5 days ago3 min read

Why the Theory of Inflation Enhances our Understanding of the Universe

Author: Rin Takahashi

Editors: Miriam Heikal and Justin Tai

Artist: Christina Chen

Around 13.8 billion years ago, elements, forces, stars, planets, and the universe were formed by The Big Bang. But what happened after that? According to the theory of inflation, a trillionth of a second after the Big Bang, the early universe expanded by a factor of 10^26–from the size of a single bacterium to the size of the Milky Way.

The Big Bang theory, first published in 1927, explained how the Universe was formed: a dense, single point that inflated and stretched. This theory accounts for the Cosmic Microwave Background (CMB) and the origin of light elements. The CMB explains how the universe was filled with radiation left over from the Big Bang. The origin of light elements explains that nucleosynthesis, also known as the creation of new atomic nuclei, was primarily driven by the Big Bang, producing light elements such as hydrogen, helium, and lithium.

However, the Big Bang theory has a significant flaw, as it doesn’t address some major questions of how the Earth was created. Around 1980, Alan Guth introduced the theory of Inflation as an extension of the Big Bang theory. This theory succeeded in answering three major questions that the theory of the Big Bang couldn’t: the horizon problem, the flatness problem, and the monopole problem.

First, it resolves the horizon problem of distant regions of the universe appearing to have similar temperatures. After the universe was formed, the CMB, which still exists in some regions, was released. However, scientists are still questioning why every location where the CMB exists has around the same temperature. The theory of inflation explains this: right after the Big Bang, the universe was tiny, allowing it to mix and equilibrate before rapidly expanding. This process resulted in similar temperatures in different regions.

Secondly, the theory of inflation addresses the flatness problem. When the total visible universe is measured, it is stated to be completely flat. This flatness is created when the universe is in perfect balance and it is at the critical density, the average density required to stop the universe from expanding. Additionally, the calculated mass density of Earth equals the critical density, indicating that the Earth is flat. During inflation, the universe expanded rapidly while maintaining its critical density, resulting in a flat surface. A similar effect is observed when a balloon inflates: the surface flattens as it expands.

Lastly, the theory of inflation answers the monopole problem, which states that if the early universe was scorching hot, many heavy, stable magnetic monopoles would have been produced. However, according to scientists, monopoles have not been observed throughout history. The Inflation theory suggests that during the rapid expansion following the Big Bang, all the magnetic monopoles created became widely dispersed, reducing their density in any observable region, making them difficult to recognize with today’s technology.

The theory of inflation arose as an expansion of the Big Bang theory, addressing many of the problems it introduced and providing a deeper understanding of how the universe was formed. Although some scientists don’t believe in the inflation theory due to the lack of direct evidence, ongoing research continues to support it. Perhaps a completely new theory, yet to be discovered, will ultimately solve the mystery of the universe.

Citations:

Chris Pattison. “Can We Explain Why the Universe Is so FLAT? | Inflation and the Flatness

Problem.” YouTube, 27 Sept. 2021, www.youtube.com/watch?v=l8UUlOOuF_g.

Accessed 22 Sept. 2024.

Griswold, Britt. “WMAP Big Bang Elements Test.” Nasa.gov, 16 Apr. 2010,

wmap.gsfc.nasa.gov/universe/bb_tests_ele.html. Accessed 22 Sept. 2024.

Howell, Elizabeth, and Andrew May. “What Is the Big Bang Theory?” Space.com, 26 July

2023, www.space.com/25126-big-bang-theory.html. Accessed 20 Sept. 2024.

NASA. “WMAP Big Bang CMB Test.” Nasa.gov, NASA, 20 Feb. 2024,

wmap.gsfc.nasa.gov/universe/bb_tests_cmb.html. Accessed 22 Sept. 2024.

published, Paul Sutter. “The Mystery of Magnetic Monopoles.” Space.com, 13 June 2018,

www.space.com/40868-where-are-all-the-magnetic-monopoles.html. Accessed 24 Sept.