The Doctor (Doctor Who) Time Lords a fixed number of twelve regenerations, meaning that every Time Lord had a total of thirteen incarnations including the original. The plot of "The Time of the Doctor" involves the Doctor receiving a new cycle of regenerations from the Time Lords before his expected demise, triggering the regeneration into the Twelfth Doctor, played by Peter Capaldi. The origins of the programme were explored in the docudrama "An Adventure in Space and Time" as part of the 50th anniversary celebrations of "Doctor Who", which starred David Bradley as William Hartnell. Although Time Lords resemble humans, their physiology differs in
Space and Time (Doctor Who) glass floor surrounding the console and becomes distracted by Amy's short skirt, causing him to drop the thermal couplings he was holding. This causes the three to be stuck in a "space loop" where the TARDIS materializes inside of the TARDIS. "Space" and "Time" were filmed in two days alongside the sixth series DVD "Night and the Doctor" extras "Bad Night" and "Good Night". The episodes are intended to show what life aboard the TARDIS would be like. Several editing techniques and doubles were used for the various shots where there were more than one of the same character on