One commonly cited problem with invulnerability-style immortality is that you watch the people around you wither and die while you survive. On top of that, even though you don't deteriorate, at some point you run into mental issues, where you can't make new memories and life starts to become a blur.

With that in mind, is there a scientifically plausible way for someone to be completely invulnerable to all injuries and diseases, from blunt force trauma and the common cold to cancer and genetic illnesses, but they will still die from old age at about the same age as they would have without immortality?

In addition, I'm not looking for an abrupt end, like a sudden heart attack at a random day between their 90th and 120th birthday. I'm more interested in something where the person can know "I will die soon" and has time to say goodbye of their friends and loved ones, like an elderly person dying of cancer.

I'm looking for a scientific approach, not a divine or arcane approach. Basically, humanity has developed a universal cure that makes the user immune to everything until their biological lifespan has ended. What biological mechanism could the cure use for this?

  • 5
    $\begingroup$ What's the limit on immunity? What about bullets? Getting decapitated by a train? Thermonuclear hellfire? $\endgroup$ Commented Jul 1, 2016 at 12:27
  • 8
    $\begingroup$ "is there a scientifically plausible way for someone to be completely invulnerable to all injuries" No. $\endgroup$
    – geometrian
    Commented Jul 1, 2016 at 12:56
  • 2
    $\begingroup$ What you want may not be possible, but nature has some examples that come close to it. Take a look at the amount of environmental abuse tardigrades can take without dying. $\endgroup$ Commented Jul 1, 2016 at 13:31
  • 1
    $\begingroup$ There is no known scientific process which can make one completely invulnerable to all injuries. We have no known process for someone to survive the point blank detonation of a thermonuclear bomb. However, you may find it very interesting to explore the question of what is the "self" anyways? What is this thing that needs to be invulnerable? You may be able to find approaches to immortality which are indeed resilient to nuclear events, such as those which distribute the self (such as when one thinks about one's "legacy"). $\endgroup$
    – Cort Ammon
    Commented Jul 2, 2016 at 1:26
  • $\begingroup$ I would just remove the "invulnerable to cancer" part. While cells may be invulnerable to damage, it's perfectly plausible for someone who cannot be harmed to die of an excess of these indestructible cells. Radiation, chemo, even surgery would be impossible to remove the tumor. $\endgroup$
    – Zenon
    Commented Aug 9, 2018 at 18:15

11 Answers 11


You actually cannot do it, but you could manage to accomplish similar outcomes.

Programmed death -- that's the easy part. You should read up on telomeres, they actually exist and apparently do provide programmed aging that sets a limit on lifespan. You can find a number of researchers that think telomeres are the primary cause of aging.

Telomerase can rebuild telomeres, but it is not normally active in most cells in humans and other animals. As you can imagine, this is an active area of research.

You still need to make yourself indestructible, which is impossible in a scientific, biology-based approach. If you heat any material to the point that it becomes a plasma, no biology of any conceivable type is possible. Even all of the conceivable advanced nanotech, force fields, and other magical technology can't save you if you are dropped into the sun. Surviving a nuclear explosion would be easy in comparison because the explosion does not last very long and with enough ablative shielding, you could be around long enough to die from the radiation.

If you are heated until water turns to steam, no person could survive. If you heated until proteins denature, you cannot survive -- this is also why cooking makes meat easier to chew -- the proteins are being unfolded and otherwise breaking down. As the article explains, this is already a serious problem with many proteins at 41 C / 105.8 F. Were this not so, a fever would not help to fight an infection. You could make similar observations for mechanical, chemical, and radioactive destruction of a person. Indestructibility is fundamentally impossible for many reasons.

You could increase trauma survival by the strategy of adding thicker layer of outer protection that can be destroyed and regrown without hurting the person; make it tough like scales. However, this comes at a heavy cost in terms of flexibility, weight, and it does not even make you more than a bit tougher. Bullets, fire, etc. will still hurt and kill you easily.

Might I suggest that instead of being indestructible, you could add more redundancy in critical organs and add a very effective regeneration capability so that you can regrow missing limbs and organs? Death by trauma would be possible, but infrequent. Redundancy and regeneration are clearly possible, as they exist in the real world in various degrees.

