First, humanebean. I had misunderstood Miles' plea for Hurley to shoot him, thinking he was suggesting that he can't die no matter what you do to him. I said, does that mean he can't age, either? humanebean explained it succinctly:
Miles said that he COULD die - "all of us (could)". This "now" is occurring after the events we've seen in 2004/5. If he were to be shot and killed, it in no way would affect the later events, which were already an established part of the timeline, even though they are "in the future" from the time period we are witnessing (and they are living through) in the moment. Yes, it is a mind-bender, and I don't blame Hurley for having a hard time wrapping his mind around it.
Teebore took that and went much further with it, explaining it beautifully:
As I understand it, Miles (or any other time traveling Lostie)can absolutely be killed/hurt/aged while in 1977.
While the events of 2004 take place objectively, for Miles 2004 is his past and 1978 the future of his subjective timeline.
There are two flows of time, the objective one (in which time time flows chronologically in order...1970, then 80s, then 90s etc) and the subjective one (time as its experienced by an individual).
For you, me, Ben and most people, objective time and subjective time are the same. We experience events in the order that time flows.
But for the Losties, once Ben turned the wheel, their subjective timelines got thrown out of whack from the objective timeline.
So while Ben in 1978 won't die because he's alive in 2004, Miles in 1978 COULD die because he experiences time differently than young Ben.
All of that probably just muddies the waters. How 'bout this: think of it terms of narrative. Anything can happen to Miles, Hurley, etc. because we're watching those stories unfold. We don't know what the next chapter holds.
But for Ben in 1977, we know what happens in his story: he grows up, kills Dharma, leads the Others. The events happening to Ben in 1977 are like watching a flashback: we're seeing events that already happened to the characters, even if we (the audience) didn't know about them already.
When watch a Jack flashback in season one and we see him yelling at Christian pre-815 crash, we know he won't die in that flashback because we've watched him on the island after those events. But when we're watching the island narrative again, anything could happen to Jack.
So now the Losties find themselves inserted into other characters flashbacks. For them, it's the main narrative, but for characters like Ben, everything that's happening is like watching one of their flashbacks.
And then later last night, Blam created a simple analogy that also explains it, but in a different way:
I mean no offense to those of you who don't understand how the past of the travelers is still their personal past, even though it's now in The Future, capital F, since they've traveled to The Past, capital P, but it's entirely consistent, and their past, in The Future, is still in their future as well, if they live long enough and/or don't jump back to the moment they left in a later episode. If time is immutable, then they have always been back where they are, just never come across any records of it before they traveled there.
I'm walking down Central Avenue. We're all walking down it. Everybody does; it's the only street we know. And it's a one-way street. Each of us has a cookie and we're letting crumbs fall on the sidewalk as we mosey along.
Now some blocks down Central, as a group of us passes, oh, the post office, at 2004 Central Ave., we see the sky flash. While we're blinded, we stumble onto a side street that we never knew was there — or someone pulls us into an alleyway *** — and after doubling back around on the next street over we end up back on Central Avenue, but many blocks behind where we'd been walking when the sky flashed, say by the bank at 1973 Central. (*** This is the inexact part of the analogy, since there was instantaneous transportation through time on Lost; it's not like they experienced traveling through some side-door dimension.)
We've absolutely no idea how we ended up thirty blocks behind where we'd been, but we decide to make the best of it and start walking forward again. You idly wonder if the crumbs from your cookie will still be there when we get back up to the post office, and in fact why the cookie is even in your hand at 1973 because we didn't buy the cookies until the bakery at, like, 1984 Central Avenue. I reply that of course we have the cookies, and the crumbs will still be there. A couple members of our group, whom we never really liked anyway, but still any loss of human life is a tragedy, could get paralyzed by spiders at our current location and never move forward again, but they would still have been farther up on Central Ave. earlier in the day and the people from the bakery at 1984 would still remember them: Aw... That's a shame. Hey... Wait... What do you mean they died ten blocks ago? That's impossible! They were here!
The fact that Central Avenue only goes one way, and that we've all only ever walked down it in one direction, and that our senses have been blown by skipping back in the opposite direction, doesn't change the fact that we have still physically been farther down the street before we came back around to 1973, or now that we've walked a bit farther, to 1977 — when some of our friends, who had kept walking to the airport at 2007 Central after we disappeared, join us, equally bewildered at how they got here.
I probably laid that on thicker than necessary, so my apologies for taking up so much space, but if it helps just one person my job here is done.
So, is everything clear now? Awesome. :)