On the Technical Possibility of Living Forever

I grew up in a household where the inevitability of death was a strangely common motivator. We were told, as 10 year olds, to exercise because it would help us live longer. Bad habits were frequently flagged as sources of death. Statements about our future were usually conditioned by “if you live that long.” It was a topic more on the mind of our (rather old comparatively) parents than ours, but it left an impression.

One of the single most influential books in my life, Old Man’s War by John Scalzi, is also a source of such a theme. The basic premise is that old people, in return for agreeing to dangerous military service, are given a chance to transition to a new, cloned, younger body via a consciousness transfer. As I have written before, the various ideas encapsulated in this were one of the main reasons I chose to study neuroscience in my undergraduate bachelor’s studies (alongside classical history, unrelated). Since then I have also read a number of other books that explore variations on the theme. Human constructs such as in All Systems Red, and especially human minds and human-like AIs stored in computers. The books I most associate with that are the We Are Legion (We are Bob) Bobiverse series, although it is far from alone in writing about such ideas.

My goal here in writing is a bit of an exploration of the possibility of living forever as seen here at the end of 2022. Partly it is for life planning. Should I plan on living a very long time? And perhaps more practically, I also hope to someday sit down and write a scifi book of my own, with my own take on these ideas. Spoiler: no, I don’t think you should plan for living forever, although it is not without some faint possibility. I will ignore the ethical decisions of ‘should’ you live forever, as that is already well explored in various media sources and an entire topic in its own right.

Let’s start with the simplest starting point: living forever in the same body.

Scalzi gave this one a pass with the reasoning that individual organs could be replaced, but ultimately the brain would suffer something catastrophic and that would not usually be fixable. I am inclined to agree with similar reasoning.

I do think life can be extended and improved by medicine. There are chemical aging processes which we might hope to slow and stop. There are organs which we could outright replace with lab grown replacements. Even simpler, there are good health practices that can be followed, such as exercise, which go along way towards improving longevity. Something like an average life expectancy over 100 years seems reasonable, with some individuals living as long as 150 years old. I completely made those numbers up, but as guesses they seem sound. The ultimate problem is how complex the human body is coupled by systems, like the brain, which will always be difficult to fix. Even if longer lives might be expected, there is always the simple fact that such intensive medical care would be required that for most people, the low quality of living would not be worth it, or affordable.

For proof, I offer the fact that no humans live that long yet, and that few animals, especially complex animals. How is this proof? If it were a single gene, or small set of genes, or by extension a small collection of biochemical pathways that control aging, we would already see people who live long, youthful lives due to the chances of genetic mutation and recombination spread across our truly massive human population that would yield some very long lived individuals. Yet across the world and diverse genetic populations, there isn’t much variation on maximum age length.

There is a counter school of argument. Basically, this is that evolution doesn’t favor long life because producing new individuals with new genes is necessary for a population to evolve and adapt, an evolution vs development time vs complexity tradeoff. So maybe it is “possible” to live longer, but our existing bodies and genetics aren’t capable or desiring of it, and the sort of massive genetic re-engineering required to change that would be a technological and ethical challenge unlikely to be mastered for ages, and even then would likely only work on new children and not applicable retroactively to those of us already around.

But how about if we cut the body out of the picture and just rely, as Scalzi did, on our “consciousness.” Firstly, we have to get rid of the notion that many people have from religion and other fantasy of a vague ‘spirit’ which is like a glowing light inside of you, or whatever. The idea is directly traceable to Plato around 400 BC, whose ideas of dualism were massively influential to the religions of today that started to come together around that time. The simplest proof that the brain is everything that make us consciousness and human is brain damage. Major brain damage, and sometimes even minor brain damage, can radically change how a person acts and thinks. The ‘soul’ of their nature changes, because what makes a human everything we recognize as human is in the mind. Also, we now have artificial intelligence systems which are (loosely) based on the human mind and are capable of some pretty neat things. Such AI remains vastly less advanced than the human mind (continual claims of artificial general intelligence in the media being greatly exaggerated), but it is not difficult to extrapolate and conclude that yes, an advanced system of neurons like the brain is indeed capable of generating the human consciousness as we know it.

Now we face the ‘simpler’ idea of merely capturing a person’s mind and putting it in a new body or machine. Indeed, this idea is a common enough idea that people are paying to have their brains frozen, with the hope of future reconstruction. It is an insane task to contemplate. The human mind has trillions of connections. We currently do not have the ability to visualize all of them, it is way beyond our capabilities. And even if we can figure out how to see how every neuron connects to every other neuron, we still face the challenge of internal chemistry of the cells that affects the sensitivity of the connections in critical ways.

