Question

What is the evidence for an accelerating universe?

A) White-dwarf supernovae are the same brightness regardless of redshift.
B) White-dwarf supernovae are slightly brighter than expected for a coasting universe.
C) White-dwarf supernovae are slightly dimmer than expected for a coasting universe.
D) The Andromeda Galaxy is moving away from the Milky Way at an ever-increasing speed.
E) There is far more dark matter than visible matter in the universe

Answer 1

Type Ia supernovae are used as standard candles, and their observations showing them to be dimmer than expected indicate that the universe's expansion is accelerating over time.The correct answer is option C.

Step-by-step explanation:

The evidence for an accelerating universe primarily comes from observations of type Ia supernovae. These supernovae have been used as standard candles to measure cosmic distances because they have a known luminosity.

When astronomers observed these supernovae in distant galaxies, they discovered that the supernovae were slightly dimmer than expected for a coasting universe. This implies that the light from these explosions had to travel a greater distance to reach us, suggesting that the rate of the universe's expansion has increased over time.

Therefore, the correct answer to the student's question is C) White-dwarf supernovae are slightly dimmer than expected for a coasting universe.The correct answer is option C.