In a context where downloading the brain of a person has or is about to become possible, there is a problem looming at the horizon: once there is a copy, there is the chance of getting multiple copies.

While the possibility of having hundreds of Mozart, Chopin, Einstein, Fermi, Picasso and so on is surely enticing, the risk of having hundreds of Hitler, Stalin, Mengele, Pol Pot and so on would send chills down the spine of almost everybody.

Is there a way to encode the downloaded brain (aka mind/consciousness) in a way that prevents uploading/using it more than once and only once?

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    $\begingroup$ P.S. "A way to encode": Enconding and encryption are different things. Everything represented in a computer is encoded, for the trivial reason that the only things which can be represented unencoded in a computer are (small) integers and floating point numbers. Everything else, from the letters which make up the text of this question to pictures and sounds has to be encoded as (small) integers or floating point numbers. An encoding is public knowledge; to limit the use of data to a set of authorized persons or devices you need encryption. $\endgroup$
    – AlexP
    Commented Jan 24, 2023 at 13:44
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    $\begingroup$ Wouldn't send chills down the spine of Chuck Norris. Rambo, maybe. Superman, definitely. But not Chuck Norris. $\endgroup$
    – JBH
    Commented Jan 24, 2023 at 15:45
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    $\begingroup$ You have a bogus prolem here. Thousands of leaders, even evil ones, won't do squat, they need a crowd to lead to whatever glory they envision. Thus I don't see a problem, whoever wants to make thousands of Hitlers would find out that they happen to turn into artists in the absence of followers and with a need to eat and survive. Mengele was a subclass of "mad scientist", having thousands of these would likely fail to result in anything bad without financing and actual ideas to implement. Etc, all villains here are only dangerous if alone and supported, copying them won't make much harm. $\endgroup$
    – Vesper
    Commented Jan 24, 2023 at 17:22
  • $\begingroup$ @Vesper Not sure, some Hitlers may become arts teachers or even department leaders -- remember, they are all ambitious! This will... say, alter the character of the institution! All the Pol Pots will rule over large families ... many of the Mengeles will become dentists and just love to do root canals ... there is so much damage these psychopaths can do! $\endgroup$ Commented Jan 25, 2023 at 13:34
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    $\begingroup$ Or a messenger, accountant (the extent of Hitler's experience and ambition when young.) There's an element of "powerful psychopaths are made" needs taking into account. $\endgroup$ Commented Jan 25, 2023 at 13:44

7 Answers 7


Two simple premises:

  1. The scanning process is destructive (careful: Graphic images).
  2. There is no way to store the scan other than in the next wet brain; the scan is only possible brain-to-brain. (Because no computer has enough capacity/only the brain is holographic/consciousness is a quantum state etc.)

This ensures that there is only exactly one copy, ever.

  • $\begingroup$ This presumes you can first only have a living original to make a clone from, and the result will be one living clone and no living original. Thus no Mozarts and such. These restrictions would only be good if an old rich person desires immortality, as the copied brain would just assume the old one's position together with his (younger by default) body, allowing the same personality to remain and rule further. The first premise should be dropped if OP desires that there should be a copy AND the original at the same time. $\endgroup$
    – Vesper
    Commented Jan 26, 2023 at 7:42
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    $\begingroup$ @Vesper Everything you say is correct. May I add that "if OP desires that there should be a copy AND the original at the same time", then the requirement "no multiple copies" is much harder to achieve; strictly spoken, the desire makes the requirement impossible: At most one can achieve "no multiple wet copies". Of course, this difficulty is what may have prompted the OP to ask this question in the first place. If they can curb their desire though and adhere to my premise, the requirement of a single copy is much easier to achieve. $\endgroup$ Commented Jan 26, 2023 at 8:23

Encode Classical data in Quantum States

I suspect your question is inspired by this recent question about why uploading the mind destroys the brain. My answer to this question uses the same principle as my answer to that question.

No one can be copied because everyone is already a copy. When you are born, your brain is part classical and perhaps part quantum. Shortly after birth, the software of your brain is put it on hardware that is fundamentally quantum. Then the no-cloning theorem says you cannot be copied a second time.

Classical data can be encoded in quantum states. For example a number $\alpha$ in the interval $[0,1]$ can be encoded by putting a particle in a quantum state $Q$ such, that when the spin is measured, it will point upwards with probability $\alpha$ and downwards with probability $1-\alpha$.

What makes this encoding special is that you can never get your hands on $Q$ itself. You can only collapse it to get a single result. Up or down.

The no-cloning theorem is a stronger version of this. The theorem says you can never operate on $Q$ to get an independent identical copy. After all, if we could do that, we could get a million billion copies, collapse them all and estimate $\alpha$ by the proportion of upwards pointing particles.

If you have two particles in states $Q$ and $P$ they can interact with each other(or with themselves) without collapsing. This allows much more complicated things to be done compared to having to particles that each point up or down, but you don't know which.

