Post Big Bang Term Paper

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Big Bang and the Evolution

Of The Universe

One of the most important questions posed by astronomers and cosmologists revolves around exactly how the universe was created and although most lay persons think that the universe is infinite with no beginning and no end, this viewpoint has been shown to be inaccurate, due to many advances in the science of cosmology over the last ten years or so based upon the conception of the Big Bang which forced scientists to view the creation of the universe as a "finite phenomenon, possessing a history and a beginning" (La Rocco & Rothstein 2007, Internet).

This conception of the Big Bang, a term first coined by astronomer Fred Hoyle in 1950 and defined as a cosmology in which the universe expanded into being from a dense state at a finite time in the distant past, is often described as a type of explosion which occurred some 15 billion years ago; however, this was not "a conventional explosion but rather an event filling all of space with all of the particles of the embryonic universe rushing away from each other" which in essence laid "the foundations of the universe" as it currently exists in space and time (La Rocco & Rothstein 2007, Internet).

As most cosmologists now agree, the universe is indeed expanding, but in order to understand the direction of its history, we must look far into the very distant past to find evidence that the universe emerged from a small, dense state, one that appears to have originally had zero size. It is this apparent beginning that has come to be known as the Big Bang which can also be viewed as a cosmic supermarket in which all of the elements and particles that now exist in the universe were created and allowed to escape into the void of space. For most cosmologists, the knowledge imparted by elementary particle physicists provides an account on exactly how matter and radiation behave at very high temperatures so that the distant past of the universe can be reconstructed as close as possible to its apparent beginning via the Big Bang.

In the late 1970's, the study of the most elementary particles of matter became connected with the sciences of astronomy and cosmology, a good example being the "symbiotic relationship between cosmology and the study of elementary particle physics provided by the conjunction of high precision experiments" at the European Center for Nuclear Research in Geneva, Switzerland, and cosmological theories on nuclear reactions which occurred only seconds after the Big Bang (Sullivan 2004, p.167). These two approaches have revealed a myriad variety of an elemental particles known as neutrinos, "ghostly particles which interact so weakly with every other form of matter that they are extremely hard to detect," even though they pass through the bodies of every human being every single second (Sullivan 2004, p.168).

In essence, cosmologists are now quite convinced that there were three varieties of neutrinos which served as the impetus for the Big Bang in the first few seconds of its existence and it is important to know of these varieties of neutrinos as they exist in nature, due to fixing the total density of radiation and matter during the very early phases of the universe following the Big Bang. During this time, the expanding universe was hot enough for nuclear reactions to create the lightest elements, such as hydrogen and helium, by the fusing of neutrons and protons in various chemical combinations.

At earlier times, such as milli-seconds before the Big Bang, the temperature of the universe was so high that all elements heavier than hydrogen "were broken up as soon as they were formed," and during the first ten seconds or so, the build-up of light elements was slow due to breakups but then climaxed "in a frantic rush of nuclear activity after perhaps a hundred seconds" before being quickly shut down by falling temperatures and density (Sullivan 2004, p.172).

The essential outcomes of these nuclear reactions is all dependent upon knowing the relative number of protons and neutrons which will help to determine the number of nuclei that arise, such as deuterium, "an isotope of hydrogen," helium and lithium. Thus, when the universe was younger than single second old after the Big Bang, the number of protons and neutrons would exist in equal number, due to the "interactions between them which essentially replicates one another and maintains an equal balance. But after the Big Bang, perhaps less than one second later, "the rate of expansion became too large for weak interactions to maintain perfect proton-neutron equilibrium" (Sullivan 2004, p.173).

In recent years, astronomers and cosmologists have made very extensive observations via highly-technical computer-based instrumentation to confirm the existence of these elements in great abundance throughout the known universe. The European Center for Nuclear Research conducted numerous experiments in the 1980's which produced "a very large number of short-lived particles known as Z. bosons which are more than 90% times as massive as protons" and which decay quite rapidly into lighter materials, such as neutrinos" (Sullivan 2004, p.180). Thus, it is our knowledge of these short-lived Z. bosons which helped to predict how important light nuclear elements were in the formation of the known universe and subsequently the success of the current Big Bang scenario which has generally been accepted by astronomers and cosmologists alike. However, since the early 1990's, new evidence has come to light indicating that the old Big Bang scenario is not only in possible error but is also far more complex than previously thought.

One of the most important and ground-breaking discoveries linked to the Big Bang is cosmic radiation background which initiated the beginning of serious inquiry into the Big Bang cosmological scenario. The properties of this background radiation was soon realized to share the same intensity in all directions within the universe and when this intensity was measured at various frequencies, astronomers and cosmologists came to understand that the characteristic variation in intensity related to frequency "was a signature of ultimate heat which came to be known as black body radiation" (Sullivan 2004, p. 183). However, as a consequence of the absorption and emission of radiation by molecules in the Earth's atmosphere, astronomers were unable to confirm that the entire spectrum of radiation was that of heat radiation. In 1989, this problem was overcome by NASA's Cosmic Background Explorer (COBE) satellite which managed to measure radiation above the Earth's atmosphere throughout the entire spectrum which confirmed that the universe was at one time much hotter, an indication that something spectacular had occurred along the lines of the Big Bang. Thus, all of these and other measurements related to cosmic background radiation brought about some solid conclusions about the structure of the known universe. For example, it was clear that the universe was expanding at approximately the same rate in all directions, and second, it appeared to be extremely well-ordered, meaning that this expansion was proceeding at the same rate in all directions (i.e., isotropic).

In order to more fully understand exactly what the Big Bang was and how it influenced the formation of galaxies, nebula and planets, we must consider the "cast of characters" which make up the Big Bang. These are photons, "a quantum of radiant energy," protons and neutrons as found within and without atoms and molecules, electrons and their anti-particles known as positrons and neutrinos and their anti-particles known as anti-neutrinos. All of these materials and many others, at least as far as modern-day cosmologists are concerned, were part of an immense sequence of events "that took place in the Big Bang in terms of the time since expansion began" ("The Hot Big Bang 2007, Internet) some 10 to 15 billion years ago. This sequence goes as follows.

First, within 1/100th of a second after the Big Bang, the temperature of the universe stood at approximately 100 billion degrees Kelvin with density "more than a billion times that of water." All electrons, positrons, neutrinos and anti-neutrinos are in equilibrium with photons, while anti-neutrinos combine with protons "to form positrons and neutrons" and "neutrinos combine with neutrons to form electrons and protons." At 1/10th of a second, the overall temperature of the universe has been lowered to about 10 billion degrees Kelvin as has the density to about 10 million times that of water, resulting in "an approximate equal balance between neutrons and protons ("The Hot Big Bang" 2007, Internet).

At about one second after the Big Bang, the temperature and density of the universe has lowered considerably and neutrinos "cease to play a role in the continuing evolution" of the universe. At this point, the abundance of protons exceeds 76% of all the material, while the abundance of neutrons has fallen to about 24%. At about 3 billion degrees Kelvin and some fourteen seconds after the Big Bang, the average energy of all particles in the universe has decreased significantly to a point where photons cannot produce electron-positron pairs which causes… [END OF PREVIEW]

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Post Big Bang.  (2008, March 25).  Retrieved February 22, 2019, from

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"Post Big Bang."  25 March 2008.  Web.  22 February 2019. <>.

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"Post Big Bang."  March 25, 2008.  Accessed February 22, 2019.