Jen and Sarah spent the next week doing research. The Internet was filled with contradictory information about monetary theory and economics, and neither of them really had the background to evaluate the arguments that everyone was having.

However, Sarah reminded them both, they didn't need to look at a perfect system, just one that worked. So, they started digging through Wikipedia articles and online textbooks on the history of money and how they came to be.

"Hey, did you know they used to use salt as currency?" Sarah asked as she skimmed through a particularly fascinating documentary about Middle Age East African economies.

"Is this some kind of joke about mining salt?"

"No, it's real, look. And apparently the word salary is from the Latin word salarium for money used to buy salt," Sarah continued fascinated.

Of course, they couldn't use something as simple as salt to represent money. In fact, they couldn't use any commodity either.

Over the last week, one of the alien traders caught wind that gold was extremely valuable on Earth, so they'd brought them in by the ton load. Gold was still useful for electronics and some dentistry, but the price of gold, mostly propped up by its value in rarity, crashed hard.

The problem with currency in galactic trading, as Sarah discovered, was that there wasn't a single commodity that was equally rare in every system.

No, whatever alternative they come up to the laughably outdated barter system had to be built on something far more rare and valuable than gold.

Something that even the most powerful human empires in history have struggled to collect.

It had to be built on trust.

"That's the system most modern currencies are based on," Sarah claimed, "you only accept dollars for work because you trust that you're going to be able to wake up tomorrow and spend it on… everything you need."

"Hmm well, we can't just ask them to take US dollars," Jen giggled. This would be so much easier if that weren't true.

"Why not?" Sarah asked, playing the devil's advocate.

"Well… well, like you said, they won't trust it! I certainly wouldn't if I were a trader! Furthermore, who knows? Maybe they have a printer in their ship that can duplicate money! Maybe we should ask them for that next time we bring Zarko some pears," Jen said, thinking out loud.

"I doubt it. The government keeps a lot of secrets about how they make Dollars , and I don't want the Secret Service knocking on my door," Sarah said. Until this week, she hadn't known that this was one of the lesser known duties of the USSS. Now that she knew it, it made the thought of attracting their attention even less palatable, "you're right. What about digital casino tokens? We can produce something that translates to Dollars and have our own system that tracks it all."

"Sure, that's not too hard to make. We would have a centralized money supply, where we don't trust each end point…" Jen continued on the brainstorm, thinking in terms of the technical system, "ok, so say we make SarahBucks, and peg its value to the US Dollar. One pound of pears would be worth 1.5 SarahBucks, one pound of sirloin steak is 6.99 SarahBucks at Safeway. That still doesn't explain how we'll get people to use it."

"I'm not sure. I need to think about this more," Sarah yawned, tired. "And I hate that name."

They agreed that they were stuck, and that SarahBucks was absolutely a terrible name.

Livermore Spaceport, Earth

A month after the spaceport opening, Sarah noticed that it had become less of a tourist attraction. There were far fewer people standing around gawking at the aliens, and a lot more companies trucking their best-selling products into the spaceport for trade.

After their abuse of Jen's cousin's employee pass got discovered by the spaceport authorities, Sarah and Jen had started placing their own bids on getting into the spaceport through the official channels. Thanks to their existing connections with the managers at the spaceport and a growing bank account of value, they could still get in to continue their lucrative trade for magical alien goods.

A bit of a rich-get-richer type of situation.

The flavor of the month were these Bohor magical air filter machines that aggressively scrubbed the air of… anything you want them to.

The Bohor planet is basically the planetary equivalent of a toxic dump.

Sure, it had biomes; it wasn't a Star Wars sci-fi planet where the entire planet is either a desert or an ice-cold tundra or a forest. But the entire planet had been polluted so heavily by its occupants that it lowered the life expectancy by half before the Bohors found a solution:

They simply filtered their entire atmosphere through air filter machines and then buried the toxins and garbage they got out of it in a very deep landfill, somewhere where very few people lived. Pretty much the kind of solution you'd expect out of a species that created the original problem in the first place.

Zikzik, the alien that was the same species as Zarko, overheard a human asking about their rocket fuel and climate change, and brought in a cargo hold of them.

It was a massive hit.

Earth's climate change problem wasn't nearly as bad as Bohor, but it was relatively simple to program these machines to suck carbon out of its atmosphere and… bury them in a landfill.

At first, few of the human traders bought them, thinking that it was going to be at least a while before the problem became big enough that big governments were going to come to them to try to address the issue, but they had it all wrong.

