How does the theory of inflation explain the near-uniformity of the cosmic microwave background?
A) Prior to rapid inflation, all regions of space were close enough to bounce radiation back-and-forth and reach the same temperature.
B) Matter expanded into regions of space that had no matter, and thus ended up at the same temperature.
C) The expanding universe would have cooled.
D) Matter was near the critical-density for a universal collapse, which smoothed out the differences in temperatures.
Question 2
Place the following items in order of actual physical size, from smallest to largest.
A) planets and stars are about the same size, solar system, galaxy
B) star, planet, solar system, galaxy
C) star, planet, galaxy, solar system
D) planet, star, galaxy, solar system
E) planet, star, solar system, galaxy
