How is it that neither of the Doctors knew what to do in the end of the Children in Need Special ‘Time Crash’ from 2007?

They both just threw it off as a timey wimey instance of the younger Doctor already seeing what the older Doctor did therefore he remembered when he was the older Doctor to do what the older Doctor did when he was the younger Doctor (ouch).

But how does that explain the paradox?

Someone had to know what to do? No?

  • Jeff's answer is correct. Something many people seem to overlook is that Doctor Who plays with all sorts of time travel scenarios however is convenient for the current story (sometimes with in-universe excuses, other times not). So the fact that Stable Time Loops are frequently averted in Doctor Who doesn't mean that they can't/won't be used or aren't valid scenarios. That's part of what wibbly-wobbly hints at -- viewers have all sorts of preconceived notions about the linearity of cause and effect, but it is just too complicated to make easy hard-and-fast rules about all timelines.
    – PeterL
    Commented Oct 4, 2013 at 19:09
  • 1
    @PeterL: Even the episode which introduced the "ball of timey-wimey STUFF" features (at its core) a stable time loop. Hell, it featured minor stable time loops within the larger stable time loop.
    – Jeff
    Commented Oct 4, 2013 at 19:52
  • Yeah, for sure, they use it a few times; they have in the older series as well (like in "The Visitation"). Other times they have shown changes to the past to not create stable time loops (e.g. "The Name of the Doctor"), cause damage until "fixed" ("Father's Day"), or events forcibly correct around a fixed point ("The Waters of Mars"). I just see a lot of questions around Who (here and elsewhere) where there seems to be an assumption that time travel follows certain hard and fast rules about how time loops work -- in Who, they are very flexible to the needs of the writer. :)
    – PeterL
    Commented Oct 4, 2013 at 22:10
  • @PeterL: and if the writer is Steven Moffat, as it was for ‘Time Crash’, you’re pretty much guaranteed to have a stable time loop in there. (See also ‘Blink’ and ‘The Big Bang’.) Commented Dec 8, 2013 at 23:55
  • @PeterL: and the 2011 Comic Relief shorts Space and Time. Commented Dec 16, 2013 at 23:45

1 Answer 1


For simplicity, I will refer to the Doctors by their numbers (5 & 10).

10 is in the TARDIS, preforming some routine maintenance. He has his temporal shields down, because the maintenance seems to require it.

Because Time is less than stable relative to the Doctor, especially given he's in a TARDIS (5 & 10 both) a slight malfunction in 10's work pulls 5 forward for a short time and causes the 'Belgium' problem.

At this point, 10 realizes that this is the event he recalls from when he was 5. If he has an eidetic memory, he then acts exactly as he had seen himself act. 5 watches and hears what 10 says (which is somewhat nonsensical to us, but would make sense to the Doctor, especially given time to think it over).

10 quickly solves the 'Belgium' problem, and gets to have a heart-to-heart with his younger self, though he's careful not to give away anything too terrible. He mentions the Master, but only in passing.

If he does NOT have perfect memory, as 10 seems to indicate, 5 will have more than adequate time, given a complete overview of the steps involved to figure out the theory so that he'll be able to recreate it when the moment comes.

There is no paradox here - it is a Stable Time Loop. Granted, the information from the future only exists because it was seen in the past, but the Doctor (both 10 and 5) explains how that happened: Wibbly, Wobbly, Timey-Wimey.

Warning: All links are to TVTropes. TVTropes articles which prominently feature The Doctor. You already clicked, didn't you? You poor, damned fool.

  • 3
    Please put the TVTropes warning BEFORE the goddamn links in future answers. Thank you.
    – Saturn
    Commented Oct 5, 2013 at 9:16
  • 2
    @Omega: I'm sorry, so, so sorry.
    – Jeff
    Commented Oct 5, 2013 at 17:29
  • Needs a reference to bootstrap paradoxes :-)
    – Rand al'Thor
    Commented Feb 16, 2016 at 13:01

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