Inflation

To solve several important issues in cosmology, in 1981, cosmologists introduced the theory of inflation, suggesting that the early Universe expanded exponentially fast for a fraction of a second after the Big Bang. One of these issues in cosmology is the horizon problem.

Let us assume that the universe is in fact not expanding, and imagine 2 photons were released early in the universe at the same time, one freely traveling until it hit the North Pole, and one hitting the South Pole. The two photons couldn't exchange information from the time they were released due to the time that would be required to successfully send the information from these two photons. One photon would be two times the age of the universe. They would be outside if each other's horizon. However we see that the photons must have communicated somehow because of the Cosmic Microwave Background Radiation. (CMBR)

The CMBR has close to having exactly the same temertaure in all directions over the sky. We can solve this problem by the theory of inflation. Regions we have today are widely separated were closer together in the early universe and this would explain why protons from these regions have close to exaclty the same temprature.

One of the examples we learned about in class to represent a model of the expansion of our universe was the balloon analogy. A person at any point on the balloon might consider themselves to be at the centre of the expansion, as all other points on the balloon are getting further away which represents the planets and galaxies.

So pretty!