Please DO NOT add to this discussion.
We know that travelling "sideways in time", into other universes and dimensions, was definitely possible in the classic series. A very good indication of this is "Battlefield", where knights from a parallel continuum cross over into the Doctor's reality, once in the Dark Ages (when King Arthur dies), and again in contemporary times (Ancelyn, Morgaine, etc). It's also strongly implied that at some point in his future, the Doctor will travel into the Arthurian dimension and become known as Merlin. But in the new series, it's been stated that following the Last Great Time War, dimensional barriers around our universe (and possibly others) have sealed, making inter-dimensional travel nigh impossible in all time zones throughout history. So if these barriers are in place, how did all that dimension-hopping in "Inferno" and "Battlefield" occur? And I know it isn't strictly speaking canonical, but what about the Seventh Doctor's interactions with Death's Head, a cross-dimensional traveller, in the DWM comic strips? It should be noted that in one issue of Death's Head's regular series, the Doctor briefly went to the Marvel Comics universe. So how does all of this tie in with the Time War, and inter-dimensional travel being impossible for everyone, everywhere? EJA 09:49, April 9, 2011 (UTC)
The same reason that I've given you for the last two questions that you asked. The walls of the universe were sealed after the Time War. Inferno and Battlefield both occured before the Time War. The Timelords are gone now, but they weren't erased from existence. They still used to exist, even though they don't exist in any time now. It is easiest to understand if you look at Timelord history from the Doctor's point of view. When we see the first seven Doctors, who haven't fought in the Time War yet, the Time War hasn't happened yet, and its effects are not felt. When we see nine through eleven, he has fought in the Time War, the Time War has happened, and its effects are felt.Icecreamdif 14:48, April 9, 2011 (UTC)
Will the Doctor still travel to Arthur's world and become that reality's Merlin at some point in his personal future though? And did Ancelyn and Morgaine still cross over to our world after the Time War? Sorry, but I just find all this a bit confusing. EJA 20:43, April 16, 2011 (UTC)
He's already done the Merlin thing in One Fateful Knight. --Revan\Talk 20:48, April 16, 2011 (UTC)
Maybe so, but did the events in "Battlefield" still occur from the perspective of the rest of the universe after the Time War? The way I see it, the War rewrote history so that, as far as the rest of the universe is concerned, it's never been possible to travel to other realities. This would retcon the events of "Battlefield" out of existence, as if the walls of reality are sealed across all of time and space, neither Arthur nor Morgaine could've slipped through. The Doctor will still remember those events, being a being "outside" of time, but no one else will. Remember, it's not just the post-War Doctor who can't travel to other dimensions, it's anyone else, and not just in his home universe either. EJA 21:06, April 16, 2011 (UTC)
The Timelords weren't wiped from existence, they were just all killed at the end of the war. If episodes involving interdimensional travel were wiped from history, the Doctor wouldn't have found out that the Stahlman drilling project was dangerous in Inferno, and the entire world would have been destroyed in the 1970s(or 80s). Before the Timelords were destroyed interdimensional travel was possible. Their destruction doesn't rewrite history to make interdimensional travel impossible, and the Doctor could have easily crossed universes and become Merlin offscreen before the Time War. I haven't seen Battlefield in a while, but from what I remember the implication was that the Seventh Doctor became Merlin, so that probably happened in the gap between Survival and the TV Movie.Icecreamdif 01:31, April 17, 2011 (UTC)
"Battlefield" strongly implies that the Doctor who visited Arthur's world is another regeneration, in the Doctor's future. Ancelyn and Mordred did not recognise the Seventh Doctor by his face, but by his manner, and when Mordred was reporting to his mother, he told Morgaine "[Merlin] has a new countenance." To which Morgaine responds "He has worn many faces." The people of Arthur's world have knowledge of regeneration, and it's entirely possible that the Doctor's time as Merlin spans several incarnations of himself. The Doctor may well have done his Merlin routine prior to the Time War, in his eighth or ninth incarnations, but I still wonder if this period of his life is still in his future, as of his eleventh self. And I've also just remembered that during "The Stolen Earth/Journey's End", wasn't it implied that the ease with which Rose and co. were able to hop between realities was somehow due to Davros' setting off the Reality Bomb, which was actually averted by the Tenth Doctor and his companions? EJA 09:25, April 17, 2011 (UTC)
