Practice Questions

1.What is the age of the universe?

14 billion years

2. Describe the big bang theory

It states that the universe started as as single concentrated point, then an explosion sent energy and matter outwards. Even today, this matter is moving outwards, so the universe is currently expanding. This means that galaxies are moving further away from us and from each other, causing the universe to expand. 

3. State two pieces of evidence that will support the big bang theory.

1. Qualitative red-shift of light from galaxies that are receding

• When galaxies move away from us, the light they emit is red-shifted.

• This means the light’s wavelength is stretched, so it shifts towards the red end of the spectrum.

• The faster a galaxy moves away, the greater the red-shift.

2. Galaxies’ speed vs distance = evidence of an expanding universe

• Observations show that more distant galaxies have a larger red-shift, meaning they’re moving away faster.

• This shows that space is expanding in all directions.

• It suggests that the universe is getting bigger, like a balloon inflating.

3. How red-shift provides evidence for the Big Bang

• Since galaxies are moving away from each other, they must have once been closer together.

• Red-shift shows the universe is expanding, so in the past, it was small, hot, and dense.

• This supports the Big Bang theory, which says the universe began from a single point and has been expanding ever since.

4. 1998 supernova observations and how scientists develop theories

• In 1998, astronomers studied the light from distant supernovae (exploding stars).

• These supernovae were dimmer than expected, which meant they were farther away than they should have been if the universe’s expansion was slowing down.

• This showed the expansion of the universe is speeding up — it’s accelerating.

• Scientists used this evidence to improve the Big Bang model by including something called dark energy, which may be causing this acceleration.

• This shows how new observations help scientists develop and refine theories over time.