Lost (TV series): How could it be possible that older Miles and Younger Miles live at once?

While this is a good question, it’s one that could be asked of all the time-traveling characters - on LOST and on any other show - where people travel to the past.Matter can neither be created nor destroyed. All the atoms and molecules that your body consists of have existed, in one form or another, since the dawn of time. As Carl Sagan said, “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff.” So even if a character can go back further than their own life, it’s unlikely that anyone can go back so far that the molecules of their body do not yet exist.This means the real question isn’t ‘How were two Miles (Mileses? Milii?) alive on the island at one time’ but ‘How does any fictional time traveler go into the past if the matter that makes up their bodies predates them and cannot exist in two places at once?’If you ever find a non-fictional answer to that question, I’m willing to spring for the energy bars and the period costumes if you can provide the plutonium, flux-capacitor, and the DeLorean. Dibs on getting Ben Franklin drunk!

He and most of the other major characters had one or more doubles. There was no time travel.This was most easily seen in the case of the ship's doctor. The doctor's body washed up on shore with a shaving cut that showed evidence of some days' worth of healing. The supposed doctor on board the ship, who had a FRESH shaving cut, then said, "That's impossible. I'm the doctor." Shortly afterward, Keamy slit his throat & cast him overboard, saying, "Sorry, Doc." What that revealed is that the doctor's double had stowed away, then slit the real doctor's throat and cast him overboard, but gave himself a shaving cut to try to match the doctor's. Keamy on hearing about the body then realized the "doctor" in his presence was in impostor who needed killing.