We are only up to the 5th episode of LOST in SA, but I thought I would also put my theory up for discussion.
I think the survivors on The Island are caught in a kind of Closed Timelike Curve or time loopback which is an extention of Einstein's General Theory of Relativity. This particular loop is governed by The Island and has the sole purpose of allowing people who are essentially good to resolve issues in their past.
For each person, the loop will go through a number of iterations depending on whether the person is able to resolve their issues within each loop.
Some of these survivors have been on The Island in a previous loop, but are not aware of it. They probably lived for some time on The Island and were responsible for the oddities that they find here. For example, the radio tower. What if the current survivors (Sayid) built a radio tower in a previous loop and then began broadcasting. In this current loop they would find it intriguing that there is a radio tower on the island and would wonder who built it because they are unaware of any previous loops.
There is also a feeling of recognition among the survivors. Some have the feeling that they have seen each other before. What if they recognise each other and things from previous loops because of some latent memories of the loops. (e.g. Rose finds the sound of The Beast familiar because she heard it in a previous loop and Jack finds the cave)
People who have managed to resolve their issues do not return for the next loop.
The Island does not allow anyone to leave until they are ready to do so. We find evidence of this when Boone tried to save the drowning woman. As a lifeguard, he should have had no problem doing so, but he himself began to drown as The Island prevented him from leaving its area of control.
Locke as the Guide
The Island also identifies a person who will act as a Guide to assist the others in resolving their issues. In this case it is Locke. He was shown the "Beauty" of the Island and its ability to help good people who have been overcome by darkness. The Island has given him the use of his legs as reward for fulfilling this role.
I read summaries of all episodes already shown in the US, and I believe that some of the things that have happened support the time loop theory
The numbers that were being broadcast from the radio tower could have been broadcast by Hurley himself in a previous loop. The numbers were then heard by Danielle's crew and by the two guys in Australia and then passed onto Hurley, who won the lottery with them. The numbers are significant because they are all less than 49. They are typical Lottery numbers.
Ethan and Claire
Ethan could be Claire's current unborn child. He was born in a previous loop. If he is, then he is the only person who was born on the Island and therefore cannot escape it. He also cannot die because dying is one way in which people who have resolved their issues, leave The Island. His only way to escape is to use the time paradox which says that you cannot go back in time and kill your own grandfather. He believes that if he kills Claire, he will break the time loop and destroy himself in the process. However he might not have been able to bring himself to kill his own mother, so he thinks that if he meets himself (Claire gives birth in his presence) one of him (Baby or grownup Ethan) will cease to exist. The speculation that he was breathing when they buried him supports this inability-to-die theory
The Island has also endowed Walt with special abilities that will help The Island fulfill its purpose. Walt helped The Island by burning Michael's raft so no-one could leave until they are ready.
It's an interesting theory, but it can't work because of something J.J. said in an interview.
Now i can't tell you exactly what he said since it's a spoiler, but it's one that won't affect you for the upcoming episodes, just tell me if you want to know.
You've brought a few good ideas though, which might fit to another intersting theory, keep it coming !
Please leave Einstein and generally accepted physics out of it.
Otherwise -- interesting theory! However, I'm not sure I see what the evidence for it is.
If you like that sort of thing, I hope you are familiar with Babylon 5. Now there was a complex story that paid off on almost all of its threads. I'll mention just one. In the pilot episode, the human head of the space station is greeted by the ambassador of another race. But the name the human is addressed with is that of the godlike lawgiver of a third race, who lived 1000 years in the past.
Welcome, Osiris! It's great the way the show is gaining such an international audience.
I think your theory is pretty cool, and well explained, too. Not sure I entirely buy it, but it's very imaginative and well-worked out. (Reminds me of a more complex version of the Star Trek NG episode where the Enterprise kept blowing up).