BIG BANG  A-Z  For Layman

                                           - By Chirag Joshi.

main article......... continues !

If the Earth's orbit is known, then can be measured and X, the distance to the galaxy can be found using X = . Thus, this calculation could not be used alone to determine the enormous distance between our galaxy and the others, which would enable us to estimate the age of the universe. So scientists figured out that they could find the specific distance to the nearest galaxy moving away from the earth with the help of Hubble Telescope. They divided that distance by the amount of red shift of that galaxy, to show the time of the Big Bang.The formula is:

(Distance of a particular galaxy) / (that galaxy's velocity) = (time)
Or
(4.6 * 1024 m) / (1 * 107 m/sec) = 4.6 * 1017 sec

(LaRocco, Rothstein) 4.6 * 1017 sec is approximately 15 billion years. This calculation is almost exactly the same for every galaxy that can be studied (LaRocco, Rothstein).However, because of the uncertainties of the measurements produced by these equations, only a rough estimate of the true age of the universe can be produced.

So, what happened after the Big Bang? After the Big Bang happened, the universe was extremely hot, and particles were going away from each other in all directions. After 10 - 43s the universe began to cool down (LaRocco, Rothstein). As the universe expanded further, it cooled down more and began to form common particles. These particles are called baryons and include photons, neutrinos, electrons and quarks, all of which have become the building blocks of matter and life as we know it (LaRocco, Rothstein). During the "baryon genesis period", there were no recognizable heavy particles such as protons or neutrons, because of the still-intense heat. At that moment, there was only a quark soup (LaRocco, Ruthstein).

Between one and three minutes after the creation of the universe, the Big Bang theory suggests that protons and neutrons began to react with each other to form deuterium, an isotope of hydrogen. Deuterium, or heavy hydrogen, soon collected another neutron to form tritium (LaRocco, Rothstein). Rapidly following this reaction was the addition of another proton, which produced a helium nucleus (LaRocco, Rothstein). Scientists believe that there was one helium nucleus for every ten protons within the first three minutes of the universe. After further cooling, these excess protons captured an electron to create common hydrogen. Consequently, the universe today is observed to contain one helium atom for every ten or eleven atoms of hydrogen (LaRocco, Rothstein).

 It was not until 500,000 years later that the universe cooled enough so that hydrogen and helium could form even leaver elements by fusion processes (www.essays.cc). Our own sun fuses Hydrogen nuclei together to form Helium nuclei (www.essays.cc). Indeed, stars have the ability to carry out fusion processes on larger atoms than Hydrogen. The presences of heavy metal atoms have been detected within the solar atomic spectrum. Unfortunately, the fusion process takes huge temperatures and densities. The high temperature and densities create plasma where atoms have been stripped of their electrons. The fusion process produces very large amounts of thermal and radiant energy as a result of converting a very small amount of Hydrogen into Helium (www.essays.cc). Even back at the early universe's high temperature, it took another two billion years of cooling for enough clumps of interstellar dust and gas, called molecular clouds, to achieve stability in the universe (LaRocco, Rothstein). From these molecular clouds, stars were able to form due to compression of the material by gravitational forces.
 

In the core of a star, the fusion that takes place causes the stars to emit light, because fusion process produces very large amount of thermal and radiant energy. If the star is initially large enough, its death happens in the form of a supernova explosion. During this explosion, in less than one second, every element up to and including uranium is synthesized by fusion and dispersed into space (www.essays.cc).
As time passed in the universe and more and more supernovas exploded, the heavy element content as a whole increased, so new stars were more enriched.
 

The diagram below (LaRocco, Rothstein) shows that the particles were remarkably uniform at the time of the Big Bang, which illustrated the homogeneity of the early stages of the universe. However, NASA's Cobe satellite also discovered that as the universe began to cool and was still expanding, small fluctuations began to exist due to temperature differences (LaRocco, Rothstein). These fluctuations verified prior calculations of the possible cooling and development of the universe just fractions of a second after its creation. These fluctuations in the universe provided a more detailed description of the first moments after the Big Bang. The Big Bang theory provides a viable solution to one of the most pressing questions of all time. It is important to understand, however, that the theory itself is constantly being revised. As more observations are made and more research conducted, the Big Bang theory becomes more complete and our knowledge of the origins of the universe more substantial (LaRocco, Rothstein)

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Steady State Theory

The other theory of universe creation is the Steady State theory. Hermann Bondi, Thomas Gold, and Sir Fred Hoyle proposed it in 1948 (Wikipedia). They found the idea of a sudden beginning to the universe philosophically unsatisfactory because Bondi and Gold suggested that, "in order to understand the universe we needed to make observations of its distant parts, which would of necessity be observations from the past." In order to interpret those observations we must use the laws of physics, and those have been formulated at the present time (Wikipedia).
 

Hoyle approached the problem mathematically and tried to solve the problem of the creation of the matter seen all around us, which in the Big Bang theory is all created at the start. He proposed that the decrease in the density of the universe caused by its expansion is exactly balanced by the continuous creation of matter condensing into galaxies that take the place of the galaxies that have receded from the Milky Way, thereby maintaining forever the present appearance of the universe. In order to produce the matter, a reservoir of energy would be required. In order to prevent this reservoir being diluted by the creation of matter and by the expansion of the universe, he made this reservoir negative. The expansion and creation now work against each other and a Steady State of energy is maintained (Wikipedia).
 

The steady state theorists explain the hydrogen-helium abundance by the presence of supernovae. Originally the big bang theory suggested that all the heavy elements were produced at the start of the universe, but now it is accepted that only the helium and a little lithium was produced then and both theories now accept the role of supernovae in the creation of heavy elements.
 

Steady State is not without problems though. The discovery of quasars in 1966 provided evidence contradicting the Steady State theory (Wikipedia). Quasars are "very small but brilliantly luminous extragalactic systems, found only at great distances" (O'Donnell). Their light has taken several billion years to reach the earth. Quasars are therefore objects from the remote past, which indicates that a few billion years ago the constitution of the universe was very different than it is today. Most cosmologists, now no longer accept the Steady State theory particularly after the discovery of microwave background radiation in 1965, for which Steady State theory has no explanation (Wikipedia).
 

The question remains which of these theories is best suited to explain how our universe came to be. Most scientists accept the Big Bang theory. It makes sense that there should have been some incident happened that is making the universe still expand. As far as Big Bang theory says, there should be some big blast happened way back in time that making the universe expand.

Pg 3. Bibliography and Glossary     .