All of the Star Trek series of the '90s/'00s overlapped quite a bit (in writers/universe/stories/cast) and some of the later ones fill in some of those missing details.

The Federation has a currency, "Federation credits" -- they discuss a deal priced in credits for control of the Barzan wormhole, and Federation crew use these credits to make purchases at the Ferengi-run bar on Deep Space 9. The Ferengi keep all their wealth in the form of latinum, precisely because it can't be replicated. Presumably the only reason they need these credits is to facilitate trade between species; I don't remember them ever discussing how the crew get the credits.

The replicators' energy comes from the ship's warp engine, the same thing that powers everything else, and from recycled material. They can both convert matter to energy and energy to matter. We know they use the ship's energy because when Voyager is stranded with limited fuel, the first thing the captain does is ration replicator usage by the crew, and pick up a chef to start cooking fresh food instead of replicating meals. The energy source for the engine, in turn, was controlled annihilation of matter (deuterium) and antimatter (anti-deuterium). The ships all had Bussard ramscoops with which to collect deuterium from interstellar space for use as fuel -- that was the red part on the front of the nacelles on the Enterprise D in TNG for example.

In an episode of ST:DS9, they discuss the fact that the Federation does restrict the ability to replicate dangerous objects like weapons without authorization. Trade in weapons is always implied to be heavily regulated.

All that said, most of it is really left to our imaginations. I was hoping Star Trek: Enterprise, the prequel to the rest of the series, would shed some light. Unfortunately it wasted 3/4 of its time on weird time travel plots that could've taken place in any of the series, and only tried to get back to explaining how the Federation came about at the very end... just before being cancelled.

Portraying the mechanics of post-scarcity has the same problem as showing a truly alien species: Our imagination is simply not up to the task because we've never seen anything like it to template it on. Avoiding the issue and focusing on smaller stories that exist within post-scarcity is the only way to maintain suspension of disbelief.

If and when we reach true post-scarcity, our society will change in ways we simply can't predict. Our economic models are no use there.

But things get a lot easier if you just assume everyone in Trek is a LARPer who can just do that because why the fuck not.

I think the best explanation to this is akin to the explanation they had for the transporter (with it's "Heisenberg compensator"): they simply didn't know. They couldn't explain it, and they didn't want to throw out some bullshit detailed explanation -- they just asked "what if this was a thing?". Now since it's a thing, I don't think you would expect people to routinely exploit it (that would have been figured out by then), although that might have been interesting.

Someday one author came about and proposed that they simply have no money. Instead of saying "Well that couldn't work!", they just went with it, leaving interesting voids to be filled.

Altogether, I agree there are so many things left unexplored, but they could only do so much with the limited time and while actually telling a compelling story. Remember, this is a TV show, it's meant to draw emotions, be compelling, and tell political stories about people.

>Like what exactly is a replicator, and how does it work?

It takes matter, and rearranges it into something else less boring. Using science. Ish. Things. Lasers.

>Can anybody replicate anything on them?

Depends on the episode.

>Including weapons and drugs?

I think certain weapons were impossible to replicate but you certainly could crank out as many guns and knives as you liked. But of course, being a utopian society, such things would be unthinkable, so it's not an issue.

>If not, who decides what they can make, and how do they enforce it?

Nobody. It's a perfect society. Everyone is nice and peaceful because they choose to be. No wars (with other humans - aliens are fine), no famine (except for that one thing in the original series), no money (or something). They just use the replicators and holodecks for aggressive but entirely wholesome and not at all sexual sports and research and interactive fiction, because the humans of the future have evolved beyond the need to be interesting. Except for Barclay. And La Forge, because one time he created a holodeck model of this girl he had a crush on. Which was awkward when she showed up and he had forgotten to close his porn folder.

>They presumably require energy, and where does that come from?

...subspace or something. Dilithium. Quantums. Shut up.

>Is there a limit to how much stuff a person can make?

Probably just the size of the replicator console thing. And energy. By Voyager they had entire starships made up of holograms so who knows?

