Here is a question worth taking literally, because it is the one that decides whether mind uploading is a route to revival or an elaborate way of making a stranger who shares your memories: if a future machine read every connection in your preserved brain and ran a perfect simulation of it, would that be you, or merely an extremely good copy of you? Most discussions of uploading rush past this question to the engineering. We are going to sit on it, because for cryonics specifically, the answer changes everything and we genuinely do not know it.
Mind uploading, or whole-brain emulation, follows directly from a claim made elsewhere in this Codex: that you are the information structure of your brain, the specific wiring of its neurons and their connections, not the particular atoms that happen to implement it today. If that is true, then biological repair is not the only conceivable way back. A sufficiently detailed scan of a preserved brain, mapped at the resolution of individual synapses, could in principle be reconstructed, either as new tissue or as a running emulation on some future substrate. It is a second candidate revival route alongside in-place biological repair, and a preserved brain is exactly the kind of thing it would need as a starting point.
Why a preserved brain is the natural input
The reason uploading is relevant to cryonics at all is that both bets rest on the same foundation: structure carries the person. Vitrification is designed to hold the brain's architecture still, the connectome locked in place, even though the tissue is not biologically running. That is precisely what any scanning-based revival would need: not a living brain, but an intact map. Whether the future reads that map back into biology or into a simulation, the thing it reads is the same preserved structure.
This is worth being clear about, because it is a strength of the cautious position rather than a commitment to the wild one. Cryonics does not require uploading. It preserves the structure and leaves the route open. If biological repair turns out to be the path, the preserved brain serves it. If high-resolution scanning and emulation turn out to be the path, the same preserved brain serves that instead. You do not have to believe in uploading to choose preservation; you only have to notice that preservation keeps the option alive, which is exactly the logic behind how we might achieve revival in the first place.
The continuity problem, taken seriously
Now the hard part, the one that no amount of engineering progress will resolve on its own. Suppose the scan is perfect and the emulation runs. It has your memories, your personality, your sense of being you, and it sincerely believes it is the same person who lay down to be preserved. Is it?
There are two honest positions, and reasonable people hold each. The pattern view says yes: you are a pattern of information, the substrate is irrelevant, and a faithful continuation of the pattern is a continuation of you in every sense that matters. On this view, the atoms in your head are swapped out constantly through your life anyway, and you survive that, so why should a change of substrate be different? Tim Urban's walkthrough of what makes you you lays out how slippery the intuitions get once you start pulling on this thread.
The continuity view says not so fast. It worries that a copy, however perfect, is a new entity that begins life convinced it is you, while the original is simply gone. The classic intuition pump: if the scan could be done without destroying the original, you would have two of you, and they cannot both be the one true continuation. If the second one is just a copy when the original survives, why would it become the genuine article merely because the original was destroyed in the scanning? This is not a question physics can answer. It is a question about what personal identity actually is, and philosophy has argued about it for centuries without a verdict.
We do not resolve it here, and we are suspicious of anyone who claims to. What we will say is that the question is real, it is unsettled, and it bears directly on whether uploading would count as survival for you specifically. Biological repair sidesteps the worst of it by keeping the same physical brain in play, which is one honest reason to regard in-place repair as the less philosophically fraught route, even if uploading proves easier to engineer.
How far the engineering actually is
Set the philosophy aside and the technical requirements alone are humbling. A human brain has on the order of 86 billion neurons and a far larger number of synaptic connections, and a useful emulation would need to capture that wiring at something close to synapse resolution, then model how those connections behave. We can image small volumes of brain tissue at that resolution today, and we have full connectomes for very simple organisms, but mapping and simulating an entire human brain is far beyond current capability, by orders of magnitude in both scanning throughput and computing power.
So this is firmly future technology, and it would be dishonest to present it as anything else. It is not ruled out by any known law of physics, which is the strongest thing that can truthfully be said for it, and it is the same standard we apply to revival generally: revival is currently not possible by any route, uploading included. Mind uploading is a serious idea worth tracking, not a plan with a delivery date. It belongs in the same calibrated bucket as the rest of the field's long bets, alongside open questions like whether revival could ever be free of defects.
Mind uploading is a real candidate route to revival and a real philosophical gamble at the same time, which is exactly why preservation aims to keep the structure intact and leave the choice of route, and the verdict on identity, to a future better equipped to judge.
The honest position, then, is a held one. We preserve the brain's structure because structure is what every plausible revival route needs. We take uploading seriously enough to name its requirements and its deepest objection rather than sell it. And we admit, without flinching, that whether a copy of you would be you is a question we cannot yet answer, only refuse to throw away the chance to ask.