Among all areas of current research in modern cosmology and astrophysics, perhaps no area is more exciting and mysterious than the study of the nebulous component of our universe known as "dark energy". In short, dark energy is an invisible component of our universe that is completely unlike matter or radiation. Although theorists have proposed many possibilities for extra components (beginning with Einstein's cosmological constant), until recently there was no compelling observational evidence for adding another component to the universe. Prior to the "discovery" of dark energy, most theories of cosmology were based upon a universe composed only of matter and radiation. However, with the release of astrophysical observations in 1998 that suggested that the expansion of the universe was accelerating, it became clear that modern cosmological theories would need to be drastically changed.
