The doppler effect, when used with light, produces a shift of frequencies to red. Well, no matter which direction you look, there is a shift to red! That means that the universe is expanding or moving away from us in every direction. The idea, is that this could only happen if all matter was once in a single point, and there was an explosion. This explosion from a single point is called the big bang theory.
A nebula is a cloud of gases that can coagulate to become a new star.
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Speciation is an evolutionary process by which a new species comes into being. A species is a group of organisms that can reproduce with one another to produce fertile offspring and is reproductively isolated from other organisms. Speciation can be driven by evolution, which is a process that results in the accumulation of many small genetic changes called mutations in a population over a long period of time. There are a number of different mechanisms that may drive speciation. One of these is natural selection, which is a process that increases the frequency of advantageous gene variants, called alleles, in a population. Natural selection can result in organisms that are more likely to survive and reproduce and may eventually lead to speciation. A second process called genetic drift describes random fluctuations in allele frequencies in populations, which can eventually cause a population of organisms to be genetically distinct from its original population and result in the formation of a new species.
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