Question: Dear Sara, How are you? I find your job increadibly interesting and I LOVE learning about space and the universe. I have some questions which I would like to get answered: What do you think the universe will be like in years to come? What would happen after the world has "died"? Please answer these questions because I find it extremelly interesting!!

Sara Imari Walker answered on 21 Jun 2011:

Hello lydia!!! Awesome! I find space and the universe extremely interesting too!!! And, my job is super fun, I am so lucky to be able to do this stuff!

There is a lot to say about both of your questions =)

First, about the whole universe – That’s a lot in a question! The universe is in a pretty interesting stage in its development right now – its basically primed for life! Look at us – we have galaxies, stars, and nice comfy planets. Its a great universe to be in! It wasn’t like this early on, and it won’t be very far in the future. But for quite a while (and I mean billions if not trillions of years a while) we will continue to have these things. Stars will be born and they will die, spreading the elements they create around the cosmos for new planets to also be formed and maybe eventually die. The whole process will go on for ages. But the universe as a whole is also changing to. It is expanding with time – this expansion will eventually get so fast that it will rip apart the universe. First it will be such that any given galaxy will become a lonely wanderer in its own hubble volume (that’s the part of the universe we can see – so imagine no other galaxies out there). Then galaxies, followed by solar systems, then stars and planets will no longer be stable, and eventually atoms won’t either. The universe will consist of empty space with some photon radiation (that’s light particles) and a bunch of black holes. The black holes themselves aren’t indefinite either – they can evaporate (through Hawking radiation – named for the one and only Stephen Hawking!) producing elementary particles. So eventually all the black holes will disappear and nothing will be left but a bath of photons. This has been called the “heat death” of the universe. But don’t worry its TRILLIONS of years off. That’s much much much longer than the universe has even been around for yet. There are alternatives too such as a “big rip” or a “big crunch” but last time I checked the heat death is the most commonly accepted end state for our universe. But, there might be other universes out there, so the story goes on!

On the world ‘dying’ part. Well do you mean what would happen for humanity and life on Earth? If you just mean the universe, than that is basically described above – it will go on without the Earth, likely for trillions of years. But if we humans or any other organisms on this planet want to survive the death of Earth we better find a way for better space travel. We have lots of scientists now, so-called planet hunters, combing the skies for other “Earths”. What they are looking for is habitable worlds with liquid water orbiting other stars. The goal right now is not to send humanity there, instead we are looking for other places that might harbor life. But who knows. Maybe we find an exoplanet next year that ends up being humanity’s home several million years from now. Almost anything is possible!! Exciting stuff huh??

Great questions Lydia! Keep it up!!