Is dark matter really needed ?

I didn't know what "Dark Matter" was...so i just Google'd it and from the few results i've read, seems like no one really knows what Dark Matter is, some results talk like it might not exist. Can someone explain it in layman's term for me so i can understand better?

I didn't know what "Dark Matter" was...so i just Google'd it and from the few results i've read, seems like no one really knows what Dark Matter is, some results talk like it might not exist. Can someone explain it in layman's term for me so i can understand better? Shaka5, “Dark matter” is a theoretically created proposition by scientists to try and explain why galaxies spin, rotate and otherwise behave in a manner that does not agree with mathematically calculated predictions.According to scientific calculations, to explain the way galaxies spin, etc., the galaxies should contain some 90... [More]

Thats really interesting, like to know how any experiments turn out.

Wonder if we would realize if someone slowed down the earth??? :P :P

Scientist's can not take back the Unproven Existence of Dark Matter! Do they realize how many T.V. and Movies use Dark Matter as a base for their stories? That's 40 years of Rewriting to do! And what about Tachyons. At faster than light speeds their Mass should be more than enough to equal Dark Matter!

Scientist's can not take back the Unproven Existence of Dark Matter! And what about Tachyons. At faster than light speeds their Mass should be more than enough to equal Dark Matter! Tachyons have no mass, and the more energy they lose, the faster they become. As they have negative mass, the more collisions they have, the more energy they lose, there velocity can become infinate. There's no evidence of Tachyons in the universe today, and they have never been reproduced in laboratories. Although, it's theorised that tachyons existed during the Big Bang, but outside of the universe. Where physics... [More]