This is a letter to a person living 2 billion years from now:
What does the sky look like?
No – let me start over. Are you there? The odds are against you being there. Very few species on Earth have had a run of more than a few hundred million years. And nothing has made it more than a billion.
But let's say you're there. Can you take a picture of the sky? And can you send the picture back in time to me?
Is the sky bright? Is it lit up blue with new stars? Has the Milky Way been replaced by a giant ball of light?
This is what scientists say is supposed to have happened by the time you read this letter. The Andromeda galaxy was supposed to have merged with ours, creating a new, spherical galaxy.
Here is how we, right now, think it's going to happen ... in this stunning -- STUNNING -- video from a program called Science Friday, which we linked to 2 billion years before you read this.
Did we see it happen? Did we set up a time lapse camera, over one billion years to capture this celestial coming together? Did we see the explosions of new stars forming? Are you witnessing the creation of a bigger black hole?
I find it incredibly inspiring to think that maybe you see a brighter sky than I see. Your nights are brighter. You see nebula without the use of a telescope. Your galaxy is twice as big as mine.
It makes me really envy you. If you exist.
I like to think of you. I think of you in a plaid shirt and blue jeans. Think of you as having stubble. I think of you as feeling a little lost. I know you have problems. I do, too. I know you're struggling to make that girl like you, and make your mom happy. Just because you have cooler spaceships than we do doesn't mean you're not human.
You and I are people, without power, especially compared to the grand forces of the universe.
But you and I are people, we are made of the same stuff. Out of the universal substance – strings, atoms, molecules, dirt – as out of wax, nature fashioned me, and will break me up and use the material to form a tree, and then a colt, and after that a man and then some other thing. Not one of these will endure for more than a brief span. As for the beings themselves, it is of no greater hardship to be taken to pieces than to be put together. But I find hope in the idea that it is possible, maybe inevitable, that some part of the universal substance that made me now makes you.
I don't have any power to make that happen. I don't have any power to make you exist. But I like to think of you.
And I hope that you don't spend any time thinking about me. I'm dead and gone. I don't matter anymore. No one who is dead really matters anymore, except insofar as you can learn from them. I hope you're thinking about the person who is coming 2 billion years after you die. I hope you are making decisions with that person in mind. Because in order for that person to exist, she will have to exist in a different solar system. Two billion years after you, the sun will be too hot for us to live on Earth anymore. Hope you guys are working on some sweet spaceships. Hope you're going to find that girl a place to live.
Look up at the night sky. You probably see about twice as many stars as I do. I hope that, aound one of the stars, is a planet you can live on. Try to find it. Try to think ahead.
P.S. -- Here's a super slo-mo video of what the collision is supposed to look like. Did we get it right?