I am working on a sci-fi story and need a way to clone a person, body and mind. I also want it to be done without "far future technology" where anything goes. I want it to be simple and crude, but also believable. And I might have found it...


It's the near future. A interstellar spacecraft is sent to colonise a new solar system, a great feat, done on a budget. A generation ship is unfeasible so instead they send a small craft with the ability to recreate the crew upon arrival (or whenever maintenance is needed).

So, this is how it is done:

Upon birth a sensory device is implanted in the brain of some babies. This device is connected to all of the nerves leading into the brain, it reads and registers all of these nerves firing. This means all of the signals sent to the child's brain is logged. (At the time this was marketed as a "backup", sold to overprotective parents.)

All of the data is stored in a harddrive somewhere. The children grow up and are around the age of 25 when this project asks for volunteers, some of them volunteer.

When the cloning initiates a cell is placed in a artificial womb and grows into a fetus (simple enough). As the fetus develops a system of wires is inserted into their brain and locked on to the same nerves as earlier.

When they are due for birth the system kicks on and starts stimulating the same nerves that registered stimuli in the original, to create a false input for the brain. The child stays in the womb and is being feed the experiences the original lived, all in real time. The womb also function as a sensory deprivation tank, to prevent any real input.

When all the data have been transferred (the clone is around 25 years old at this time) the clone is born for real. He or she are now free of artificial input, a perfect copy of the original crewman, and can go on to confidently fix the leaking cooling system. (Sorry still 800 years to destination, maybe next time)

From the clones point of view they are growing up on earth, learns and loves, volunteer, hand over their "backup" harddrive and BAM... suddenly they are covered in goo, lightyears away from earth and hundreds of years in the future.

So the question is: How believable is it that this mind cloning method could work?

  • $\begingroup$ This is almost exactly the plot of the Novel Cyteen en.wikipedia.org/wiki/Cyteen It's also the primary principle behind implanting memories in replicants from the Bladerunner series. $\endgroup$
    – DWKraus
    Oct 18, 2021 at 0:58
  • $\begingroup$ I like how you call a solution that involves copying and replaying a mind, something that we have absolutely no idea how to do right now (or if it even can be done), "simple and crude" ;) $\endgroup$
    – xLeitix
    Oct 18, 2021 at 10:22
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    $\begingroup$ How do you solve the problem is muscle memory? The "mind" doesn't exist in the brain alone, even if the rest is possibly residual. $\endgroup$ Oct 18, 2021 at 13:19
  • $\begingroup$ I think there's no real difference between a moment before and a moment after birth (except breathing with lungs). I don't think the baby is "switched on". But a sensory continuum. So you might need to start recording before birth, perhaps. $\endgroup$
    – Pablo H
    Oct 18, 2021 at 13:56
  • $\begingroup$ Why exact clones? Wouldn't any sufficiently capable and motivates crew do? $\endgroup$
    – Pablo H
    Oct 18, 2021 at 15:00

2 Answers 2


Summary: The problem with replicating a mature brain by replaying its past experiences is that if there are ever any differences between the brain state of the clone and the brain state of the original, the clone will be unable to learn by interacting with the world, as the illusion of true feedback will be irrevocably broken. This inability to learn will not just cause a different version of a person, but, depending on the stage of child development at which it occurs, will break the clone to the point where their brain is barely human. Because of the butterfly effect, divergence in clone brain state could occur from even the smallest unaccounted-for differences. Ensuring that the clone's brain state is identical would require eliminating random, thermodynamic differences in the developing brain, ensuring that the brain state was identical after fetal development, and simulating brain injuries like concussions.

An unspoken assumption of replicating a mature brain by replaying its past sensory experiences is that the brain will develop the same way every time. However, this isn't the case — even with a cloned cell, your proposed artificial womb means the environment of fetal development will be different. Let's look at the consequences of this.

If you've ever watched a baby, you'll notice that many of their movements are somewhat random-looking. This is because they are just kind of trying everything out to determine their place in reality. "I feel angry, and then move my hand, and then feel my hand move, and then it hits the floor, and it hurts!" Discoveries like these are critical to child development as the child learns to adjust its behaviors to avoid negative feedback. If the cloned fetus is even a little different from the original one, the clone won't be able to associate intentions to actions to feedback — it will just feel painful feedback and have no mechanism for adjusting itself. It will spend its life trapped in a kind of hell in which it is an unwilling voyeur, a forced non-participant, in someone else's life, like an awful variant of locked-in syndrome. The clone may never learn to speak, to walk, or even to breathe, and when it wakes up covered in goo in a spaceship far away, it will be something less than human.

