This story was amazing! A contender for my #1 favorite EP episode (though that would require a grudge match with Friction), and probably in my top 5 short stories ever.
It really surprises me how much I like this, actually, since from a distance it seems to be the didactic hard SF that so often bore me in the big magazines. But, really, it was great in every way. The narrator did a great job reading it. The oddity of these creatures and this world was given in digestible portions while the story unfolded WHILE not straying from the protagonists point of view. The science was not just for the sake of science but also gave purpose to the character, an understanding of their world, and even philosophy of the mind.
Especially compelling was the concept that the entire world is run by a long exhale from some higher power--following that idea further might imply that there will be a renewal of the world on the next breath (perhaps when someone realizes they've been neglecting these bots and renews the tank).
I tend to get a little bored with scientist protagonists in classic stories (and this has a classic feel to it, in a good way). Most scientist characters just aren't that interesting, they're smart in some generically defined way, and they come up with some clever solution to the problem to avert disaster at the last minute. But THIS guy is not only smart, he's also got GUTS in a major way. It takes some major courage to dissect your own brain. Although it also requires your drive to learn to be more powerful than your concern for yourself and others. What if he'd accidentally damaged his brain in a way that blocked the airflow to certain areas, he could have come out of there with psychopathic behaviors and harmed his fellow creatures. I'm glad it didn't go that way, but I'm just sayin...
One thing that I did wonder about, though, is no one seemed to consider simplifying their life to prolong it. For instance: do they need so many clocks? Presumably the clocks expend energy to run, so if you knew that every tick was a slice off of your life when you'd previously thought your life more or less indefinite, wouldn't it drive you nuts?