Wasn't the smoke monster in the first season? That's not reality at all. Weren't dead people walking around the island? Again, not reality. I'm not saying magic is seriously the answer to everything and that it's a fair copout, I'm just saying that you can't expect a scientifically factual explanation for something that to begin with is completely fictional in every way.

I guess maybe you guys were looking for sensible reasons to begin with (eg. nanobots or whatever) but for me it was all one big fictional story with unrealistic things from day one. I never looked at it as a reasonable, level-headed show that would provide in great detail an explanation that is, at least in theory, almost passable as science fiction or something, something that could someday become reality.

As soon as dead people started walking around, as soon as there was a smoke monster, as soon as there were temples, as soon as there was time travel, I never expected any kind of decent explanation because, for me, these things can't be explained in a realistic way at all.

EDIT: But for what it's worth, I think the light is actually more than just "omg light". Much like what Jacob drank (the stuff his Mum gave him) is actually more than just "omg drink". Maybe it's where Lucifer himself is kept for all we know. Could be all sorts of things.