Daniel Faraday might have hit it big with the time delay in his little experiment.
Could this be why the island's inhabitants don't age?

It seems like a 31 minute delay isn't enough to effect a 20 year non-aging of Richard Alpert. There's something else about it I think... something else I don't have a clue about.

i think the 31 minute delay is just an outward physical manifestation showing that there is something between this island and the outside world. also don't forget that daniel told lapidus to take the exact same bearing out as he did in. so he can't waiver at all or he will end up...?

Yes, I agree with pchee. Whoever launched the rocket missed their bearing (time?) by just a little and that is what we saw on the timer. I don't think that they are only 30 minutes behind, I think that those on the freighter miscalculated the exact time of the island by whatever time discrepancy Dan's timers showed. The "exact bearing" thing was also pretty convincing of a time warp of some kind. They had to follow the exact bearings to end up in the time where the freighter was waiting for them.

I guess I had really thought there was only one bearing in/out like the submarine had a bearing and michael's boat when he left.
But, maybe when you leave he island your bearing determines where/when you end up in the real world. Maybe being able to travel in this way is how they arrive and change events in the world.
Maybe juliet's sister is cured of cancer by them going back and giving her something to cure her in advance and ben's threat concerning juliet staying or else is because he could just as easily send someone else back to the past to keep them from curing her. He might could continue doing this at will.
Sort of a "Back to the Future" situation.
Maybe whoever controls the island has enormous power in this way.
a guy could get rich like this.

The payload only showed a 20-30 minute time discrepancy. It's possible that those 20-30 minutes are compounded or multiplied the longer you spend on the island (the longer time on the island goes on). Someone like Alpert, who has been on the island very long would have benefited most from the anti-aging.

Yeah I do agree with the fact that staying on the island longer will decrease the aging over time.

I want to know how the Freighter knew the exact bearing to get into the island.

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"How stupid are you Miles?" - Jack

I don't think the amount of the time discrepancy (31 minutes) is as important as the fact that there is one. Daniel was there for the sole reason of finding that fact out for a certainty. Those on the outside have seen the evidence that the island exists, but have not been able to find it because......
I think the island exists in a time warp/ripple. It floats in and out of different periods of time. That is why you can't find it. Given the time and the coordinates that you use it may not currently exist in your time. That is why Faraday was so insistent that the helicopter pilot stay "exactly to the bearings" they used to get there.... no matter what. Depending on which coordinates you use to leave the island you will find yourself in an alternate time in history. Ben/others have learned to map where each coordinate will take them in time and use it.

Ben has a guy on their boat... maybe he was able to tell them the correct bearing in order to gain their trust and support... the bearing must be true because ben gave a bearing to Walt and his dad when they left on the boat

I think it could be quite possible Michael and Walt are on the freighter. But, I still do not think they would be given the level of trust and security to gain the kind of information Ben would want or need. I think he has someone embedded that has been there for a long time and would never be suspected as working for him. The fact that he said he had a "man" inside almost makes me think it is a woman.