After lots and lots of work, team of biologists and computer scientists finally made what was deemed to be nearly impossible - a (digital) brain uploading and simulation system. Like every emulator ever, it doesn't recreate brain at physics-level accuracy: that actually already existed for a while, but was so demanding in terms of computations that is was only done as proof-of-concept, well beyond affordable even for the richest.

Instead, brain is simulated based on (complete) understanding of its mechanisms, excluding simulation of cellular and any lower levels, thus making it require much less resources to run. HLE (High Level Emulation) at its finest, if you're familiar with that sort of thing.

In regards to brain activity, main point is that brain is still accumulating memories and impressions. I wrote a more detailed description, but it may be slightly off-topic, so hiding it under the spoiler.

Person keeps interacting with their surroundings, although now also simulated ones. They both can interact with others (of their choice) uploaded in this manner and use various means (mail, chats, video chats and such) to interact with real world. To avoid post-uploading adaptation, all brain inputs and outputs match to what body used to provide.

But this is where question from the title comes in: without cells aging (a nice bonus of not simulating them, I guess) and brain working in theoretically perfect conditions from biological standpoint, will it eventually wear out? While neurological degradation and diseases are often linked to old age, it seems that the longest living human known to science was "mentally sharp" until the end of her life. All in all, 120 years of functioning appears to be well survivable for brain functions, with rest of the body being a limiting factor instead. But without body and even its own cells acting as a limiter, will brain keep working well forever? If not, how long is it likely to take until issues show up?

P.S.: of course, brain uploading is not the only way to waive aging of cells and rest of the body away. One could think of a brain-in-a-jar scenario with brain cells also modified not to count their aging while keeping functioning (and, somehow, fully avoiding cancer), which can be considered the same as HLE-simulation scenario I've described.

  • $\begingroup$ Is it a digital simulation? $\endgroup$ Commented Mar 7, 2021 at 1:03
  • $\begingroup$ @chasly-supportsMonica Yes, first scenario assumes a digital simulation (I was thinking it's clear, but it seems not to be. I'll edit it in then.), although, as later noted, "simply" using actual brain in perfected conditions can be considered to be equal. $\endgroup$ Commented Mar 7, 2021 at 1:07
  • $\begingroup$ If it is digital then you can make as many copies as you want. If one copy "dies" just load a backup. It comes down to how long digital storage lasts rather than how long a brain lasts. Same with the processor. As new processors come in, you can run the model faster. Just keep updating the media and hardware. $\endgroup$ Commented Mar 7, 2021 at 1:10
  • $\begingroup$ @chasly-supportsMonica And that's the exact question that I'm interested in - why (and would) a brain instance die after a while? After all, if it's a wearing out-based issue, simply loading a backup prior to disaster won't reliably avert it. $\endgroup$ Commented Mar 7, 2021 at 1:14
  • 1
    $\begingroup$ What is this brain doing? Is it continuing to learn, forming new memories? How does it live in its world? Does it have sensors to the outside world? Is it housed in a moving robot? $\endgroup$ Commented Mar 7, 2021 at 1:19

4 Answers 4


Yes they will "decay" - but only when viewed with a modern lens.

Social values change over time. Best practice changes over time. Social common knowledge changes over time.

I'd fully expect someone who was uploaded with minimal mental arithmetic capability to be able to improve their maths skills in the simulation. Your simulation will link neurons together and reinforce them as they practice. That process should work if they've been in the simulation for 5 minutes or 5 centuries.

However, if after 500 years of practice on how to multiply two numbers in their head, there's a new method of teaching it, the consciousness would be resistant to change as what's its already learnt is working. I don't think it will be incapable of learning - it just won't see the point in trying when they're old way still works.

Now apply this to social values. Imagine a perfectly simulated brain from 1840 still alive today. They can still do long rapid division of pounds, shilling, and pence. They know where they stand on the "Pluto is planet" debate: Neptune isn't a planet either. They think women are unable to comprehend complex issues that need voting on. They can still optimise cotton production per slave. They use racial slurs.

People dying of old age is actually a really good way of getting social progress - grandpa doesn't like foreigners, but he'll be dead soon. Great grandpa still hates the Germans for gassing his buddies in the trenches.

Were I to talk to one of these people, I would think they've decayed:

  • "Wow you're really racist and sexist." - therefore you've morally decayed.
  • Solve this problem using SI units "urgh what does 'kg' mean - how many ounces is that?" - you can't do basic maths therefore you've mentally decayed.


  • Frame challenge - if money can be made, it will be. The length of time a single brain can be maintained is arbitrary and irrelevant to society.

The Uploading/downloading infrastructure would exist as a service-industry.

People learn, are changed by their experiences, sometimes deliberately take new paths. When a brain learns, it would periodically upload it's new state to as an update to the cloud. Data storage is less and less expensive over time (all things being equal), so the cost of this would reduce over time.

