Quantum immortality



Quantum immortality says that a person will never die. As we know the person bound to die in world 'A' (say) may survive on other worlds 'B', 'C',.... as there are always two possibilities in the form of dying or not dying. But how can we say that that person will live forever, assuming that all humans have a bounded biological life time? After that finite age, that person will die in all worlds. Then how can immortality be explained being based on many world theorems?


Posted 2014-05-01T11:57:51.330

Reputation: 215

1@Asphir Dom. I'm neither a physicist nor a MWT enthusiast. But MWT is supported by "real" physicists such as Sean Carroll. In "Something Deeply Hidden" he goes into some depth about the quantum suicide scenario and possibilities for MWT experimental verification, though his main defense is a kind of negation of alternatives by way of Ockham's Razor. The "immortality" I assume would extend through "worlds" technologically extending our lifespans. And how many angels can dance in a quantum universe...? – Nelson Alexander – 2020-09-28T14:23:16.057

3To CLEAR your mind. QM has NOTHING to say about many worlds. Many worlds is a purely philosophical idea and has nothing to do with physics at the moment. Nothing. Nothing.. n o th i ing. – Asphir Dom – 2014-05-01T12:09:14.830


@Asphir Dom: That position depends on the somewhat curious idea that a physical theory has absolutely no implications for what exists in the real world, i.e. - on whether the multiverse exists. It also takes for granted, wrongly, that experiments do not refute single universe theories: http://www.daviddeutsch.org.uk/many-minds-interpretations-of-quantum-mechanics/

– alanf – 2014-05-01T14:38:03.283

There is a book, The physics of Immortality ("http://en.m.wikipedia.org/wiki/The_Physics_of_Immortality"). It is horribly unreadable, but I think it considers this in detail.

– dgo – 2014-06-09T19:44:29.630

wouldn't QI state that we don't die but keep very nearly dying, getting as close to death as is biologically possible? so not escaping the attacker, but ending up with tragic brain damage – None – 2016-12-24T04:56:02.310

1Its worth pointing out that there are more interpretations of QM than this; for example consistent histories; for some reason, many worlds exerts some strange fasconation - I've felt it too; too bad, the media hypes it up a little too much; a bit like the mania for multiverses. – Mozibur Ullah – 2017-01-24T02:14:04.147



This scenario stems from quantum indeterminacy, the fact that we can predict certain events at the quantum level, such as the decay of a particle, only by probability. We can know how likely it is the particle will decay within a given period of time, we cannot know conclusively that it will or will not. Furthermore, according to most mainstream interpretations of quantum mechanics, the particle exists in an indeterminate state where it is both decayed and non-decayed, until we observe it, and solidify which state it is in. The multi-worlds view of quantum mechanics, however, theorizes that each event happens in both ways, in two different worlds that split permanently from one another. From our points of view as conscious observers, therefore, we are at the end of a random path proceeding from the root of an infinite decision tree out to the end of one of the unimaginably numerous branches. The math seems to work out about the same with either interpretation.

Quantum immortality is a variation on Schrodinger's famous "cat" thought experiment, where a cat's life or death depends on the decay of a single particle. Under the standard interpretation of quantum mechanics, it seems as though the cat must be both alive and dead until we view it. Under the many worlds interpretation, the cat is alive in one world, dead in another. This leads to the idea that there must be some world in which the cat lives forever.

On the surface, this only covers the case where the cat's death is caused by the experiment --the cat could still age and die even in a world where the particle never decayed. However, if a world truly branched off for every quantum decision point, then one could find worlds in which the cat never aged, or aged backwards, or spontaneously exploded, or any other extremely improbable scenario, as long as it could be constructed from some set of quantum decisions. This defies common sense, but then, so does much of quantum mechanics. In the end, which interpretation of QM you favor may come down to which set of nonsensical scenarios you find least objectionable.

Chris Sunami supports Monica

Posted 2014-05-01T11:57:51.330

Reputation: 23 641


There are several reasons why quantum suicide is typically raised. The first is that the other interpretations are typically extremely unclear about how the world works and what exists in reality, see


As a consequence, they are unclear about how whether the terms that appear in equations correspond to reality, so it is difficult to say anything about what implications the theory has for anything.

The second is that in the MWI everything that can happen does happen. People sometimes naively think this implies that literally anything can happen. But this need not be true. It may be the case that if you put a gun to your head and pull the trigger there may not be any universe in which you survive.


