There are places where the "Why is there only one Derek?" question becomes a problem, but I don't think that's the case here. The first Derek would have been set back in time to, say, 2007. We can either assume that a causality loop is created within Cameron's timeline, or else Derek changes history, creating a new timeline with a new John, John-prime. Either John or John-prime sends back Cameron to 1999, Cameron changes history, both John and John-prime never exist to send back Derek, and it falls on the shoulders of John-double-prime to send Derek back. Outcome: only one Derek.
It's when we ask ourselves why subsequent changes in history don't result in more Dereks being sent back that we begin to have issues. But Cameron's (John's or John-prime's) Derek isn't really a problem that way.
My problem is that the difference between Cameron's timeline and the one we'd have to assume Derek was sent back from (John-double-prime's) has a lot more differences than a red or green button: Sarah not dying of cancer, John meeting Cameron, etc. We have to assume there's some type of pretty effective temporal inertia keeping the butterfly effect in check.
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Date: 2010-01-11 10:37 pm (UTC)It's when we ask ourselves why subsequent changes in history don't result in more Dereks being sent back that we begin to have issues. But Cameron's (John's or John-prime's) Derek isn't really a problem that way.
My problem is that the difference between Cameron's timeline and the one we'd have to assume Derek was sent back from (John-double-prime's) has a lot more differences than a red or green button: Sarah not dying of cancer, John meeting Cameron, etc. We have to assume there's some type of pretty effective temporal inertia keeping the butterfly effect in check.