Universe's Expansion and Dark Energy

The video explains the expansion of the universe, highlighting how galaxies appear to move away due to increasing distances, not actual movement. It discusses the Big Bang as the origin of this expansion and the role of gravity, which was expected to slow it down. However, the discovery of accelerating expansion in 1998, attributed to dark energy, changed our understanding. This suggests the universe will continue expanding indefinitely, ruling out the possibility of a 'big crunch'.

What is the primary reason galaxies appear to move away from us?

• Galaxies are physically moving away.

• The space between galaxies is expanding.

• Galaxies are shrinking.

• The light from galaxies is getting dimmer.

What does the term 'redshift' refer to in the context of the universe?

• The color change of stars.

• The cooling of the universe.

• The stretching of light waves as galaxies move away.

• The shrinking of galaxies.

What was the initial expectation about the universe's expansion after the Big Bang?

• It would reverse direction.

• It would stop immediately.

• It would slow down over time.

• It would continue to accelerate.

How does gravity affect the expansion of the universe according to initial theories?

• It accelerates the expansion.

• It has no effect.

• It reverses the expansion.

• It slows down the expansion.

What significant discovery did astronomers make in 1998 about the universe?

• The universe is cooling rapidly.

• The universe is static.

• The universe is contracting.

• The universe's expansion is accelerating.

What is the term used to describe the force causing the accelerated expansion of the universe?

• Dark energy

• Gravitational pull

• Cosmic wind

• Dark matter

What does the concept of dark energy challenge in our understanding of the universe?

• The existence of galaxies.

• The speed of light.

• The size of the universe.

• The role of gravity in the universe.

What are the two possibilities for the universe's future discussed before the discovery of accelerated expansion?

• Big freeze and big rip

• Big crunch and eternal expansion

• Static universe and shrinking universe

• Collapsing universe and expanding universe

What does the discovery of accelerated expansion suggest about the universe's future?

• It will keep expanding indefinitely.

• It will become static.

• It will eventually stop expanding.

• It will collapse into a big crunch.

What was the expected outcome if there was enough matter in the universe?

• The universe would expand forever.

• The universe would collapse into a big crunch.

• The universe would shrink.

• The universe would become static.