Strange, considering that it started with the huge explosion of the “Big Bang”… “The biggest problem in the universe” was born from a simple question (Katsuhiko Sato) | Bluepack | Kodansha (1/2)

How did the universe begin?

This is a difficult problem that many physicists have addressed. The Big Bang theory, which states that the world began with a fireball, is famous, but many things are still not fully understood.

The “inflation theory” has been proposed. In this series, a world-renowned expert on inflation theory explains its essence in an easy-to-understand way. Introducing the wisdom of physics that approaches the secrets of the creation of the universe.

*This article was written by Katsuhiko Sato.Inflationary cosmology: what happened before the big bang?This is an excerpt and re-edited version of (Bluebacks).

A difficult problem that the Big Bang Theory cannot solve

– I don't know why, but the universe was born as a ball of fire. As it expanded, the temperature gradually decreased, gas solidified, stars were born, galaxies and galaxy clusters formed, and the diverse and beautiful universe we see today was formed.

This is an overview of the Big Bang Theory. The Big Bang theory has been supported by actual observations. Although this is true, there are actually some difficult problems with this theory. In this article, we'll look at that first.

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First of all, we have no choice but to believe that the universe began at a singularity. The singularity is the point where the laws of physics break down, where the density is infinite and the temperature is infinite. The fact that the universe is expanding means that if you trace back time, the universe will become smaller and smaller, and the energy density will become higher and higher. If the universe began at some point, the energy density would eventually reach infinity.

In other words, we have no choice but to believe that the beginning of the universe was the point at which physics broke down. In Christendom it is called the “stroke of God,” and unless we come up with a concept that transcends physics, the universe will not begin. You might think it's arrogant, but physicists want to talk about creating the universe using only the laws of physics, without relying on the power of God. However, the Big Bang Theory alone cannot do this.

Second, the Big Bang theory does not answer why the universe became a ball of fire. This does not explain why the early universe turned into a ball of fire. It can be said that this does not explain the beginning of the universe.

Another problem is that the Big Bang theory cannot explain the origin of the current structure of the universe. When the size of the universe was very small, there was a slight variation in density called “density fluctuations”, which later led to the solidification of gas mainly in regions of high concentration, and the formation of stars, galaxies and galaxy clusters. It is believed that such an unevenness was created by the structure. However, the Big Bang theory can only create very small fluctuations, making it theoretically difficult to create the kind of shadowing that could become the seeds of galaxies and galaxy clusters in the early universe.