Astrophysics

Why do the stars shine? How did our galaxy form? Will the universe expand forever? These are the types of questions asked by astrophysicists in an attempt to understand the processes which cause our universe, and everything in it, to behave the way it does. From the low-energy gravitational interactions between planets and stars, to the violent, high energy processes occurring in the centers of galaxies, astrophysical theories are used to explain what we see, and to understand how phenomena are related.

For thousands of years, astronomy was simply an observational science—humans could observe phenomena in the sky, but had no physical explanation for what they saw. Early humans could offer only supernatural explanations for what they observed, which seemed drastically different from what they experienced in everyday life. Only in the twentieth century have scientists been able to explain many astronomical phenomena in terms of detailed physical theories, relating them to the same chemistry and physics at work in our everyday lives.

Astrophysical experiments, unlike experiments in many other sciences, cannot be done under controlled conditions or repeated in a laboratory; the energies, distances, and time scales involved are simply too great. As a result, astrophysicists are forced into the role of observer, watching events as they happen without being able to control the parameters of the experiment.

For centuries, humans have made such observations and attempted to understand the forces at work. But how did scientists develop our picture of the universe if they could not reproduce what they see in the laboratory? Instead of controlling the experiments, they used what data they were able to obtain in order to develop theories based on extensions of the physical laws which govern our day-to-day experiences on Earth.

Astrophysics often involves the creation of mathematical models as a means of interpreting observations. This theoretical is important not just for explaining what has already been seen, but also for predicting other observable effects. These models are often based on well-established physics, but often must be simplified, because real astronomical phenomena can be enormously complex.