The Many-Worlds Interpretation of Quantum Mechanics states that every time some event is observed (e.g. a coin flip), the Universe splits into separate universes, one for each possible outcome (e.g. Heads universe and Tails universe), and the conscious observer will find themselves in one of these universes (e.g. either see the coin come up Heads or see it come up Tails) with a likelihood proportional to the number of ways this event can happen (e.g. you’ll probably never see a coin land on edge)
This is false and misleading in various ways.
1) in MWI, splitting events are gradual, in the sense that the relevance of one ‘world’ to another continuously drops from ‘high’ to ‘utterly negligible’ without a sharp cutoff. There is a connection to observation, but it’s a confusing one that MWI ought to be helping one avoid making.
2) splitting events produce thermodynamically large quantities of worlds.
3) the likelihood is indeed a sum over the various paths, but the coefficients on the paths are complex-valued and span many orders of magnitude. I grant that these details might normally not be relevant for such coarse-grained matters as biology, but if you’re going to survive, say, a heavy object smacking into your head at high speed, this is going to be a major issue—all of your survival paths are much smaller than the fatality paths.
4) Nothing is keeping you off of such doomed states, so once you find yourself in one, you’re about to get really lucky (or die). Nothing except going timeless, but...
5) You can’t both take the timeless perspective and invoke quantum immortality. QI is all about the subjective case, and the timeless perspective requires, among other things, not taking the subjective case.
summary: If, hypothetically, I tried to catch a terminal-velocity bowling ball with my face, your theory says I would experience the bowling ball doing nonfatal damage and then stopping just before killing me, and my theory says I would experience changing my mind and getting out of the way of the bowling ball. It looks like our key disagreement is whether Quantum Immortality only operates over short timescales. You say it only acts in an instant, and I say it acts over long time intervals as well.
longer argument: I’m not convinced by your argument yet. Specifically:
1) I agree that two worlds may be very similar or very different or many places in between. However, my consciousness observes exactly one world at once. Do we have a disagreement about reality, or only about word definitions?
2) I agree that splitting events produce massive numbers of worlds (I have no idea how many, but I’m guessing no more than the volume of the Universe divided by the cube of the Planck length). Does this invalidate my argument (that I’ll live forever without appearing to get lucky)?
3) I agree that the likelihoods are a sum over various paths whose magnitude ranges from approximately 1 to approximately 0. I also agree with your intuition that if I ended up in a situation with a high-velocity bowling ball partially inside my head then my survival paths are much much less likely than my death paths. However, my argument is that Quantum Immortality works backward in time, if that makes sense. For example, consider all the ways I can walk through a bowling alley—a 10-minute-long time interval. Quantum Immortality means I will not experience death during that 10 minutes. Looking at all of the different worlds in which I don’t die in the bowling alley, it’s most probable I’ll find myself in one where I walk safely and nothing weird happens, and really really improbable that I’ll throw a bowling ball straight up in the air and then try to catch it with my face and then have the bowling ball spontaneously lose its momentum right before impact. This looks like where we disagree. This is clearer in your next point...
4) I’m kept off of those doomed states by Quantum Immortality. I disagree with you here, and I’ll make two arguments why...
4a) My conscious experience already averages over large lengths of time relative to quantum processes. The brain runs at about 10Hz. In the time it takes for one neuron to fire, many many quantum processes have time to happen. Since my consciousness only collapses the universal wavefunction once every 1/10th second, I see no problem with looking at the problem as if my consciousness only collapses the universal wavefunction once every 10 minutes, or once every lifetime.
4b) When I look at the real world, it looks like I’m kept away from doomed states. Why was I so ridiculously lucky as to be born in the current era, where human immortality is a possibility for the first time in history? Timeless Quantum Immortality provides an answer: because it’s more probable that I’ll live forever from the World I experience now, than it would be for me to live forever from most other worlds. Being born an ancient Sumerian or a dolphin would require many more improbable events to get me to immortality. Being born in a post-Singularity culture where immortality already exists would require a more complicated Universe. My existence looks like it’s one of the most likely ones of the set of all possible Universes in which I don’t die.
4c) I go to sleep (lose consciousness) and wake up again. QI seems to predict that I would never fall asleep, because I stop observing when I’m asleep and so I couldn’t observe that instant. Timeless QI has no problem with me falling asleep and then observing I’m alive and awake hours later.
5) QI is all about the timeless perspective because it requires looking at worlds splitting into other worlds from a perspective outside of time. I’m just doing what regular QI is already doing, just on a longer timescale.
(Rather than start with the main point I’ll follow your responses and conclude)
1 - word definitions. This was one of those that was not wrong, but unclear.
2 - another point that was kind of sketchy-looking. It wasn’t directly wrong, but it looked overly simplified. You’ll see why in a few points.
I’m guessing no more than the volume of the Universe divided by the cube of the Planck length
A better limit would be not more than 2 to the power of that. Hilbert space is very, very large.
3 - this seems to be going out of order.
Quantum Immortality means I will not experience death during that 10 minutes
Regular old Quantum Immortality takes as an axiom that you cannot experience death. If you could, then the whole thing falls to pieces.
As for the universe putting you in a safe place, well then, you are fortunate. How does this argument apply to people who die? Did they not have subjective experiences? What makes them different from you?
4 - the heart of the matter
Since my consciousness only collapses the universal wavefunction once every 1/10th second
This is seriously, majorly wrong, and the reason I complained about point 2. Your brain decoheres a zillion times per second. Your consciousness is far, far, far into the classical regime.
