Big Bang

2060 Words9 Pages
it is important to understand what Big Bang Theory (BBT) is and is not. Contrary to the common perception, it is not a theory about the origin of the universe. Rather, it describes the development of the universe over time. This process is often called "cosmic evolution". Over the last several decades the basic picture of cosmology given by BBT has been generally accepted by astronomers, physicists and the wider scientific community. However, no similar consensus has been reached on ideas about the ultimate origin of the universe. This remains an area of active research and some of idea current ideas are discussed below. That said, BBT is nevertheless about origins In addition to being a theory about the origins of the basic building…show more content…
In both cases, the model implies that the universe is expanding into some larger, pre-existing volume. In fact, the theory says nothing like that. Instead, the expansion of the universe is completely self-contained. People often have difficulty with the idea that "space itself expands". An easier way to understand this concept is to think of it as the distance between any two points in the universe increasing. First, the distance between A and B is a function of time and second, the distance is always increasing. To really understand what this means and how one would define "distance" in such a model, it is necessary to have some idea of what Einstein's theory of General Relativity (GR) is about: "Space tells matter how to move, matter tells space how to curve." Another way of describing GR would be something like: "Energy determines the geometry and changes in the geometry of the universe, and, in turn, the geometry determines the movement of energy". So, given this, how does one get BBT from GR? The basic equations come directly from Einstein's GR equation under two key assumptions: First, that the distribution of matter and energy in the universe is homogeneous and, second, that the distribution is isotropic. A simpler way to put this is that the universe looks the same everywhere and in every direction = cosmological principle. If we adopt these simple assumptions, the implications for the geometry of the universe are quite profound. First, one
Open Document