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The branch of science that studies the Universe as a whole, in the large, is called cosmology. Cosmology doesn't deal with details; in fact, about the smallest thing a cosmologist is interested in is a galaxy. A galaxy typically contains a mere 100 billion stars.

Cosmology is a real science, although a lot of what we read about it seems so strange that it reads more like science fantasy. Cosmology's closest links are with astronomy, which provides the raw observational material it needs. The rest of cosmology is mostly made up of physics, chemistry, and statistics. Physics, because it contains Einstein's theory of gravity, the most significant force in the Universe at large. Chemistry, because the diverse elements around us contain clues about the nature of the Universe. Statistics, because cosmologists, like pollsters, are always trying to squeeze as much information as possible out of small samples of a vast population. The most ambitious surveys that are planned will only provide cosmologists with information about 0.1% of the galaxies that we can detect with modern telescopes.

To a cosmologist, questions about the structure and history of the Universe are primarily questions about the role of gravity. Because gravity can act over huge distances, it is the force that has the biggest effect on the character of the Universe as a whole. Our best theory of gravity is still Einstein's "General Theory of Relativity", and so a lot of cosmology is an attempt to discover how Einstein's theory applies to the Universe.