51.   In one sense, the results only deepen the mystery of the dark matter.

52.   In simulations by supercomputers, the models with neutrinos alone or cold dark matter alone failed to lead to the construction of a universe looking like it does today.

53.   Just getting a measure of ordinary dark matter is reassuring to cosmologists.

54.   Many physicists believe the dark matter will turn out to be swarms of particles predicted by their theories but not yet detected directly in particle accelerators here on Earth.

55.   Much more of the missing mass, physicists think, could be something more exotic and sluggish, which they call cold dark matter.

56.   More elusive than dark matter is this phantasm called mathematics.

57.   Neutrinos, a form of the faster-moving hot dark matter, are everywhere.

58.   Now, though, we seem to have dark matter on our radar screens.

59.   One of the most fruitful places to hunt down dark matter is in the clouds of hot X-ray-emitting gas that fill large clusters of galaxies.

60.   One possible solution is to assume that the dark matter particles are self-interacting, bouncing off each other occasionally like billiard balls through some other force.