Redundancy is not a panacea, additional resources are needed to make it possible, and biologically speaking, counter-productive overall if the biological cost exceeds the advantage of surviving trauma. We have two kidneys, only one is required for normal function, but lost of one results in a shorter lifespan. Loss of one lung is survivable. Loss of one heart is a bigger problem.

A better strategy than having 2 of every critical organ, is distributed function, where the organ is distributed throughout the body. Bone marrow production of blood cells is an excellent example of distributed function, but it is only possible because the blood vessel network is already everywhere. A distributed kidney would require a network for urine collection -- there is very little room for additional networks within the body.

If you could also make external backups of your brain and genetic material, even death would be reversible via cloning and downloading your consciousness from a backup. Immortality would be a logical consequence of such. However, if you have legal and ethical strictures against it, it would only be available to criminal elements able to remain outside the bounds of the law. Unbound population growth would be a good reason for this to be illegal. As a controlled and complicated technology, you could perhaps enforce this legal restriction nearly all of the time.

I started thinking about being dropped into the sun if you were completely invulnerable. Seems like it would be unpleasant. The surface of the sun is actually a pretty good vacuum (about 1e-6 atm.) so you would fall a very long way until you reach neutral buoyancy, certainly many thousands of miles into the interior. At that depth, pressure would be over 1000 atm, insanely bright and hot. Little variation in conditions, though convection currents would move you around. Of course there would be nothing to eat, and nothing to do. You would be looking forward to your programmed death. Maybe, if you were lucky, you could go insane quickly and not have to suffer for many years.

  • $\begingroup$ Redundancy reminds me of Space Marine from Warhammer 40K (2 hearts, 3 lungs... Amongs many many things). They are not invulnerable... But damn hard to kill... And old age is an issue(although most end bloodily before reaching it) $\endgroup$
    – Patrice
    Commented Jul 1, 2016 at 13:47
  • $\begingroup$ I think that their is no ethical argument to start killing people to avoid "unbounded population growth". This can be stopped with birth control measures. With uploaded minds you always have an option of waiting in a data storage vault for a long time. If told that the government is coming to kill them for nonsensical "ethical" reasons most people will rebel, escape or not make it easy. Is their anywhere that kills everyone deemed too old? No $\endgroup$ Commented Jul 1, 2016 at 15:54
  • 3
    $\begingroup$ @DonaldHobson - and other people will object that being unable to procreate (planned or not) is morally unacceptable. When the population keeps rising, eventually the majority of the population will gladly vote down immortality, or it will be imposed on them by the privileged few in charge. I did not intend that it was a good justification in terms of morality or popularity, just that it was entirely plausible. It has also been used in science fiction which justified, killing and/or sterilizing the imperfect, killing at a given age, etc. Limited reincarnation seems much more ethical to me. $\endgroup$ Commented Jul 1, 2016 at 16:05
  • $\begingroup$ I don't see an answer to the question here, but a long discussion on ways to provide immorbidity and arguments against invulnerability. Where's the explaination of having a lifespan in spite of this technology? $\endgroup$
    – JDługosz
    Commented Jul 2, 2016 at 0:00
  • $\begingroup$ @JDługosz -- telomeres were mentioned as programmed death and the limit on lifespan at the very beginning of my answer. I did not explain how telomeres do so because a good explanation of telomeres would be considerably longer than the rest of my answer. As I suggested, read up on telomeres to understand the basics of how telomeres factor in lifespan and aging. $\endgroup$ Commented Jul 2, 2016 at 2:32

There was an article by Brandon Sanderson about how superpowers are basically magic.
If you want Wolverine style healing, where you could burn him down to a skeleton with a few gristly bits and he'd be able to regenerate, then just say that eventually the magic runs out...

Another idea, is that the individual has another organ responsible for making the substance that promotes the regeneration, but the organ can't regenerate itself. Eventually the organ wears out and starts to fail, which means that the healing factor begins to diminish, and then possibly reverse so that rapid aging occurs.

If you want less magical and something more plausible, say that it's nano machines that are rebuilding the tissue. They wear out over time and have to be replaced. But it's a conscious choice for him to go get the procedure done. After living X number of years, where the friends and family are aging and dying away, the hero slowly loses the will to keep going on and so decides not to get the next set of nano bots.
Or possibly they can only perform the procedure a limited number of times.
If it was an experimental procedure there might be side effects that don't show up for X years, and once they begin to appear he has to retire or die quickly...

