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.

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 of redshift in the light coming from distant galaxies, which indicates that they are moving away from us and from each other at increasing rates.

What Do We Mean When We Say That the Universe