So let's say you have a starship like in Star Trek and you want a Replicator, but don't have the ability to convert matter to an energy form to pass their electrical cables. Basically you have an advanced 3D printer.

What Raw Resources would you need to make just about anything with this device?
Could you reliably and easily transport these materials through a cable system that doesn't have huge cables from a cargo hold?

Also, I know we can print meat, but could we print things like a cooked egg? Or even an uncooked egg?

I'm trying to figure out whether it is better to have such devices in crew quarters on a ship rather than a refridgerator, a mess hall, or some other way to get food and supplies. And also what type of "plumbing" would be needed to set it up.

  • 1
    $\begingroup$ Personally, I would say it's easier to have such stuff centralized, perhaps specialized: Near the mess hall, there's the food "printing" station, complete with warehouse. If you want luxury, you can have a system to send the finished food through the ship, otherwise you eat in the mess hall - or have someone of lower rank bring the stuff to you. Food could be printed "rare" and prepared in a kitchen. The printing system for technical stuff is near the technical area, etc. This way, you can optimize local storages for specific needs (metals, etc. will only rarely be needed for food preparation) $\endgroup$ Jul 5, 2017 at 8:01
  • $\begingroup$ "Magic" I think the answer you want here is "magic." And as technology and magic are the same thing, the details are irrelevant. Which is why shows like Star Trek never explained how it worked beyond some meaningless technobabble. It wasn't important to the story and any attempt to explain it just breaks the suspension of disbelief. $\endgroup$ Jul 5, 2017 at 18:09
  • $\begingroup$ @Draco18s magic solves everything as does author says so. This is not a useful comment. $\endgroup$
    – Durakken
    Jul 5, 2017 at 22:45
  • $\begingroup$ "Is the inner workings of this machine important to the story? No? Skip it." $\endgroup$ Jul 5, 2017 at 22:49
  • $\begingroup$ @Draco18s The question (and hopefully my answer...) is important. Star Trek was a fantastic show, but some of what it relied upon - FTL warp drive, energy->matter conversion in replicators, transporters - is not just beyond our current technology but beyond our current understanding of physics. This is an attempt to provide some of the same results but through a scientifically plausible mechanism. That could make for a much more believable story - and features or malfunctions of this could even feature in the story, depending on the author's whims. $\endgroup$ Jul 5, 2017 at 22:54

3 Answers 3


For raw resources, as a baseline, I would say that you need everything non synthetic on the periodic table, with some advisory on which radioactive elements you want (they can be useful in applications like medicine but you probably don't want Joe Blogs running around with plutonium or thorium). Almost every element is used for something so if you don't have a particular element you won't be able to make something that needs it.

If you can predict what you'll need you can limit it to those elements required. So if it's food only then you'll only need biologically important elements. If you're fabricating metal then you'll only need the base metals as well as alloying elements. If you need to do a bit of everything then you come back to that baseline of pretty much everything.

As for transport there are a few possible ways. First up i'm assuming that there is a elemental store of the most commonly used elements for a particular machine in situ to provide an immediate response to common requests.

Then to restock you could: Melt or dissolve everything and pipe the liquid through or powderise the solids and make a slurry. But I feel that this would require a tube for each element so as not to contaminate or cause unwanted reactions which would quickly require a massive bus of tubes so my personal favourite is a pneumatic tube type system (probably an electromagnetic version of the sytem). As the machine gets low, or receives a request for an element it doesn't have it sends a signal to the central storage requesting a top up, this top up it popped in a capsule and whisked away to the correct machine.

As to printing complex structures like eggs. We can not do it today but it is likely just a matter of time.

