In the Doctor Who episode Father's Day, Rose:

Saves her father from dying in a road accident

This creates a time paradox because that undid her being there in the first place, and doubly so because it also undid her earlier self from traveling back a second time.

But later in the episode, the Doctor warns her that if she touches her younger self, this will also create a paradox.

If so, why doesn't her seeing her younger self create a time paradox? Why is it only touch?

Or is this not a time paradox, just extra weakness to a already weak point in time?

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    I fixed some of the capitalization and punctuation, but the question is still very confusing. What is it you want to know, exactly? Also, why the spoiler block? This is a pretty old episode. Dec 1, 2013 at 4:25
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    @Donald.McLean: “why the spoiler block? This is a pretty old episode.” Only from the point of view of your timeline! Dec 1, 2013 at 12:03
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    @tryingToGetProgramming: “and she only need touch herself” — I think you’re confusing Doctor Who with Secret Diary of a Call Girl. Dec 1, 2013 at 12:07
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    @Donald.McLean i want to know (1) why touching herself causes something to happen, (2) is this thing that happens a time-paradox, or does it cause a reaction only because the reapers are already there, and (3) why doesnt seeing herself cause a similar reaction (whatever the reaction may be). and im not sure exactly when to or not to put spoiler blocks. Dec 1, 2013 at 13:13
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    @Donald.McLean: Maybe. Not so much for an 8-year-old just getting into Doctor Who now. Personally I don’t think spoiler tags cause a problem for people who have seen the episode. Maybe there should be a cut-off though. I don’t know if there’s an agreed position on meta. Dec 1, 2013 at 17:11

2 Answers 2


A paradox in Doctor Who is created when an action occurs that causes future actions to change in a way that makes the current actions impossible. There are tons of examples in the new series' that show when this does and doesn't occur. (An extensive description of Doctor Who paradoxes is found in my answer to this question.)

In Father's Day, when the "second" Rose saves her father from dying, she changes her own past in such a way that she likely never met The Doctor in the first place. Having two parents would have likely changed important factors such as where she lived and where she worked during the time when Rose (the episode) occurred. This is a paradox.

The second time a paradox is created is a lot harder to explain, but I suspect the word "paradox" is being used incorrectly here. The Doctor points out that having two of the same person in the same place "weakens" the fabric of time at that point, so having the touch would logically be even worse. By the time adult Rose touches infant Rose, the paradox is already in place; she has simply made things worse by weakening the already disrupted timeline, allowing the recent past events to "bleed through".

AFAIK we haven't seen anything else like this in future episodes; though there have been cases where other companions met their earlier/later selves, they've never made physical contact that I remember. There have been dozens of cases where different incarnations of The Doctor meet and interact, but in those cases there is usually some external force working to keep the timelines intact, or else (e.g. Time Crash) their meeting is even more catastrophic than the Rose's. The only other possibly-related event we see is when the sonic screwdriver touches an earlier/later version of itself, it always produces a nasty shower of sparks, and a remark from The Doctor about the "temporal disruption" it's causing.

Most other examples of paradoxes occurring in Doctor Who all seem to fit this basic pattern:

  • In The Sound of Drums / The Last of the Time Lords, the paradox happens when future humans come back to kill past humans, who then couldn't exist in the future to come back and kill anyone, etc.
  • In Angels Take Manhatten, the paradox happens when Rory kills himself after watching himself grow old and die as a prison of the Angels, meaning he never became the Angels prison and thus never had a reason to kill himself, etc.

Also note that time seems to be very "flexible" in this regard; there are many more cases of people changing past events, but having those events "repair" themselves, e.g. Waters of Mars, without creating a paradox. The key trigger seems to be when the newly-broken timeline becomes "unfixable" that a paradox happens.


Just seeing someone doesn't matter and won't necessarily create a paradox. There are multiple instances of such or similar events later in the series, some utilizing a fez or other companions.

A paradox describes a situation that essentially prevents itself from happening - or something you can't logically explain or solve.

A simple logical paradox would be something like "This statement is a lie". If that's true, this is a lie as well, so it's not actually the case. But with that being said, this is once again true,...

In this example Rose created the paradox by undoing the reason they went there: With her father alive she never had a reason to go back to that day (and maybe didn't even meet the Doctor in the first place). Due to this this never happened, which - at that point in time - is impossible (since they're there). So they didn't go back in time to save him, which results in him dieing and Rose going back there to rescue him.

Just seeing her former (or future) self won't change anything unless she'd tell herself something that would influence her later decision (e.g. "don't trust the guy with the blue box").

  • if so why does touching herself cause the reaper to enter the church and consume the doctor? Dec 1, 2013 at 13:19
  • That's no paradox as-is. It's just a special constellation if you'd like to call it that way. This by itself, won't cause any significant problems, as is shown in later episodes (series 6; see Michael's last paragraph before the separator). It's more like a "discharge" weakening a shield (the integrity provided by the old walls of the church).
    – Mario
    Dec 1, 2013 at 14:01
  • ok so why doesnt it happen with her younger self seing er older self, once the paradox is already there? Dec 1, 2013 at 14:06
  • The effect is obviously not strong enough to have any significant impact. As with the mentioned sonic screwdrivers touching each other. Nothing happens while they're some space apart. The spark emmits once they touch each other.
    – Mario
    Dec 1, 2013 at 14:11
  • "Everything I say is a lie" is not a logical paradox, it's just a false statement. I think the paradox you were looking for is "This statement is a lie."
    – Martha
    Dec 2, 2013 at 18:32

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