Big bang

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Across
  1. 3. leftover energy
  2. 8. one of first elements to form again
  3. 9. all existing matter
  4. 10. one of the first elements to form
Down
  1. 1. a way to measure waves
  2. 2. what are protons and neutrons
  3. 4. waves toward us
  4. 5. set of facts
  5. 6. silent explosion
  6. 7. waves moving away us