'In the early 1900s Willem de Sitter used relativity theory to suggest that the universe is doing this'
expanding
UNIVERSE: In the early 1900s Willem de Sitter used relativity theory to suggest that the universe is doing this
In the early 1900s Willem de Sitter used relativity theory to suggest that the universe is doing this
In the early 1900s Willem de Sitter used relativity theory to suggest that the universe is doing this
UNIVERSE
expanding
UNIVERSE