The service of downloading the experiences/states to a new brain would be available to as many who wished it, funded by the marketplace.

Unintended consequences.

These could range from espionage from interested countries to steal scientific data or to engineer "selective retention of useful updates" to change the political attitudes in the brains of rival powers. They could potentially: simplify, scramble or outright replace with spies or sleepers the brains of key figures.

Social engineers - with all the right motivations, and no clue about consequences might change or tweak the memories in ways which aim at a socioeconomic paradise on your world, but produce the most aweful dystopia imaginable or the extinction they seek to avoid. This option is not limited to non-establishment political movements, but extends to governments and the CEOs and staff within service providers.

Power structures inherent to the nature of humanity could become stultified and dogmatic with the same people in power for their "experience" and understanding. Immortality would seem to trend towards a static hierarchy in society unless measures are taken. Dictators will keep the power to themselves and trusted advisers (maybe with the odd "tweak" here and there to ensure compliance.

  • $\begingroup$ Those consequences look thoroughly appalling to me. It sounds like excellent material for a futuristic horror story! The lesson here: think twice about what technology you want to have in your story, because the odds are high that there's something abominable that people can do with it. $\endgroup$
    – Palarran
    Commented Mar 8, 2021 at 23:36

With perfect (this is important!) simulation of the human brain in its prime condition (the reasons for brain function deterioration are more complex than just cellular ageing) no wearing out will happen because there is nothing to wear out. Cognitive abilities (thinking, reasoning, memorisation, etc.) can be affected, however.

Your simulated person may face two types of problems:

  • 'physical'

These are problems related to 'hardware': memory capacity, brain plasticity, and alike. Does your simulated person have unlimited memory? What are the quality and speed of recall? Do they have to overwrite old memories in order to store new memories?

Is a simulated brain capable of creating new connections between brain cells? How fast does it happen? What happens to the old connections?

How the sensory input is simulated? Just a functioning brain is not enough for the human psyche (as contemporary human beings have) to function properly. All other body parts and the outside stimuli are required.

  • psychological

All psychological problems boil down to a simulated person's ability to adapt to what is basically immortality.

Some of them are similar to what Ash mentioned in their answer — an ability to adapt to changing society and learning new ways to do things. I am much more optimistic than Ash, though, I believe that it is possible to teach an old dog new tricks and people can change their opinions and attitudes, especially, when they are under pressure to do so and appropriate teaching and training methods are used. In fact, older people may have certain advantages over younger people when it comes to learning: Experience and self-knowledge. Your perfectly simulated brain also should not have many problems that older people experience when it comes to physical brain function, so some of the simulated persons may learn much faster and more efficient than young geniuses.

I think that acceptance of immortality and its consequences for an individual would be the crucial factor determining the state of your simulated persons. We are mortals living in a mortal world. Everything has an expiration date. Depending on a culture we might not want to think of it but it is something that we all understand very well. An immortal existence is vastly different. For one, those immortal beings will have to see the world they know and the people they love to disappear. If they cannot cope with this fact they will lose their will to live and eventually stop functioning.

A problem specific to the computer simulation would be the inability to have 'proper' contact with the physical world. How will a simulated person deal with the fact that they now exist only in the digital world? Can they accept this mode of existence? Can they invest emotionally in other digital persons? Can they trust themselves and their feelings? Can they be sure that they are still them and not some altered or faked version of themselves? There are also problems of safety and privacy, but those would bother mostly those who are familiar with computers.

The life expectancy of simulated (or physically immortal) persons should be no less than modern humans provided that all the infrastructure is in place and stable and, theoretically, can be extended to infinity if all psychological and physical problems are solved completely. As for individual longevity, it will depend on a person's ability to cope with psychological problems and the quality and quantity of stimulation. If modern people are uploaded into a simulation, many of them will cease functioning shortly due to the inability to adapt to new conditions. However, some people may actually thrive being freed from the restrictions of the physical world and coming to terms with their new existence. Well-designed and systematically implemented psychological adaptation programmes will increase transition success rates and general life expectancy.



There is one fundamental problem that you will have to solve for your simulated people — loneliness. Immortal existence is one of infinite loneliness and inability to connect with others. Can other simulated people fulfil the role of friends and family? If they cannot all simulated persons will eventually die unless they transcend humanity.


The process essentially creates a digital model of a human brain, if I understand correctly.

The thing with digital models is that they are mathematical formulae, very complicated indeed, but still mathematical objects. They are not physical objects, and are not subject to any physical limitation. Mathematical objects exist outside space and time, they are eternal and incorruptible.

As a mathematical object, the digital model of the brain won't ever die. On the other side, it is not alive: it is just a long complicated formula, which, when interpreted by a suitable data processing system, can give a human observer the impression that they are interacting with another human.

A ghost in a machine.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .