Thesis:The Big Bang theory is the most widely accepted scientific explanation for the origin of the universe. There is a substantial amount of observational evidence supporting the theory, and more data continues to be collected as research progresses.
Summary:The Big Bang theory is the model most broadly accepted by the scientific research establishment for the birth of the cosmos, or universe. After decades of observation, verification, and testing, the amount of convincing scientific evidence supporting the theory is overwhelming, and the predictions based on the theory about the behavior of matter and energy in the universe have consistently been demonstrated in reality. Physicists and cosmologists continue to elaborate upon the basic concepts of the model using data from increasingly sophisticated equipment.
History of Cosmology
Researchers, philosophers, and poets alike have long grappled with questions about how and when the cosmos began, where matter came from, and whether time and space are finite or infinite. Humanity's understanding of cosmology has shifted many times over the course of recorded history. People once believed that the heavens were composed of divine celestial material, though it is now known that the planets and the stars are comprised of large balls of gas and minerals. Scientists once thought that the length of our Milky Way galaxy was no more than a few tens of thousands of light years (one light year equals about 5.88 trillion miles); current figures for the size of the galaxy hover around 100,000 light years across or more. The focus of scientific research has shifted as well; controversies over the relative importance of Earth's position within the universe have given way to larger debates about the origin and future of the universe itself. To date, the theory of the Big Bang represents by far the most complete and convincing scientific response to these questions.
The Big Bang Explained
The most basic version of the Big Bang theory proposes that all the matter that would eventually make up the many galaxies of the universe was compressed together into a single point marked by unimaginably high temperature and density. In its entirety, all of the physical substance of the universe is thought to have fit into a tiny area approximately the size of a fist, and perhaps even smaller than that. Then, about 14 billion years ago, according to the most current cosmological estimates, a sudden change in the state of energy gave rise to a tremendous sudden expansion (sometimes called "inflation"). This explosive event caused what had previously been densely packed matter to be abruptly thrown out into space, where it began to rapidly move apart, creating time and space as it went. Slowly, fundamental subatomic particles such as electrons and positrons reacted and combined to form elements, which in turn clumped together to shape planets and galaxies. The powerful cosmic explosion that precipitated all this is known as the Big Bang. Ever since this astonishing occurrence, physicists assert, the universe has continued to expand and cool down.
Twentieth-century Belgian astronomer Georges Lemaître first proposed the idea of an initial cosmic explosion leading to an inflationary universe. At the time, the major competing cosmological theory claimed that the universe is and always was in an essentially static, unchanging state. Initially the scientific establishment as a whole was more inclined to support an eternal steady state model, largely due to prevailing scientific ideas about such things as the age of the universe and the stability of the universe's overall density. However, the debate among cosmologists heated up when it became clear that the Big Bang theory was consistent with various scientific observations. For instance, it explained the curious fact that data from telescopic observations of the sky showed faraway galaxies moving ever-faster away from Earth. Given the speed and direction of this cosmic movement, the idea that all matter once originated from a single tremendously dense spot began to seem less far-fetched.
Evidence of the Big Bang
It is important to recognize that science does not strive to establish absolute truth, as all scientific statements are open to re-evaluation. A scientific hypothesis becomes an accepted theory when it manages to explain most or all of the available observational data about a given phenomenon, and when, based on that theory, specific, testable predictions consistently match experimental results. Although scientists were initially skeptical, decades of research and observation have transformed the hypothesis of the Big Bang into a robust, well-established theory, backed by an abundance of supporting evidence from different sources.
The Big Bang theory suggests certain things about the state of various physical characteristics of the universe, and an examination of hard data shows that these ideas do, in fact, match reality. For example, scientists calculated that the extremely high temperatures present at the time of the Big Bang would result in a particular proportion of hydrogen and helium in the universe; measurements of these elements subsequently reflected precisely this proportion. Also, the theory predicts that the expansion and cooling of hot gases after the Big Bang would leave behind a consistent level of leftover radiation throughout the universe that is uniform in temperature, a phenomenon known as cosmic microwave background radiation (CMB or CMBR). In 1965, two communications engineers in New Jersey recorded signs of just such radiation in the form of noise in their radio receiver. This historic discovery was the first tangible evidence of the Big Bang, but not the last.
In the mid-1980s, a group of National Aeronautics and Space Administration (NASA)-sponsored scientists sent a satellite into space, (COBE, or the Cosmic Background Explorer) designed to study CMB and collect data that would support the veracity of the Big Bang theory. In particular, the COBE team wanted to see if the current temperature of the CMB matched a particular profile predicted by the theory's calculations and known as a "blackbody spectrum" of radiation. According to measurements made by an instrument designed by physicist John C. Mather, it did. In addition, his colleague George F. Smoot analyzed the measurements made by a separate instrument on COBE. This information allowed Smoot to produce a startlingly detailed picture of the formation of the early universe. Again, these results closely matched earlier predictions, and provided answers to some questions about how matter may have initially spread throughout the universe. In 2006, Mather and Smoot were jointly awarded the Nobel Prize in Physics for their work, which is considered the most compelling evidence supporting the Big Bang theory.
Faith-Based Challenges to Science
In recent decades there has been an increasing tendency among conservative Christians in the United States to challenge established scientific theories that they believe to be in conflict with religious ideas about the age of the universe and the way the world came into being. Creationist thinkers, who call their description of the divine origin of the universe "intelligent design," frequently write about what they consider to be holes in scientific explanations. Faith-based criticisms of the theory also often point out that scientists do not understand all of the mechanisms that brought about the Big Bang. They call into question every piece of the abundant evidence for the model.
The scientific indications that the Big Bang actually happened are extremely varied and sound. While open questions still remain, the mere fact of their existence by no means shows that the theory is weak. Research into the Big Bang progresses every day, and work in the new frontiers of physics, such as quantum mechanics and string theory, continue to add to our understanding of the model. Recently, for example, Penn State University physicist AbhayAshtekar and his colleagues developed a method of mathematically describing the changes in the early universe, based on loop quantum gravity. By positing the existence of another shrinking universe, their work suggests answers to the burning question of what may have happened before the Big Bang. In addition, as experimental equipment becomes more sophisticated, scientists are able to acquire more and more finely-tuned data about the CMB using instruments such as the Wilkinson Microwave Anisotropy Probe (WMAP).
Conclusion
As technological advances bring more data to the table, scientists are increasingly able to substantiate predictions made by the theory of the Big Bang, and to add to the model's sophistication. The Big Bang theory is a comprehensive, scientifically valid explanation for the origin of the universe that is widely accepted by the scientific community. The variations in the basic model and the differing scientific interpretations of various aspects of the theory only point to its robustness.
Ponder This
1. Do you agree with the author that "while open questions remain...their existence by no means shows that the theory is weak"? What questions could potentially undermine the strength of the Big Bang theory? Explain.
· 2. Does the author provide enough scientific data to support the validity of the Big Bang theory? Discuss.
· 3. Since there can be no absolute proof for a scientific theory, what does it mean when an idea becomes established or well-accepted by scientists? Does the author convincingly argue that the Big Bang is such a theory?
· 4. In your opinion, is it an increase in religiosity or a lack of scientific education that is driving the current movement toward teaching "intelligent design" in American schools? Explain.