# Dark Matter **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [November 21, 2012, 4:54pm UTC](https://boards.straightdope.com/t/dark-matter/641730 "2012-11-21T16:54:06Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [November 21, 2012, 4:54pm UTC](https://boards.straightdope.com/t/dark-matter/641730/1 "2012-11-21T16:54:06Z")
What if we’re the ghosts in the real universe? The real universe is happily chugging along with the scientists of the real universe trying to figure out why their calculations predict about 20% more matter ought to exist than what actually does. Little do they know, we’re that 20%, happily living our lives while occupying the exact same space at the exact same time as they are, each of us oblivious to the other because our particles don’t ever bump into theirs. Spooky! ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [November 21, 2012, 5:00pm UTC](https://boards.straightdope.com/t/dark-matter/641730/2 "2012-11-21T17:00:34Z")
See, there’s a simple explanation for everything. We have to stop overthinking these things. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [November 21, 2012, 5:55pm UTC](https://boards.straightdope.com/t/dark-matter/641730/3 "2012-11-21T17:55:46Z")
We Are Spirits in the Material World? ---
**Author:** ![MegaBee](https://avatars.discourse-cdn.com/v4/letter/m/f0a364/32.png) [@MegaBee](https://boards.straightdope.com/u/MegaBee)\ **Post date:** [November 21, 2012, 6:05pm UTC](https://boards.straightdope.com/t/dark-matter/641730/4 "2012-11-21T18:05:44Z")
What if the Ghostbusters are busting US? ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [November 21, 2012, 6:54pm UTC](https://boards.straightdope.com/t/dark-matter/641730/5 "2012-11-21T18:54:32Z")
We are IN the real universe withOUT being able to detect others IN the same space? Boy do we have a thread for you. In Great Debates…countdown to infinity in 42 seconds… > **[Calling all Great Minds: The Theory of Everything](https://boards.straightdope.com/sdmb/showthread.php?t=672144)** > > Calling all Great Minds: The Theory of Everything The Theory of Everything Premises: We don’t see in three-dimensions, we see in two-dimensional surface area. We can only see the OUT sides of objects. What we call dimensions are determined by... ---
**Author:** ![MegaBee](https://avatars.discourse-cdn.com/v4/letter/m/f0a364/32.png) [@MegaBee](https://boards.straightdope.com/u/MegaBee)\ **Post date:** [November 21, 2012, 7:46pm UTC](https://boards.straightdope.com/t/dark-matter/641730/6 "2012-11-21T19:46:00Z")
> [@Dallas\_Jones](#): > > We are IN the real universe withOUT being able to detect others IN the same space? > > Boy do we have a thread for you. In Great Debates…countdown to infinity in 42 seconds… > > [Calling all Great Minds: The Theory of Everything - Great Debates - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=672144) Holy crap. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [November 21, 2012, 8:55pm UTC](https://boards.straightdope.com/t/dark-matter/641730/7 "2012-11-21T20:55:30Z")
> [@MegaBee](#): > > Holy crap. Holy Crap! Not just for the thoroughly. . . uh . . . _unconventional_ OP there, but even more so for the 11 pages of discussion therefrom arising! This is going to surpass the famous [.999=1 thread](http://boards.straightdope.com/sdmb/showthread.php?t=32760)! ---
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [November 22, 2012, 12:52am UTC](https://boards.straightdope.com/t/dark-matter/641730/8 "2012-11-22T00:52:09Z")
> [@Dallas\_Jones](#): > > We are IN the real universe withOUT being able to detect others IN the same space? > > Boy do we have a thread for you. In Great Debates…countdown to infinity in 42 seconds… > > [Calling all Great Minds: The Theory of Everything - Great Debates - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=672144) I don’t belong in that thread. I’d be the guy eagerly raising his hand and saying “ooh, pick me!” while everyone else in the class is saying “shut up dude, we all just want to go home!” ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [November 22, 2012, 2:46am UTC](https://boards.straightdope.com/t/dark-matter/641730/9 "2012-11-22T02:46:14Z")
> [@Mosier](#): > > What if we’re the ghosts in the real universe? > > The real universe is happily chugging along with the scientists of the real universe trying to figure out why their calculations predict about 20% more matter ought to exist than what actually does. Little do they know, we’re that 20%, happily living our lives while occupying the exact same space at the exact same time as they are, each of us oblivious to the other because our particles don’t ever bump into theirs. > > Spooky! Shadow matter _aka_ [mirror matter](http://en.wikipedia.org/wiki/Shadow_matter) is what you are thinking of. ---
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [November 22, 2012, 3:04am UTC](https://boards.straightdope.com/t/dark-matter/641730/10 "2012-11-22T03:04:11Z")
> [@Der\_Trihs](#): > > Shadow matter _aka_ [mirror matter](http://en.wikipedia.org/wiki/Shadow_matter) is what you are thinking of. From the little bit I could understand of that article, that seems like exactly what I’m thinking of. So, let’s say this stuff exists, and it’s all over the place. It’s forming stars and planets and galaxies that we’ll never see, except we still experience the gravity from it. Some of it will even form black holes, but since gravitational effects are pretty much the only way we can detect black holes in the first place, we’d never know if a particular black hole is made of dark matter, or “real” matter! In fact, two black holes, one “dark” and one “real” could end up taking up the same space, and multiplying the gravitational effects of each other. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [November 22, 2012, 10:49am UTC](https://boards.straightdope.com/t/dark-matter/641730/11 "2012-11-22T10:49:34Z")
My understanding is that in general, evidence indicates that dark matter does not interact with itself in the way that matter does. When galaxies collide, there are gravitational interactions due to mass. However, particles that collide also interact, adding an additional component to the interaction (glowing gas, changes in energy and direction). Evidence from galactic collisions seems to show (we can only infer dark matter behaviour) that the dark matter halos interact in a purely gravitational sense and that other interactions are minimal. The halos appear to move through each other while the non-dark mass slows down and heats up. The still moving dark matter halos are revealed by the gas they do drag with them. This would tend to support the WIMP (Weakly Interacting Massive Particle) hypothesis, and counters the MACHO theory (in such a collision, compact massive objects would interact and heat up, revealing themselves). However, we have a long way to go before we can be sure about anything relating to dark matter. Si