“How did we get here? How did all this happen?”

Those are Dr. Jack Shepherd’s big questions as Season 5 of “Lost” arrives – at last! – on Wednesday.

Fans have their own questions, some of them more concrete. As in: Where did the island go when it vanished with a flash and a clunk in last May’s Season 4 finale?

With just 34 original episodes left before “Lost,” one of the greatest mystery series in TV history, ends its run next year, answers to many questions are forthcoming.

I’ve seen the first two episodes of the new season and, although I’ve been sworn to secrecy, I can tell you that viewers will be shocked at how many questions are cleared up in the first two hours of the new season.

Still, just 34 more episodes seems like a very short time to put all the pieces of this big, fascinating puzzle together. So in honor of the debut of Season 5, let’s concentrate on five big, pivotal mysteries that we’d like to see addressed.

1. What are Ben’s real motives in trying to gather the Oceanic 6 and get them back to the island?

Are his goals diabolical or, somehow, benevolent? Benjamin Linus (Michael Emerson) remains a mystery wrapped in an enigma. All we really know about him is that he lies, and that he turned the frozen wheel that caused the island to vanish.

2. How does the island’s mysterious healing power work?

How did the island make Locke (Terry O’Quinn) walk again and cure Rose’s (L. Scott Caldwell) cancer, yet let Jack (Matthew Fox) get appendicitis and Ben a spinal tumor? For that matter, why do pregnant women on the island die and fatal injuries prove fatal?

3. What do Hurley’s numbers mean?

Those numbers – 4, 8, 15, 16, 23, 42 – have turned up everywhere from a winning lottery ticket to the Dharma station called the Swan to the dashboard of Hurley’s refurbished Camaro. Hurley (Jorge Garcia) believes the numbers are cursed. The online game the Lost Experience (www.thelostexperience.com) suggested that they form a scientific equation predicting the end of humanity.

4. Who are the Others, where did they come from and what do they want?

Who or what is their invisible leader, Jacob? How do they seem to travel freely off the island. And why doesn’t Richard (Nestor Carbonell) appear to age?

5. What is special about baby Aaron?

Why does danger surround him, and why did the psychic insist to his mother, Claire (Emilie de Ravin), that she must not let her child be “raised by another”?

‘Lost’ theories

“Lost” fans have lots of theories about the central mystery of the show. Here are some popular ones.

• The island is purgatory. Everyone on Oceanic Flight 815 died, but rather than going to heaven or hell, some wound up in a place where they must work their way to heaven.

• Injured after the crash, the characters are hallucinating. Or one, most likely Jack, is hallucinating it all.

• Someone or something (maybe scientists) is manipulating the castaways as an experiment.

• Last spring, USA Today asked readers to submit theories, then had “Lost” creators evaluate them. Find that feature online at tinyurl.com/6yrcnb.

‘Lost’ resources

Many Web sites are devoted to examining “Lost” exhaustively. Here are some of them.

• Lostpedia (lostpedia.wikia.com), an online community, news source and general “Lost” clearinghouse.

• TheFuselage.com is the “Lost” creative team’s official site.

• Lost-TV.com bills itself as the first unofficial fan site.

• Lost-media.com offers an extensive episode guide.