Soon as word got out this was an option, big companies and philanthropists started lining up at their doors. As it turned out, literally sucking the carbon dioxide out of the air was easier and cheaper than modifying many of their industrial practices to actually be environmentally green. They didn't need to run more efficient factories to claim to be carbon-neutral; just pump as much carbon into the air in exchange for undoing that by sucking it out of the atmosphere after!

Some bean counters at a think tank in DC predicted that a few more shipments of these air filters will fix Earth's climate problems by themselves in about a decade, so every trader had a waiting list of corporations with PR problems willing to buy them.

Sarah and Jen had a couple vehicle manufacturing companies on their list who were trying to get Bohor air filters to use in lobbying for looser emission standards for their dirty gasoline cars.

Today, there were traders on all the landing pads, and they were all carrying air filters. Zarko's ship was there, and he was loading fruits into his spaceship with an alien looking forklift. Sarah and Jen approached his ship and noticed the truck driver standing there.

"Hey Benny, tempting the poor aliens with cherries this time?" Sarah waved good, grinning and looking at his cargo.

Technically, Benny is a competitor, or at least he drives for a competitor. The massive fruit conglomeration he worked for, Chuckita, had not neglected to notice the massive business opportunity sitting right here as many others have, and are now delivering straight to the aliens in exchange for massive profit margins.

But Benny was a good guy. One time Jen and Sarah were having some trouble finding a buyer for a bunch of legally dubious alien psychedelics. Benny was in his late 50s, not that great with the Internet either, so he'd introduced them to whom he referred to as "my money launderer". Aka, his 22-year-old son, Benny Jr, who had a habit of buying weed and other less than legal items off the deep web. Benny Jr had found a buyer for them within minutes and even generously offered to handle the deal for them to spare them the risk of meeting some psycho hopped up on an alien high in a dark alley somewhere.

"Heh! One of the bat aliens loves sweets but has a low tolerance for sour, so they treat cherries as some kind of an odd challenge fad. They eat a random cherry, and it's either so incredibly sweet they start drooling out of the mouths, or it's a sour one, and they freak out," Benny replied, in a low voice as if he were trying to keep it a big secret. "Zarko showed me a video, and it's the most hilarious thing I've ever seen".

"I think I've seen that one, have you seen the one where they drink wine?" Sarah chuckled at the memory. Alien videos have been a big hit on YouTube. Some human merchants were trading fruit for aliens to take videos of the galaxy. Which they monetized, of course.

"No," Benny's ears perked up. Chuckita doesn't make wine, but if selling wine to aliens was going to be a thing, they were a big supplier of grapes… "Is it gonna be a thing?"

"Well guess what we brought today?" Jen also grinning from ear to ear, and holding up a big carton of low-quality box wine.

"Awww seems like I'm always one step behind you guys," Benny moaned in exaggeration, "I tried to get my money launderer to tell me what aliens would want but all he does is play video games on the Internet, kids these days."

Luckily, Zarko chose this moment to step out to spare them from more good-humored ribbing from the boomer. "Ah Sarah and Jen, you brought the grape wine this time!"

"Yup," Sarah beamed, "and I see you've run out of air filters to trade again!"

"Sadly yes," Zarko tilted his head in shame, "my ship is overdue for a cargo space upgrade, but I haven't found a port that would do it for fruit yet. Next time?"

"Alright! Alright! We'll leave our special wine with you, but you better get us some extra good filters next time!" Jen scolded mockingly. Zarko has gotten a lot more comfortable doling out IOUs since the first time.

"Of course. Only the best for you two," Zarko said with a greasy human smile imitation that almost made Sarah laugh out loud. It reminded her of a ridiculous cartoon sloth.

"By the way," Sarah asked casually, "how much is a spaceship worth on your planet?"

Zarko sobered up his expression and looked at her curiously. It was a question that other humans had asked before. To him, it was a good sign. This meant that they all dreamt of the stars. But he didn't expect such a question from someone as seemingly practical as Sarah. She had a lot of fruit, sure, but fruit doesn't build spaceships.

After thinking for a while, he replied honestly, "ships aren't traded for one single item. My family traded for the parts to build mine for generations."

He pointed at his spaceship.

Zarko proudly explained, "this is the work of eighteen generations of trading. My family was one of the richest on Zeep-zep. For thirteen generations, they traded for each of the parts on this beauty. Then, for the last five, my ancestors traded excess food from the tenant farmers on their land to expert craftsbeings that could put it together."

