Doctor Who's 2024 Christmas Special Quietly Explains A Major Part Of Jack Harkness' Origin Story

Warning: Spoilers ahead for the 2024 Doctor Who Christmas special, "Joy to the World."

"Joy to the World" adds a massive piece of canon into the Doctor Who universe that subtly explains one of the abilities of John Barrowman's Captain Jack Harkness. Although the story of the 2024 Christmas special sweeps aside its pivotal piece of sci-fi lore, the magnitude of the introduction and its impact on the larger universe can't be ignored. As one of the best Doctor Who companions not from present-day Earth, Jack brought something very interesting to the position, but his pre-installed backstory left some intriguing gaps. Thankfully, one of the more compelling blank spots has now been partially filled.

Barrowman played Jack during Russell T Davies' first stint as the Doctor Who showrunner, and he enjoyed a brief return to the role alongside Jodie Whittaker's Thirteenth Doctor during the Chris Chibnall era. Perhaps most significantly, he led the Torchwood cast between 2006 and 2011 in all four seasons of the first of the revival-era Doctor Who spinoffs. He has been absent from Doctor Who's Disney era due to behind-the-scenes issues, but "Joy to the World" proves there is still a lot to be learned about the former Time Agent.

The Time Hotel In "Joy To The World" Confirms Humanity Has Access To Time Travel By The 43rd Century In Doctor Who

The Doctor has almost no need for his TARDIS in the 2024 Christmas special

Ncuti Gatwa's second festive adventure as the Fifteenth Doctor takes him through several periods of Earth's history. Of course, this isn't anything new for Doctor Who, but it becomes interesting when it's considered that he largely refrains from using his TARDIS in "Joy to the World," and instead uses the Time Hotel - which is located on Earth in the 43rd century. It may seem like a fun and exciting gimmick - which it is - but writer Steven Moffat's introduction of the Time Hotel brings with it a big reveal about humanity's temporal development.

As recently as Doctor Who's season 14 two-part finale, the Doctor quietly confirmed he monitors humanity's access to time travel and has tried to ban UNIT from developing the relevant technology. However, Doctor Who's new UNIT team in the 21st century is revealed to have built a Time Window to allow them to view the past. It's primitive by Time Lord standards, but it's still a step towards humanity's access to times other than the present day. This progress has clearly carried on by the time of "Joy to the World," as proven by the Time Hotel in 43rd-century London.

Doctor Who's 2024 Christmas Special Brilliantly Adds A Stepping Stone To How Jack Harkness Can Travel Through Time In The 51st Century

Jack's Vortex Manipulator suddenly doesn't seem like such a huge leap

Despite running into Christopher Eccleston's Ninth Doctor in 20th century London in Doctor Who season 1, Jack originates from the 51st century, and he's revealed to be a former Time Agent. His time with the Time Agency is proven by the fact he still owns a Vortex Manipulator - a wrist-worn device that allows him to travel through time. Before "Joy to the World," there was a huge period between the 21st century and Jack's native era that failed to explain how he, a human, could so confidently traverse time. Now, the Time Hotel provides a major milestone in humanity's advancement.

The Doctor looks down on the Time Agency for their method of transport, but Vortex Manipulators have been proven on more than one occasion to be able to move people through space as well as time.

The Doctor looks down on the Time Agency for their method of transport, but Vortex Manipulators have been proven on more than one occasion to be able to move people through space as well as time. The Time Hotel also shares both abilities, as the rooms in the building lead to locations all over the Earth's surface as well as in various periods of the planet's history. So, at some point between the 43rd and 51st centuries, that building-sized technology becomes compact and advanced enough to wear on a wrist strap and be used by characters like Jack Harkness.

Humans On Earth Having Access To Time Travel Is A Huge Addition To Doctor Who Canon

Those on Earth can now hop through time whenever they like (if they can afford it)

Guests lingering in the lobby of the Time Hotel in the Doctor Who episode "Joy to the World." — The lobby of the Time Hotel in Doctor Who

Jack's connections with the Time Agency have long proven that humanity would eventually gain the ability to travel to the past and the future. However, Barrowman's character didn't grow up on Earth. Instead, he lived in a human colony on an unnamed world, although it has been revealed that he lived in a specific region on the planet's surface, called the Boeshane Peninsula. So, time travel technology had often been implied to be limited to certain sects of humanity - like the Time Agency, and it therefore had almost nothing to do with Earth.

Additional Doctor Who media, like comics and novels, have mentioned the Time Agency and eras close to Jack's, but the canonical nature of these arcs is questionable as they generally haven't been addressed in the main show or its spinoffs - like Torchwood. Therefore, "Joy to the World" is the first solidly canon Doctor Who story to openly address not just humanity's access to two-way time travel tech, but the humans specifically located on Earth.