Across
- 6. More stable particles called protons and ______________ started to form when the Universe was one second old.
- 7. Time, space and, ___________ all began with the Big Bang
- 8. After 300,000 years, the universe filled with ___________ of hydrogen and helium gas
Down
- 1. the Universe suddenly _________________ when it was born
- 2. As the Universe expanded and cooled, energy changed into ______________of matter and antimatter
- 3. before the Big Bang, the Universe was hotter and ____________ than anything we can imagine
- 4. The Universe started in a bubble thousands of times smaller than a _________________
- 5. In a fraction of a second, the Universe grew from smaller than a single _________ to bigger than a galaxy