First of all : Hi everybody !
I am new on this forum and I also have an other particularity : I am french ! So, don't be surprised if my english is not so well, because it may be. I apologize for this.
I discovered this website a few days ago, just after playing Chrono Cross for the first time (yes, the game actually was never released in Europe so it's not easy for us to play it...) and here I fell in love with the article "Principles of Time and Dimensional Travel" ! I am one of these who love that kind of reflection. I have always been one of the big fans of Chrono Trigger to.
So I'm currently still reading this amazing article (I have not finished yet), but I thought about an explanation of the problems raised in the article by the theory of the Lavos pocket dimension. Here is my theory :
Actually, Lavos would not be in a pocket dimension !
The fact that his shell is still broken in 12000 BC if Crono destroyed it previously in 1999 AD in the game is explained this way : when Lavos faces opponents, he sends them in 1999 AD to fight them here, where his power is maximum. It is possible because we know that Lavos can create time portals. However, the only moment where he doesn't do this is during the Ocean Palace incident. So that, it also explains why his shell is not broken at this moment, even if Crono broke it in 1999 AD earlier in the game.
But then, you would obviously ask me why Lavos can emulate the Guardian robot from the future. Well, the answer is quite simple actually. This robot (as probably the most big part of the robots) is created by men BEFORE 1999 AD ! (Crono will just fight him later in the future, where he still exists.) We can also observe that during the Ocean Palace incident, Lavos does not emulate the Guardian.
Finally, this theory also explains why, if we lose during fighting Lavos, the scene is always the same scene of 1999 AD (except when we lose during Ocean Palace incident, but here it's normal ^^). And it's an easier conception to.
Does it seduce you ?