We have ways to generate light and direct it with our own technology. Humans have had the ability to do this for even longer. Within the last number of decades, we have begun understanding what light is and how it works, how photons are generated, etc.
I have imagined a magical system in which it is possible to create and/or project/direct light. There is also the ability to do so with "darkness," which will be defined as a localised absence of any sort of illumination in this question. However, while light would shine from a source, one might be able to "direct" the darkness as if it were a fluid. As an example, if you are familiar with Avatar: The Last Airbender, something akin to water-bending comes to mind, though it need not be as "solid"--or perhaps tangible is the better word?
Never thought I would call liquid water 'solid'...
Is there a way to describe this projected "physical" darkness, taking into account real science and by taking grossly large liberties with any physical limits, in a "scientific" manner? I would rather it not involve any matter to physically block the light, but if it is handled well it would work. There aren't any limitations presently in the magical system, apart from there not being infinite energy (which may be the major limiting factor here, for all I know). You may assume that annihilating a city/continent/planet/star with the power requirements is not an issue, nor are localised absolute-zero (or supernovae-like) temperatures, if your answer requires them.
Note that this does not need to conserve energy (or, I guess by extension, mass) as the effect will only persist as long as it is controlled, and any energy not in the world already will enter, be used, and promptly exit. Picture it like a sink, or a black hole sucking stuff in as a "white hole" spits stuff out.
- Looking at such a darkness, one might see only blackness as no light would bounce off. I can imagine it being a very strange thing to see, as it will likely have no perceivable depth. Perhaps it would look perfectly 2-D in a 3-D world? (Note: Vantablack)
- With a strong EM waves, light can be "bent" in an terribly small way, but I fear the other effects that a sufficiently powerful EM wave would have on any matter it passes through.
- I may need to come up with a completely different way to explain this, stepping almost completely outside of the realm of physics.