Thursday, 25 April 2013
"...involved giving the whole ship negative mass...Only a physicist who knew Dirac holes well enough to call them 'Pam' would have thought of the notion...'" (p. 63)
It took me a long time to learn that Paul Dirac's initials were PAM.
The physicist, Gordon Arpe, who thought of the negative mass drive did not know Dirac holes as well as he thought. His idea was that the ship, no longer a material object, would accelerate away from Earth, surpassing the speed of light. Instead, unable to exist in the positive mass macrocosm, it collapses into the microcosm where, having some of the properties of a Dirac hole, it is echoed by an electron elsewhere in the universe so that, when it is returned to positive mass and thus to the macrocosm, it re-enters the macrocosm at its other location much further away from Earth than intended, so far away that locating the Sun is problematic.
The ship can cross interstellar distances by jumping in and out of the microcosm but expands and loses air with each jump so that it soon becomes unreuseable. Another means of interstellar travel has to be found. This story could easily have been written as a comedy.
The ship's passengers include the planetary explorer Hammersmith so the story "Beep"/The Quincunx Of Time, referring to a planet called Hammersmith, can be regarded as a sequel. In "Beep"/Quincunx, electrons echoing each other are used not for interstellar travel but for instantaneous communication by means of the Dirac transmitter which is found to receive all such messages transmitted from any point in the four dimensional continuum, past, present or future.
Thus, Blish fully explores every possible fictional application of Dirac holes.