In this blog post, we will examine the origins of the universe from the perspectives of science and faith through the question, “If God created the universe, what can science prove?”
Humans have always wondered about their origins. Seeking answers in religion, the creationist theory that the universe was created by God has long been taken for granted, and it has only been recently that we began to observe the universe scientifically and predict its origins. Therefore, despite the Big Bang theory supporting modern cosmology, there are still many unknown substances and worlds in the universe, as well as unproven theories. However, in order to continue our efforts to uncover the origins of the universe, we must understand the theories that have been proposed thus far, and in order to derive new theories, we must understand the evolutionary process of existing theories. Therefore, I will explain existing theories in accordance with the major trends in the evolution of cosmology and discuss their limitations.
Until the 19th century, the dominant theory was that the universe was static and unchanging. Einstein believed that the universe was uniform and that its average density did not change over time. In other words, he claimed that the universe was in a state of stasis, neither contracting nor expanding. However, applying the gravitational field equation, it was calculated that the universe would contract due to its own mass, and Einstein attempted to explain the static universe theory by deriving the cosmological constant, a force opposite to gravity, from his general theory of relativity.
However, in 1929, Hubble’s law of cosmic expansion proved that the static universe theory was wrong, and Einstein admitted that the cosmological constant was the biggest mistake of his life. After the static universe theory was abolished, the era of the expanding universe theory began.
The expanding universe theory is broadly divided into the steady state theory and the big bang theory. The steady state theory is a theory that the universe maintains an average density and expands, existing eternally without a beginning or an end. In 1948, Fred Hoyle, Hermann Bondi, and others jointly proposed this theory, but it had a fatal contradiction. For the universe to expand while maintaining a constant density, new matter must be continuously created to fill the empty space, which contradicts the law of conservation of mass and energy. George Gamow pointed out this contradiction, and the steady state theory was abandoned in 1965 with the discovery of cosmic background radiation.
The Big Bang theory, which won the competition with the steady state theory, is also called the Big Bang theory, and was first proposed by Alexander Friedmann and Lemaître in the 1920s. They discovered the contradictions in the steady state theory and wrote a paper, but Einstein initially ignored them. After Hubble’s law of cosmic expansion was announced and the static universe theory was abolished, physicist George Gamow published a paper in 1946 proposing that the early universe was in a state of high temperature and high density before rapidly expanding, thereby systematizing the Big Bang theory. One of the pieces of evidence for the Big Bang theory is the cosmic microwave background radiation first observed by Penzias and Wilson in 1964. The early universe was in a state of extreme heat, with electrons existing as free electrons and scattering photons, causing the universe to be cloudy. About 400,000 years later, as the universe continued to expand, the temperature dropped to about 3000 K, and electrons were attracted to atomic nuclei to form atoms, and photons were finally freed and began to spread into space. The light that spread at that time is what we now observe as cosmic background radiation. Another piece of evidence is the amount of helium in the universe. The amount of helium in the universe is too large to be explained by hydrogen fusion within stars alone. This means that there was a time when the entire universe was hot enough to produce helium through hydrogen fusion. In other words, by proving that two deuterium nuclei combined to form a helium nucleus for about three minutes after the Big Bang, the existence of the Big Bang itself was proven.
The Big Bang process described in the Big Bang theory, which is currently accepted as scientific fact, is as follows. In the beginning, the universe was smaller than an atomic nucleus, and all the matter and energy that make up the current universe were compressed into an extremely high density and temperature. Then, with the Big Bang, the universe expanded rapidly and cooled down. During this process, matter began to appear, with the first particles being quarks and leptons. Quarks combined to form protons and neutrons, and antiparticles such as antiprotons and positrons were also created. One second after the Big Bang, neutrons, which are relatively heavier than protons, began to decay and become protons. Neutrons and protons combined through nuclear forces to form deuterium nuclei, and two deuterium nuclei combined to form helium nuclei. This process continued for about three minutes after the Big Bang, and the hydrogen and helium created at this time make up most of the matter in the universe today. After that, the universe was a chaotic mixture of various particles. Photons were bound to electrons and could not move freely, making the universe look like a murky soup. Approximately 380,000 years after the Big Bang, the temperature of the universe dropped to around 3,000 K, and electrons that had been unable to combine with atomic nuclei due to the high temperature were able to combine with atomic nuclei to form atoms, allowing photons to spread freely throughout space. The light that spread freely at this time is the cosmic background radiation that we observe today at a temperature of around 2.7 K.
Since then, matter has clumped together and combined to form nebulae, stars, galaxies, and other structures, creating the universe we live in today. Of course, the Big Bang theory cannot be said to be 100% accurate, and it is possible that an omnipotent god created the universe. However, as scientists, I believe it is wrong to conclude that the unknown is the work of God. We must continue to study and ponder endlessly, exploring the history of the universe from its beginning to the present, and strive to contribute to the future.