Posted 2014-05-01T11:57:51.330

Reputation: 6 821

2I'm sorry to say that I think it is you who is being naive here (about the implications of the interpretation). It is physically perfectly possible for a bullet to pass through your brain and leave it, for all practical purposes, unaffected. However, the probability of this is so minute, that it hardly makes sense to distinguish it from 0 in one universe. But in the multiverse setup, everything that can physically happen does indeed happen. This only points to the vastness of this proposed multiverse. (BTW: This is not quantum suicide, which is triggered by a quantum bit.) – None – 2014-05-01T15:41:43.397

2However, you'll have to take into account all universes in which you survive. And given the conditional probabilities, even if you survive you'll almost certainly will find yourself in an universe where you got serious non-lethal brain injury, not in one where the bullet passed your brain without any damage. In other words, if you believe in quantum immortality you are better off not trying to shoot yourself. – celtschk – 2014-05-01T20:58:47.033

@celtschk You raise an excellent point. I am not quite sure how these thought experiments deal with non-instant death. (Is there even such a thing as instant death?) Once you find yourself in a world where your life-expectancy is greatly reduced due to half your head being missing, is there any way to get yourself to a more healthy world after your imminent demise? I don't see how. :) – None – 2014-05-02T04:24:37.497


The many worlds theory (MWT) is about as wildly Scholastic as counting angels on pins. But it does have supporters among "real" physicist (Sean Carroll, Brice DeWitt, I believe) and, odd as it sounds, this is due to experimental purism and Ockham's razor, accepting the experimental results and the mathematically simplest explanation, with the least alterations in existing theory.

Or something like that!

As to your question, it seems easy to imagine the immortal traveller (shall we call him Captain Kurzweil) hitchhiking through worlds in which technology extends the lifespan in an infinite regress... or progress. Of course, Capt. K would need a lot of quantum computing memory to retain anything like an identity.

Since nobody has reported direct empirical evidence of "mortality," our conscious lifespans are, in fact, enclosed from the "inside" in a kind of Zeno's paradox of infinite non-arrival. So perhaps quantum immortality is our actual condition, with moments of anamnesis or miraculous resurrections as statistically accumulating "proof."

Or maybe not. MWT is at least good for speculative exercises and as a cautionary tale of how far theory can stray from experiment, often fruitfully. In any case, I believe physicists who incline to it would remind us that "world" is very crude picture of what is implied here. Probably better to treat MWT as a description of time and consciousness in some idealist philosophy.

Nelson Alexander

Posted 2014-05-01T11:57:51.330

Reputation: 11 748


when you asking about human live or death, you have assumed an one way timeline. when you have one way timeline, you have assumed everyone will properly die).

there is only few additional information can completed the theory.

  1. each end of life cycle is the begin of the next life cycle. it can defend immortality even in one way timeline approach.

it depends on how big the loop is, to make you feel you are not repeating your life.

in fact i think quantum immortality is trying to against it instead of saying the mythical impressive prospective of quantum physics.


Posted 2014-05-01T11:57:51.330

Reputation: 183

Hey there, thanks for the answer -- is there any chance you could unpack this a little bit further? (Why is this a persuasive answer to the question for you? What research could confirm it?) – Joseph Weissman – 2017-02-09T22:19:35.797


