How Was the Universe Born? This has been one of the oldest and most challenging questions in human history.
The Birth of the Big Bang Theory
The Big Bang theory proposes that the universe began from an incredibly small and dense point, followed by a powerful explosion. Time, space, and matter were created, then continuously expanded and cooled to form stars, galaxies, and other celestial bodies.
This theory was first suggested by physicist Georges Lemaitre in 1927. He formulated a mathematical model describing the origin and evolution of the universe based on Einstein’s theory of general relativity.
Initially, Georges Lemaitre’s theory wasn’t widely accepted and was even ridiculed by British physicist Fred Hoyle, who coined the term “Big Bang” sarcastically. Hoyle himself championed the steady-state cosmology, suggesting that the universe is eternal, unchanging, with no beginning or end.
However, in the 1950s, advancements in observational technology and new discoveries gradually provided more evidence and support for the Big Bang theory. One of the most crucial pieces of evidence was the cosmic microwave background radiation.
The Big Bang theory, often referred to as the Big Bang, is a prominent cosmological model that describes the early stages of the universe’s formation. Image: Zhihu
The cosmic microwave background radiation refers to the first light emitted about 380,000 years after the universe’s birth, which still permeates the entire cosmos 13.8 billion years later. It was first accidentally detected in 1964 by American physicists Arno Penzias and Robert Wilson. They used a radio telescope to detect faint noise coming from all directions in the sky.
After ruling out various sources of interference, they realized that the noise could be a form of radiation from the distant past. At the same time, American physicist Robert Henry Dicke and his colleagues were preparing to search for the existence of cosmic microwave background radiation using similar equipment. When they heard that Penzias and Wilson had discovered it, Dicke immediately contacted them and confirmed their discovery.
The Big Bang occurred approximately 13.8 billion years ago, making it the age of the universe. Image: Sciencealert
Penzias and Wilson went on to win the Nobel Prize in Physics in 1978 for their discovery of the cosmic microwave background radiation, while Dicke and his team missed out on the honor for not publishing their theory in time.
The discovery of the cosmic microwave background radiation stands as strong evidence for the Big Bang theory because it closely matches the temperature and frequency predicted by the theory. Moreover, it is evenly distributed across the sky, indicating high uniformity in the early universe. However, recent observations from the Webb Space Telescope have posed some challenges to this theory.
The cosmic microwave background radiation refers to the first light emitted about 380,000 years after the universe’s birth, and it still pervades the entire universe after 13.8 billion years. Image: Zhihu
What Did the Webb Space Telescope See?
According to the Big Bang theory, the universe was initially a uniform, high-temperature plasma with high density and no discernible structures or matter for the first few million years. As the universe cooled and expanded over time, small density fluctuations began to grow and amplify. These density fluctuations caused matter to clump together in some regions and become sparse in others.
This process led to the formation of regions where nuclei and electrons could combine to form neutral hydrogen atoms, known as the recombination era. During this time, there was no light source, and the universe was dark and transparent.
The recombination era ended around 13 billion years ago when the first generation of stars and galaxies began to form and emit intense ultraviolet radiation. During this period, stars and galaxies underwent rapid and complex evolution.
Theoretically, early galaxies should have the following characteristics: firstly, they should be irregular in shape, lacking distinct structures or clear rotational motion. Secondly, they should be dim and have low density due to the absence of heavy elements and dust. Lastly, they should be relatively small because matter was distributed unevenly, and gravitational forces were not uniform or stable.
However, the Webb Space Telescope has presented us with a completely different picture from what was expected. According to recent publications in journals including Nature, Science, and Acta Astronomica, the Webb Space Telescope has found something that doesn’t align with expectations.
Firstly, some galaxies appear to be exceptionally bright and dense, exceeding theoretical predictions. For instance, the Webb Space Telescope observed a galaxy approximately 13.2 billion light-years away, shining as brightly as 100 billion Suns, and denser than the Milky Way, making it one of the earliest and densest galaxies known.
Secondly, some galaxies exhibit well-defined spiral structures and flat disks instead of irregular shapes.
Moreover, the Webb Space Telescope has discovered over 1,000 primitive galaxies in an area about 13 billion light-years away, while theoretical simulations suggested there should be only a few dozen galaxies in this region.
These primitive galaxies constitute one of the largest and densest groups of pre-galaxies known. These findings have surprised and puzzled astronomers because they do not conform to what the Big Bang theory predicts.
According to the theory, these primitive galaxies should have remained in their original, chaotic state, rather than developing complex and mature characteristics. So, how did these primitive galaxies form and evolve? Did the Big Bang explosion truly occur?