Lecture 23
Geometry and Fate of the Universe

Key Concepts:

Evolution of the Early Universe

Also look at Cosmology FAQ

The Four Forces
Force	Acts on	Examples
Strong	quarks	holds nuclei together
Weak	quarks,electrons,neutrinos	radioactivity
Electromagnetic	charged particles	atoms and molecules, electric fan
Gravity	everything	solar system, your chair on the floor

all four forces were one at the beginning
phase transition: forces separate themselves out
symmetry breaking: tiny bit more matter than anti-matter produced (one part in 1 billion?)

Big Crunch: if the universe has enough matter in it (closed), the gravity wins and the universe collapses on itself.
A critical, coasting, or accelerating universe will exist "forever". The universe will continue to change:

more and more matter gets locked up into low mass stars, planets, WDs, NSs, and BHs, and not recycled
in one trillion years, even the longest-lives stars will burn out, and the galaxies will fade into darkness - only cold WDs, NSs, and BHs remain
in 10²⁰ years, these stellar remnants are either drifting in the intergalactic space or sink into the supermassive BHs formed in the centers of galaxies
in 10⁴⁰ years, all remaining atomic matter will have disintegrated into radiation and subatomic particles
in 10¹⁰⁰ years, the only remaining objects (BHs) would have evaporated by Hawking radiation or quantum-tunneled into pure energy.