  • $\begingroup$ I object to your first sentence! I happen to be excellent at the 100m Thorium-Disposal-Sprint! $\endgroup$
    – Joe Bloggs
    Jul 4, 2017 at 11:25
  • $\begingroup$ So you are suggesting Having about 90 cables? Some magnetized? some liquified, and some pushed through with some sort of air pressurization? Wouldn't that be a bit much to have in a wall? $\endgroup$
    – Durakken
    Jul 4, 2017 at 21:21
  • $\begingroup$ @Durakken No, what I'm suggesting is you don't want those 90 cables and instead have a single tube which operates on the same principals as a pneumatic tube system, though not necessarily powered by compressed air. $\endgroup$
    – Static
    Jul 5, 2017 at 1:46
  • $\begingroup$ So a pneumatic system that has compressed raw resources in capsules where at the end point grabs, reads some sort of tag, and places in the cartridge position, like a regular printer. When the cartridge is used up it is sent back out? That seems sensible to me... The problem I see is how do you handle things like gold which seem like they need to be melted... and batteries. It seems any device that comes out of this thing would have a random charge state... $\endgroup$
    – Durakken
    Jul 5, 2017 at 15:56
  • $\begingroup$ For eggs, I suggest printing a chicken instead. $\endgroup$ Jul 5, 2017 at 18:03

Without energy to matter converters or desktop controlled fusion (to create one element from another), you need to have as input every element that you want in your output.

You don't need every element - just the most common. The trace elements can be added with special "element cartridges". Based on earth's composition == most commonly used for lots of things Wikipedia list of earth's most abundant elements:

  1. Iron (32.1%)
  2. Oxygen (30.1%)
  3. Silicon (15.1%)
  4. Magnesium (13.9%)
  5. Sulfur (2.9%)
  6. Nickel (1.8%)
  7. Calcium (1.5%)
  8. Aluminum (1.4%)

That covers 98+% of the earth. Plus you need a few more elements that are biologically important Wikipedia composition of the human body

  1. Carbon
  2. Hydrogen
  3. Nitrogen
  4. Phosphorus
  5. Potassium
  6. Sodium
  7. Chlorine
  8. Magnesium

which together with the first 8 elements comprise 99+% of the human body and most of the things humans eat.

Assuming your advanced starship has nanotechnology capable of performing any reasonable chemical transformation, you just need to have your elements in an easily stored form that is also easily transportable from cargo hold to your shipwide system of replicators. This would certainly include liquids at room temperature. Water (hydrogen + oxygen) and alcohol (carbon + hydrogen + oxygen) provide some key elements on their own and both are excellent solvents for many other elements. In addition to ordinary liquids, gases (e.g., nitrogen) and possibly slurry for large amounts of silicon, iron or similar elements could be piped from the cargo hold to the replicators as well.

A handful of pipes should be sufficient:

For example, a simple saltwater solution includes hydrogen + oxygen + sodium + chlorine, and can include potassium (as potassium chloride) very easily. Additional elements can be included as long as they are mixed thoroughly so that distribution is consistent. Magnesium is a relatively significant element in Earth sea water and can be included here too.

Alcohol can dissolve many things better or more easily than water.

Noble gases can be mixed together with nitrogen as a gaseous feed. I wouldn't include hydrogen or oxygen in that pipe as they can be extracted from the water and alcohol.

Total pipes: minimum 4 (water solution; alcohol solution; slurry for silicon, iron, etc.; gas) but probably 6 - 10 total depending on combinations of elements if multiple water, alcohol or other solutions will more easily provide a useful and homogeneous (each pipe should provide a homogeneous mixture so that your nanobots don't have to wait for anything to be available) mix of elements and to avoid dangerous interactions. Plus the "trace element cartridge" installed manually as needed for gold, silver and other small (by quantity) but important elements.

Route the bundle of pipes as a group together throughout the ship - similar to running cold water + hot water or power + phone + network cables. Every replicator will have everything it needs on tap to produce tea, Early Grey, hot, a raw or cooked egg, steak and potatoes or a replacement part for the Retro Encabulator.

