When astronomers discovered that galaxies are moving apart from each other, this led to the “Big Bang” theory on the origin of the universe. However, when they were better able to precisely measure the rate of expansion, they were shocked to realize that the expansion is actually accelerating. This defied logic because over time gravity should be slowing the expansion. The only explanation for this was that there must be an as yet undiscovered, unmeasured force, far stronger than gravity, which was repelling galaxies. Scientists dubbed this strange force “dark energy.”
Dark energy is called “dark” because nobody really understands what it is. However, there is definitely something happening to accelerate the rate of expansion. In fact, to account for the expansion, scientists estimate that 74% of the universe is dark energy. Although it would not happen until billions of years in the future scientists fear that dark energy will cause the universe to expand so much that the universe will die in a cold “Big Chill.”
The first person to propose the existence of dark matter was Fritz Zwicky. This came about because the velocity with which the outer portions of galaxies were rotating was far too fast given only the visible matter. The only way to account for this was to postulate that there must be more matter. However, as with dark energy, nobody could see or measure this matter; hence it was called “dark matter.”
Though not as much as dark energy, dark matter also makes up a significant part of the universe. By calculating the orbital rotation of galaxies, along with the amount of visible matter, scientists estimate that 22% of the universe must be dark matter. Remarkably, this implies that the known, measurable matter and energy in the universe only account for 4% of its makeup.
Do Dark Energy and Dark Matter Really Exist? Mathematics is rarely wrong. But science often is. Given the accuracy of the measurements concerning the expansion of the universe and the velocity of galaxy rotations, there is unquestionably something there we do not understand. So, in some form, dark energy and dark matter almost certainly exist.
However, since each concept has been studied for under 100 years, the little that we think we know about dark energy and dark matter is at best incomplete and at worst completely wrong. But as little understood concepts, dark energy and dark matter offer young scientists a wonderful opportunity to make great strides and advancements in an exciting new field.