The main idea of quantum (the name "big world immortality" may be better) is that if I die, I will continue to exist in another branch of the world, where I will not die in the same situation.
This map is not intended to cover all known topics about QI, so I need to clarify my position.
I think that QI may work, but I put it as Plan D for achieving immortality, after life extension(A), cryonics(B) and digital immortality(C). All plans are here.
I also think that it may be proved experimentally, namely that if I turn 120 years or will be only survivor in plane crash I will assign higher probability to it. (But you should not try to prove it before as you will get this information for free in next 100 years.)
There is also nothing quantum in quantum immortality, because it may work in very large non-quantum world, if it is large enough to have my copies. It was also discussed here: Shock level 5: Big worlds and modal realism.
There is nothing good in it also, because most of my survived branches will be very old and ill. But we could use QI to work for us, if we combine it with cryonics. Just sign up for it or have an idea to sign up, and most likely you will find your self in survived branch where you will be resurrected after cryostasis. (The same is true for digital immortality - record more about your self and future FAI will resurrect you, and QI rises chances of it.)
I do not buy "measure" objection. It said that one should care only about his "measure of existence", that is the number of all branches there he exists, and if this number diminish, he is almost dead. But if we take an example of a book, it still exist until at least one copy of it exist. We also can't measure the measure, because it is not clear how to count branches in infinite universe.
I also don't buy ethical objection that QI may lead unstable person to suicide and so we should claim that QI is false. I think that rational understanding of QI is that it or not work, or will result in severe injuries. The idea of soul existence may result in much stronger temptation to suicide as it at least promise another better world, but I never heard that it was hidden because it may result in suicide. Religions try to stop suicide (which is logical in their premises) by adding additional rule against it. So, QI itself is not promoting suicide and personal instability may be the main course of suicidal ideation.
I also think that it is nothing extraordinary in QI idea, and it adds up to normality (in immediate surroundings). We all already witness to examples of similar ideas. That is the anthropic principle and the fact that we found ourselves on habitable planet while most planets are dead. And the fact that I was born, but not my billions potential siblings. Survivalship bias could explain finding one self in very improbable conditions and QI is the same idea projected in the future.
The possibility of big world immortality depends on size of the world and of nature of “I”, that is the personal identity problem solution. This table show how big world immortality depends on these two variables. YES means that big world immortality will work, NO means that it will not work.
Both variables are unknown to us currently. Simply speaking, QI will not work if (actually existing) world is small or if personal identity is very fragile.
My apriori position is that quantum multiverse and very big universe are both true, and that information is all you need for personal identity. This position is most scientific one, as it correlate with current common knowledge about Universe and mind. If I could bet on theories, I would bet on it 50 per cent, and 50 per cent on all other combination of theories.
Even in this case QI may not work. It may work technically, but become unmeasurable, if my mind will suffer so much damage that it will be unable to understand that it works. In this case it will be completely useless, the same way as survival of atoms from which my body is composed is meaningless. But this maybe objected, if we say that only my copies that remember that me is me should be counted (and such copies will surely exist).
From practical point of view QI may help if everything failed, but we can't count on it as it completely unpredictable. QI should be considered only in context of other world-changing ideas, that is simulation argument, doomsday argument, future strong AI.
Dr Jacques Mallah PhD has arrogantly been asserting for the last few years that quantum immortality is obviously wrong. This is a rebuttal to his argument, his primary argument can be found on https://arxiv.org/: "Many-Worlds Interpretations Can Not Imply ‘Quantum Immortality’".
For the record I don't necessarily believe quantum immortality is right or wrong but I think it could be.
His primary arguments come down to the decrease of 'measure' of consciousness after a likely death event like proposed in quantum suicide. And the fact that we find ourselves in normal lifetimes he suggests that if we were immortal then we would likely be much older than we are. I will point out flaws in these two arguments and also add some of my own arguments.
The measure argument:
The measure argument is THE primary argument Jaques uses, basically because he thinks that proponents of QI are uneducated and don't understand quantum mechanics or the wave function. Despite the fact that Everett the discoverer of the many worlds interpretation believed in quantum immortality himself.
Basically to summarise MWI after every Planck second the world splits into many(possibly infinite) many parallel universes, in each of which different events occur. However in order that future times not be more likely than past-times the probability of an event is subdivided each time so that every event in a chain of events makes the overall chain less likely.
