Across
- 4. A model of the universe where the universe it totally flat and infinite.
- 6. A form of matter that acts in opposition to gravity
- 8. A model of the universe where the universe expands forever
- 9. The stage in the early history of the Universe when ultraviolet photons from the first stars ionized the gas filling space
- 10. Visible matter
- 12. The average density of matter required for the Universe to halt its expansion
- 13. The condition of being uniform in all directions
- 15. The stage within a million years of the big bang when the gas became transparent to radiation
- 16. The time required for the Universe to expand to its present size
Down
- 1. A cosmic structure formed by a giant wall of galaxies
- 2. The mysterious force that causes the rate of expansion of the universe to accelerate over time
- 3. A model of the universe where the universe is shaped like a ball
- 5. Leftover radiation from the Big Bang
- 7. Matter that does not contain protons and neutrons
- 11. They discovered cosmic microwave radiation
- 14. The property of being uniform