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How fast can nanites work

Tangential to the above question. This is for a novel about a somewhat near future. The conceit is that very advanced nanites, plus computers that are able to read our minds, equals something like sorcery. You still have to create or find schematics, but you can essentially think of a thing and the nanites will make it real. There are obviously limitations. Nanites could only create energy indirectly, for example, and couldn't give you powers that defied the laws of physics. But they could create all new organisms or make things that would be too intricate for conventional manufacturing. These are nanites at the viral or bacterial scale, which can change one molecule into another molecule by manipulating the atomic bonds. Our bodies do it, so I'm assuming we can make nanites that do it.

The way I imagine it now, people customize their environment and their own bodies a lot, as quickly as their moods change. People are effectively immortal, can teleport themselves anywhere with WiFi signal, and change forms into anything that obeys the laws of physics and preserves their brain and its functions. As it stands now, transforming from a standard human to something like a dragon would take just a few seconds, thanks to the ubiquity of the nanites. But the more research I do, the more I'm convinced that speed is not actually possible. I've solved the power and communication problems, but transport and movement of the nanites is a more fundamental task that no one seems to know the upper limits of for sure.

Obviously, it's a story and things don't have to be completely realistic, but I'm trying to make it at least plausible. The construction process has to follow the laws of physics that we know are definitely true. Or at least, stay close to the edge of what's possible. I need to know how the construction of a whole organism would be broken down, and especially, how long it would take in an environment completely saturated with nanites.

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  • $\begingroup$ Welcome to worldbuilding. First of all, we are not a forum, thus we have no (dead) threads. We have questions about worldbuilding, and we answer them. Questions need to be well defined and shall enable objectively measurable answers. Thus, we don't fish for thoughts. Please take the tour and visit the help center and, once you have made yourself familiar with our community, rework your question to fit our standards. You are not providing enough information for us to make a proper answer. $\endgroup$
    – L.Dutch ♦
    Jun 6, 2019 at 8:23
  • $\begingroup$ For a zeroth order approximation, nothing can be constructed faster than the construction materials can be brought to the construction site. So, for example, if you order the swarm of nanites to build a refrigerator for you, and assuming they work infinitely fast, they cannot complete the refrigerator faster than you can supply them with some 40 kg of steel, 1 kg of copper, about 1 liter of paint, about 2 kg of insulating foam, etc. $\endgroup$
    – AlexP
    Jun 6, 2019 at 10:10
  • $\begingroup$ Due to the popularity of building things this way, the ground and most buildings are made with CHNOPS bricks. These are bricks made of the most essential elements for biological life: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulphur. Other elements are not too far away, but biological things are a favorite and a necessity, so those elements are purposefully moved into close reach. $\endgroup$
    – Mara
    Jun 6, 2019 at 10:36
  • $\begingroup$ If you encourage people to "eat" the environment to build things at will, I imagine your world quickly looking like a minecraft server with permissions set to "do what you want". If you're not familiar: Lava, lots and lots of lava and tnt craters everywhere. $\endgroup$
    – Muuski
    Jun 6, 2019 at 14:29
  • $\begingroup$ The Earth's crust is a LOT thicker than Minecraft's world depth though. Sure there would be people who dug down as far as they could just to see what happens, but the heat and pressure would (probably) render the nanites inoperable long before anyone reached the actual mantle. Check out the ideas for sending a train through the center of the Earth for the limitations there. But there would also be an automated system to maintain the CHNOPS supplies. Literally everybody depends on this tech for daily life during the time frame of the story, so all the logistical hiccups get ironed out. $\endgroup$
    – Mara
    Jun 6, 2019 at 20:29

3 Answers 3

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Whatever your nanites are doing, it can be basically broken down to:

  • take some molecules of A
  • place them where they are supposed to be
  • move the next molecule

This means that the fundamentals of your process are not that different from a chemical reactions.

Chemical reactions, if I remember my studies correctly, can be limited by:

  • transport: if your molecule A needs to be transported to the reaction site, the reaction rate cannot be faster than the transport rate.
  • diffusion: if molecule A is not transported but only diffused, again the diffusion rate will limit the maximum reaction rate
  • kinetic: if you need to put energy into the scene, availability of energy will also influence the reaction rate

a standard human to something like a dragon would take just a few seconds

Based on the above, your statement looks indeed not plausible: as a rule of thumb, a human weights about 1/10 of a dragon. Unless you are surrounded by a crowd, I find it hard to find the mass and elements equivalent of 9 humans in your immediate surroundings.

I think it is more realistic to make it happen in a few days, at best.

