'm your host, Elise Hu. So many mysteries remain about the cosmos, different solar systems, different planets, and what other life is out there. In her 2024 talk, Alien World Explorer Lisa Kultenegger explains how the latest tools reveal truths, not only about planets very far away, but also about who we are and how we're all connected. Enjoy.

0:40We live in an incredible time of exploration on the verge of finding out whether we're alone in the cosmos or not. This is one of the biggest questions humankind has ever asked. And now, for the first time, we have a tool that could find out. because the James Webb Space Telescope is a telescope large enough to be able to catch light from planets like ours, as small as ours, but circling other stars light years away. Because this search is a search over vast cosmic distances. Even light needs years to travel these trillions of miles between stars. So when you look up at the sky at night, you look back in time.

1:45Let's imagine you're on a planet circling our neighboring star about four light years away. Then you would see the Earth tonight like it was four years ago. On a planet 70 million light years away, you could still see the dinosaurs roam here. And it also means that out in the sky there is a star whose light arrives tonight that was sent out when you were born. Your personal connection to the cosmos. So these distances are vast, But astronomers throughout time have managed to unravel and reveal mysteries of the cosmos because light and matter interact. So light carries energy. And if it hits a molecule with just the right energy, that molecule will start to swing and rotate.

2:50So it's really the missing light, the light that doesn't make it to my telescope, that tells me which molecules the light encountered before it got to me. It's a little bit like a passport stamp that tells you where Traveler was before arriving here. So when you look at this incredible image of the pillars of creation taken by the James Webb Space Telescope, it is gorgeous. But if you analyze the light, you realize that we are watching a stellar nursery where we see stars emerge and ignite. And when you look at stars on our night sky, you reveal another astonishing truth. That you and me, all of us, are made of ancient stardust.

3:50dust. Because it took the heat in the core of a star and the violent explosion at the end of its lifetime to make the atoms that made you and me. So on a fundamental level, we are connected to each other and to the cosmos around us. And now, for the first time, we get to search for other organisms somewhere else that might be made of ancient stardust too. But when you try to find life in the universe, it is incredibly hard because planets are so much smaller and they're close to their bright and big stars. And we don't only want to find planets like ours, we want to look in their air and on their surface for signs of life.

4:50So what we do is we wait until the planet crosses our line of sight to its star, and the light from its star hits, smashes into the atmosphere of the planet before it gets to my telescope. So I can look for these passport stamps to figure out what's in the air of planets very far away. And the light fingerprint, the best light fingerprint we have for life on the Earth is the combination of oxygen and methane for carbon-based life with a water solvent on a planet in the temperate zone around its star. But I was really curious how long could this light fingerprint actually tell you that there's life on our planet?

5:48And so I figured out that for about two billion years, the biosphere has painted signs of life into our atmosphere. So for half of Earth's existence, you could tell that there is life on our planet. And if life does this somewhere else too, for the first time, we have now a chance to spot it. And so searching for life in the universe actually made me see our planet completely differently. And it lets you start to think about how different these other planets could be like. There could be planets completely covered in oceans. with waves that never break on a shore, or planets half in eternal sunlight and half in perpetual night, or planets that are covered with a purple landscape.

6:50Because purple bacteria is very sturdy. It can thrive under red sunlight. So eight out of 10 stars out there are actually small red stars. so purple might be the new green when searching for life in the cosmos. But we know that one out of five sun-like stars has a planet that could potentially be like ours. So with 200 billion stars in our Milky Way alone, that means we have billions and billions of possibilities. I founded the Carl Sagan Institute at Cornell to bring thinkers and creative minds from many different fields and backgrounds and ways of life together to create the toolkit to find life in the cosmos.

7:53And so we created a spectral database, a light fingerprint database for habitable worlds. And in case you're wondering, actually, Jurassic worlds, where space dinosaurs might roam somewhere else, are actually easier to find than a modern Earth, because there was more oxygen when the dinosaurs lived here. I'm not saying they are space dinosaurs, but I'm just saying, if you ever wanted there to be, I'm giving you options. But when you search, then one of the questions that came was also, if there's life in the cosmos, of course, I don't know that yet, but if there's life in the cosmos, could somebody looking at us with just the same technology we have, and there's a space on the sky, a strip where you have just the right vantage point to see the Earth go in front of the sun, and it encapsulates about a thousand stars within 300 light years.

8:59What's really our cosmic background? And so the question is, where could we be, the aliens? Is there life in the cosmos? I don't know. We don't know yet, but I really want to find out. Because the cosmos is 13.8 billion years old, but we all get to live in the most exciting time, where the search for life on other planets went from impossible to possible. And it's at the edge of technical capability, but we're already designing larger telescopes that could catch more light of these planets to find out if there's life out there calling another planet home. From a tiny town in Austria, when I looked up at the stars and wondered if they could be sons to their planets, to now sitting in Carl Sagan's old office at Cornell, the journey has been challenging, inspiring, and full of wonder.

10:04Because those thousands of new stars, new suns on the sky, hold a breathtaking promise that our adventure of exploration has just begun. So go out at night and find your favorite star and allow yourself to wonder, what if we're not alone? Thank you.

10:37That was Lisa Kaltniger at TED Next 2024. If you're curious about TED's curation, find out more at ted.com slash curation guidelines. And that's it for today. TED Talks Daily is part of the TED Audio Collective. This episode was produced and edited by our team, Martha Estefanos, Oliver Friedman, Brian Green, Autumn Thompson, and Alejandra Salazar. It was mixed by Christopher Faze Bogan. Additional support from Emma Taubner and Daniela Balarezo. I'm Elise Hugh. I'll be back tomorrow with a fresh idea for your feet. Thanks for listening.