Welcome back, Spherical Cow Moonions!

This week we are continuing our journey through the history of the universe and discussing inflation and reheating. We will be talking about what inflation is, what are the motivations behind inflationary theory and what happened to the universe immediately after inflation.

Please see some additions/amendments to our discussion below:

3.30 - I misspoke here! The fluctuations are actually at a level of one part in 100,000 so they are even tinier than I suggested (but still very important which we will discuss next episode).

5.55 - I have found some contradictory values to how close the density of the universe was to the critical density in the early universe- some websites say it departed from the value by one part in 10^62 whilst others say the density right after the big bang must have been equal to the critical density to 50 decimal places! The main idea is that the initial density of the universe would have been incredibly fine-tuned to the critical density which is why physicists question how the density came so close to this 'special value'. Inflation suggests one solution to this 'fine-tuning' problem.

09.30 - According to inflation, because our whole observable universe was once a tiny part of the early universe, this tiny part was small enough for light to be able to propagate from one side to other, allowing the small section to reach the same temperature. You can say that this region is 'causally connected'.

11.45 - Once again I meant to say the the fluctuations are at a level of one part in 100,000 not 10,000!

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