Scientists at the University of Oxford have studied how dark matter behaves differently in small galaxies and large clusters of galaxies. In the smaller ones the dark matter seems to be attracted to itself quite strongly, while in large galactic clusters this doesn't seem to be the case. Joseph Silk and his colleagues from the University of Oxford say strongly interacting dark matter should produce cores of dark material bigger than those that are actually there in the large galactic clusters, as deduced from the way the cluster spins.
One explanation is that there are three dimensions that alter the effects of gravity over very short distances of about a nanometre.
The team argues that such astronomical observations of dark matter provide the first potential evidence for extra dimensions. Others are supportive, but unconvinced. Lisa Randall, a Harvard physicist who has explored the possibility of extra spatial dimensions, says "Even if their idea works, which it probably does, it may be an overstatement to use these observations as evidence of extra dimensions."
Read on at Nature to learn more about this subject.