Close to the end of "The Girl Who Waited", old Amy Pond says

It's not a teleport, it's a time jump.

and her younger self replies,

They can't shunt within the same timestream.

What is the meaning of that dialogue?

(I do understand that this is Doctor Who, so it is as well possible that it just sounds cool without actually meaning anything, but I suspect there is some clever idea hidden here.)

  • 3
    It means the same think as, "Reverse the polarity of the neutron flow."
    – Buzz
    Mar 18, 2021 at 22:21
  • It's just some of that wibbly-wobbly timey-wimey stuff.
    – Cadence
    Mar 19, 2021 at 1:43
  • I wrote about it - it's possible, but maybe not.
    – mbork
    Mar 19, 2021 at 6:46

3 Answers 3


One of the meanings of "shunt" is a bypass -- electrically, a short circuit is a "shunt" and sometimes a parallel load is, too (think "shunt wound motor" vs. "series wound motor"). In transportation, a "shunt" is like a shortcut, but one that, for reasons, isn't the primary route (you'll see shunt tracks on subway maps, for instance) -- in railroad parlance it's a siding, a second track parallel to the first to allow one train to pass another.

This is the meaning Amy used in "The Girl Who Waited" -- "they can't shunt within the same timestream" is another way of saying, if they time-jump, they cross over to a new timeline; they can't bypass some of time and return to the same "track".


The dictionary definition of shunt that applies here is it means "allow movement".

Timestream refers to personal history. Generally it gets used in Doctor Who in multiple Doctor specials where each Doctor is considered to have his own timestream.

Basically Doctor Who is paradox free except for the personal history of a time traveler. See the 9th Doctor episode Father's Day. Where the 9th Doctor changed his own history and a hole ripped in the universe.

For the rest of us the details of events are constantly drifting in the details with some things being fixed. So The Doctor can step on a butterfly in the past and it won't particularly change anything that wasn't going to be changed by drift anyway. That's why observing time was a full time job for Gallifrey because history is always changing for the rest of the universe.

Amy is pointing out they can't fix the duplicate Amy problem without causing a paradox that would require a serious amount of effort to maintain. A TARDIS can do something like that maybe but it's a full time effort. The Master, for example, converted the TARDIS into a paradox machine when he wiped out humanity with the converted humans Troclafane from year 100 trillion. Time snapped back when it stopped supporting the paradox.

Though this may be a lie by the Doctor- a TARDIS can maintain a paradox - but it is a bad idea.
Also from this episode (a second use of shunt):

DOCTOR: Perhaps, maybe, if I shunted the reality compensators on the TARDIS, re-calibrated the doomsday bumpers and jettisoned the karaoke bar, yes, maybe, yes. It could do it. The TARDIS could sustain the paradox.

  • Thanks, but I hate to say that this doesn't convince me at all. After reading your answer, I came up with my own theory, will be writing another answer shortly.
    – mbork
    Mar 19, 2021 at 6:45
  • I added additional dialog from that episode to support the facts taken from multiple episodes. Mar 19, 2021 at 8:06
  • This seems much more like an answer than a guess, which is what I see in your answer @mbork.
    – Shreedhar
    Mar 19, 2021 at 8:38

OK, so after I gave it a bit more thinking I came up with another theory. How about this?

Rory has seen the Handbots appearing out of nowhere. He's smart, so he figured this may be some kind of a teleport, and his idea is to use the very same technology to get to the TARDIS. However, Amy points out that this is not a teleport, but a "time jump" (whatever a "time jump" is ;-) ), and so if they used that, they would jump out of the current time-stream (where - or when - the TARDIS is right now), and (this is even a longer shot) the whole effort of bringing the two Amys together would even be lost.

Of course, how would Amy know that is unknown, but even the young Amy has been at Two Streams for some time now (at least a week!), so she might have learned that from the Interface or her own observation (she's very clever, too!).

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