Eight Keys to Eden by Mark Clifton — Read

In the early dawn, out at the hangar, away from the main E buildings and the endless discussions going on inside them, Thomas R. Lynwood moved methodically through his preflight inspection.

Speculative thinking was none of his concern. His job was to pilot an E wherever he might want to go, and bring him back again -- if possible. To Lynwood reality was a physical thing -- the feel of controls beneath his broad, square hands; the hum of machinery responsive to his will. He liked mathematics not for its own sake but because it best described the substance of things, the weight, the size, the properties of things, how they behaved. He was too intelligent not to realize mathematics could also communicate speculative unrealities, but he was content to wait until the theorists had turned such equations into machines, controls, forces before he got excited.