What do we mean when we say that the universe is expanding?
A)Within galaxies, average distances between star systems are increasing with time.
B)Everything in the universe is gradually growing in size.
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.

Question

Quizplus · Accepted Answer

When we say that the universe is expanding, we mean that the average distances between galaxies are increasing with time. This is supported by observations such as the redshift of light from distant galaxies, which indicates that they are moving away from us at increasing speeds.

What Do We Mean When We Say That the Universe