I also feel it's important to note that "Battlefielf" itself clearly shows that the Doctor's future has already happened, he just hasn't experienced it yet in his personal timeline. By that reckoning, the Time War would also have already happened during the events of that story, and would already have concluded. So logically, any fundamental changes it wrought on the structure of space/time would already be felt. EJA 09:29, April 17, 2011 (UTC)
If the Seventh Doctor wasn't Merlin, it could easily have been the Eigth Doctor, from before the Time War. During the Stolen Earth and Journey's End interdimensional travel was possible because the reality bomb caused all universes to collapse, so the walls of the universe were damaged. Once the Doctor-Donna stopped Davros from using the bomb, the bomb was never launched, so the walls of the universe never collapsed. It was also during this time that the Cybermen escaped the void. In Battlefield, the Doctor's future hadn't happened yet, but it was going to happen. Its the same concept as when the Second and Sixth Doctors ran into eachother in The Two Doctors. The Second Doctor hadn't regenerated yet, but he was going to in the future, and with all the time travelling he did he ran into himself. It's also the same with River Song. In Silence in the Library/Forest of the Dead the Doctor hadn't met River yet, but he was going to in his future. In Battlefield the Doctor hadn't become Merlin yet, but he was going to in his future. However, time is in flux and only the fixed points in time are a certainty. In both Forest of the Dead and The Big Bang, River and the Doctor worried that their future meeting might never happen if the Doctor died. In The Two Doctors the Second Doctor became an Androgum, so the Sixth Doctor became one as well. Time can be rewritten, so during Inferno and Battlefield the Timewar wasn't going to happen, but it wasn't a fixed point in time, so time was rewritten, and the war did happen, but the interdimensional travel in Inferno and Battlefield still occured, because the war hadn't happened yet.Icecreamdif 14:34, April 17, 2011 (UTC)
I think everyone's forgetting that if inter-dimensional travel isn't possible now, where does Iris Wildthyme stand in all this? Gallifrey102 10:21, April 18, 2011 (UTC)
The Time War, by its very nature, was fought across all of time and space, and always happened. It had already happened/was happening during the classic series. Gallifrey was already destroyed by the time "Battlefield" took place, so the walls of reality would already have been closed. EJA 20:30, April 28, 2011 (UTC)
But it hadn't happenned yet to those involved relative to their personal timelines. The Time War only seems to have affected races during the latter years of their own evolution e.g. Forest of Cheem, later humans. --Revan\Talk 20:32, April 28, 2011 (UTC)
The Time War had not happened yet during the Classic Series, even if it was fought across all of time. We actually don't know that the Time War was fought across all of time, although it probably was, it is possible that it was only fought in a handful of timezones. Either way, as the Tenth Doctor said, time is not linear, but is a great big ball of timey wimey stuff. This means that even if the Time War was fought across all of time, it had not always happened. The fact that dimensional travel was possible in the classic series proves this. From the Doctor's point of view the Time War had not happened yet, so the Time War had not happened yet. If Gallifrey was already destroyed by the time Battlefield took place, how did the Doctor go to Gallifrey in The War Games, The Deadly Assassin, The Invasion of Time, and all the other Gallifrey episodes. Despite the non-linear nature of time when time travel is involved, Time Lord history does have a linear progression, beginning with Omega and Rassilon discovering time travel, continuing through all the Time Lord episodes of the classic series, and ending with the Last Great Time War. Before the Last Great Time War, the Timelords still existed, and interdimensional travel was possible.Icecreamdif 02:52, April 29, 2011 (UTC)
I like to call this the 'Soon-to-have-happened' tense.
Gallifrey102 09:55, April 29, 2011 (UTC)