The standard example is the twin-slit experiment. Photons are put in a quantum state where they are over here with say 1/2 probability and over HERE with 1/2 probability. Even though you send the photons one at a time, you get behaviour as though there was "half a photon" in both places and they interact with each other.

The brain's classical operations should be put on hardware that uses quantum states to perform the same operations. The brain uses twin slits to decide what to eat for breakfast this morning. We can see what ends up on your plate. But we cannot make a doppleganger that does the same thing without collapsing your brain into an inert jelly pudding.

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    $\begingroup$ Incidentally, Bobiverse covered this by making the cloning process imperfect. Every time Bob was cloned, you got a meaningfully different Bob (clones of clones would result in more dramatic differences from the original). So you might clone Mozart and get someone who is kind of like Mozart, but will not exactly be Mozart. $\endgroup$
    – JamieB
    Commented Jan 24, 2023 at 15:08
  • $\begingroup$ Although the quantum state cannot be copied, it can be moved (e.g. downloaded to a new body) using quantum teleportation (a feature that preserves many reasons one might want to upload a consciousness while still disallowing copies) $\endgroup$ Commented Jan 24, 2023 at 23:35
  • $\begingroup$ This makes great story, but as a minor quibble from a physics / hard-science standpoint: Although you couldn't reproduce the original state precisely, nothing forbids you from getting arbitrarily close. Sure, you don't know what the original would have chosen for breakfast, but 35% might still choose cereal, 35% skip breakfast, and 30% oatmeal... and none of the copies' contacts would know which was "real"... $\endgroup$ Commented Jan 25, 2023 at 17:27
  • $\begingroup$ Not a physicist (so my understanding of quantum is limited), but I've studied quantum computing - my understanding is that quantum systems not only can't be copied, but also can't interact with or be observed from the outside without collapsing to classical, and that the collapse is system-wide. This means that in order for a quantum brain to voice any of the thoughts in its head, the entire system would have to (momentarily) collapse into classical space. Copying at that moment would still be possible. $\endgroup$
    – Tim C
    Commented Jan 25, 2023 at 22:13
  • $\begingroup$ I suspect after uncountably many generations of clones, the two different clones could become identical both belonging to the subsequent chain of two completely different individuals. Although there is very slim chance but non-zero. $\endgroup$ Commented Jun 8, 2023 at 7:58

The short and easy answer would be no. However, there are other ways to regulate.

The problem:
Moving a consciousness out of a biological "grown" environment into an artificial/digital one presents your problem. Since a digital environment has been man-made, it can be replicated. And since it can be replicated, it can be copied. If there was a sure fire way to restrict illegal copying of any kind of data, it would already be widely used by every digital content platform. Without any handwavium, undiscovered futuristic tech, or magic-type restrictions (for example there's only one "soul" that's attached to a copy) there can be no hard restriction.

Legal restrictions:
How this was "solved" in the TV series Altered Carbon was by making it highly illegal to have multiple copies to exist at once, at high penalties or even death. How the solution would work (not necessarily true to this series), is by having large government controlled facilities monitoring the copies. This would be either by directly controlling the manufacturing of the copies, or by a world wide internet-like web constantly monitoring the status of any copies currently active.

Restrictions on manufacturing:
Another way to restrict multiple copies is to have a legal or moral requirement for the digital copy to be destroyed after it is downloaded into an artificial body. This could be government controlled as above, or could run on an honour system with the companies who create the copies.

More arbitrary restrictions:
Other restrictions you could put on the process would be time and money for example. It could be extremely costly to create and/or maintain a digital copy of a person, let alone multiple. Regardless of the positive effects this might have, it might still be too costly in the long run.

It could also take multiple years or even decades to create a single artificial human. Therefore you should be really sure that you want to create this person. It could also be that the new copies burn out very quickly and have a short lifespan. This would not only restrict the work they could do in that short time, but it would also make anyone who creates a copy think twice on whether it's worth the effort.

The last thing I would consider is a more moral one. How effective would it be to have multiple copies of the same person? Would that at all work in the grand scheme of things?

In the film series Star Wars there are multi-million personnel armies made of the same clone. However if we swap this for a digital clone or android, we would run into some very interesting problems. As you might know the storm troopers from Star Wars have been meme'd to death for being terrible shots. This isn't entirely canonical but does display a glaring problem: as soon as multiple super-soldiers would be created, someone would find their weaknesses and flaws and use it to effectively take down large swathes of these soldiers.

Your worry "hundreds of Hitler, Stalin, Mengele, Pol Pot and so on would send chills down the spine of almost everybody." is very true, it would definitely send chills down everybody's spines. However realise that most of these dictators were a product of their time and position. They got to where they were by using and abusing the troubles of their time and manipulate large amounts of people. But could they efficiently produce that position of power again? Would they be able to once again get the people behind them in a similar manner, when the people have already gotten wise to them and their methods have already been committed to history? Apart from a cult-like following, it would very well be possible that the general populace won't let them get away with that kind of thing again. Especially not if there were two of the same person, people with that kind of disposition would sooner take each other out as soon as possible rather than help each other.

