At the end of series 9 episode 11, Heaven Sent,

the Doctor discovers that in order to escape the prison he's been put into, he must live through the same short period (it's not clear how long, but probably at most a few days) billions of times, resetting his body at the end of each iteration to the same state it started in.

So how old is he at the end of the episode? Clearly

his body has only aged at most a few days,

but what about his memories? Does he recall

all those billions of iterations of the same short period?

Is there any sense in which he's now

four and a half billion years old?

  • Oh, I was waiting for this one. +1. Does he REALLY remember every iteration of the cycle?
    – tilley31
    Dec 1, 2015 at 1:10
  • I tried to ask that question, but the spoiler tag didn't work...ended up deleting it. Guess I'll try later.
    – tilley31
    Dec 1, 2015 at 1:18
  • 1
    @tilley31 Fixed it for you!
    – Rand al'Thor
    Dec 1, 2015 at 1:20
  • 1
    @tilley31 You may want to turn your question (+1, btw) into an answer to this question. That's a pretty definitive statement that he does remember, although Politank-Z's answer also provides good evidence that he doesn't. It's weird and contradictory...
    – Rand al'Thor
    Dec 1, 2015 at 1:27
  • Link for easy reference. Anyway, it's not contradictory: he remembers, but only at the end when confronted with the azbantium, which triggers his memory. Somehow.
    – Mr Lister
    Dec 1, 2015 at 8:22

3 Answers 3


All indications are that The Doctor

started each cycle in the same state: believing that he had arrived, for the first time, directly from Earth. Every time he noted the passage of time from his reading of the stars, he had the same expression of confusion or disbelief. He had to rediscover his surroundings each time.

There is one sense in which

his true age is in the billions of years: the cumulative copies of him did toil away for all that time. He is aware of this fact; however, the knowledge is not first-hand. From chronological aging of his body and first hand experience, he is exactly one cycle older then when was he teleported to the castle for the first time.

All of this is, of course, subject to contradictory revelations, but there was nothing in the episode which clearly indicates otherwise.

  • “there was nothing in the episode which clearly indicates otherwise” — there is some dialogue that might suggest otherwise. Dec 1, 2015 at 8:58
  • 1
    Indeed, but if that proves out, it involves elements not yet revealed. He says he remembers, but he doesn't say exactly what he remembers. I would say that he is remembering the combination of incidents from his childhood and clues from the castle to lead him to understand his predicament, and how long versions of him have been stuck in it. This is a story in progress, though, so I freely accept that my interpretation is largely conjectural.
    – Politank-Z
    Dec 1, 2015 at 17:52
  • oh I’m with you. I don’t think it really makes sense for him to literally remember, although one can certainly imagine the Doctor understanding how long he’s been there on a level deep enough to be similar to remembering. Capaldi’s emotion when saying the words certainly has force. Dec 1, 2015 at 18:28
  • 2
    Best season since Eccleston, says I.
    – Politank-Z
    Dec 1, 2015 at 18:29
  • 2
    He needs to last long enough to anchor a Neil Gaiman episode. Those made Smith shine, imagine what Capaldi could do with such material.
    – Politank-Z
    Dec 1, 2015 at 18:48

We know that the 12th doctor is somewhere between 2000 and 3000 years old when Heaven Sent begins.

HE then spends 4.5 billion years there, making copies of himself every time he knows he will die. (A week for each one seems plausible.) Some people may argue that therefore he only aged a few days, but I want to look further at the copies.

He ages a week, makes a copy that is the same age. That copy then ages a week and makes a copy that is therefore 2 weeks older than the doctor when he first arrives. So, we can conclude that the the copies are the same age as the doctor, and therefore he really did age around 4.5 billion years.

  • 6
    I disagree that the doctor is making a copy of himself as he is at the end of the cycle. He is making a copy from the buffer of the teleporter. The copy will be as old as he was the the first time he stepped out of the teleporter..
    – Blackwood
    Dec 10, 2016 at 14:19
  • 4
    @Blackwood is correct. From the transcript: "The room has reset, returned to its original condition when I arrived. That means there's a copy of me still in the hard drive. Me, exactly as I was, when I first got here, seven thousand years ago."
    – Rand al'Thor
    Dec 10, 2016 at 16:11

Each doctor was literally a different doctor. A clone, if you will. The Doctor is the same age at the end of the episode as the beginning. In the scene where the Doctor continued the cycle, he literally says he is “Burning the old me, to make a new one.”

  • 1
    This answer would be a lot more persuasive if you edited it to include some supporting evidence. May 9, 2022 at 0:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.