Like a lot of post-scarcity ideas, to me, Star Trek essentially ran on magic. A lot of that had more to do with the necessities of sci-fi on a low budget (the only reason transporters existed, for instance, was to they didn't have to spend effects money on shuttlecraft) than thinking hard about actually making it work. It just did. The holodeck, literally, could create self-aware sentient beings if you asked it to. Riker got cloned when a transporter beam reflected off the clouds of a planet or something. The Enterprise got pregnant and had a space baby. That was a thing that happened.

No one cared enough about science fictional speculation to actually try fleshing things out, because that would take time, cost money, and potentially mean taking dramatic risks. Rather, they just came up with a new particle, or kind of energy, or swirly whatever, of the week that would defeat the monster, or other swirly whatever, of the week. Now and then they would just drop the ball on some potentially awesome plot points, like the aliens invading from subspace that snatched people out of their beds and did surgery on them (real creepy stuff) or the Ikonian Empire (apparently a big deal, left magic portals everywhere, completely forgotten about) or the parasites mind-controlling certain Federation higher-ups (leading to the only head-explosion in Trek history.)

But the truth is, the "science fiction" was just stage dressing for utterly banal drama. Probably the books got into it more deeply. The Borg was nice though, until it wasn't.

Edit: I shouldn't say 'no one cared.' Reading blogs by people like Doug Drexler, clearly a lot of people cared, just all too often the plot didn't seem to permit much complexity or insight.

I think it's telling too that the vast majority of the fanfic I've seen seems to be fantasy romances between various characters rather than exploration plots or stabs at technical explanations or something non-banal.

Sure we get the Starfleet Technical Manual, but that was tossed as non-canon almost as soon as it hit the stores.

I've seen lots of this brought up before as well. One things the ST shows really spend lots of time on is not exploring the society the show occurs in. And when it does it's internally inconsistent. Lots of questions are answered in the deep nerd lore about the universe, but you shouldn't need to buy canon reference books about some show to find out things like "replicators have trouble replicating heavier elements" so monetary instruments have to be produced out of non-replicable materials.

I think part of this is the need to have character driven stories. Which I'm basically fine with, but I really want to see more exploration of the universe the characters are in. Defining the rules of that universe helps establish the environment the characters have to operate in. With clever writing this can add extra flavor to the story.

This might be one of the reasons I like DS9 the best, they do a little bit of both, exploring the setting a bit (establishing internal and external politics, trade, war, alliances, factions, economics etc.) while having quite good character driven stories in this setting.

For example, the principle planet in the story, Bajor, needs to rebuild. The Federation offers to help by providing industrial replicators. There's an entire story about how the fairly few industrial replicators the Federation can provide drives a political story involving the remnants of the Bajoran freedom fighter/terrorists. It's not the best Sci-Fi ever written, but it's a pretty strong story and helps really define this corner of the universe with better granularity than 4 other series and better than a dozen moves did over hundreds of hours. Some questions are left unanswered, but you can make some assumptions like, why doesn't the Federation provide more replicators? Is there something about the technology that makes them hard to manufacture? Why can't replicators replicate other replicators? Perhaps there's some component that prevents that? etc.

It sets limits on the Federation's powers and logistics without using the typical plot device of introducing a more powerful alien or enemy or whatever.

Star Trek is Starfleet. There's such pitifully little information on the life of non-Starfleet folks...heck there's almost nothing produced on non-officers in Starfleet outside of Chief O'Brien. And he seems virtually indistinguishable from his officer colleagues except being a bit more badass than the normal space pajama wearing explorer.

Every once in a while the series touches on economics: transporter credits, or replicator limitations when buying a gift for a friend. But by and large it throws those glimpses away as soon as it shows them.

It's a huge missed opportunity for the shows; the life of civilians in the Federation. How do they get goods and services? What motivates them to work other than pure self-actualization. What about menial jobs? There's so much territory to explore, and it's never explored at all and instead we end up with more fan-service throw away romance episodes.