Two ways dark energy could destroy the universe | Katie Mack | Big Think

Two ways dark energy could destroy the universe
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The universe is expanding faster and faster. Whether this acceleration will end in a Big Rip or will reverse and contract into a Big Crunch is not yet understood, and neither is the invisible force causing that expansion: dark energy.

Physicist Dr. Katie Mack explains the difference between dark matter, dark energy, and phantom dark energy, and shares what scientists think the mysterious force is, its effect on space, and how, billions of years from now, it could cause peak cosmic destruction.

The Big Rip seems more probable than a Big Crunch at this point in time, but scientists still have much to learn before they can determine the ultimate fate of the universe. "If we figure out what [dark energy is] doing, if we figure out what it's made of, how it's going to change in the future, then we will have a much better idea for how the universe will end," says Mack.
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KATIE MACK:

Dr Katherine (Katie) Mack is a theoretical astrophysicist and assistant professor of physics at North Carolina State University. Her research has focused on dark matter, the early universe, galaxy formation, black holes, cosmic strings, and the ultimate fate of the cosmos. Dr. Mack's latest book, "The End of Everything (Astrophysically Speaking)" discusses five universe-ending possibilities proposed by cosmologists and what that grand finale would look like.

Check Dr. Mack's latest book "The End of Everything (Astrophysically Speaking)" at http://amzn.to/3aEwsUx
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TRANSCRIPT:

KATIE MACK: Understanding what dark energy is, understanding what it is that's making the universe expand faster is an incredibly important thing for understanding the future of the universe. Right now, the evolution of the cosmos is dominated by this mysterious dark energy that we can't see, we don't understand. If we figure out what it's doing, if we figure out what it's made of, how it's going to change in the future, then we will have a much better idea for how the universe will end.

Dark matter is very different from dark energy. People often get these two ideas confused because they're both called dark. And also because there are connections between matter and energy. People might have heard of E = mc2, this idea that there's a way to relate the mass of something to its energy, that's from Einstein. In this case, dark matter and dark energy don't seem to be related to each other in any way, that we know. They're both called dark because we cannot see them and they're mysterious. That's where the similarity ends. Neither one is dark in the sense of being black. They're dark in the sense of being invisible. They don't emit light, they don't absorb light, they don't reflect light. They don't seem to interact with light at all, as far as we can tell.

Dark matter seems to be something that interacts via gravity so it has mass, it's matter. But it doesn't seem to interact via the other forces of nature in any way that we've been able to tell. Dark energy only does this thing where it makes space expand, it interacts only with space. And there's a possibility that dark energy is just a property of space that every little bit of space has a little bit of expansion built in, and as the universe gets bigger and bigger, there's more and more space, and so that expansion starts to win out over the gravity that's trying to slow it down. And so, the universe starts expanding faster and faster. That's one possibility for dark energy, that it's just a cosmological constant, it's just part of how the universe works, that it has this expansiveness built into it.

But it's possible it's something else. It's possible that whatever is making the universe expand faster and faster is something weird and different, something that acts in a totally different way. That also accelerates the expansion of the universe, but maybe it changes over time in some way that we don't understand. One of the possibilities for that is something called phantom dark energy. Phantom dark energy would be something where dark energy is getting more powerful over time. That means that in a particular volume of space, the amount of dark energy in that volume starts growing. And that would actually lead to a total apocalypse in a relatively short time. What it would do is it would start tearing apart things in the universe. If dark energy is not a cosmological constant, if it's this phantom dark energy, then the amount of dark energy is going to get higher over time. And so...

Read the full transcript at https://bigthink.com/videos/what-is-dark-energy