|Black holes may constitute all dark matter (Photo credit: girl_onthe_les)|
Despite the appearance of the Higgs Boson earlier, there is still a great deal of difficulty for physicists in describing all phenomena in accordance with the so-called Standard Model. Lately it has become commonplace to regard the matter we cannot see but "know is there" -- Dark Matter. As mysterious as that sounds, as if it were Darth Vader land, there must also exist Dark Energy as well.
I am not so certain about the mathematics, being that it requires supercomputers to resolve all the measurement and sensor data, so all I can do as a normal human is to imagine scenarios where the Dark stuff is involved. I do not count the Higgs particle as Dark, because it was something we could detect only in abnormal conditions; it was not just the everyday stuff throughout the Universe.
Anyway, even the speed of light, c, seems an arbitrary "Dark" thing, since the actual measured speed of light is a definite value but why that is remains unknown. Light travels forever, as wave packets called photons, through the "empty" vacuum of space, most of the time. A photon can be absorbed by atoms along the way, although much of the time the photons will simply be re-emitted at some other frequency. But the paths that photons take are so straight that only the bends in space caused by gravity or refraction have any effect.
When trying to envision a particle of anything that has mass as pushing its way through a thick syrup, so that the larger the particle the more resistance and viscosity, I must sort of translate the scene from the waves into little balls of various sizes. This cannot be how physics really is, only a particular fantasy image trying to analogize it. Things that are so fundamental cannot really be modeled by things that are so complex. It would be like trying to model Lego blocks using planets and stars.
The laws of physics are not real in the sense that a book is real. Those laws are the descriptions of whatever is happening out here in the real world -- outside of the mental world in the book's content. The laws of physics could be entirely false, so far as our book has them written, yet the world would go on as usual. The world is real, and it works however it works, whether we understand it or not. Because gravity behaves in such-and-such way with matter and time, all the rest of the Universe now exists. It matters nothing whether we really understand how that could ever work -- it does work and here we are.
One cannot say, 'Since I don't understand how the Universe could ever exist, therefore God created the Universe'. That doesn't make any sense at all. Invoking other unsolvable puzzles is not an acceptable way to solve puzzles.
We are all living together in this gravity well of Earth, in the gravity well of the Sun, effected by the gravity wells of all the other bodies in the solar system and ultimately by the gravity well of our entire galaxy, dark matter and all. Although the inverse square of the distance makes the effect of gravity very tiny from long distances, it has whatever teensy effect it has, but sometimes only as much as a single proton might have upon the whole Earth. But the chain reactions of all matter spread through space as an invisible glue must then tie all the Universe together, as tenuous as that might be.