  • 1
    $\begingroup$ +1 for the planned opt-out, where the superhero decides that "it's time". $\endgroup$ Commented Jul 1, 2016 at 13:37

This is a human-mindset rule, not the kind of rules you find in real physics. So my first thought is to make it magic based, as these are the kinds of rules you get with magic. This answer caused you to edit the question, wanting a non-magical solution: the alternative is people impose the rule.


The god or magical being responsible for your invulnerability has a time limit on her patronage. Granting immortality or more than a moderate increase in lifespan due to good health and freedom from injury would run afowl of much more powerful beings who set up the whole cycle of souls business.


This is not a technological limitation, but a law imposed by society. Having people never die would result in overpopulation or stagnation, so the technology has purposfully been built with a limited lifespan. If world leaders and ultra rich were seen to abuse it, there would be war between the superpowers who are trying to share the planet's resources between them, so each government polices the usage very seriously.

Perhaps, if you want an extension, you have to sign up for a colony ship and emmigrate.

  • $\begingroup$ I'm looking for a more scientific approach, not a divine or arcane approach. Basically, humanity has developed a universal cure that makes the user immune to everything until their biological lifespan has ended. What biological mechanism could the cure use for this? $\endgroup$
    – Nzall
    Commented Jul 1, 2016 at 12:11
  • 1
    $\begingroup$ Than use tags, and specify this in the question. (I see you updated the question) $\endgroup$
    – JDługosz
    Commented Jul 1, 2016 at 12:16
  • 1
    $\begingroup$ @Nzall Well, none. There's no reason whatsoever why something that heals your burnt leg or radiation damage (for example) cannot repair all ageing related damage. People don't die of old age - they die of diseases and injuries. Sure, those get worse as you age, but the exact same approach your ultimate cure uses could also stop ageing effects entirely. If you can repair genetic and cellular damage, you can also repair old age. $\endgroup$
    – Luaan
    Commented Jul 2, 2016 at 11:33
  • $\begingroup$ @Luaan my point exactly. It has to be a rule imposed on a level that understands the human psychee, not a basic physical principle. I elaborate on that theme here. $\endgroup$
    – JDługosz
    Commented Jul 2, 2016 at 12:09

(May not be really worthy of a answer, but too long for comment)

If I had that same sort of problem, I would look at any probable solution based on cell behavior. A wild example would be the presence of a form of "super white cell" who can boost recovery, prevent sickness by it s effectiveness... Once you find such a solution, you could simply add a form of degenerescence to theses cells, they perform perfectly for the first X years (in your example, 90years), then they start to slowly loose their effectiveness.

The effect would first be minimal, but slowly creeping into the loss of this immortality, until you can die naturally.

This solution may be a little cheap, but allow the host to have warning ("hey, this cut didn't heal as fast as it should have"), and allow painless way to die.

If you want to prevent all natural causes but age, the degenerescence of theses cells could be a form of cancer, that even those super cells can t cure, or a form of auto immune sickness. Either the cells are slowly going mad until they kill the host by the same way a cancer kill, either they actively start to kill the host by misreading more and more cells as threat and destroying those.

That way, the host would be conscious of the loss of his immortality, but that would be a slow and probably really painful death.

The only thing I lack is knowledge in biology to think of a way to build that super cell.


Easy: have the effect wear off.

The details depend on how exactly the invulnerability is accomplished. For example, if you have rapid regeneration like Wolverine, you could say that the regeneration is a consequence of some hyper-active stem cell population that is short lived, so must constantly replenish itself. After a certain time, the cells suddenly (or gradually) lose their ability to divide, and once the reservoir of these cells is exhausted, the regenerative powers are gone. This isn't really all that different from how we age already. The person could feel this by feeling more "tired" and less energetic.

Or suppose the invulnerability is generated by some kind of cloud of smart nanomachines. The machines can be manufactured at a certain time, and have a time-to-failure curve much like other electronics: They will usually last at least X years, and rarely last more than Y years. The decay could be sensed by various reductions in the quality of the protection: Perhaps the nanites start generating more and more noise, create dust, take more energy to fuel, or whatever else.

