What would it be like to be caught between worlds?
The world of the living and the world of the dead.
The world of the living and an other world of a distant alien planet.
Both are plausible explanations of the island in LOST. It is true because of the lack of concrete canon to support the sci-fi story lines with actual physics.
Peppered throughout the discussions of the island are scientific concepts like "portals," "worm holes," time travel experimentation, psychological conditioning, and unique electromagnetic properties. But to suspend belief in a science basis for the island, what do we have to consider?
An island that cannot be seen or mapped from the sky is not an island. It is something else.
An island that can move and disappear is not an island. It has to be something else.
But since Eloise Hawking could calculate its apparent location (with some assumptions), the island's movement must follow a pattern. Nature follows patterns. So does the Earth's electromagnetic grid. The island could be moving to intersection points along with Earth's electromagnetic grid. This makes the island a ship and not an island.
Electromagnetism and bending of light are principles in research for stealth technologies. To make things appear invisible, magicians use mirrors and distraction (such as a pretty assistant) to make the illusion complete. Mirrors, distractions and illusions were all story points in LOST.
What is the purpose of an island moving along an electromagnetic grid? It could be "recharging" itself from specific deep core entry points. It may need a certain amount of energy or flow to "contain" its own power system (which malfunctioned several times to create time skips and purple skies).
Some viewers believed the island was a space-time portal. The teleportation of Locke and Ben to Tunisia was proof of it (in a small scale). The capture of Flight 815 from the sky could be another example as well as all the ship wrecks. It could also explain the "immortality" of Jacob since he controlled the island and thus controlled time itself. One could equate Jacob to that of being a Time Lord.
No one has really thought about the island as being a TARDIS like device piloted by aliens. But in a UFO observatory conspiracy theory, an island would be a good cover to house a base to spy on human beings. A remote island would be a great place to bring humans to do experiments on. You don't need to be gray aliens to poke humans; as shape shifting beings you can create yourself in the image of your laboratory animals.
Jacob and the Man in Black did admit that bringing humans to the island was part of their grand game. An experiment on how humans react to the island conditions, with MIB lamenting that humans always screwed up in the end. MIB was so frustrated with it that he wanted to go "home." But Jacob would not let him - - - basically making him/it a prisoner on the island. So MIB used the corrupt humans in order to rebel against Jacob, to seize control of the island ship to leave Earth.
It does sound like a Dr. Who story line: who controls the TARDIS can control the universe. As Widmore desired control of the island, there were others like Ben who tried to protect it from becoming a weapon of power. But Ben was corrupted by that same power when he purged Dharma.
Therefore, we have the literary means of the island being the center piece between two worlds. The debate is what is the other world? Is it the religious connotation of the after life (as adored by the temple and the Egyptian mythology)? Or it is a sci-fi based drama based upon the Faraday notebook and Dharma stations?
In either situation, it puts our castaways not as lost survivors of a transportation disaster, but human guinea pigs in a science fiction fantasy world.