A similar thing would be true for the artists you listed. They were artistic revolutionaries of their time, and gained their popularity by charming a lot of people right then. But are they still at their height of popularity now? Would they be again? I would predict a large amount of people would label their "new" works as not "true" works. After initial hype they would not live up to the already existing catalogue. For the same reason certain bands aren't "the biggest rock band in the world" anymore despite still being around today in the same capacity.

Everyone and their ideas have an expiry date, and the human body is not necessarily the only the only limiting factor for this.

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    $\begingroup$ Excellent points about people being a product of time and place! $\endgroup$
    – PipperChip
    Commented Jan 24, 2023 at 15:12

Ok, we can upload/download brains, that's the thoughts/consciousness/soul/ghost of a human being. Let's sweep the practical and philosophical problems under a very thick, very large rug! Let's also assume that there can be some digital representation of a person's brain such that given proper hardware, a full brain can be reconstructed (and whatever "activate" button produces a copy of the person's mind).

Lossy Reproduction

Taking a problem from data compression, you lose a bit of quality every time you incorrectly (and cheaply) copy data. Like with MP3 compression, perhaps the copies loose a bit of information every time. Maybe these losses are minor and cause quirks, like the copy enjoying vanilla more than chocolate ice cream, but maybe they are major differences, like loosing major cognitive capabilities.

This is, to be honest, only a minor barrier. As we have seen with the MP3 format, this really doesn't stop people from producing copies.

The Mind is A Quantum System

Although we see neurons and neurotransmitters right now, maybe consciousness (and thus cognitive abilities, attitudes, etc) rely on quantum phenomenon. If this is true, and considering interacting with quantum systems irrevocably changes them, the mere act of reading a mind interrupts and destroys the original.

If the mind-downloading process is "analog" enough this raises a hard physical barrier to copies. Yes, you can position a new brain with all the bits in place from a previous scan, but when you hit "activate" some other person is created. Sure, they may have similar abilities, but most reasonable people say it is not a copy. You cannot reproduce the essential quantum phenomenon, only move it.

  • $\begingroup$ I like the quantum system idea because it could be used to place two burdens on the original copy. One is that the act of reading the data is disruptive of the data (e.g., reading quantum data violates the heisenberg uncertainty principle). Another is that it can be used to justify a time limit for using the data. Quantum data dissolves to chaos much faster than newtonian data. Thus, use it or lose it and once you've used it you've lost it. $\endgroup$
    – JBH
    Commented Jan 24, 2023 at 15:48

Transcription is terrible.

You have one copy of Beethoven's 3d Symphony. It sounds very different each time. It is because the orchestra playing it is a middle school orchestra and a different middle school orchestra each time. An orchestra whose members have never heard the piece and have not rehearsed. These various orchestras have in common only their inexperience with their instruments and with reading music, combined with an implacable relentlessness - each of these orchestras powers through to the end each time.

There is a tremendous variety in their product. There is not much worry about getting multiple Hitlers. Probably not even one. But you get something!


Make it physical

Let's face it: electronic data is the most copyable form of information ever discovered by human beings. You're going to have a hard time making something non-copyable in that kind of format.

Instead, have it be some kind of genetic or chemical material that gets output. Generate such a small sample that the act of analyzing that material is enough to destroy it or make it useless for future analysis. That way, whatever reconstruction machine you'll be using it in will only be able to use it once.

If you really like the idea of having it in data, you can also do that in tandem with the chemical sample. In this case, the sample would merely act as a 'key' that would be supplemented with additional important data from the cloud - someone's brainwave pattern, perhaps.


Digital Rights Management

Games and video services 'phone home' to check whether you're entitled to consume that media -- why would your brain be any different? Set up a simple management wrapper around the digital self that checks with external servers that no-one else is using the lease to run that brain right now before running the simulation of the person.

This might lead to one or two very minor issues.

  • Your brain was evaporated and failed to send the "I am relinquishing the lease" message to the server. You won't be able to respawn until the lease expires.
  • You wander out of connectivity and the lease is going to expire before you get WiFi back. What happens? Does the management software shut you down at the end of the time?
  • Does your relativistic time agree with the lease server? You might be able to exploit that (or not be able to respawn for a while)
  • The lease server has extended downtime, and no-one can respawn.
  • The management software is only mostly unhackable, so people can bypass the system.
  • If you run the hacked management software, you are implicitly trusting the hackers.
  • You are implicitly trusting the company to decide to do the right thing.
  • You are implicitly trusting the company to not go out of business.
  • If you're a friend of the CEO of the company, you can probably just ask someone to bypass the checks, for yourself or your army of clone workers.

As you can see this is a perfect solution with no drawbacks!


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