An interesting twist could be "backup bodies". Suppose people are not actually invulnerable, but their mind is constantly synchronized to some server, and when they die, their consciousness is immediately downloaded to a new body. This is more a lich-and-phylactery type invulnerability, but you could incorporate the weakening nicely by having it cause gradually more and more memory loss at successive stages, or having an initial period of severe disorientation and confusion following revival. This period gets longer and more severe every time (or over time, eg. due to aging of the brain), and eventually the "revived" person just becomes a zombie indefinitely, never managing to "snap out of it" to re-boot their consciousness.

By the way, if your goal is immortality without increased lifespan, you can simply say that everything has been cured except for dementia. The central nervous system has a very unique and complex nature, and sooner or later it just starts dying off. It is unclear exactly why, and while some factors can make the rate of this dying slower or faster, ultimately it is inevitable. Unlike all other organs, however, you can't just replace or regenerate the CNS, because it contains information, and once neurons die the information is lost. If the CNS suffers severe damage, even if all of that damage is somehow repaired, the effect on the personality of the individual could be catastrophic. So you could accomplish what you want by making sure your "magic cure" takes care only of tissue damage, not loss of information.

  • $\begingroup$ Wearing off begs the question of simply getting more. The CNS information idea is sound. $\endgroup$
    – JDługosz
    Commented Jul 2, 2016 at 3:45
  • $\begingroup$ @JDługosz Not necessarily. Perhaps simply getting a booster injection of the immortality serum doesn't work because it needs to have adjusted to your body in complex ways (stem cells establish programmed reservoirs, nanites self-calibrate). Again, this recalls why simply injecting some stem cells doesn't make you young in the real world. I suppose ultimately it does come down to information, whether stored in the brain, in the stem cell populations, in the genome (telomeres) or in external devices (nanites). $\endgroup$
    – Superbest
    Commented Jul 2, 2016 at 4:31

Yes, it is. A Hayflick limit. There is an actually existing "division counter" inside the body cells that can result the needed scenario.

The cells of the animal (human) body can only divide limited number of times. This is because they are not capable of copying the whole genetic material: prolog and epilog of the "life book" in the DNA are not passed to the daughter cells. To work around this, start and end of the "book" just contains non-coding junk that does not carry the required information. However after the cell divides many times, this propagating damage reaches vital regions where real information resides, and the cell cannot longer divide, or the daughter cells die soon after division.

Having such a "clock" would not prevent cells from being arbitrary active and smart, dividing and regenerating the body, even from very significant damage, as long as the "counter" is still above zero.

The lost border sequences are only "regrown" at the start of the new organism and shortly afterwards.

  • 1
    $\begingroup$ So if the super-healing technology doesn't affect this, what does it do exactly? $\endgroup$
    – JDługosz
    Commented Jul 2, 2016 at 0:05

Make it expensive.

Biologically expensive, I mean, not the monetary kind. Have it have a cost, a real survival-type cost, and that cost will be your limiting factor. If you don't want a "suddenly-drop-dead" scenario at your cutoff, have the healing or whatever last a certain amount of time, then after its gone the individual is at the mercy of our original healing, immune system, etc - which isn't nothing, but isn't immortal either.

Maybe the process that makes them invulnerable needs a steady supply or periodic doses of handwavium (mineral, tech, chemical, whatever). Getting cut off by itself won't kill a person (after all, we live without the handwavium), but it will slowly erode the invulnerability as whatever mechanism it is lacks the supplies to continue, and the individual will age, get injured, and eventually die as inevitably and unpredictably as those without the process do.

Maybe they get a single-dose supply of the handwavium with the treatment, and it has enough for about a hundred years, and the invulnerability wears off after its gone. It might last less time if it is used more heavily (lots of expensive regeneration), or a bit more time if carefully husbanded. Or the process itself just gets worn out after that amount of time, and can no longer process the handwavium to heal with. Maybe the handwavium starts giving other problems (anything from sickness to insanity) after that span of time, or there are increasing problems with issues the healing won't cure (like mental problems, insanity) so it's either not possible, or not wise, to re-dose people.