"Wait, eighteen generations?" Jen gasped. Eighteen generations ago, her family were probably peasants on a farm in Korea or something…

"Yes," Zarko said, looking at them with a little of pity. "After getting the spaceship, my family has traded in it for twelve generations, through civil wars and disasters."

He did some math on his hands, and said, "that's about four hundred of your years. That's why it's very unlikely that you will never go to space."

Looking at the stunned expression on their faces, he tried to lighten the mood. Zarko said mischievously, "unless you're willing to part with some more of your fruit, in which case I'll let you sit in the back seat for a whole route!"

"Hold on, back up, I'm still stuck on the multiple generations part," Sarah said seriously. "You're saying you're flying on a spaceship that started to be built thirty generations ago? That's… about a millennia for us."

"Yes," Zarko answered, "and that's why only thirteen families on my planet have had the privilege of owning one in our long history. No offense, but that's why I think no human will ever own their own spacecraft for at least fifteen more generations."

Something is wrong here, Sarah thought. The budget for NASA's FTL spacecraft was in the hundreds of millions. Yes, for a fruit farmer, that would be many generations of work if all their descendants worked in the same industry. But there were over three thousand billionaires on Earth, not including the tens of thousands of corporations that had assets or market value over a billion. And the prices for the spacecraft would surely go down as time went on…

For a planet like Zarko's to only have thirteen spaceships over generations of their development…

As they were walking away, Benny asked, "have you guys noticed something weird about the way these aliens do business?"

"Yes." "God yes." They said in unison.

"We've been thinking about it for a while, but these guys not having money is a major problemo," Sarah said, looking around surreptitiously, "Zarko and Zikzik keep talking about not being able to find someone who can upgrade their hulls for fruit. And sometimes they come with nothing good, and we're supposed to just drive our fruits all the way back!"

"And if you think about it, if they were human ships, think about truckers who don't own their trucks. We'd have loans or something to deal with the cargo space problems, and they'd be paid for by profits in a few trips," Jen added.

"The numbers he gave us for spacecraft ownership seem insane," Sarah agreed. "Your company could probably afford to order one right now, not to mention hundreds of others. They must all be dirt poor!"

Benny seemed relieved that he wasn't the only one who was thinking this, "exactly! I'm thinking we just introduce them to the concept of Benjamins and solve all their problems and ours. Would certainly make the return trip a lot easier for me if I didn't have to drive all the way to Berkeley for junior to launder all this crap!"

"We thought of that too," Sarah said as Benny pretended to groan again, "but we couldn't figure out how to get them to take money with no intrinsic value."

"Oh that shouldn't be too hard," Benny said, who's clearly already thought through this problem in his head, "we play a little game called good cop, bad cop."

"Good cop bad cop?"

"Sure, it's a mind game the cops play, where they put you in a room-"

"Yeah we know what it is, but how does that help us?" Sarah said impatiently, an idea tugging on her subconscious.

"Well you see," Benny clearly smugly enjoying this moment where he's thought of something that the duo did not, "you two come with an empty truck next time, and you tell Zarko that you'll give him a wad of clean crisp cash, fresh from the bank, for some of his air filters. And when he asks you why he'd take the cash, you just tell him that he can give it to me in exchange for some of my fruits."

"What does that have anything to do with good cop bad cop?!" Jen asked.

"That has nothing to do with good cop bad cop," Sarah chimed in, but the idea was beginning to form in her head, "but it's a good start. We don't want to deal in cash. It's too risky. It could get the feds onto us and there's a bunch of laws around it that I'm not sure about."

"But what we can do is have an internal money system for traders pegged to the US Dollar!" Jen completed.

"Yup, so when Zarko comes back next time, we tell him he has an account with the Bank of Benny, we give him a fancy looking card that has his bank account number and give him a pin code, and we deposit a certain amount of BennyBucks into his account for giving us air filters. Then when you come around, Zarko gives you his card and pin, and gives you BennyBucks for your fruit," Sarah finished.

"Aha. And then I come to you two, say, I would like to convert BennyBucks in my Bank of Benny account to good old American dollars," Benny extrapolated, completing that final step.

"Yeah! We'll just wire you the money and everyone gets theirs," Sarah exclaimed, happy they've finally thought through the loop and gotten someone on board.

"BennyBucks is a terrible name though," Jen said, calming everyone down a little, "and why are we getting so excited over the basic concept of currency? And why haven't aliens figured this out? Maybe it's against some kind of space trading code."

"Who knows? Maybe we just try it on Zarko and see if it works out," Benny said, a glint in his eyes, "and then we expand, galaxy-tically."

"Galactic credits!" Sarah exclaimed, "that's what we'll call it."

