The Beginning of the Universe - Big Bang Theory
General relativity, which Albert Einstein devised in the early 20th century, called for a static world, meaning that it was neither expanding nor contracting. However, Georges Lemaître, a Roman Catholic priest, discovered that Einstein's theory could be worded to show that the cosmos was expanding and that it started as a "primordial atom." Soon later, American astronomer Edwin Hubble saw that faraway galaxies were moving away from the planet while using a cutting-edge telescope. This demonstrated both the expansion of the universe and, implicitly, its creation.
This new idea, which Hoyle helped popularize as the "Big Bang theory," was contested by atheist cosmologist Sir Fred Hoyle in the middle of the 20th century.
The following is how NASA scientist for many years Robert Jastrow explained this development.
The narrative comes to an unfortunate end for the scientist who has lived by his belief in the validity of reason. As he pushes himself over the last rock to reach the highest peak after scaling the mountains of ignorance, he is met by a group of theologians who have been sitting there for generations.
What is dark energy?
The unknown component responsible for our universe's pace of expansion accelerating over time rather than slowing down is known as dark energy. That goes against what one may anticipate for a cosmos that was created in a Big Bang. In the 20th century, astronomers discovered that the universe is expanding. They believed that the expansion may either last forever or, if the cosmos had enough mass and self-gravity, would ultimately reverse and result in a Big Crunch. It has since developed in early 21st century cosmology. We now perceive the cosmos to be expanding more quickly than it did billions of years ago. What may be accelerating the rate of expansion?
The first hint that a ground-breaking discovery was about to be made occurred in 1998 while examining Type 1A supernovae. Because they always emit the same amount of light, these enormous explosions of dying huge stars are incredibly helpful to astronomers because they can be used as "standard candles" to determine distances in the cosmos. This concept is pretty basic. Think of the nighttime fireflies: they all have the same intrinsic brilliance. You can determine their distance by calculating how bright they appear in relation to where you are.
Two multinational teams of astronomers, including Australian Brian Schmidt and Americans Adam Riess and Saul Perlmutter, conducted the survey in 1998. Their goal was to determine the Hubble Constant, or the distance between Type 1A supernovae, using eight telescopes located around the world (although in reality, as the rate of expansion of the universe varies with time, it is technically not a constant).
The survey's results were startling. They were far further away and much fainter than they should have been for distant supernovae that detonated when the cosmos was just 2/3 the age it is now. This implied that, if existing theories were accurate, the cosmos had grown considerably more quickly than it should have.
The discoveries were first received with much suspicion in the astronomical community, but the observations were quickly repeated by other teams and various techniques. By the turn of the 2000, it was evident that the universe's expansion is not slowing down as previously thought. In fact, it is speeding up.
Even stranger, until seven or eight billion years after the Big Bang, the expansion had been decelerating as one would anticipate. The expansion was initially being restrained by gravity, but for reasons that are yet unknown, a mystery "anti-gravity force" began to take control and overcame this restraint. As a result, the expansion reversed its slowness and began to speed.
The qualities of this unusual dark energy appear to match Einstein's cosmological constant, also known as his fudge factor and afterwards referred to by Einstein himself as the biggest professional failure of his life, which only serves to deepen the enigma. Einstein preferred the static cosmos proposed by steady-state cosmology, which was prominent in the early 20th century. He despised the concept of an expanding universe. In order to stop the cosmos from expanding as it is currently viewed, he created an anti-gravity force whose origin is unknown. Later on, Einstein withdrew this hypothesis since it was not confirmed by evidence.
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