Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

This episode is sponsored by Skillshare.

Many a good and great thing has risen from the ashes after a fire consumed what came before.

It is possible our universe may be one such example, destined to be torn apart in the fiery birth of a successor.

So today we are returning to our civilizations at the end of time series to discuss the Big Rip,

one potential scenario for how our universe might end.

In our earlier episodes, Black Hole Farming and Iron Stars,

we were contemplating how civilizations could survive even after

all the stars in the universe had burned out, many trillions of years from now.

This is the fate of the universe in scenarios such as heat death or proton decay that slowly

run the clock out as the universe expands and cools and entropy wears us out.

The big rip goes a very different way by pulling the universe apart even faster than it currently expands, and eventually

escalating those expansion forces, what we call dark energy or phantom energy in some cases,

until they are so powerful they can rip whole atoms apart, not just galaxies.

Which might seem like a peculiar comment if you're not already familiar with dark energy

and Hubble expansion, given that ripping atoms or their nuclei apart should be easier than

ripping apart entire galaxies, which is certainly true, so we'll explain that today too.

Now, for those familiar with Hubble expansion, odds are you have heard of the big rip

scenario before, even if just in sensationalist headlines about the universe being destroyed

...