Across
- 4. gravitational, electromagnetic, nuclear strong and weak
- 5. of the same kind
- 8. if the density of the universe is less than the critical value
- 10. the universe was in an extremely high state of energy
Down
- 1. the speed that light travels
- 2. the atoms that were present become neutral and the radiation can flow through
- 3. the study of the universe
- 6. when matter was formed
- 7. how hot or cold something it
- 9. the SI base unit of temperature