The universe is made up of 2 types of matter: ___________ matter, which is made up of atoms, and _________ matter, which is not.

Question

Fritz Zwicky hypothesized that galaxies inside the Coma Cluster were being held intact by ___________.
Scientists believe that galaxies would break apart if ______________.

fill in the blank

Answer 1

1. Baryonic; dark
2. Dark matter
3. Dark matter
4. There wasn't enough visible mass to hold them together.