Big Bang

Question 1

State Big Bang theory

Answer 1

universe began from one point – a singularity that was infinitely small and infinitely hot and has been expanding ever since.

Question 2

CMBR

Answer 2

microwave radiation that has been detected from all directions in space. This provides evidence
for the Big Bang

Question 3

Explain CMBR

Answer 3

When the Big Bang happened, it is thought that there was high-energy radiation everywhere, and as the universe expanded and cooled, this radiation would have lost energy and been red-shifted. The remains of this radiation is what we call Cosmological Microwave Background Radiation (CMBR)

• CMBR has a black body distribution with a peak that corresponds to a temperature of 2.7K

Question 4

How is the relative abundance of
Hydrogen and Helium used as evidence
for the Big Bang? (4)

Answer 4

• During the Big Bang, Hydrogen was converted into Helium
  via nuclear fusion.
• The expansion of the universe caused it to
  cool, meaning it was no longer hot enough to fuse elements.
• About ¼ of all Hydrogen was converted into Helium, resulting
  in a ratio of H:He of 3:1.
• The observed distribution of matter
  now is 73% hydrogen, 25% helium and 2% everything else,
  which follows the predicted ratio.