Across
- 2. the degree or intensity of heat present in a substance or object
- 4. speed of light
- 5. nonluminous material that is postulated to exist in space
- 9. the average density of matter required for the Universe to just halt its expansion, but only after an infinite time
- 10. having a physical property which has the same value when measured in different directions
- 12. early time of the universe
- 15. a particle representing a quantum of light or other electromagnetic radiation
Down
- 1. a change in frequency due to the Doppler effect
- 3. the era that started when the gravitational effect of matter began to dominate the effect of radiation pressure
- 6. molecules formed by atoms consisting of antiprotons, antineutrons, and positrons
- 7. the SI base unit of thermodynamic temperature
- 8. the negatively charged antiparticle of a proton
- 11. of the same kind, alike
- 13. a source of nuclear energy
- 14. the origin and development of the universe