What are dark matter and antimatter?

According to my husband, who attributes his vast store of knowledge to having taken "The 5-Minute Course In How to Know Everything," dark matter is part of an equation developed by astrophysicists, who posit that the universe appears to be expanding more rapidly than can be accounted for by visible/detectable matter, and this expansion must therefore be caused by "other" matter that cannot be visibly or otherwise detected, and the origin of which is not known at this time.  They have termed this unexplained matter, "dark matter." As regarding anti-matter: an atom is comprised of protons (which have a positive charge), neutrons (which as their name suggests have a "neutral" or no charge), and electrons (which have a negative charge.)  Protons, neutrons and electrons which have been altered to have their opposite charge (these would be negatively-charged protons or anti-protons; anti-neutrons; and positively charged electrons or positrons) are termed “anti-matter,” which has been described as a mirror image of matter. In an experimental situation such as a particle accelerator, if an anti-matter particle is collided with its counterpart of a normally-charged particle at a speed approaching that of light, they annihilate each other in an explosive conversion of matter being released as energy, more powerful than a classic atomic explosion–BUT, for human observation purposes this has only been achieved on a tiny scale, as it has not been possible to get larger groups of opposing particles together for a bigger collision.  This type of explosion, on a universe-sized scale, is theorized to be of a magnitude capable of producing a "black hole," which is why so much (unfounded) adverse publicity and public fear was generated in October of this year in the experimental start-up of the Large Hadron Collider in Switzerland, amid numerous protests all over the world and a number of legal attempts to prevent the start-up. 11.26.08