What is cosmic inflation? How does inflation solve the horizon problem? What is the flatness problem?© BrainMass Inc. brainmass.com October 4, 2022, 1:14 pm ad1c9bdddf
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What is Cosmic Inflation?
Cosmic inflation is also known as the Inflation Theory which says that shortly after the universe came into existence, it expanded very rapidly. This relates directly to the Big Bang Theory. From nothing, or singularity, an explosion occurred, and from that point, all matter expanded - or like a balloon, inflated and is still moving away from the original point of creation. Imagine dropping a stone or rock in the middle of a very calm lake - from the point where the rock entered the water, you get a round ring, or wave, moving away from the center. However, in the universe, there are no boundaries to stop this expansion outward. This is cosmic inflation.
The Horizon Problem
First, the Universe is estimated to be about 14 billion years old. We measure distance on the Universal scale in terms of how fast light travels due to the vast size of the Universe so these distances would be light years. With the Universe being 14 billion years old, it would make sense that the farthest we can see from where we are is 14 billion light years away. In another billion years, if anyone is still living, we would be able to see 15 billion light years away. But, right now, if there is anything farther away, the light hasn't had time to get to us yet. So when we look at the night sky in the East, we see 14 billion light years in that direction, and when we look at the night sky in the West, we see 14 billion light years in that direction. The Horizon Problem is no matter which direction we look, the cosmic microwave background radiation (CMBR) is almost exactly the same temperature everywhere we look. So it would make sense that, like an oven, the temperature in one part of the Universe has had time to radiate and warm up another part of the Universe. The problem being that the farthest point to the west is 14 billion light years from us, and the farthest point to the east if 14 billion light years from us, meaning these two points are 28 billion light years apart. With the Universe only 14 billion years old, there hasn't been enough time for heat to travel from one side to the other - at most it could only radiate or travel half way if it were moving at the speed of light. So, the theory of Cosmic Inflation explains this because if everything started at one singular point and expanded rapidly from that point, it would make sense that everything started at the same temperature, and expanded staying at that same temperature.
The Flatness Problem
When we say the Universe is flat, we're not talking like a flat, two dimensional piece of paper - think more of a balloon. When it's deflated, it has wrinkles and irregularities, but as it expands, as in cosmic inflation does with the Universe, the edges flatten out and irregularities smooth out as the balloon expands or inflates.