They agreed that it was the least worst name that they'd come up with so far. It was boring, but when it came to finances, maybe boring and cliché was a good choice after all.

"Explain again. I am trying to understand," Zarko said two days later as he offloads the air filters he'd promised.

"C'mon dude, for the fifth time," Sarah exasperated, "it's not that hard. We give you a bank account card and have you set up a secret number…"

Jen had spent the last two days coding up a storm. Technically, a simple debit system wasn't that hard, but she had to make a website interface that Benny could go up to and enter his account, Zarko's card information and amount, then let Zarko type in his code…etc. She'd mused that it would have been easier to just do this all in a cloud-based spreadsheet, but that wouldn't scale up if they had more customers.

Sarah had the account cards laminated and designed a logo: the letters GC, for Galactic Credit, and a stylized version of a Milky Way in the background. Part of the value in a trustworthy system is to look official, and you can't get much more official than laminated cards.

"Yes, I understand that part," Zarko said, clearly displaying his frustration on his facial expression as well, "but I don't understand why Benny would give me his fruit for just entering a number."

"Because we have an agreement with him that he'll take it in exchange for fruit!" Sarah was sure this was the umpteenth time she had to explain this, but clearly Zarko was not getting it.

"Is it similar to a debt?" Zarko said suspiciously, as if debt was this dark magic that the humans were performing on him, "I have never heard of this kind of debt before."

"Yes, it's a debt, of sorts," Jen cut in. The last time he had asked this exact question, they'd said no, and that led to fifty other questions and explanations that went nowhere, so nothing could go worse if they said yes-

"Ok. I don't understand," Zarko did his sloth version of a sigh, it was cute, but at the same time frustrating for Sarah and Jen, "But I can try it. I know you two are not trying to trick me. Do I get my fruits before I take off?"

"Yes! You go to Benny-" Sarah started.

"Yes! And that's it. Benny gives you his fruit," Jen cut her off, knowing that this was about to launch into yet another long, long line of questions they just can't deal with right now.

Sarah set up a new account for Zarko, asked him for a 6 digit base ten pin code (thank god Zarko was a ten digit species) which he promptly memorized, and hoping that Jen's prototype website wouldn't fail, showed him how they were "giving" Zarko 40,000 Galactic Credits for 8 Bohor air filter machines into his account ("No, you can't have my iPad. It's on your account card now. Show this to Benny later.")

"Well that worked out great," Benny said as he watched them wire him the $25,000 for his truck shipment of fruit. Though his costs were in the low thousands, he could have easily fleeced Zarko for his full 40k. But they all agreed that wasn't the point, which was to get Zarko to see the benefits of using a currency system abstracted from goods and services.

"Dude, you weren't there," Sarah complained, "I don't understand why he had such a hard time understanding money. Money equals goods. Bing bang boom. It's like these guys don't have the capability for abstract thinking."

"No they definitely do. You can't build spaceships without abstract math and science," Jen said, "but he clearly had a deathly aversion to using money. I think it's tied to some taboo to debt somehow. All the other species must have it because none of the aliens we've met have even mentioned anything close to a real economy."

"Whatever it is," Benny sighed happily, "I'm just happy I didn't have to go home with my truck full of weird alien toys."

"Yup. The next step is to get all the human traders to take credits. At least they'll have no problems understanding the benefits."

Sarah made some calls to the trader licensing office at the spaceport. There she found a manager willing to part with phone numbers and contact information for the other human traders, for an "information fee" of course, and started making calls to the other human traders.

It wasn't easy. Some traders were representatives of bigger food companies, and didn't have all the flexibility to make these kinds of decisions. And others no doubt were thinking of copying their system for their own profit. But they all saw the benefits of a unified network of currency debiting because they've been suffering the same problems that Sarah, Jen, and Benny had been.

Over the next few days, all the human traders agreed to take galactic credit from the aliens, which they knew they could exchange for cash with Sarah and Jen.

"We are officially in business."

In economics, there's a distinction made between different kinds of money. There's commodity money, usually gold or silver. There's representative money, which is currency backed by commodities like gold or silver. And then there's fiat money, which is not backed by any intrinsic value, but rather by government decree, hence fiat.

Galactic Credits fall into some kind of weird hybrid category between representative and fiat money. They're backed by the Dollar, which is fiat money, but also which makes them representative money. This means that the people issuing them, in this case Jen and Sarah, are not supposed to create them without also having a corresponding US Dollar in their bank account.

