Crossing Times, Time Gains and Station-Keeping in a Wormhole Shortcut

A wormhole whose mouths sit one astronomical unit apart replaces an external light-travel time of 499.0 seconds with a through-throat crossing of 3.336e-04 seconds at one tenth of light speed over an assumed ten-kilometre internal path, a gain of 1.50e+06. For mouths separated by the distance to Proxima Centauri the external signal time is 1.379e+08 seconds and the gain rises to 4.13e+11. At nine tenths of light speed the traveller's clock runs slow by a Lorentz factor of 2.29 relative to the mouths. The arithmetic of the shortcut is therefore not the problem: it succeeds by six orders of magnitude on the shorter baseline and by nearly twelve on the stellar one. The burden the numbers expose is station-keeping, because a shortcut this effective converts small relative drifts of the mouths into large fractional errors in arrival time and aim. Computed from stated assumptions, not measured.