"Investigation," he said. "You're a darned good librarian, Rhine. You tabulate and I'll try to juggle it out." Rhine went to the draftman's table and sat down. "I've maintained all along that the Lawson Radiation was the by-product of faster-than-light travel," he said. "Ignoring the argument of aliens and such, we have good evidence at present. There is a body of negative mass approaching Terra. This negative mass is approaching Terra at a velocity not only exceeding the velocity of light but traveling several hundred times the velocity of light." He paused. Then he sat down--hard. "What's the matter?" she asked, seeing the look of consternation on his face. "The photographs," he said bleakly. "Yes?" "Can a rifle bullet traveling faster than sound be heard before it arrives?" he asked enigmatically. "No." "Then a body traveling faster than light cannot be seen before it arrives! Those pictures show a region of the sky and a few stellar catastrophes that took place years ago when the light left there unless--" "Unless what?" "Unless the telescope made of the teleport mirror effect utilizes a type of radiation that propagates faster than light." Rhine nodded. "If celestial bodies can travel faster than light," she said, "it stands to reason that some form of energy can travel faster than light also. After all, matter is one form of energy." Carroll smiled quietly. "This is negative matter," he said. "And so far as I have been able to calculate, the only thing that can avoid the Einstein increase in mass with increase in energy would be some object having negative mass. But negative mass is as meaningless a term as negative energy." "A gentleman by the name of Dirac got the Nobel Prize for postulating states of negative kinetic energy," said Rhine. "The positron," nodded Carroll. "Then it must make sense." "It does. A normal body possessing energy tends to dissipate that energy by transferring the excess to other bodies possessing less than it does. A body possessing negative energy would demand that energy be applied to it in order for it to acquire a state of energy equilibrium. "The positron, according to Dirac, is a state of negative kinetic energy which is satisfied only when the energy of an electron is applied to it. In the process known as 'pair-production', where hard gamma strikes matter and releases an electron and a positron, it is actually a case of separating the electron from its positron, leaving in effect a 'hole' in the level of energy. "It is a man whose bills are not paid but are merely covered by written and certified checks. Send away one check and you have a debit in the man's account. The positron is satisfied very quickly, however, since there is a large excess of free electrons to fall into place.