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    $\begingroup$ The comparison to a chemical reaction is perfect. +1. $\endgroup$
    – JBH
    Jun 6, 2019 at 14:41
  • $\begingroup$ I do realize that, so I need to know the speed of that transfer. Assuming teensy tiny little bucket lines, no single nanite would necessarily have to travel that far. So it might be more an issue of how many nanites could you pack into a given area of the human body, for example, before it hinders the function of the body? How close together would they have to be, or how concentrated would they have to be, to make that material flow like water? Or waft like smoke? $\endgroup$
    – Mara
    Jun 6, 2019 at 20:35
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    $\begingroup$ Thing is the gathering is arguably embarrassingly parallel simply add more nanites. The real limit especially for biological work is the maximum rate the body can get rid of the waste heat from the chemical reactions without the equilibrium core temperature rising. Remember hit around 37.7C and complications of heat exhaustion start to kick in, hit around 40C and you are looking at a medical emergency requiring immediate cooling before the resulting cell death and other damage results in the loss of the patient. Limit here is likely hundreds of watts max certainly not kilowatts. $\endgroup$
    – MttJocy
    Jun 7, 2019 at 13:29
  • $\begingroup$ Having said that I guess this issue is not that much different to the kinetic issue. It's just that it means especially where very heat sensitive biological structures are present like anywhere in the body you need to be concerned with the energy liberated by exothermic process or energy consumed by endothermic ones. Whichever of those is dominant would become a limiting factor though you could perhaps somewhat mitigate this if you don't mind using a giant piece of machinery like a heart lung bypass machine to externally condition blood temperature using heat exchangers etc. $\endgroup$
    – MttJocy
    Jun 7, 2019 at 13:59
  • $\begingroup$ There would likely be specialist nanites tasked with heatsink. There would be nanite motherships that would churn out specialist babies appropriate to the wide variety of tasks required, sort of like a very complex bee colony but on a microbial scale. I'm assuming that once we mastered the basic idea of these things, it would be much easier to program them to a lot of different purposes, not just construction. $\endgroup$
    – Mara
    Jun 7, 2019 at 14:17
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I don't think this could be used for Biological Fabrication

Assuming you could fabricate organic matter on-demand and graft it onto existing tissue or reconfigure existing tissue to something else at a molecular level there's going to be a problem with the immune system. The DNA in those cells will be altered and the body will identify it as foreign tissue. White blood cells will attack and attempt to "reject" the transplant. You could I guess go on immuno-suppressants or program the nanites to do it but then you're immuno-compromised and if there's a problem with the nanites you will die painfully.

Whatever shape the final product takes it's also going to have to be controlled by the same set of nerves and muscle groups or there's going to be neurological problems. The motor cortex will have no idea what to do with a tail or wings if those have never been connected to it before. I would think it would take the equivalent of physical therapy to learn to use a significantly different body plan.

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  • $\begingroup$ I'm imagining that people would be able to copy both brain and body of existing animals to compensate for the difference. Need to smell things? There's an animal that already has all the specialized hardware (organs) and software (brain) to do it. Do a scan of a dog's brain and body and upload it as a template for people to customize, and you have at least the beginning of a super scent modification. The immune response is just a matter of having nanites specialized to that purpose (hypothetically). $\endgroup$
    – Mara
    Jun 7, 2019 at 14:20
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    $\begingroup$ Altering the body is one thing. That’s just interfacing with the peripheral nervous system. Alter the brain and you’re not even the same being anymore. Something of the original organism (and I don’t see how this could be anything but the brain) has to remain intact and unmodified in this organic chimera or the immune system will reject that instead. $\endgroup$
    – Adam Coville
    Jun 8, 2019 at 6:31
  • $\begingroup$ If we understand the brain well enough to design computers that can read our minds, and interpret those signals into physical images and objects, we likely would be able to engineer modifications to the brain. For the antibody rejection issue, again, nanites could be programmed to suppress that response. This opens up a lot of moral conundrums, but so does the whole idea. So does brain manipulation. So does artificial immortality. That's kind of the point of the whole story, are the moral and ethical implications. $\endgroup$
    – Mara
    Jun 10, 2019 at 7:25
  • $\begingroup$ I'm not going to say this is impossible, we are dealing in science fiction - but it is my feeling that you are underestimating the scale of that problem. In 2010 the Japanese "Kei" supercomputer, utilizing 705,024 processors and 1.4 million GB of RAM was able to simulate 1 second of human brain activity acting at 1% brain capacity. It took kei 40 minutes. Now, I'm sure that will continue to advance over time but to capture and transcribe that in realtime and miniaturize it is very far on the horizon. I would find it hard to suspend disbelief if I was reading a SciFi that used this. $\endgroup$
    – Adam Coville
    Jun 13, 2019 at 11:33
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I think you are correct that a few seconds is too short for the nanites to build a real dragon out of raw biological materials. (See this video on how fast nanites can build things: https://www.youtube.com/watch?v=FmgYoryG_Ss )

I would say that the correct realistic timeframe for the nanites to actually build a dragon (from scratch) is probably several years. This is based on the fact that actual living cells (IE "real life nanites") seem to take this kind of order of magnitude of time scale to grow large organisms. Yes, artificial nanites might be faster (in the same way a Jet is faster than a Falcon) so this is very speculative.

Already Built dragon teleports in

However, you have already said people "can teleport themselves anywhere with WiFi signal". Why not have the dragon already built somewhere and the nanites could simply transmit the persons mind over from their human body to their draconian one, while teleporting the (now asleep) human body somewhere safe and teleporting the dragon into the humans previous location. (The mind transfer being, in my mind, by far the most technologically plausible step of the entire set-up).

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  • $\begingroup$ That's an idea, but teleportation is only made possible because nanites. They deconstruct you in one place and rebuild you in another. People also make copies of themselves all the time. $\endgroup$
    – Mara
    Jun 7, 2019 at 14:23

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