What do we mean when we say that the universe is expanding?
A. Everything in the universe is gradually growing in size.
B. Within galaxies, average distances between star systems are increasing with time.
C. The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing.
D. Average distances between galaxies are increasing with time.
Answer:D
What do we mean when we say that the universe is expanding?
A. Everything in the universe is gradually growing in size. B. Within galaxies, average distances between star systems are increasing with time. C. The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing. D. Average distances between galaxies are increasing with time.