Over the years our scientists have done a lot of analysis of our universe. One thing they've noticed is that there's not as much visible matter in our galaxy as there "should" be on paper. The math of galaxy formation and our flat galactic plane all suggest a much more massive universe than we can see. So where is that mass?
Dark Matter is a catch-all term for mass that doesn't show up in our telescopes. There's many competing theories of what Dark Matter is, and why we can't see it. These explanations range from tiny subatomic particles to massive clusters of collapsed stars. In all likelihood, it's a mix of several types.
Dark Matter isn't so much a coherent category, it's more like an expression of things we don't yet understand. In that way discussion of "Dark Matter" is a bit like labeling a map with "Terra Incognita", "Parts Unknown", or "Here Be Dragons". The various types of Dark Matter are united only in that they are hypothesized to exist naturally, they are Invisible or at least very difficult to detect, and they have mass.
There's likely to be five times as much dark matter as normal matter in our universe. In fact, the universe may be composed of 74% Dark Energy, 22% Dark Matter, and just 4% conventional matter. On the other hand, Dark Matter might not even exist.
Dark Matter increases the gravitational effects holding galaxies together. In this regards, it's sort of the opposite of Dark Energy - which pushes galaxies away from each other and make the universe expand.
possible Dark Matter subtypes:
- Cold Dark Matter
- Daemons in astrophysics
- Dark Matter Halo
- Hot Dark Matter
- Light Dark Matter
- Mirror Matter
- Scalar Field Dark Matter
- Self-Interacting Dark Matter
- Warm Dark Matter
Alternatives to the Dark Matter hypothesis:
- Dark Fluid is a sort of space storm front that could account for the effects ascribed to both Dark Energy and Dark Matter
- Modified Newtonian Dynamics aka MOND
- Nonsymmetric Gravitational Theory has lead to some Modified Gravity proposals
- M-Theory suggests that multi-dimensional forces outside our universe may have gravitational affects that just "look" like Dark Matter to our math.
Game and Story Use
- Adventure Seed: Ogres of the Ice World
- Dark Matter can serve as Phlebotinum or spaceship fuel.
- Dark Matter can form an invisible a Navigational Hazard or Interstellar Terrain
- Dark Matter may play a key role in this week's Negative Space Wedgie
- Dark Matter may prove to be the key to inventing Invisibility technology or Stealth In Space.
- An Alloy of dark matter and exotic matter would not interact with light or radiation, and would have properties of antigravity. Of the four fundamental forces of the universe, it inverts one and ignores another.
- If Dark Matter doesn't exist, it means there's some fairly large errors in our current scientific model of the universe. That's one frighteningly big can of worms. FTL, Time Travel, Antigravity, who knows what's possible in a universe where all our math and science are flawed? Hint: Whatever you want in your game is what's possible. This is a flimsy hand wave over some very soft science, but it may make various types of alternative science seem more realistic.