The Big Bang
The Big Bang
Dr. Zaghlool Najjar
In the Holy Quran we read:
"Haven't the unbelievers seen that the heavens and the earth were joined together (in one singularity), then we clove both of them asunder.” (21:30)
This verse reflects the unity of creation as a dominating factor in the orderly form of the universe throughout its evolutionary history from one stage to another.
However, long before discovering the established phenomenon of the red shift, and its logical consequence of describing our universe as an expanding one, scientists used Einstein's theory of general relativity to extrapolate back in time and came to the striking conclusion that the universe had actually emerged from a single, unbelievably small, dense, hot region (the Hot Big Bang Model of the universe).
Formation of the Universe
George Gamow formally proposed the model in 1948, after a lengthy discussion on other models of the universe by a number of scientists (e.g. Albert Einstein, 1917; William de Sitter, 1917; Alexander Friedmann, 1922; George Lemaiyre, 1927, etc.). Lemaitre is credited for introducing the idea of the "primeval atom", where galaxies originated as fragments ejected by the explosion of this atom.
In 1948, George Gamow modified Lemaitre's hypothesis into the "Big Bang theory" of the origin of the universe. In this theory, Gamow proposed that the universe was created in a gigantic explosion, whereby the various elements observed today were produced within the first few minutes after the Big Bang, as the extremely high temperature and density of the universe would fuse subatomic particles into the chemical elements.
More recent calculations indicate that hydrogen and helium were the primary products of the Big Bang, with heavier elements being produced later within stars. The extremely high density within the "primeval atom" would cause the universe to expand rapidly. As it expanded, the smoky cloud of hydrogen and helium thus formed would cool and condense into nebulae stars, galaxies, clusters, super clusters, black holes, etc.
This explains the original singularity of the universe; its explosion to a huge cloud of smoke from which the different heavenly bodies were formed by separation into eddies of various masses followed by condensation. The condensed bodies were arranged into stellar systems, clusters, galaxies, supergalaxies, etc., and the formed galaxies started to drift away from each other, causing the steady expansion of the universe.
The Glorious Quran describes these three successive stages in the verses (21: 30), (41: 11) and (21: 104). The first and the third of these verses are discussed above, while the second reads:
"Then He (Allah) turned to the sky while it was smoke, and ordered it the earth to come into being willingly or unwillingly, they answered: we do come in willing obedience*" (41: 11)
Big Bang Evidence
As the universe expanded, the residual radiation (radiant heat) from the big bang continued to spread outwardly and to cool down gradually until about the 3K (= - 270°C) of today. This relic radiation was detected by radio astronomy in 1964, thus providing direct material evidence for "The Big Bang Model".
Further evidence in support of this model is provided by the chemical composition of the observed universe. This amounts to about 74% hydrogen and 24 % helium (by mass), with only traces of other elements that in total amount to about 2%. All the recorded hydrogen in the observed universe and almost all the recorded helium are primordial, although some helium is currently produced by nuclear fusion of hydrogen in the sun as well as in other stars. Nevertheless, the total mass of hydrogen produced by the process of nuclear fusion within all the stars since the beginning of creation amounts to only a small percent.
It is calculated that when the universe was 3 minutes old, its temperature must have been 109 °C (cf. Ohanian, 1985, p. D-6). At such a high temperature, hydrogen was subject to nuclear fusion, leading to the formation of helium. Theoretical calculations show that the fusion reactions led to an abundance of about 75% hydrogen and 25% helium, which is a remarkable agreement with the observed abundance. This further confirms the Hot Big Bang model for the creation of the universe. The Hot Big Bang model has steadily and successfully battled other explanations for the origin of the universe, and the model has been gradually refined with time.
Hot to Cold
The "Hot Big Bang Model" for the origin of the universe envisages a beginning from an extremely small, hot, dense initial state some 10-15 billion years ago. This initial, minute body exploded and started to expand, forming the still expanding, vast, cold universe of today. The model predicts the formation of nuclei, the relative abundance of certain elements, and the existence and exact temperature of the cosmic microwave background radiation (or the glow of radiation left over from the initial explosion, which is currently permeating the universe).
The prediction of the cosmic background radiation made by Ralph A. Alpher of Union College and Robert Herman of the University of Texas at Austin was confirmed by Arno Penzias and Robert W. Wilson of Bell Laboratories in 1964.
Despite its success, the Hot Big Bang Model leaves many features of the universe unexplained. For example, the universe today includes a vast number of regions that could never have been in causal contact at any stage in their entire history. These regions are moving away from one another at such a rate that any information, even traveling at the speed of light, could not cover the distance between them. This "horizon problem" makes it difficult to account for the striking uniformity of the cosmic background radiation (cf. J.J. Halliwell, 1991, p. 76). Other unexplained features in the Hot Big Bang Model include the "flatness problem", the origin of large scale structures such as galaxies, galactic clusters and super clusters, etc.
The Inflationary Universe
In 1980, Alan H. Guth of M.I.T. suggested a further refinement of the Big Bang model that he called "the inflationary universe scenario". In this scenario, the universe is believed to have started with a very brief, but exceedingly rapid period of expansion (for about 10-30 second), in which matter consisted of scalar-field particles (white in the Hot Big Bang model, the matter ******* of the universe is presumed to have been a uniformly distributed plasma or dust).
As mentioned by J.J. Halliwell (1991), the origin of the universe in the inflationary scenario can be explained as follows: by following the expansion of the universe backward in time, the size of this vast, complex universe tends towards zero. Here the strength of the gravitational field and the energy density of matter tend towards infinity. This means that the universe appears to have emerged from a singularity; a region of infinite curvature and energy density at which the known laws of physics break down. These conditions are a consequence of the famous " singularity theorems", proved in 1960 by Stephen W. Hawking and Roger Penrose of the
The Big Bang
موضوع: The Big Bang
