Across
- 3. A physical substance that occupies space
- 7. A system of stars held together by gravity
- 8. A repulsive force that counteracts gravity
- 9. The continuous stretching of space itself
- 10. Distant galaxies are moving away faster
Down
- 1. Invisible, unknown form of matter
- 2. Expansion will make universe cold and empty
- 4. All matter will go back to a singularity
- 5. An invisible force of attraction
- 6. Violent expansion will tear apart matter