Inflation is one of the leading theories explaining the structure of the cosmos, first proposed in 1979 by Alan Guth as a major refinement of the Big Bang theory. In this post, I will explore the basics of inflation as well as how it resolves some problems with the Big Bang theory.

The basics

Cosmological inflation proposes that between 10−36 and 10−33/32 seconds after the Big Bang singularity, there was an inflationary epoch wherein the universe underwent an immense, exponential expansion of gargantuan scale. In a trillionth of a trillionth of a second, the universe expanded more rapidly than the speed of light itself- this does not violate Einstein’s dictum that light-speed is the universal speed limit, however, because it is empty space …show more content…
As previously mentioned, this does not violate the light speed barrier, despite seeming to do so at first glance. Einstein’s special relativity does indeed inhibit objects from moving faster than light in local reference frames, where curved spacetime can be treated as flat and unchanging (much like how Earth’s horizon can appear flat, since it is curved on an immense scale). However, for instances where spacetime curvature is large enough to be relevant, special relativity ceases to apply and instead general relativity comes into play. This allows object separation to increase faster than the speed of light.

Relative to inflation theory, metric cosmic expansion is postulated to have been caused by a quantum field. A field having triggered cosmic inflation would solve the problem of how, in order for our universe to exist as it does at present, the initial conditions during the Big Bang would have had to be very fine-tuned and contrived- this is wholly unrealistic, and not very scientific. Conversely, this theorised quantum field would be what is known as a scalar field that assigns a value to every point in space, driving inflation and allowing the universe to flourish. It has been creatively dubbed an …show more content…
Inflation was first proposed since it remedied the following problems pertaining to the Big Bang theory:

The flatness problem

The universe’s geometry has been experimentally confirmed by the WMAP satellite to be nearly flat. However, the Big Bang predicted that as time progresses, curvature should increase, not flatten. Therefore, for our universe to be as flat as we know it to be today, an extreme fine-tuning of initial conditions must have necessarily taken place- but this is far too large a coincidence to postulate.

Inflation resolves this, since the period of accelerated expansion it conjectures stretches the curvature of our universe to near flatness, as visualised by WMAP.

The horizon problem

The uniformity of the cosmic microwave background radiation’s temperature indicates that all regions of the universe must have been in contact with each other at some point in history. However, if following the Big Bang model, there are regions of space in the sky which are so far apart that it is impossible for them to have been in contact. The time taken for light to have travelled between these spots is higher than the universe’s age itself, which makes no