What is the universe made of?
The suprising fact is that we don't know.
Stars and gas
Stars and gas in the Galaxy (and in other galaxies) are made of
hydrogen (about 75%) and helium (about 25%) plus a small amount
(~1%) of heavier elements.
Is there anything else?
What could it be?
Davison E. Soper, Institute of Theoretical Science,
University of Oregon, Eugene OR 97403 USA