What I learned from this awe-inspiring animated explainer video from Kurzgesagt – In a Nutshell.
- Ninety-seven percent of all stars will eventually become white dwarfs.
- White dwarfs have a long lifespan! Up to 100 billion billion years. That's 10 billion times longer than the universe has existed.
- Intelligent life has a few billion years to learn how to move close to white dwarfs in order to survive. (In other words, it's a good idea to start planning now!)
- When a white dwarf dies, it will become a black dwarf. The universe will begin the slow process of heat death, and all life will die.*
- If protons decay the universe will eventually dissolve into nothingness.
- If protons don't decay, then they will become iron spheres, suspended in a black cold universe. This will be the forever end state of the universe.
*Not in the video, but Freeman Dyson has put forth the idea (in his wonderful book, Infinite in All Directions) that as long as there is a temperature differential (and there always will be), energy can be used to support life. Imagine a system that harvests energy for 10 billion years, which is enough to power a computer with a universe simulation in it for one second before shutting down. The next time, it has to harvest energy for 20 billion years to run the simulation for a second. This could go on literally forever, and the conscious entities in the simulation would not be aware of the long hibernation periods. Other physicists have shot down Dyson's "Eternal Life Postulate."