Could someone capable of regenerating from a single cell or cell nucleus survive their body being vaporized? It doesn't have to be perfect vaporization, it just has to look like they've been turned into a fine mist. No blood stains or gore. More practically speaking, I'm prepping this character to have a nuke dropped on them and wanna know if it's possible for them to survive after being reduced to a nuclear shadow like the ones in Hiroshima.
closed as off-topic by JDługosz, Hohmannfan, bilbo_pingouin, Frostfyre, TrEs-2b Sep 12 '16 at 19:05
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"Dune" proposed that the DNA of a person stored not only their memories but those of all ancestors. But that was written at a time when our understanding of data compression and memory was way more sketchy. (Assassin's Creed does the same thing, but they make no pretense of being hard SF.)
Given today's state-of-the-art... much harder. You'd need an animal that stores all memories in every cell of its body. Maybe its brain does the active thinking, but backups are stored elsewhere. Maybe the backups are made during sleep? But! you'd need not just the memories but the instructions to reconnect the neural net as part of regeneration to be stored in that single cell. The data density would be incredible. I bet you can find some chemistry that would support that kind of storage, but I doubt it could be done from ANY cell. Maybe there are a couple hundred at most scattered through the body. And restore would only be as complete as the most recent backup. Maybe you can have real-time back up, but that would press my suspension of disbelief, personally.
Also, you'd have to be careful... any live reboot cells that flaked off would turn into a full copy of the person. Another reason to make it only a few cells in the body, not every cell.
Aside from the points mentioned by SRM there is the issue of growth time and mechanism.
The single cell would have to be able to act independently collecting resources and replicate with virtually no DNA damage. It means that the cell must be by itself a living being, and it fits the description of bacteria.
Given that each of the cells have all the memories of the being (somehow), they would be acting as a colony, exchanging information cell to cell.
Note: acting as colony also implies that if you cut it into pieces they don't have to grow into individuals (which all would have the same memories). If the pieces can join they would merge in a single colony.
Given that the human body has around 3.72 x 10^13 cells in their body, and taking red blood cells for template, which can replicate at the speed of 2.5 x 10^6 per second. We could estimate the time to reach the biomass of a human being from a single cell...
For ease of calculation, I will say that:
- the cells have eternal life (no natural death, no DNA damage)
- the cells duplicate in number each iteration
- the cells after 1 second reach the total count of 2^21 = 2097152 (approx. 2 x 10^6)
This means that in 1 second there are 21 iterations. With 2 cells after the first iteration, 4 cells after the second one, 8 after the third, and so on.
They would reach 2^45 = 35184372088832 (approx. 3.5 x 10^13) after 45 iterations. Given that there are 21 iterations per second, this takes approx. 2.57 seconds.
Although we are disregarding the nutrients! - the blood cell can divide very fast because they are in a nutrient rich environment.
Say, if we want 64kg of biomass in 2^45 cells, each one (under the uninformed assumption that there is tissue differentiation) would be approx. 1.8189x10-12 Kg. That is also how much that single cell would have to absorb in 1/21 seconds and we assuming that the conversion is 100% efficient.
Of course, you could say that it goes directly into animal form, perhaps building a feet first and then a leg and so on. Yet all the built structure is there wasting resources. So doing it this way is bound to be slower.
If we assume that only the ground is nutrient rich, and only a fraction of the cells is able to access it (because it is in direct contact with the ground) then it will be a bottle neck for the replication process. Only as much as cell are in contact with the ground will be able to replicate per iteration.
We already calculated the minimum time in approx. 2.57 seconds. For the maximum it would be if only one cell can replicate at a given time. I calculate that to be approx. 53128 years. How fast or slow would depend on the nutrients intake. Consider that it would be absurd to keep re-growing an inefficient form, in particular after you have a decent fraction of the biomass of a human adult.
So... there is no reason why this super intelligent bacteria has to build a humanoid. For the initial phase it is more efficient to spread in the ground as to get more resources in the same time. Or perhaps the initial phase it acts like a plant, growing roots into the ground to extract nutrients.
The being could choose any form. In fact, with some effort (and down time) it could change from the form of an animal to another. At least for the growth phase the idea is to choose a form that allows to absorb more nutrients as to minimize the bottle neck.
With that in mind, it could start moss-like/plant-like, and then move to a small animal (perhaps some insect, such a fly or an ant). Once it is in the form of an small animal it can move more easily to find good source of energy, continue to grow until a different from is more efficient (for instance it will eventually be too big to be supported by exoskeleton, so it would need to grow an internal skeleton).
In the meantime it would be moving away from absorbing nutrients by direct contact to using a dedicated digestive system that can process more complex molecules and deliver them to the rest of the body via a circulatory system. Yet there is no reason to think that the ability to absorb nutrients by contact is lost, or that humanoid is the final (let alone preferred) form.
The main problem lies with regenerating the person from a single cell. Problems with regrowing all those cells to become a whole body are problems are enough. But other answers have dealt with them, so it's game over there.
Regenerating an entity from a single cell will only produce an organism that is to all intents and purposes a biological copy of the original, but now mostly vaporized person. This is a clone in the strict biological sense. It won't be a duplicate of the original person.
To regenerate the person, that single cell needs to contain the complete memories and the neurological and psychological profile of the brain and mind of the person. Even if you could rebuild, recreate or whatever it takes to regenerate the biological bit, that is, their body, this body or its brain has to have the information imprinted on its brain and nervous system to make that regrown body into an accurate replication of the vaporized person. Now if that could be done then regeneration could be plausible and possible.
The brain is a massively complex structure and what constitutes a person is more than just our brains it is the entire panoply of experience that shapes and moulds the mind of the person. To migrate this brain and mind information from a vaporized body via a single cell to a regenerated body is an incredibly complex task. Possibly this information could be stored externally to the original body itself and the single cell used as the template for the regrown body.
Now, hypothetically, our person could be regularly uploading the total contents of his mind to some kind of computer system (the sort of computers 1990s science-fiction was so keen on) and his mind could be downloaded into the regrown body. This, if it could be done, would constitute the form of regeneration the OP is interested in.
There were suggestions that DNA could be used as an information storage medium. So, hypothetically, the person could have his information translated into DNA storage. But for him to be regenerated this information has to be stored in exactly the right cell that survives vaporization.
The system to make this work would have to include the following. A scanner to copy all the information needed to regenerate the whole person. A mechanism to translate this information into DNA and lay it down in a sufficient number of cells that just in case the person is vaporized, at least, one cell will survive to enable the person to be regenerated. It's not difficult to imagine all this machinery might be bigger and bulkier than the person they are trying to protect. This is a trifle difficult.
The technology to do this, either the regular uploading or the DNA storage, will be so highly advanced that only far future civilizations are likely to possess it.
If someone can devise a way to make this regeneration work, it would have to be something totally marvelous.