Summary for Non-experts

Abstract

We discovered most of what we currently know of the Universe by looking at electromagnetic radiation with telescopes. Most familiar are the telescopes we can actually “look through” with our own eyes, which means that one is seeing visible light. But that is just one of many types of electromagnetic radiation. Other examples of such radiation are radio waves, infrared light, and ultraviolet light. The difference between these different types of radiation is the wavelength of the waves this radiation consists of. In general, electromagnetic radiation consists of waves in the electromagnetic field, where the wavelength determines what type of radiation it is. This way there is a whole spectrum of possibilities, with each type of electromagnetic radiation associated with its own frequency range. Every frequency range requires a different type of telescope to observe the radiation. Just as we cannot see radio signals with our eyes, we also need a different telescope to observe X-ray signals than to observe visible light.