Brad Hogg
Astronomy 1050
Final Paper
Cosmology at a Glance
Human history has always been an important facet of life through the epochs and eons of existence. From the most recent of events in the world, such as the development of cloning, space travel, and the creation of the atomic bomb, extending back to the development of gunpowder, the discovery of the density formula, and even back to the creation of writing, mankind has always tried to track its history, often through science. We’ve studied things such as geophysics, quantum physics, and marine biology. We’ve studied rocks, plants, and fossils. The weather has come under our scrutiny, as well as the study of human nature and patterns. We’ve studied microbiology, examining the smallest things we can see. And we’ve thrown our interest out towards that which dwarfs us, such as the solar system, and its many components. But we still press on, driven by the need to know one question: where’d it all start?
Cosmology is the study of the answer to that question. It’s the study—and speculation—of the origins and evolution, or growth, of the known universe. It’s also the speculation of what the unknown universe might hold. Since mankind first began to discover the space beyond Earth, they have tried to understand it, and to explain it. Of course, this has brought up many arguments from myriad groups, with a seemingly endless string of theories about the beginnings of the universe.
The origins of cosmology itself, however, are quite clear. It begins with a simple question: why is the sky dark at night? In 1576, Thomas Digges came to the conclusion that the universe is unbounded by limits, and filled with stars. Isaac Newton produced a theory very close to this, as well. However, this poses a problem, as one would essentially be able to see a star at any given point in the sky. This would cause the entire sky to shine like a star at night. However, as most humans can see, the sky is quite dark at night. This suggests a boundary, an end, a finite universe; this is a definite foil to the system of Digges and Newton.
The system of a Newtonian reality also posed a problem, because time in this reality would tick perfectly forever, no matter where it was. Clocks would act exactly the same, no matter what their location in the universe. This was disproved by the theoretical mathematician Albert Einstein. His special theory of relativity describes how motion affects measurements of time and distance, with the equation:
where the variable T represents the time interval measured by an observer moving relative to the phenomenon at hand, and T0 represents the time interval measured by an observer not moving relative to the phenomenon at hand. However, Einstein’s calculations did not allow for a static universe, so he decided to add a cosmological constant, which essentially provided a sort of pressure balance, thus preventing expansion or contraction of the universe. This was an action that he would come to regret some years later, with the introduction of the Hubble theory.
Edwin Hubble is credited with the next big discovery in cosmology. In 1929, he was able to find that the greater the distance to a galaxy, the greater the galaxy’s redshift. Thus, this proved that remote galaxies are moving away from us, with speeds proportional to their distances. The only explanation that scientists could equate with this was that the universe was expanding. And how could this exist, in a Newtonian ideal?
Scientists and astronomers, now having proved that the universe was not what it had seemed for so long, were now presented with a new problem. They knew that the universe was expanding, but what they didn’t know was why the universe was expanding, or how they could begin to explain it. They also didn’t know where the center of the universe was. They knew that it couldn’t be the Earth, as that would violate the Copernican principle that we do not occupy a “special” place in the sky. Eventually, it was generally accepted that another theory of Einstein’s, made in conjunction with his general theory of relativity, was true. This theory assumes that the universe is homogenous and isotropic. In layman’s terms, the universe looks the same everywhere and everyway.
With that satisfactorily explained, scientists moved on. Many stayed behind, though, because one question had most certainly not been answered. The question that started this all was still a mystery: where’d it all come from? Many began to say that, judging from the fact that Hubble’s redshifts had proven to be billions of years old, that the universe had obviously been denser. This led, by natural intuition, to the realization that the universe must have been created in some sort of primordial explosion, or the Big Bang. This, in turn, was tied in to most theories known to man.
However, the Big Bang theory came under heavy fire from religious Christian groups, as it suggested something which they were not really ready to cope with. Ask any Christian how the universe began, and they will answer with Genesis 1:1, “In the beginning God created Heaven and Earth.” This really doesn’t allow for any exploding to occur, and the Big Bang theory is often discredited by Creationists.
All religious arguments aside, the Big Bang theory is one of the most important in cosmology, as it gives a concise and definite possibility as to where it all began. Furthermore, there is continuing proof that it did happen. Last year, on BBC News, news was released about the new discovery of the polarization of the Cosmic Microwave Background, or CMB. The CMB is the “afterglow” of the Big Bang, and is radiation that comes from all directions in space. It dates back to approximately 400,000 years after the Big Bang. The polarization of this field has been expected, but since proved, has provided some relief for various astronomers.
Since the beginning of known time, mankind has thirsted for knowledge about why they came about. In order to find this out, they’ve consistently bettered their own technology, in order to continually make discoveries. They’ve developed cloning, space travel, and myriad other processes and tools for exploration and discovery of their surroundings. The telescopes that they’ve built, both on Earth and on, have assisted immensely, as well. The true answer of where we came from may never actually be discovered. However, we’ve come to develop a pretty good picture, anyway.
Bibliography
http://www.gsu.edu/other/timeline/cosmo.html - A timeline from 1576 (infinite universe) to 1980 (inflationary Big Bang).
The Holy Bible New International Version, Copyright 1984, International Bible Society, 1820 Jet Stream Drive, Colorado Springs, CO 80921-3696
Universe, Sixth Edition, Copyright 2002, Printed in the United States of America – The class textbook
http://news.bbc.co.uk/2/hi/science/nature/2271377.stm, BBC News, September 20, 2002