Dark matter

Either advertently (in which case he's either keeping his cards close to his chest, or else perhaps he assumes it's blindingly obvious) or inadvertently, Al Reynold's new (Clarke shortlisted) novel House of Suns provides one possible explanation for dark matter. Maybe it's ordinary matter but we just can't see it; and maybe we can't see it because some form of FTL link, such as a wormhole, connects us and it. To preserve causality, the passage of information--like photons--between it and us would have to stop. I don't know (I don't believe) anybody has yet proposed that explanation for the universe's missing mass.