Dark Energy

This is probably one of the most interesting topics right now due to the fact that very little is known about it. Dark Energy is what this mysterious force is called, however it has nothing to do with the similarly named Dark Matter. This was first discovered because of what they found about the expansion of the universe (more on that later) which required an explanation more then normal matter and Dark Matter could provide. Thus they called it Dark Energy, and is believed to make up approximately 70% of the universe. Einstein first theorized it calling it a cosmological constant, but then retracted it believing that it was a mistake, although now it's seen as the most prominent explanation for Dark Energy. It's believed that this energy is the energy due to empty space, and that it acts like anti-gravity repulsing instead of attracting, so with more empty space then there would be more Dark Energy. However, there are other theories of what Dark Energy is, another prominent explanation is that for quintessence. This theory believes that Dark Energy is a quintessence field, like there are EM fields, and the difference with this then the cosmological constant theory is that quintessence varies with time and space. There are still other theories, unfortunately this is all still theory, it has yet to be proven, and no one really knows how or why Dark Energy exists. There is a lot of research underway to figure it out Dark Energy and see what it really is, which should prove interesting to future generations of astrophysicists.