The Big Bang Theory
The Big Bang model is a theory about the early development of the universe. The Big Bang theory says that the Universe was once in an extremely hot and dense state and this expanded rapidly (this is known as big bang). This Big Bang or the rapid expansion caused the young universe to start cooling down and resulted in the formation of the presently state of the universe. According to measurements, the Big Bang occurred about 13.7 billion years ago. The Big Bang theory was proposed by Georges Lemaitre. He called his theory "the hypothesis of the primeval atom". The basic framework of the model is completely relying on the Albert Einstein's theory of general relativity and also on certain simplifying assumptions.
In the year 1929 Edwin Hubble discovered the distances of galaxies which are far away were generally proportional to the value of their redshifts. This observation indicated that all distant galaxies and clusters have an apparent velocity which is away from a centre point. The farther the galaxy is, the higher is the apparent velocity. Thus it can be concluded that is the distance between the galaxies in increasing today, then in the past everything must have been close together. Large particle accelerators have been built in the past to conduct experiments in the conditions of high density and temperatures. The tests resulted in significant confirmation of the Big Bang theory. The term Big Bang was coined by Fred Hoyle in 1949 in a radio broadcast. After the cosmic microwave background radiation was discovered in 1964 and its spectrum was found to match that of the thermal radiations emanating from a black body, most of the scientists became quite convinced by the fact that something like the Big Bang must have occurred in the past and that would have resulted in the formation of the universe.
There are two major assumptions on which the Big Bang theory is based. One is the universality of the physical laws and the other is the cosmological principles. According to the cosmological principle the Universe is homogenous and isotropic (on a large scale). Initially these ideas were considered as postulates. But today efforts are being made to test both these assumptions and find evidences for them. For instance, strict tests have been conducted on general relativity and it has successfully passed them. The tests have been conducted on the scale of the solar system. Although, the scientific community was once divided over the truth of the Big Bang model but today scientists prefer the Big Bang model over several other cosmological models. A few features of the theory like inflation and baryogenesis are still under speculation. They contribute by explaining certain very important features of the Big Bang model but they can be replaced by certain alternative ideas. The alternative ideas when incorporated into the Big Bang model will not affect the rest of the theory. Some of the unsolved problems of physics include discovering the exact and the accurate explanation for these phenomenon.
In the year 1929 Edwin Hubble discovered the distances of galaxies which are far away were generally proportional to the value of their redshifts. This observation indicated that all distant galaxies and clusters have an apparent velocity which is away from a centre point. The farther the galaxy is, the higher is the apparent velocity. Thus it can be concluded that is the distance between the galaxies in increasing today, then in the past everything must have been close together. Large particle accelerators have been built in the past to conduct experiments in the conditions of high density and temperatures. The tests resulted in significant confirmation of the Big Bang theory. The term Big Bang was coined by Fred Hoyle in 1949 in a radio broadcast. After the cosmic microwave background radiation was discovered in 1964 and its spectrum was found to match that of the thermal radiations emanating from a black body, most of the scientists became quite convinced by the fact that something like the Big Bang must have occurred in the past and that would have resulted in the formation of the universe.
There are two major assumptions on which the Big Bang theory is based. One is the universality of the physical laws and the other is the cosmological principles. According to the cosmological principle the Universe is homogenous and isotropic (on a large scale). Initially these ideas were considered as postulates. But today efforts are being made to test both these assumptions and find evidences for them. For instance, strict tests have been conducted on general relativity and it has successfully passed them. The tests have been conducted on the scale of the solar system. Although, the scientific community was once divided over the truth of the Big Bang model but today scientists prefer the Big Bang model over several other cosmological models. A few features of the theory like inflation and baryogenesis are still under speculation. They contribute by explaining certain very important features of the Big Bang model but they can be replaced by certain alternative ideas. The alternative ideas when incorporated into the Big Bang model will not affect the rest of the theory. Some of the unsolved problems of physics include discovering the exact and the accurate explanation for these phenomenon.
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