Ludvig

 was a scientist who worked at the same science institute as his friend Von Richter.

As recounted by the Fourth Doctor in one of his time tales, Von Richter spent years working on a time machine in secret. After completing a prototype (which could not be steered accurately but was still held by Von Richter to be "time-worthy"), he showed it to Ludvig, who was appalled that Von Richter's "once-brilliant mind" had fallen so low as to seriously considered an "impossibility" like time travel. Von Richter persuaded Ludvig to give him a chance, and they stepped inside the machine to take it for a test flight.

Though they both experienced a strange feeling, they found, when they stepped out again, that they were in the same era. Convinced that he had been mad to think it might work, Von Richter promised to stick to theoretical work in the future and began to dismantle his machine. However, as the Doctor knew, the machine had actually worked, whizzing through time at great speed for the few seconds it was active — being glimpsed in many eras as a shining object in the sky — before it happened, by coincidence, to land back where it had started, giving the illusion that it had stayed unmoving. (COMIC: Dr. Who's Time Tales)