Astrophysics (Cosmology)

Question 1

What is the Big Bang Theory?

Answer 1

The Big Bang theory states that both space and time originated with the expansion from a singularity

Question 2

What is Cosmic Microwave Background (CMB) Radiation and how does it prove the Big Bang Theory?

Answer 2

• The early universe was in thermal equilibrium and the radiation from then had a black body spectrum, which has traveled through space
• as space has expanded, the wavelength decreased and became red-shifted.
• This reduces the temperature of the black body spectrum and the radiation should be visible from every point in space.
• The discovery of radiation that was equally everywhere in the universe also had the same wavelength that we would expect from these many years of red-shifting and cooling

Question 3

Cosmological Red-shift

Answer 3

Cosmological Red-shift is an increase in the wavelength of light due to the expansion of the universe which makes the source and the observer move relative to each other.

this was observed when the line spectra of distant galaxies were compared to the same elements from the Earth. It was shown that the light from distant galaxies had shifted to greater wavelengths

the shift is measured in a ratio (Z) of the change in wavelength over the original wavelength. it has no unit

Question 4

What is Hubble’s Law?

Answer 4

It describes Hubble’s observation, that for most lines in the spectra of other galaxies, the amount of Cosmological Red-shift was approximately proportional to the distance of the galaxy from us.
*Thus, the velocity is proportional to the distance.

Hubble’s law describes the speed at which celestial bodies move away from each other at the present time and changes because of the expansion of the universe if accelerating.