It is often said that the reason why we “know” the Big Bang took place is because the Universe is expanding and if time were played backwards then everything would have started from the same point at the same moment in time. That moment, when everything started moving apart, is what we call the Big … Continue reading Why believe in the Big Bang?
Astronomy versus Cosmology
The word "astronomy" means the arrangement of the stars but we apply it to the arrangement of the entire Universe, not just stars. It is an observational science, since experiments are difficult to perform on solar systems and galaxies - let alone the entire Universe. Cosmology, on the other hand, is more philosophical and is … Continue reading Astronomy versus Cosmology
Compare and Contrast
A really useful revision tactic (and also quite a common type of exam question) involves looking at the differences that exist between two related things in the same area of physics. These comparisons can be very simple, such as the definitions of scalars and vectors, or they can be more complicated, such as competing theories … Continue reading Compare and Contrast
How did the Universe begin?
As was the case when we considered models of how the Universe is structured, when it comes to explaining the beginning of the Universe you again need to know about two competing ideas. You also need to know about the evidence that either supports or questions each theory. One theory is the Steady State Theory. … Continue reading How did the Universe begin?
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