Lately, I've been reflecting on Daniel Faraday's chalkboard reference to the Kerr Metric, which describes what a few scientists theorize might be a safe and navigable trajectory through spacetime back into the past.
After much reflection, I've come to the conclusion that Faraday's reference isn't meant to point to any particular method of time travel. It's meant primarily to establish that time travel is theoretically possible. Same with the Penrose diagrams in Daniel's notebook -- they depict generic violations of causality rather than anything specific from the show. In all such cases (the Blast Door Map equations are another) the writers are simply delivering on their promise that everything will be explained by realistic pseudo-science.
I think it was a poster named lostmio who once suggested that time travel is a kind of MacGuffin. At first that notion annoyed me, but I've come to believe she was basically right. Ultimately, there is no deeper explanation than "electromagnetic radiation from the Swan unstuck Desmond in time," and "the Island's natural Casimir effect sustains wormholes." We can keep looking for more specific explanations forever, and they will always be true because none of them are false. Ultimately, however, all that really matters is that time travel is consistent with the theoretical limits of physics.
In that regard, Lost resembles the works of Edwin Abbott and HG Wells, which combine science fact and fiction to highlight interesting aspects of the former. The show also reminds me of the those crazy hypotheticals you read in popular science books by Stephen Hawking, Kip Thorne, Michio Kaku, and Paul Davies. The show is depicting what happens when human beings encounter technology from an arbitrarily advanced civilization -- the Fourtoes -- bounded only by the theoretical limits of physics. I've got to believe some kid will watch this show and be inspired to study science.
It's certainly had that effect on me...