Layman here with an affinity for astronomy, space and everything associated with it. I'm a big fan of the space oriented programs on the Discovery and Science channels and I was watching an episode recently that got me to thinking about the origins of Dark Matter (DM) and Dark Energy (DE). Do any of you know if any thought has been given to the creation of DM and DE as byproducts of space being created? As I understand it, as the universe expands it essentially creates space where nothing was before. To be honest, I know nothing about what that even means: creating space where nothing was before.
Your question is quite complex, since dark matter and dark energy are two different things, that only have in common that they are called "dark" and are hypothetical quantities. They are hypothetical, because we only defined them as mathematical quantities to make physical laws, we invented, comply with the observations.
what is the origin of dark matter? In 1930 Fritz Zwicky observed the coma cluster. The coma cluster is a cluster of galaxies that move amongst each other based on their gravitational pull to one another. He found to his surprise that the galaxies in this cluster were moving faster than the gravitational pull based on their visible mass would predict. Since the visible mass of the galaxies couldn't explain the movement of the galaxies, he suggested there was another, yet unseen, matter in that cluster that contributed to the gravitational pull. He called it "Dunkle Materie" (he was Swiss) - Dark Matter. Later studies on the rotation of galaxies also showed that the rotational speed of the galaxies couldn't be explained by the visible matter in those galaxies, so another dark matter needed to be present to explain for the anomaly.
after adding the hypothetical dark matter in the laws of nature many things could be explained on the theoretical level. The forming of galaxies clusters in the current observable universe and the fluctuations of the cosmic microwave background could be explained with dark matter. The theory here brings the existing physical laws in accordance with the current observation. The problem is that dark matter has not yet been proven to exist in experiments. It has not been observed and many theories exist on what that dark matter could be.
Dark Energy has a different history, leading to a similar thing. When Einstein laid out his theory of general relativity he included in his field equations a cosmological constant, lambda, to be able to come to a static universe based on his equations. He assumed the constant to be zero and therefore come to a static universe. A negative constant would mean the universe would shrink and a positive constant would mean the universe would expand.
Unfortunately, Hubble showed that the universe was not static, but expanding and in the 1990's measurements showed this expansion was accelerating. Now the cosmological constant was not zero and an explanation needed to be found why the universe was expanding ever faster. For this expansion an energy is needed that counters the gravitational pull of the (dark) matter in the universe and increases with each expansion of this universe. Later observations from a supernova in 1998 and the Boomerang and Maxima experiments on the cosmic microwave background gave strong evidence of the existence of dark energy. This is, when we believe the standard model of cosmology is right.
The problem with dark energy is that in the most cases the laws of cosmology are correct and explain the universe. This means that dark energy must be real, or the cosmological laws must be altered. Currently, the search for dark energy is going on. The definition of dark energy in the models explains the expansion in of the universe and also the fast expansion during the early years of the universe. However, dark energy is a hypothetical quantity and has not been observed yet.
I hope this gave you a brief history how dark matter and dark energy have come into astrophysics. Don't mix it up with the dark force. That's not even hypothetical and only exists in certain movies.
Dark Energy is exactly that (according to many theories) Wikipedia has a decent explanation. Every cubic meter of space contains the same amount of dark energy and that doesn't change even when space expands or contracts over time.
Dark matter is something quite different. As far as we can tell it behaves pretty much like ordinary matter, except that it passes freely through other matter and itself, and does not interact with electromagnetic radiation. It moves around under the influence of gravity, and becomes more dilute as space expands.