It is reasonable to believe the Big Bang Theory is correct

To start off, I will summarize the main lines of evidence for the big bang theory and attempt to explain why what caused it, or what came before, is not necessary for it to be a reasonable theory. First however, a few words on scientific theory. In science, a theory is a well-tested explanation of a diverse array of facts. [1] In order to qualify as a theory, something must not only explain previously known facts, but also must make predictions on what one would expect to find if the theory were accurate. The big bang theory does both of these things. The evidence: I. Recession of Galaxies Starting in the 1912, astronomers were able to measure the spectra of light from distant galaxies. As more and more data came in, what they found was that the vast majority of galaxies showed red-shifted spectral lines, meaning that the galaxies were moving away from us. When this data was cross-checked with distance measures for the galaxies in question, it was found that recessional velocity increased as a function of distance. In other words- all galaxies are moving away from us, and the further away a galaxy is, the faster it is moving away. This became known as hubble's law. A more detailed description can be found here: . http://astrosun2.astro.cornell.edu... Now, given this data, only two parsimonious conclusions are possible: either we are at the center of the universe, or the fabric of the universe itself is expanding. As the universe is vast, and we are but a very very small part of it, it is much more reasonable to conclude that the expansion is happening everywhere. We can even measure the rate! The current estimate is around 71 km/s per megaparsec. Of course, if the universe is expanding, it must have been smaller in the past. In fact, we can extrapolate backwards to a time when everything in the visible universe was exceedingly densely packed into an exceedingly small volume (though nowhere does the theory require a singularity). Additionally, this data is NOT well explained by any models positing explosion as opposed to expansion. For example, it is not observed that the mass of a galaxy and its recessional velocity are correlated, even though the force of an energetic explosion would manifest differently in objects of different masses (ie Newton's Second Law) II. Cosmic Microwave Background In the early 40s, when the Big Bang theory was first proposed to explain Hubble's findings, George Gammow and his colleagues predicted that a hot dense beginning would produce a burst of radiation that should still be detectable today. [2] Though most of the specific details Gammow proposed turned out to be wrong upon further investigation, but the "Cosmic Microwave Background" as it is now known, was detected in 1946 by scientists attempting sensitive microwave measurements. [3] They tried to eliminate it as static interference, but could not. We now know that this CMB radiation is homogeneous to within .0001 K in EVERY direction in the sky. We have measured it from here on earth as well as from space. It is a perfect blackbody spectrum. The Big Bang theory explains this data easily- as all hot objects emit blackbody spectra, so an extremely hot, extremely dense universe in the distant past would be expected to produce just such radiation. [4] III. Light Element Abundances Again using spectral analysis, astronomers can measure the abundances of the light elements Lithium, Beryllium, and Boron on the surfaces of stars (as well as all the other elements, but these three tell use something interesting! ). We know that heavier elements are formed by nuclear fusion of hydrogen in the cores of stars, so we would expect that older stars would have a lower abundance of these elements. This is the case. But while Beryllium and Boron abundances continue to decline as we look at older and older stars, lithium abundance levels off at 3x10 e-10 per atom of hydrogen. While this doesn't seem like much, there is no known method for creating or destroying lithium in the universe today that isn't equally applicable to boron. The "nucleosynthesis in stars" theory also predicts a much lower percentage of Helium than what we observe. A hot dense past explains all the observed abundances. [5][6] The above three are generally referred to as the "Three Pillars of the Big Bang". I will also present two other points that lend support to the idea of some type of big bang event. IV. Astronomical Ages There are many methods we can use to determine the ages of stars and galaxies. Nowhere do we find any older than around 12.5 billion years old. As low mass stars such as red dwarfs can live for trillions of years, there is no reason [7][8] V. Olber's Paradox Simply stated: if we assume a steady state universe, why is the sky dark at night? In a universe that has always existed and that is infinite in size, since stars and galaxies appear to be distributed randomly, shouldn't every point in the sky contain a star? This illustration explains it nicely: . http://ircamera.as.arizona.edu... As the night sky is dark, one of those assumptions must be wrong- the universe (as we know it at least, the kind of universe populated with stars and galaxies) must have an edge and/or a beginning. Finally, your assertion that what happened before the big bang is somehow relevant to this debate. I want to make it very clear what the big bang theory does and does not posit. It does posit that in the distant past, the universe was extremely hot and extremely dense. It does NOT posit a singularity. It does NOT posit an explosion. And it does NOT claim to explain the origin of the universe. Rather, it explains how the universe has been expanding and cooling over a period of about 14 billion years. Claiming that the BBT is wrong because it does not explain the origins of the universe is like claiming Evolutionary Theory is wrong because it doesn't explain abiogensis, or like claiming our theory of how the Solar System formed is wrong because it doesn't explain gravity. While they are certainly related phenomena, the lack of explanation for one doesn't in any way invalidate the explanation given for the other. The Big Bang isn't wrong about the origin of the universe because it doesn't attempt to explain the origin of the universe. I await your rebuttals! 1. . http://wilstar.com... 2. . http://www.britannica.com... 3. . http://hyperphysics.phy-astr.gsu.edu... 4. . http://www.talkorigins.org... 5. . http://astro.berkeley.edu... 6. . http://www.talkorigins.org... 7. . http://www.astrosociety.org... 8. . http://www.universetoday.com...