Early Theories
Different philosophers and scientists gave different hypotheses regarding the origin of the earth. Amongst those, one of the earlier and famous hypotheses was given by German philosopher Immanuel Kant. After that, it was revised in 1796 by a Laplace. His theory, known as the Nebular Hypothesis, argued that the sun was rotating slowly, and the formation of planets was associated with a cloud of material related to a youthful sun. Later, Chamberlain and Moulton in 1900 considered that a wandering star approached the sun. Consequently, a material was extended in cigar shape and got separated from the solar surface. With the moving of the passing star, that separated material from the solar surface continued to reviled around the sun and then got condensed slowly, forming the planets. This argument was also supported by Sir James Jeans and later Sir Harold Jeffrey. At a later date, the arguments considered a companion to the sun to have been coexisting, and these arguments are called binary theories.
Later, Otto Schmidt in Russia and Carl Weizascar in Germany revised the 'nebular hypothesis', in 1950. They argued that the sun was surrounded by a solar nebular containing mostly hydrogen, helium and dust. It also argued that a disk-shaped cloud wad formed due to the friction and collision of particles, and the planets were formed through the process of accretion. However, later scientists took up the problems of the origin of the entire universe and not just that of the earth or the planets.
Modern Theories
• The Big Bang Theory or Expanding universe hypothesis.
In 1920, Edwin Hubble provided evidence suggesting that the Universe is Expanding or we can say that the distance between the galaxies were found to be increasing, and as time crosses, galaxies will further move apart. According to the Big Bang Theory, there are following three stages in the development of the universe:
* First, at the very beginning, all the matter that universe existed in the form of a "tiny ball" (singular atom) at one place, which had infinite temperature and density, and an unimaginably small volume.
* Second, the "tiny ball" violently exploded at the Big Bang, which led to its huge expansion. Presently, the event of the Big Bang is widely accepted, and it is considered that it took place 13.7 billion years ago. Some energy was converted into matter, as it grew. Also, the rapid expansion occurred within fraction of a second after the bang, after which the expansion has slowed down. This first atom began to form, just within the first three minutes after the Big Bang event. Even presently, the expansion continues.
* Third, the temperature dropped to 4,500 K (Kelvin) within 300,000 years from the event of the Big Bang, and the atomic matter emerged. The universe became transparent, and its expansion, which means an increase in the space between the galaxies is evident. However, scientists believe that even though the distance between the galaxies is increasing, it is not supported by the observations that the expansion of galaxies is happening.
The Big Bang Singularity, and Expansion of the Universe...
You must be logged in to post a comment.