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The Big Bang Theory - Communications Paper

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The Big Bang

For decades the Big Bang theory has been the leading theory on the beginning of our universe. Alternate theories come and go, but mainly go. As new data and research are continually eliminating alternatives to the standard model of cosmology, the Big Bang just keeps getting stronger.

Before discussing the alternate theories to the Big Bang theory, the basics of the early universe should first be understood. The main points opposing the theory are based around a few aspects that will be defined in the explanation of the early universe. These points include inflation, dark matter and dark energy, the cosmic microwave background (CMB), and red shift.

The theory states that the universe sprung from a singularity - an infinitely dense point. A process called inflation took over from there, and all the matter expanded exponentially from one very small point to something the size of a basketball in a fraction of a second. Inflation is very important to the Big Bang theory, as it is required to explain the uniformity of particles in the very early universe, among other problems. The inflation period ended, but the expansion continued, and continues today. Expansion will be discussed further later.

The Big Bang theory cannot be proven through visual observation. Most people are aware that the light from an object 3 million light years away will take 3 million years to reach the Earth. In this way, scientists can "look" back in time to see far into the history of our universe. This is limited, however, as at one point the universe was dark. Even the most powerful telescopes of the future will not be able to look into the first billion years of our universe.

Adam Frank (2006) describes this early, and dark, period of our universe in his article describing the "First Billion Years." According to the Big Bang theory, (and Frank), immediately after the initial event and inflation took place, our universe was a consistent and smooth "soup" of particles. Radiation and matter were tightly bound. Matter that is radiated is known as "ionized" matter. Photons were constantly being absorbed and reemitted by this ionized matter. Photons are defined by Paul Shestople as "Particles which are packets of light" (1997, Glossary, P-T, para. 3). Because photons could not roam freely during this time period due to the ionized matter, this is the known as the dark ages of the universe.

About 380,000 years later, this hot soup cooled enough to allow electrons and protons to come together to form hydrogen (Frank, 2006). As the hydrogen was created, matter, radiation, and light could go their separate ways. It was at this time that the CMB came into being. The CMB is defined by Shestople as "Obeservable radiation... left over from the Big Bang" (1997, Glossary, A-E, para. 14). The CMB is the radiation that was freed as the first atoms were formed.

At this same time, photons were also freed. As Adam Frank (2006) describes, the hydrogen in its neutral (non-ionized) state did not absorb photons as we know them in the CMB, but visual and ultraviolet (UV) light were still absorbed. "The current dominance of ionized hydrogen is one reason we can see so far with optical telescopes. The Dark Ages were the epoch of cosmic history between the initial formation of neutral hydrogen and its eventual destruction" (p. 30).

Before the universe could clear to all types of photons, the hydrogen needed to be re-ionized. Scientists call this re-ionization, but this is actually the first time the hydrogen was ionized since its formation. How was the neutral hydrogen ionized? The first answer is gravity. Dense regions drew in more matter, and became denser. As the hydrogen clouds gained more and more density, they eventually ignited into huge stars, far larger than the stars we know in our galaxy today. "... These first stars were, on average, gigantic - at least 25 times as massive as the sun and ranging as much as 100 times as massive, if not more" (Lemonick, 2006, p.3). Some scientists believe these first stars could even have been as much as 1,000 times denser.

These stars burned so hot that they would have emitted both visible light and huge amounts of UV radiation. This radiation would have been able to break up hydrogen atoms, ending the "dark ages." However, these super hot stars could not live long enough to produce this effect. They burned hot and fast, and died after only a million years. The smaller dying stars exploded, shooting material into space, and the larger stars collapsed to create black holes.

The reactions within these huge stars created new elements, heavier elements such as oxygen and carbon. Lemonick (2006) explains how these elements allowed the gaseous clouds to collapse this time into much smaller stars than their predecessors, stars like our sun. "And like the sun, they would have started out generating lots of ultraviolet light before settling down to a more sedate existence" (p. 4). These smaller stars had the lifespan to be able to ionize the hydrogen. It was at this time that the dark ages came to an end. Some scientists theorize that it was X-rays and UV light spewed from black holes that brought a close to this dark time, but perhaps it was both of these theories that finally brought light to our universe.

As more complex telescopes are being created, scientists can get closer to observing the formation of early galaxies. In visual observation, redshift now comes into play. Edwin Hubble discovered in the 1920s that the light of far away galaxies have a wavelength that has been stretched, or "shifted," to the red end of the spectrum (Gaastra, 2005, p. 1). This is not a particularly surprising observation. Other wavelengths that can be observed daily by anybody are shifted in the same manner. "A good example of this is the sound of a fire truck siren as it drives by; the pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you" (Shestople, 1997, para. 6). The redshift effect is commonly used in the Big Bang theory to explain that the universe is still expanding. Galaxies observed with higher redshift are then assumed to be the oldest, farthest away galaxies.

The Big Bang is, at the foundation, based on Einstein's Theory of General Relativity. Einstein's theory states rules of gravity and its behavior. However, observations of gravity and the mass of the universe do not seem to come together very well. Scientists now need to add another piece to the Big Bang, dark matter and dark energy. The gravitational observations show that the universe must be much more dense than could possibly be with normal matter. Dark matter is defined by Shestople as "Any matter in the universe



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