Across
- 1. anything that takes up space
- 3. Heat energy
- 6. When you forget something
- 7. An old rock of a living thing
- 10. around the world
Down
- 2. someone who studies human history
- 4. When something changes
- 5. theory A theory involving strings of the universe
- 8. to keep as small as possible
- 9. all the things that exist