What the Physics!?

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Across
  1. 1. Atoms
  2. 5. Particles
  3. 8. Atomic Nuclei
Down
  1. 2. Planets, projectiles, and machines
  2. 3. Cellphone, light bulb
  3. 4. Heat
  4. 6. Space and time
  5. 7. Light bulb, telescope