It's not just the fetal environment that you'd have to make sure is identical — if anything causes the brain of the clone to at any point become different from the brain of the original in any way (even a small way) the intentions and attempted motor actions of the clone won't be able to affect its world, and its development will stall as it is relegated to live the rest of its 25 years in someone else's body. Differences that can cause the brain development of the clone to fall off its very narrow track include anything which would cause the physical conditions of the brain of the clone to differ from that of the original: things like minuscule temperature variations, blood flow to the brain, and things like concussions — how would you simulate a concussion in the clone?

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    $\begingroup$ Well, that's grimdark. $\endgroup$
    Oct 17, 2021 at 20:05
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    $\begingroup$ I suspect this is a little pessimistic for producing functional adults, but I don't think ANYTHING will give you an identical person - perhaps an approximation that self-identifies with a set of memories. Still, I can't disagree with the basics you're covering. +1 $\endgroup$
    – DWKraus
    Oct 18, 2021 at 1:09
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    $\begingroup$ +1. There are experiments with babies in which they first let the mother interact with the child via a computer screen, and then later play back the recording of the mother's face to the baby, thus removing the feedback in the interaction. The babies become very distressed when this is done, because they sense that the mother is not really interacting with them. The feedback is crucial and brain development won't work without it. $\endgroup$
    – N. Virgo
    Oct 18, 2021 at 2:16
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    $\begingroup$ I think people need to spend time and deliberately stop thinking that a human brain is like a computer and you can somehow "copy" it. Our brains are far more complex than anything we currently know. $\endgroup$
    – Nelson
    Oct 18, 2021 at 4:11
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    $\begingroup$ @user253751 The principal is flawed. The article Your brain is not a computer talks about the errors of this concept. Neurologists are finding that each person's brain is actually unique to that person, and may very well only work based on not just the current state of the neurons, but the entire history of how it got to that state. $\endgroup$
    – Nelson
    Oct 18, 2021 at 8:43

There is a lot of hand-waving involved, but because virtually no one seems to know that, there's not a big problem for the writer.

Our minds are more than just the nerves. They are the culmination of the exact pathways they have, the amount these pathways are used, the chemical composition at the time and the many many feedbackloops that constitute the entirety of the nervous system. Your sensors need to log not just the individual signals but also map every neuron and every chemical inside the entire nervous system.

So lets say your deprivation tank clone broke her harm at the age of 12. If your tank does not break it and break it exactly, the chemicals in the brain are different and you get a different result. If your tank does not offer the resistances to movement and nutrients in the exact same way, your clone will have a different muscle tone and chemical imbalance. This will cause a disassociation: at first the clone will have microscopic deviances in its decisionmaking compared to the original to the same input. But as the years go by the decisions the clone would make to the same input changes. Where the original stepped left the clone stepped right for example, and the simulation shows something else. This will instantly jar the clone out of the simulation, he'll try to figure out what is going on while the simulation keeps going, throwing input at the clone of movements and experiences the clone no longer initiates. If the clone then has to live another few years experiencing someone else's memories while incapable of changing the outcome...

As an alternative: you are trying to achieve persona copying which is a ludicrously difficult if not impossible idea. Instead you should be looking at persona approximation. For example instead of cloning you use 3D printing. It is not impossible to assume we will be able to 3D print more advanced tissues in the future, and 3D printing entire bodies should not be a too big leap once you are able to grow and print any tissue.

You 3D print just the complete baby nervous system along with the rudimentary organs and pulmonary-vascular system to support it, but nothing else. This is printed inside the cultivation sacks of your clones using the DNA of the donor. This cuts down on the amount of resources you need to keep it alive and functioning and gives your machines direct access to the nerves where you need it. Now instead of perfectly recreating the life of the donor you let the computer try to approximate it. So if the clone decides to go left or right somewhere the computer will try to steer events to ensure the clone's life is pretty much the same as the donor. A life-altering event may take place in a different location because the clone decided differently, but it did take place in order to approximate the memories and personality of the donor.

Once the clone reaches maturity it will be put in a medical coma, after which the rest of its body is 3D printed. This way you can even set the muscle tone and body structure to the requirements of the planet, although you should not deviate the body proportions and weight much to ensure the brain's control over it does not suffer. Now you have a clone with as close as possible personality.


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