The main argument of quantum immortality is that subjectively we are the beneficiary of what looks like fantastic good luck, which - call us all moody pessimists- is utterly inconceivable to us because our senses, most of our awareness, maybe nearly all we are, is focussed resolutely on a surrounding panorama of degradation, entropy and death taking place around us to which we feel ourselves to be joined, inalienable. And we are.. We are joined to it.. but only in contrast to it. Yang to ying. Different ends of the see-saw. Subjective to ‘objective’.. Mine to his. There is a clue in pronouns. They are different, for good reasons. That’s what most people don’t get, the contrast. You can’t conceive of your own subjective good luck because ..the evidence of your eyes and ears and senses which say otherwise. Your senses are fully paid-up members of the death-cult and more than half your brain too. They look outward, always outward like rays from a glowing filament into darkness, alarmed by how the darkness is always about to overcome them. They live in a culture of sharing, which insists that the fate which will befall you is the same as everyone else’s. (When it ain’t.) People will scream this is all wrong. “You will Die, horribly .. I’m telling you .. you will suffer and die like us.” (Hands grasping at your ankles.) They will say: “listen .. It’s a mugs’ game thinking it won’t happen to you.” But the screams are a shell-game, necessary propaganda. The squirted ink-cloud of their getaway. And yours. It not their subjective kernel of truth, which they could never share with you if they tried. All this doomsaying and despair, is not their true path. It’s not what they take with them. It’s just a necessary sloughing-off of their skin, a souvenir they will leave on your doorstep like an unwelcome mangled cat-offering while they fly off, unseen to you, fully-fledged and chirping happily. But the instinct “it won’t happen to me” was right, quantum immortality says. In the face of all the propaganda of empiricism: instinct is right. What we see of everyone else and everything else is a) NOT THEIR SUBJECTIVE. So there is a false commonality. We only witness our own subjectivity, not theirs. We should only compare our subjective with their subjective which, sadly can never be done without us becoming them and forgetting our own former subjective. Plu ça change.. When people tell you they are sharing their ‘true subjective‘ experience with you it is a bare-faced lie, a lie by definition. b) The very fact that we witness this disaster around us -entropy - is in fact a necessary part of our own accretion of good luck. Subjectively I am ‘the house‘, which ultimately wins, not the punter: the Casino looking out at the losers. On Friday 13th someone always benefits from a lost wallet. If Friday 13th is defined by bad luck, for that guy who benefits it’s not Friday 13th. The Anthropic Principle is highly focussed and narrow, subjective, and personal good luck is relative..to all the entropy, all the bad luck out there. All the screams of “look at me dying.” It’s two ends of the same lever. We need those screams to trumpet our own forward march, along with the crunching sound of their body underfoot, bridging the ditch. c) You’re getting older and more decrepit? You are on a certain down-slope. Compared to what? Compared to ‘your’ own youth? But what makes you think you were only that youth..and not also your poor old dad’s dotage, or something quite like it, compared to which you are eminently more serviceable. (Especially if he is pushing up daisies). Yes, quantum immortality posits that your age is not absolute but relative to a variety of surrounding way-markers. d) Which are these: all the people and versions of people and all the things which remember the reasons for your present age... measure what you ‘should be’ and so serve-you-up in your present age. In this sense - the sense in which you are remembered into existence (and senility) by your local world of and people and things - the universe IS a simulation.

But what happens when you outlive all the records and all the things and all your friends and all your family who observed you into this body? What happens when you can no longer check-in with them to be told how old to be?

Actually, there is no ‘real’ immortality unless you are happy to be frozen in time, which must mean unconscious. Nothing can consciously goes on forever as it is. The best you can hope for is still feel the same, while not being the same, replaced piecemeal and unnoticeably like the ship of Odysseus, as all the people and things who remember your origins, all the people and things who remember the original wooden parts are forgotten and die off all around you and are replaced by look-alikeees..who veer ever further from what they once were, as any copy of a copy diverges from a template. So reincarnation is done by parts, which is not the same ‘you‘ going on forever but you can hardly complain about that.

Baron Tait

Posted 2014-05-01T11:57:51.330

Reputation: 21


There are several reasons why you still might die eventually:

  • The many-worlds-theory is wrong. This is a plain and simple answer, but the most important one in my opinion. The MWT is a theory and not proven. Therefore quantum immortality is not proven either.

  • Your chance to survive is zero. Even in the MWT only possible things will happen. Your body is built to die eventually, so even under the best of all circumstances you will not exceed a certain age. You as well might not survive a car crash with zero chance to survive.


Posted 2014-05-01T11:57:51.330

Reputation: 211

As you already said: everything possible will happen (according to that theory), but not everything. So if your chances to survive that imaginary car crash are zero, then you will die in every alternate universe as well. And then there is a chance, that the many-worlds-theory is just plain wrong. – TwoThe – 2014-05-05T08:10:00.413

I reworded my answer. I think it was too confusing (even for me after reading it a few days later). I hope this one answers the question better. – TwoThe – 2014-05-05T08:28:48.463

When talking about possibilities, you need to differ between statistical possibility and an actual situation. While statistically the chance to survive a car crash is never zero, in a given situation circumstances might be in a way that it actually is zero for this one situation. – TwoThe – 2014-05-05T08:31:36.593

If you remove "You as well might not survive a car crash with zero chance to survive.", I think the answer is useful. – None – 2014-05-05T08:57:33.453

MWT is a philosophical interpretation of quantum mechanics, it's not a theory in the scientific sense. And even if it were to be one, you wouldn't be able to "prove" it, as you usually do in math, for example. – user132181 – 2014-05-05T16:47:25.460