Of course, Sarah and Jen hadn't signed an ironclad contract with the other human traders that they're always guaranteed to take their galactic credits and exchange for money, so technically that meant that one day Sarah could simply "deposit" a large number of credits in her account and buy all the goods she wanted from Zarko, or potentially the other traders.

That would, however, be slaughtering the golden goose for the meat.

After all, they didn't want to sell fruit or Bohor air filters.

They wanted to sell the concept of money.

"Why would I take this over fruit?" Zikzik sniffed. He was known as a sharp one by all the human traders. If there's any new alien fad coming down the pipeline, chances are Zikzik is the first one to touchdown with a cargo hold full of it.

Unlike many of the other traders, he was fairly consistent in his dealings. This much fruit is for this much air filters. He knows his price, and he lets you know it too. Everyone suspected he kept careful records of all his selling and buying somewhere in his ship, but he's never brought them out. Maybe he just had a sharp memory.

"It's very consistent," Sarah insisted, trying to appeal to his affinity for a stable and predictable exchange, "one pound of fruit today is the same as one pound of fruit tomorrow, and you can deal in fractions."

Completely ignoring that most fruits are seasonal, and price changes, and inflation, she thought, let's start here.

"Fractions, you say?" Zikzik seemed thoughtful, or maybe he's just scratching an itch on his snout, Sarah could never tell with these aliens.

"Yes, fractions," said Jen detecting the slightest bit of opening, "you can trade your air filters for credit. Then you can trade maybe three quarters of your credits to fill your cargo with fruit. The next time you come down here to Earth, you would only need to bring half the amount of air filters as the first trip, combined with the credits you have left, you can leave with a full cargo load anyway!"

Is that how that math goes, Sarah thought, but didn't cut in, as Zikzik seems to be nodding, an oddly universal gesture for affirmation.

"Five eighths of the credits," Zikzik argued, "The air filters are harder to get now because the Bohor are running low, and they need time to make more."

Bargaining! There we go! That's what we're talking about! Sarah almost pumped her fists in the air and gave him a high five, not a great idea given how sharp his claws are as she found out when trying to shake his hands a couple of weeks ago.

"Ok, you would still have to negotiate that amount with each human trader," Sarah replied adding, "but they all deal in Galactic Credits."

They signed him up for an account, gave him a card, and set up his pin code. It had only taken half an hour to get Zikzik on board, which was significantly faster than the hours they'd taken to explain this to Zarko, despite them being the same species. Was it xenocist that she'd assume it was going to take just as long, Sarah wondered.

Looking at the line of traders, she sighed. This was going to be a long day.

Luckily, Zikzik accepting the credits made for great advertising. He was known for being a sharp trader, so if he doesn't think it's a scam, it must not be, right?

Sarah and Jen managed to get two other traders that day onto credits, and one more who was dipping his proverbial toes into the water.

It was a good day.

Jen had been working hard. The Galactic Credits website was now on its 16th major iteration. She'd beefed up the security on it, to make sure none of the other human traders got any funny ideas. Backups became more automatic and frequent, and there was now a rollback and dispute mechanism, not that it was being used yet.

Sarah had also been working hard. She'd been sitting in meetings all day with legal, finances, and now they had a small army of people who were ready to help out if they got into trouble there. Galactic Credits is now officially a tax paying LLC incorporated in the great state of Delaware.

Benny Jr, who had just finished college, had come in as well. He was no good at talking to clients, but he's what the duo would refer to as "street smart". Occasionally, the alien traders would bring in some exotic or ahem, dubiously sourced items, and he would know exactly where to convert that into cold hard cash. On the spreadsheets, his dealings were adding up to a nice fat padding on the margins for Galactic Credits, which to this point, hasn't been making any money other than in the fruit and air filters exchange business.

They were now working out of a rented office in downtown Livermore, with a very nice view of a brick-lined pub that offers numerous craft beers and the old railroad that runs through the heart of town.

Ironically, there's a Bank of America branch across the street, not far from the office itself, the company that had invented the BankAmericard and started the credit card revolution, seemingly oblivious to this new competitor moving into town, literally and figuratively.

They had many brilliant finance experts who were working on something, surely, but established financial institutions are not always great at moving fast and adapting to changing technology. There were many regulations to worry about, and the stakes were a lot higher.

There's something very quaint about the town itself. Some people didn't consider it part of the Bay Area metro area itself, but with the latest BART expansion station they recently built, that's been less and less true.

Now, it was literally the town where the train tracks ended. And where the final frontier began.

For the people in the office, it's also where they dreamt about a new financial revolution in the galaxy.