You are taking the words out of my mouth. Such ideas are the consequence of a profound ignorance and misunderstanding of the human mind and body. Every era has its paradigms; in the Baroque, it was the clockwork, and clockwork was the way to explain nature, the human mind included. Today's paradigm is the computer, and everything is considered a computer. That's only a gradual difference in wrongness.

@ Peter - Reinstate Monica The human mind actually destroys itself as it learns. Neurons are lost as the connections are made.

First let me say: I agree. At the same time, what might or might not be possible in the future is kind of unknown. Especially as we really don't understand most of the brain. But main point is: If you do go down this route, appreciate the non trivialness of such a task.

Yeah, this answer simply says "it is really hard - so it is impossible". Which is logically wrong. There are things that we can conceive that contradict Physics (going faster than the speed of light) - but this is not one of them. Arguably you are a different person every second but you feel like the same person. The fidelity that you would need to recreate the neural states to "feel like the same person" is currently unknown.

@DavidMulder Sure, a swarm of nanobots crawling in through the nose to 3D print an entirely new brain on a molecular level should do... although, now that I think about it, you might want to deep freeze the body first. The heart can run itself but the lungs can't, so if the printing takes more than 10 minutes the fresh brain won't have a functioning body to operate. Anything less than a molecular print, I wouldn't trust.

For this reason it is not possible to download a mind into an existing brain. But it is still possible to 3D-print a brand new brain with that mind in it. Brains are write-once devices.

I completely agree with the practicalities pointed out in the first half, but I think the second half runs away with one interpretation of a mind snapshot and ignores others. If you assume perfectly accurate technology, it would be possible to take an atom-by-atom snapshot of a brain (which is more a copy of the physical matter than of the mind), and recreating that snapshot should yield the same brain and therefore mind (and emotional system) contained within. What matters here is the precision of your technology and how/if/where inconsistencies can be introduced.

@ user253751 Ah, yes, 3d printing. The favorite handwavium last resort of the desperate. Why not 3D print the entire clone of the human? Better yet, do away completely with conception and birth, and 3D print the entire rest of the human race? All of the life forms on earth, in fact. 3D print live dinosaurs, forget DNA. How about 3D printing enough life forms to populate the entire universe? Reduction to absurdity. Once you start down that path, there is no return.

@JohnDvorak: If you asked if a live heart transplant was possible 250 years ago, you would've received a resounding no. There are little to no impossibilities, there are simply practical hurdles that we have yet to figure out how to cross. That's very different in terms of considering what is possible in the future. We already have iron lungs, dialysis machines and heart pumps; so it is feasible to effectively "outsource" the human body's mechanisms for a limited time.

@JustinThymetheSecond: You're ridiculing what is a perfectly reasonable counter to your needlessly definite answer. 3D printing is a very real technology and there is already research into both lab-growing and printing organic matter, so this is definitely not a case of handwavium or lampshading. Also, just because something can be 3D printed does not necessarily mean that you suffer no practical issues with scalability. Even the Sith Empire with its vast amount of clones only had a finite amount of resources and abilities.

@Mike Wise Which in any case makes the question completely unanswerable except by handwavium, introducing 'that which is not known' as a solution. 'Then magic happens' is the inevitable and immutable answer to everything.

@Flater Ah, yes, the human-created and defined 'Sith Empire', the perfect scientifically valid example of the sound application of the sum of human knowledge. Or, perhaps more accurately, the perfect example of fiction-created illusionary reality. Yes. anyone who 'rejects reality and substitutes their own' can come up with a valid answer to the question.

@JustinThymetheSecond Because the question asked about brains, not humans, that's why. The brain-printer only prints brains. 3D printing is a known technology, and with future advances in medical science it's entirely plausible we will be able to construct artificial brains. Probably not with 3D printers, which are a simplification - specialized brain-printers will probably be required.

@Flater: "take an atom-by-atom snapshot of a brain" – is this even possible in theory? I'm really no physicist, but wouldn't the uncertainty principle interfere with taking such a snapshot?

@Schmuddi: Granularity matters here. While ultimate precision may not be manageable, any approximation of a Planck length would reasonably suffice, at least for the purposes of realistic worldbuilding. Keep in mind we're already working under the assumption of being able to map a mind one way; which already means dealing with uncertainty principle when it is a process that takes a non-zero amount of time. So yes, within the scope of the question, it is sufficiently justifiable.

@JustinThymetheSecond: The point of the example is to show that even for a civilization with a significantly higher availability of resources and overall galatic reach (which is a form of handwavium), finite resources are still a very reasonable limitation on what can be achieved.

What about using a small electronic device, like a stick, containing other people memories, from which you can semiconsciously access data from the main brain? You are not relieving data person's life, you're merely traversing the memories.

@JustinThymetheSecond You may want to read through worldbuilding.stackexchange.com/questions/159965/… regarding dead human brains being the same as living human brains.

I would put it thus: not with our technology; we're nowhere near being able to do that. Yes, you'd have to somehow mould every neuron and synapse (and possible more) which is something that we absolutely have no idea how to do. At the same time, we also don't know of any laws of physics that would explicitly forbid doing it. Speculating on what future technology will or will not be able to do is a rather impossible task, so for now I'd say that handwaving it away with "future technology" for plot reasons is perfectly acceptable and won't break any suspension of disbelief.

That said, it's probably a good idea to make the process look long, complicated and delicate. Like, it could take months to "clone a brain", and if interrupted it could not be resumed. The intermediate stage upon interruption would probably not survive, or be some sort of zombie (hey, that has plot possibilities!)