Good morning, Hank. It's Tuesday, so I co-host a podcast called Crash Course: The Universe with the astrophysicist Dr. Katie Mack. And while making it, I recently learned what will become of me in the long long run, like in 10 billion years. And it's a bit discouraging.

But first, a broad observation about human history. We know very little about the distant past, right? Like, we don't know when people started to have names or what their names were. We don't know when humans developed language. We don't know much about what our relationship was like with the other humans that coexisted with us, like Neanderthals and Denisovans. Our species has been around for like 300,000 years.

And for almost all of that time, very little information has been passed down to us. And so when I think of human history, I often think of it as the story of humans getting better and better at preserving and passing down information. Like, there could have been great plays made 30,000 years ago, but I can't read them or see them performed, whereas I can see great plays from 2000 years ago.

I can't see a photograph of London from 1200 CE, but I can see one of London from 1900 CE. And now, of course, we have tons of technologies for preserving and passing along information. Not just photographs and writing, but also video and music recording and digital archiving.

And so it's tempting to me to see the human story as the story of accumulating more and more knowledge and information about each other and our universe. It's a line of progress that begins before cooking fires and ends with us understanding what's keeping the stars apart and how old the universe is. It begins with nobody's name or story being recorded and ends with everyone’s name and story being recorded.

But of course, that imagines that the rollercoaster of information accrual only goes up, which we know is not the case, right? Like, we know that humans, like all Earth species, have a temporal range, an amount of time they get to be a species. There was a time, in fact, lots and lots of time before humans.

And there will be time, in fact, lots and lots of time, after humans. Nothing we’ve ever observed in our universe is permanent, and we can be reasonably sure what’s going to happen with Earth and all Earth life, including us. So here’s a little glimpse ahead in the podcast to what I learned from Dr. Mack will eventually happen. The sun is getting brighter, and in a little while, about a billion years, it will become so bright that all the oceans on Earth will boil. A little while after that, the sun will become so bright and large as a red giant that it will consume Mercury and Venus and probably, although not definitely, Earth.

Also maybe some other planets, but those aren’t as personally important to me. So anyway, the sun will be a red giant for a long time, and then eventually it will shrink down into what's called a white dwarf. This white dwarf will contain what remains of the sun, Mercury, Venus, probably Earth, maybe some other planets, and it will be like the size of the Earth, but it will be unfathomably dense, like hundreds of thousands of times denser than Earth.

So that's where we're headed. We're headed to probably being part of a white dwarf. Now, not so long ago, some researchers were looking at a distant white dwarf, and they noticed inside that white dwarf some elements that they wouldn't expect.

And what they concluded is that probably that star had once been a red giant that had consumed some of the planets in its solar system. And that's why they were seeing those elements that usually wouldn't be made from a star. And so what they were seeing in that white dwarf were the remnants of those rocky planets.

And that's probably what we will be. In the distant future, Earth's love stories and technology and birdsong and everything else will be a bit of pollution inside the sun's white dwarf. It'll be the small collection of elements that the star itself wouldn't produce.

And that'll be us. All of us, all that remains of us. Nobody will have a name or a story.

All sentient beings observing that white dwarf would see is that a rocky planet got too close to a red giant. In making this podcast, I've been thinking a lot about how we cannot leave a permanent legacy, and how like the urge to do something eternal for this world is just like the wrong urge. We don't need to remember everything or record everything.

We remember what we can and record what we want, not for eternity or posterity, but for the people we share this planet with and the people who will come after us in whatever remains of our future. I don't know why we're here, but it's certainly not to leave a permanent mark. That mark will only be engulfed by our star, assuming that somehow we survive the next 300,000 years, and the next 3 million, and the next 30 million and the next 300 million.

It can't be about forever. It has to be about now and what we can see coming. We can't know much about ancient humans, but one thing I would guess about them is that, like us, they couldn't hope in forever.

They had to hope in themselves and in future generations. We are the embodiment of their hope, just as future generations will be the embodiment of our hope. And maybe that's why we're here.

To ease present tense suffering, to solve problems not just for each other, but also for the people who will inherit this earth. And most of all, most of all, to live in brief wonder on this, our brief planet. Hank, I’ll see you on Friday.

PS - Hi, I hope you’ll watch or listen to the Crash Course Universe podcast. Links in the dooblydoo. Also, the podcast was made with funds from last year’s Crash Course Coin.

The Crash Course Coin is available only for the next few days. It’s an essential part of how we fund Crash Course. You can learn more at crashcoursecoin.com.