[Book Sip] Why Is the Universe Born from the Big Bang Dark?

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The universe is known to have been born 13.8 billion years ago from the Big Bang. The various changes that occurred in the universe immediately after the Big Bang have long been a subject of interest for scientists. This book captures the struggles of scientists trying to explain the moments right after the Big Bang. It is an effort to find answers in an unknown world. Although the discovery that the universe is expanding was made through Einstein’s theory of relativity, the question of why remains unanswered. Dark matter and dark energy, which make up 95% of the universe, also remain in the realm of the unknown. The author seeks those answers and explains the broad flow of cosmology in simple language.

Through this book, I will guide readers on a journey to the first moments of our universe. Starting from Einstein’s revolutionary insight into the nature of time and space, we will examine how this idea led to the discovery of the Big Bang?the hot and dense state from which the universe was born. I will also do my best to explain the process of exploring the early history of our universe using various instruments, from telescopes to particle accelerators. Based on this, we will focus on the puzzles, mysteries, and unresolved problems that make the first fractions of a second of our universe chaotic. How did our universe come to have so much matter and so little antimatter? How could dark matter have formed? How and why did our universe experience a brief period of rapid expansion? And is this related to the fact that our universe is once again accelerating its expansion today? - p.24~25

However, 20th-century physicists realized that time and space are neither simple nor straightforward. Unlike Aristotle, Galileo, and Newton, we now understand that time and space can change and evolve, take shape, expand, and deform. Time and space can expand, contract, twist, curl, break, bend, swell, and even begin or cease to exist. Newton and Galileo could never have imagined using such vocabulary to describe space or time. Yet cosmology is built precisely on these dynamic and living characteristics of time and space. - p.36

Before Einstein, the universe was seen as a perfect, unchanging entity forever. But if the universe can change, then it must have had a beginning, and perhaps an end. Whether intended or not, Einstein gave humanity the challenge of contemplating the origin and history of the universe. - p.52

Hubble’s discovery that galaxies are moving away from us at speeds proportional to their distance provided clear evidence that our universe is expanding and changing over time. This fact carries a profound implication. Something capable of change?such as our universe?cannot be permanent or eternal. And what is not eternal must have had a beginning. It was inevitable that scientists would begin to ask about the origin of our universe. - p.83

To understand the very first moments of our universe, we also use machines that recreate the physical conditions of the distant past. These machines are not refrigerators. In fact, they are the exact opposite. Using particle accelerators, we reproduce the temperature of the ultra-early universe just one trillionth of a second after the Big Bang to study how matter and energy behave. Since we cannot travel back in time to witness the first moments of cosmic history directly, we recreate a miniature version of the Big Bang here on Earth. - p.108~109

Because of this relationship between matter and antimatter, understanding the world around us becomes difficult. If our universe was once filled with matter and antimatter, and matter and antimatter are always created and destroyed together, we cannot help but ask ourselves: How did this world come to be filled almost entirely with matter, with antimatter nearly vanished? Where did all the antimatter go? And why did matter not disappear along with antimatter? - p.139~140

We still do not know what dark matter is or what it is made of, but it is highly likely that it was created in the first moments of the universe, probably within the first one-millionth of a second after the Big Bang. Understanding dark matter will reveal not only the nature of dark matter itself but also the very early moments of our universe. Research on dark matter is, in essence, research on the origin of this world. - p.169~170

One might look in many places, but the most likely place appears to be the center of our galaxy. Through top-level observations and computer simulations, it has been found that the dark matter density near the center of our galaxy is quite high. Therefore, it was expected that dark matter particles there would interact and annihilate at very high speeds, producing enormous amounts of gamma rays during the annihilation process. - p.202

The results from the LHC have shaken particle physics to its core. In the late 20th century, theoretical particle physicists successfully predicted several particles, which were subsequently discovered in increasingly powerful accelerators. It was a truly impressive series of successes. However, our insight seems to be reaching its limits. Particles predicted long ago in connection with supersymmetry stubbornly remain hidden. Perhaps supersymmetry or something similar is within reach, and our confidence may soon be restored. But for now, it is fair to say that we do not understand how to solve the hierarchy problem, how to complete the Standard Model, or how dark matter fits into the quantum structure of our universe. - p.231~232

Nothing can travel faster than the speed of light through space, but space itself is not bound by this constraint. The speed at which points separated in space move away from each other due to the expansion of space can be any value. As a result, light or signals we send will never reach these distant galaxies. Likewise, signals sent from inhabitants of those distant galaxies will never reach us. Because of the continuous expansion of space, we can never communicate with, see, or contact those distant places in any way. They are completely disconnected from our observations, and we have no influence over them. - p.250

As cosmology advances, there are increasing reasons to consider the existence of other universes. Many of these universes may be very different from ours, while some may be quite similar. Either way, I am talking about worlds completely separate from the region we can experience. Worlds that cannot be reached even by the most powerful telescopes. - p.283

Fortunately, there remains much other information about our universe that we have yet to access. The cosmic microwave background was formed at a specific moment in cosmic history?about 380,000 years after the Big Bang?when the charged nuclei and electrons filling our universe mostly transitioned into neutral atoms. Since this transition, neutral atoms have been emitting various kinds of light. The light emitted by this atomic gas of the universe is the most powerful tool for the next generation of cosmologists to study our universe and its first moments. - p.338

The First Moments of Our Universe | Written by Dan Hooper | Translated by Bae Ji-eun | Haenamu | 348 pages | 18,000 KRW