Our Mathematical Universe: My Quest for the Ultimate Nature of Reality

by Max Tegmark

Dark matter clusters, dark energy doesn’t. Dark matter dilutes as it expands, dark energy doesn’t. Dark matter attracts, dark energy repels. Dark matter helps galaxies form, dark energy sabotages.

Observers living in parallel universes at Level I observe the exact same laws of physics as we do, but with different initial conditions than those in our Universe.

Quantum-Mechanics Cheat Sheet

Lack of wavefunction collapse implies Hugh Everett’s Level III multiverse