While many physicists and astronomers refer to that unknown mass as subnuclear particles of " dark matter, " others _ like veteran supernova hunter Saul Perlmutter of the University of California's Lawrence Berkeley Laboratory _ hold that some mysterious other force is speeding the expansion of the universe.
22.
As Earth's first visitor to the planet Saturn and the first to discover the nature of the sun's magnetic field, Pioneer's long career in space has ended with new reports on cosmic radiation at the outer edges of the solar system and new data on the wind of subnuclear particles that flow perpetually from the solar surface.
23.
Neutrinos are among the most elusive subnuclear particles because they have no electric charge and little or no mass; the likelihood of any speeding neutrino colliding with an atom along its course through the universe is so remote that nearly all the neutrinos reaching the earth pass right through it, unimpeded by almost 8, 000 miles of solid matter.
