Such an offset is predicted during collisions if dark matter interacts with forces other than gravity, potentially providing clues about what the substance might be. (sciencedaily.com)
It is known to be very homogeneous, not very dense and is not known to interact through any of the fundamental forces other than gravity. (sciencedaily.com)
Held in a shielded vacuum enclosure within the spacecraft, the cubes should feel essentially no outside forces other than gravity. (scientificamerican.com)