  • $\begingroup$ Do I understand your answer correctly? You want to have solutions of "elements" and then some black box makes whatever out of these elements? You use water as a solvent and as a supplier of oxygen and hydrogen and then add some other stuff like NaCl for those elements? So far I don't have a problem, I just want to know if I understand it correctly. But then you start to lose me. What exactly do you want to do with your alcohol? It would be a logical supplier of carbon, but something seems to be dissolved in it? $\endgroup$
    – Raditz_35
    Jul 4, 2017 at 14:40
  • $\begingroup$ Too few characters. Now you want to use strong acids because elemental iron (and so on) are not easily dissolved just in plain old water. What about en.wikipedia.org/wiki/Iron%28III%29_chloride - you used NaCl earlier? Why does one need to prepare those solutions from raw elements in bulk? Same story with Potassium. Yes, you can "dissolve" Potassium in water, but really why would you not simply use a KCl solution to start with? The same logic can be applied to any element. Btw I'm not saying you are wrong, I'm just confused $\endgroup$
    – Raditz_35
    Jul 4, 2017 at 14:42
  • $\begingroup$ Still too few characters: I see 3 different approaches here, but I might be totally wrong: 1) You just have elements in any form, doesn't matter which (use water and NaCl solution and somehow you end up with whatever you want to build with that). 2) You solute something in some alcohol which suggests you plan to use larger, (organic) molecules as building blocks. 3) You store elements in their pure form and then supply them when needed. Which one is it? $\endgroup$
    – Raditz_35
    Jul 4, 2017 at 14:47
  • $\begingroup$ @Raditz_35 I'm not a chemist, so I don't know the best way to get every element. But my idea is that the most commonly needed (and some of the less common too, if they happen to add easily) will be piped in using a water solution, an alcohol solution or some other liquid - either to provide elements directly by separating through common chemical reactions and/or nanobots into the elemental forms to then be built up into the desired molecules or using molecules directly (you need water in Tea, Earl Grey Hot, so separate the water and use it). For trace-but-necessary elements add separately. $\endgroup$ Jul 4, 2017 at 16:14
  • $\begingroup$ Oh ok i understand. Then i think this is a perfect answer if cleaned up a bit. I'd just skip the strong acid part and make clear that other solvents might be needed if more complex precursors are desired. I can't think of an element other than noble gases you would need anything other than water for and a gas can be supplied easily $\endgroup$
    – Raditz_35
    Jul 4, 2017 at 16:48

How does your body do it?

A fluid carries nanoscale capsules of all kinds. Each is tagged with its contents, and it’s expandable to new types as well.

The unit grabs the capsules it wants and passes the rest. Common capsules carry atoms for most common uses. Specialized jobs may need different capsules bearing unique atoms.

The fluid is looped, so the central supplier can see what’s coming back and top off what was taken. If mpre rare capsules are needed, the fluid runs through the loop until enough is gathered, and the supplier can be informed of the need and dump a quantity into the stream.

  • $\begingroup$ So you're suggesting a plumbing system that carries nanites? The problem I see with this is that you would haveto have each element flowing at roughly the same speed through out the system to make sure you can get the right resource in a timely manner. That doesn't seem doable to me. I mean rarer materials would need "less" but they'd still need to have a constant stream and once someone turns on the tap, if too many are turned then it dries up that resource downstream. So I'm not sure how this could work or if there is a way around it. $\endgroup$
    – Durakken
    Jul 5, 2017 at 16:02
  • $\begingroup$ You missed the fact that it's a closed loop circulation, not a tap. $\endgroup$
    – JDługosz
    Jul 5, 2017 at 20:40
  • $\begingroup$ I don't know how that helps the problem... You still have to add it into the system and you only know that the stream is missing those elements by basing either sensing or by electrical system and then there is still a gap in the stream that is fairly large considering we're talking about a system that feeds a small city. $\endgroup$
    – Durakken
    Jul 5, 2017 at 22:44
  • $\begingroup$ Oh, so you’re worried about the latency, not the general concept. I’ll add tp my answer later. $\endgroup$
    – JDługosz
    Jul 6, 2017 at 0:26

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