With biological clone, we face an even greater challenge because even if we somehow did figure out, atom for atom, how a brain is composed and wired and functioning, it would be nearly impossible to recreate. We can’t just clone the brain, or rather, we can, but getting every neuron to migrate to the exact same spot with the exact same connections – which is critical to making you be you, just can’t happen, the chemical gradients and such aren’t going to be precise enough for the truly massive scale of the brain (in count of connections) and truly tiny scale (in terms of size) of the pieces. We could probably make a “near” clone of a person’s mind, but not actually one that is a full brain transfer. The error rate would be just too high. Possibly solved by creating many, many batches of clones of the same person and testing them to see which matches, but wow, that would be expensive.

Sorry Scalzi, but it just doesn’t seem like a few minutes on a machine would work to transfer a consciousness. I do see it possible to do an atomic level scan of a human and then basically 3D print, at the atomic level, a new brain up. This method has the advantage that we don’t even have to understand how the brain works, just the ability to exactly copy it. Such technology will likely exist “eventually” but would require some breakthroughs that make fusion look simple. It will likely be so complex that only ever the rich would have access to it, I doubt it could be scaled to handle billions or trillions of people. It would probably remain very slow, and it would have a chance for errors that could be critical, corrupting mistakes. Scary. And even a new biological brain would likely have to be replaced routinely. A possibly interesting premise for a story, but not a practical solution for the average person.

The last option is moving a person consciousness from biological to electric. This has some massive challenges, not just that you have to connect everything, but you have to have it capable of rewiring and learning itself in the same way as a human mind. Don’t underestimate the sheer complexity of all the chemical interactions in the brain that would have to be exactly recreated. The previous methods to some extent get away with copy-pasting and using existing biology, here we also have to fully understand every detail. To summarize the complexity of this, you have to exactly image a human brain down to its tiniest detail (currently way beyond our abilities) then you have recreate all the pieces, not just statically, but capturing all the dynamic details in a realistic way. An ‘infant brain in a box’ might be doable in the near future, but a full copy of an adult, memories and all, is actually a much bigger step. Keep in mind, that all people are slightly different, with genetic variation, which means you couldn’t just do this once, it would probably have to be significantly tuned for new people. And all of this has to be so reliable that it works constantly, without errors that corrupt the system. I completely think this is possible, but we are talking hundreds of years before it exists, is my guess. And this ignores other requirements, like the large computation requirements.

All in all, it seems likely we will generate artificial general intelligence capable of living forever long before we manage to do the same with a human mind.

However, there is, I think, a shortcut. It is called: transfer learning. What if you didn’t care about exactly recreating the human experience, only the “most important pieces”? The idea here is that we take recordings, as best we can, of a human experience, and then train a system that is capable of exactly recreating those. It learns the pattern of you, but isn’t a biological copy, nor even attempting to mimic biology, only a cognitive copy. This is how a lot of current AI works, more or less, so it is closer to existence. The basic problem is how do we ‘record’ the human experience – ie the intermingling of input senses, output actions, and internal experience (recalling memories, creating ideas). Basically it would still require very powerful brain imaging, and imaging that you would have to wear around as you live your life, but it wouldn’t have to be absolute precise details. Given a very large pile of recordings of your human experience, it could fill in the missing details by the mathematical methods we use today to create a mind that is “close enough” to you on a practical level.

One giant uncertainty is that we still don’t understand how the mind generates the human experience. How complicated is the parts that we, as humans, most care about? It is likely there are massive parts of the brain we could replace by other means: for example, replacing our large visual system processing with a computer visual system tailored to produce similar outputs. Instead of figuring out how the whole visual system works, just understand the important outputs, then swap in a human designed system that functions the same – this would be necessary for living in a digital world anyway. Human memory + upper level thinking are all we really need, plus some plug in sensor inputs and motor outputs. If what I just said is true, it is vaguely, maybe possible we could see such a system in as early as a hundred years time. Again, a completely random guess. Unfortunately, there is so much interconnection in the brain, that my “simplification” approach to copying a brain is a vague hope at best.

Ultimately I suspect there will never be a method for the exact recreation of all minds. There may be an exact recreation of one mind, then a system like transfer learning will be used to tune it to individuals. A key point here is that it seems likely a live person is required. A simple frozen brain would not be capable of producing the dynamic living recordings needed to customize the created mind clone.

Regardless, the major scientific project right now of mapping the human brain, creating a human connectome, does seem like the most important step required before significant further understanding is possible. That itself will only be the foundation of further simulation and mapping together all the complex biochemical understanding required.

I love this topic, I think it makes for a great part of a science fiction novel. And what’s more, I think living forever in a copied mind does indeed seem to be a real possibility. However, it seems like the complexity is such that we are genuinely many generations away from getting there, at the current scientific rate. It would also likely be a luxury only for the rich. Of course, it would also likely fail to completely capture the human experience, so many who had access would likely see reasons to choose to avoid it.

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