Assertion: universe's matter | /r/MadeOf | proton
Facets:
Source sentences:
text: After all the black holes have evaporated (and after all the ordinary matter made of protons has disintegrated, if protons are unstable), the universe will be nearly empty.
text: The elements – that is, ordinary (baryonic) matter made of protons, neutrons, and electrons, are only a small part of the content of the Universe.