Therefore the probability of anything staying the same over time (for instance a person staying alive) decreases with every split.
Basically he implies that this means that in the example of quantum suicide (the idea that because theres always a world in which you survive so if you attempt suicide you will always fail) the reduction in measure caused by the deaths in some branches implies that there must be a chance of death from the 1st persons perspective because the overall measure in the wave function has been decreased. This means the overall amount of consciousness has decreased.
To this I have several responses: Firstly its fairly trivial to come up with hypothetical scenario's where the measure (or amount) of consciousness decreases but yet from a first person perspective the first person still exists, providing that you accept that fusion of consciousness is possible.
The example I gave to Jaques was a star trek inspired idea whereby 2 identical Kirks are scanned by the transporter, there details averaged (so that causality from both is identical) the transporter then creates one dead kirk and one alive kirk on the planet or whatever. From the point of view of both original Kirks the alive kirk created on the planet forfils both the data and causality requirements necessary to be the future of both of them, the dead Kirk is entirely irrelevant and could just as well be a rock. As you may have noticed this is very similar to the setup in the quantum suicide experiment.
A further argument against his arrogant assumption is the fact that I exist at all, I am an absolutely tiny part of the wavefunction of the universe and in most branches between the beginning and end of the universe I simply do not exist at all, suggesting that from a first person perspective I 'select' branches of the wavefunction in which I exist.
Also an analogy could be found between spacetime and MWI splits. If we take the example of sleep in the vast majority of my future lightcone I don't exist. The ratio is terrible between empty space and my brain, and yet somehow I wake up every morning.
Finally it can be argued that from a first person perspective there is no 'measure' of consciousness in the universe merely the observer and the rest of the universe.
His other major argument against quantum immortality is his 'general argument against immortality' this argument can be shown to be extremely weak quite easily. Basically the idea is that if we were immortal we would expect to be in our immortal state right now, so as an example in quantum immortality we would expect to be very old.
This argument can be shown to be ridiculous very quickly:
Lets imagine like millions of people across the world do that death results in us going to heaven with thousands of angels etc. Should we not expect to be in heaven right now? NO the rules in Christianity state that we must live a mortal life first.
I am not sure about Mallah but my life occurs in a linear fashion, I did not just appear at age 40 and have experienced my age varying around the midpoint throughout my existence. Instead I started at zero and then increased in age. So in his paper the reason why Max Tegmark is not the oldest person in existence has nothing whatsoever to do with his mortality but instead is because he has only been alive X number of years.
Finally
In MWI all possible futures happen, the whole fact that we talk about probabilities of one event or the other happening is an artefact of our first person perspective. It therefore seems reasonable that splits in which I don't exist have zero probability from my point of view.
This is further backed up by the fact that the passing of time may well be an artefact of our consciousness, there is no passing of time function in either quantum mechanics or relativity, all times are equally relevant independent of an observer(entropy increases over time but there is no now independent of an observer and no obvious reason for time to flow), so in what way is an event in which I don't exist in my future? Perhaps Consciousness flows like a river around obstacles.
Expecting to experience nothing after a death event maybe like expecting your consciouness to somehow leave spacetime as nothing by definition has no space or time. Instead it seems that you either experience time freezing or as I find more likely you simply find yourself in a branch with a high measure.
Two final points:
Given the universe itself will likely one day end, how can consiousness persist for eternity? Quantum mechanics says that even the shape of spacetime fluctuates permitting time travel with very low probability (hawking, universe in a nutshell.) In principle there is a probability that any possible spacetime is connected to any other possible spacetime.
Assuming quantum immortality is true, should we expect quantum torment?
The most likely event is a medium length period of aging followed by a long period of minimal consciouness, followed by possible reincarnation through fusion with another consciouness.
I agree with your critics of this article. Moreover, his first objection is contradicting the second. Imagine the following model of QM. We have 1024 copy of Harry Potter book. Each day half of copies is destroyed. From the point of Harry it doesn't matter until at least one book exist. Number of books doesn't affect plot of the book. the same way number my copies (measure) doesn't affect my consiousness.
But if we ask there is the medium copy of the book, we will see that it is in the beggining of the pyramid, somewhere in the first or second day when ther... (read more)