As we discussed earlier that the Big Bang theory provided answers to many curious questions of human beings and also helped to solve the mystery of the existence of universe, but there are other problems that are given birth to by this theory like the question: what triggered the early universe to expand?
Allan Guth, a scientist posed this question and provided a solution by stating that the early universe was activated by a matter which behaved very differently from all the known matter to humans on Earth. It is a rule that ordinary matter attracts the other matter towards itself through a force called, Gravity, which is why things fall to the ground. But the matter that Guth discussed behaves in opposition to the laws of gravity by repelling one matter away from the other. According to Guth, the early universe must have been filled with such repelling matter which compels all the surrounding matter to move apart from each other, thus causing expansion of the universe.
Now, according to the early theories about the expansion of the universe, all matter should have been equally distributed across the entire universe making it very smooth, yet this is not the case in reality. Our galaxies are the part of the universe which are made up of the clumps of hydrogen clouds containing massive energy and matter. To solve the problem of such uneven distribution of the matter, Stephen Hawking says, “My colleague Jerry Gibbinsons had earlier proposed that an inflating universe would contain thermal fluctuations which would be blowing as the universe expanded.” Therefore, in 1982, he devised a plan about how those thermal fluctuations could have provided means to create the galaxies.
Hawking along with his colleagues was not sure whether their theory was correct or not. In 2001, NASA launched an aircraft to survey the cosmic microwave radiation thrown out across the universe at its birth, in detail. If there were thermal fluctuations or ripples, as proposed by Hawking and his colleagues, they would be shown in images taken from that space craft. The proposition was proved by the images taken from that space craft. The images revealed that the red spots were the exact locations of the present day galaxies in our universe. The red spots distinguished the fluctuated thermal radiations in cosmos. Thus the problems put forth by the Big Bang theory were solved by Stephen Hawking to some extent.