Maybe it requires a lot of energy or resources - food, or sleep, or warmth etc. This wouldn't limit the lifespan per se, but it does make it more likely that an individual might die because they were caught without sufficient resources, bringing down the 'average' lifespan. Or maybe the resources needed go up over time (because they're healing more and more damage?) so past a certain point it's physically difficult to keep up with the demand, or a different limiting factor makes it impossible. Or the resource-intensive nature of the invulnerability may even give an incentive as to why there is a socially mandated (as opposed to a biological one) lifespan cap - those past a certain age may be deprioritized or even choose to not take whatever resources allow them to maintain their invulnerability, eventually ending their lives, so there will be more resources for the children.

As a side note, I suggest really good healing/regeneration instead of invulnerability as the base mechanism for this immortality. There are enough ways to get injured or killed that to be invulnerable to all of them is pretty implausible - but letting them heal really well might make most injuries survivable, which could make them tough enough for a similar effect. Basically, not the survive-through-anything-anything immortality, rather the won't-drop-dead-unless-killed ageless version.


Give the person a 'networked brain' that copies their 'self' back to a bunch of servers every second of every day. They are essentially 'immune' to death at this point because they can just keep loading into a new body.

Perhaps to make them have a 'limit' however, you could make it so that a 'mind' or 'self' can only exist in such a state for 'x' amount of years before deteriorating beyond the point of being usable.

  • $\begingroup$ If you copy yourself it doesn't mean your conscious passes to the copy , you actually die and a clone of you takes your place. $\endgroup$
    – user22162
    Commented Jul 1, 2016 at 16:12
  • $\begingroup$ This is up for debate since nobody really understands how consciousness works. It's one of the big questions of the series "Ghost in the Shell". Am I me, or is this a new 'me'? $\endgroup$ Commented Jul 1, 2016 at 17:54

Logically speaking, you've come up with an impossibility.

There is no such thing as death from old age. A person always dies because some function of their body fails. In fact, that's pretty much the definition of death: catastrophic body failure. Most of the time, it happens when a person is old, but that does not mean they actually died because of how long they had lived.

What you're suggesting, invulnerability to "all injuries and diseases, from blunt force trauma and the common cold to cancer and genetic illnesses", is actually immunity from anything which could cause death, including all the things which cause death in old people. You can't have catastrophic body failure if your body is always in perfect condition. It's impossible for the person to die unless something is artificially inserted into the system to change or remove a person's invulnerability, making them mortal again and precluding your original immortality stipulation.

Basically, the logic boils it down to this: you can't have the person be physically invulnerable and also die. The two are mutually exclusive. Either the person isn't fully invulnerable or you have to have a programmed death (which, in my mind, is a vulnerability, preventing the person from actually being invulnerable).

Others have provided good answers on alternatives to invulnerability.


One option is social norms and pressures rather than biological processes or magic. Society itself may have structural problems if people stay in perfect shape - will people want offspring and what will those offspring do, and will the same people have power (after all, if they have power within society now and never get worse off or frail, maybe they become Comrade President of the Electricians Society For Eternal Life).

So maybe a society that found a way to engender near immunity to life's issues, also legislated that this must be reversed or treated to weaken it at some age between X and Y years old (with the person having choice about the exact timing) for all persons, so they gradually decline and die.

Social rituals might spring up around this as well. Shame? "Life Celebration Party"? Tradition of spending final years writing an autobiography or their wisdom for future GE stations? Would there be politics around extending the timing or changing it and periodic debates about it? This kind of thing would add richness to the plot.


I think to be invulnerable you body must be immune to all possible damage and constant regeneration or replacing of cells, to repair worn down cells (worn down cell is one of the cause of death where a cell that can't regenerate or be replaced is worn down as we age. And this can cause the damage of an important organ or tissue after some time if totally worn down). When your body and organs are still fresh and new, you are mortal till the ability stops. When technology is advance we can replace our body nerve without damaging it and the nerve especially. Note the brain is yourself: changing it brings a new person different from you (now that may bring a problem). But technology may provide a brain regulator: this will keep the brain from damage or repair damage cell in the brain (a drug can be made to do that). A study can be made on replacing or repairing cells, tissues and organs. To be invulnerable, an immune drug can be made for all the cells to protect, repair or regenerate the cells. But not available


You must log in to answer this question.

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