Observing does not cause collapse. Events which cause the wavefunction to split into dynamically separate parts do, and those happen at the same rate in a system regardless of how you cut it.
QI seems to predict that I would never fall asleep
Depends on how you formulate it, doesn’t it? Anyway, arguing against regular QI does not argue for your variant.
QI is all about the timeless perspective because it requires looking at worlds splitting into other worlds from a perspective outside of time
That doesn’t look like immortality to me. It looks like you dying eventually. You look at the history of your lifeline and it peters out, little by little, sometimes more at once than other times. Those decreases? Those are dying. The only way QI works is if you ignore the parts that died, and the only justification I’ve seen for doing that is by locking your viewpoint to your subjective experience. That’s what allows you to discard any cases where you don’t survive. If you’re looking from a distance, you see a whole lot of dead you-s out there.
As for the universe putting you in a safe place, well then, you are fortunate. How does this argument apply to people who die? Did they not have subjective experiences? What makes them different from you?
I believe the argument goes that they, too, are immortal… from their own perspective. Your consciousness traces its worldline, taking branches where you stay alive, and theirs does the same, but picking worlds where they stay alive. In other words, you can see them die, and they can see you die, but the consciousness, the qualia of the person who’s supposedly dying is not there; it’s gone down a different worldline.
I think that the theory is cute and quite seductive, but quite clearly wrong. The problem is, for example, brain damage: does quantum immortality allow you to experience Phineas Gage-type brain damage, or doesn’t it?
Also, I’ve been blackout drunk in college, and if quantum immortality is a thing, it’s not clear why my consciousness didn’t trace a path through the universes where I wasn’t blackout drunk. It was, after all, a loss of self, even if it was only temporary. The arguments QI uses for keeping you alive could be used equally easily to prove that you cannot become blackout drunk.
Your brain decoheres a zillion times per second. Your consciousness is far, far, far into the classical regime.
Observing does not cause collapse. Events which cause the wavefunction to split into dynamically separate parts do, and those happen at the same rate in a system regardless of how you cut it.
Eh? Observing is the only thing that causes collapse.
I agree that there are constant tiny thermodynamic events that, if observed, could cause decoherences a zillion times a second. But, usually these events are not observed.
Decoherence is me finding out which world I end up in, and this only happens as quickly as I think, once every ~1/10 seconds when I’m awake.
I’m guessing you would say that decoherence is my brain ending up in some world, and this happens every time any entropy-increasing chemical event happens.
How can I experimentally tell the difference between these? It’s not obvious because even a high-speed detector requires me to read the readout with my (slow) brain. From my perspective, the detector doesn’t collapse any wavefunctions until I look at it. I agree with you that if I looked at another brain I would see that brain decohering / doing thermodynamic stuff all the time. I also agree with you that if I looked at my own brain I would see my own brain doing a bunch of stuff really rapidly. You would say that my brain decoheres as quickly as a detector measures it. I would say that my brain decoheres only as quickly as I notice detector readouts. Until I look at the detector, my brain and the detector are in a superposition of states with different possible detector readouts.
That isn’t the relationship between decoherence and observation.
Decoherence events are when a quantum system splits into multiple parts that are no longer dynamically accessible to each other. At this point, they are in different worlds.
Observation events have to be decoherence events. Observation has no other role in quantum mechanics other than that in order to observe, you must decohere.
So, whether or not you observe things, you are in some world of dynamically mutually accessible states, and this will evolve into many dynamically inaccessible components with or without your observing it. By the time you’ve observed anything, it’s way too late to get from one to another.
I agree provided the many-worlds interpretation is correct, which seems likely.
If the consciousness-causes-collapse interpretation is correct (which seems less likely), then the special form I described might still work. But I can’t count on it.
it’s more probable that I’ll live forever from the World I experience now
This also explains why you find yourself in a world that has already perfected immortality technology.
… Oh, wait.
[EDITED to add: I see that you sort-of addressed this ”… would require a more complicated Universe”. But I don’t understand that at all. How would it require a more complicated universe?]
It’s a flawed argument but if for some reason there was a high complexity penalty to being born in an older Universe then it could be more likely to be born in a younger Universe where immortality technology has not quite been invented yet.
If, hypothetically, I tried to catch a terminal-velocity bowling ball with my face, your theory says I would experience the bowling ball doing nonfatal damage and then stopping just before killing me, and my theory says I would experience changing my mind and getting out of the way of the bowling ball.
So from the perspective of a you that I can talk to after the near miss with the bowling ball, your description makes sense. But it also makes sense to me. We are both in the universe where you changed your mind before the bowling ball hit you and you got out of the way.
But from the perspective of me in the world where you got hit by the bowling ball and died in pain, your consciousness did whatever consciousnesses do when people die. Presumably it felt the fear when it noticed he inevitability, felt the impact and then the pain, and then stopped working as the neurons in the brain stopped working, some from immediate injury, others more slowly form loss of viable environment.
The worlds in which people die exist. I am in a world where billions, of people have died. A small number I have seen die with my own eyes, a larger number I have seen soon after they died, a much larger number I know of by reliable report.
This immortality you speak of: if there are identical twins and a the age of 5 they are crossing the street and one is hit by a bus,has not some individual died? If you live in a world with MWI, and at the age of 5 for one conscious version of you the universe splits, and in one of those branches EVERY new universe generated ends in your death at a finite age at least 20 years later, while in the other branch there are some branches where you go on forever, than have there not been at least one conscious version of you which will last 20 or more years, but not infinitely, that will die?
This idea that your consciousness jumps from the dying world to somehow mystically join with the version of you in a different world is anti-intuitive at best, and non-scientific or religious at worst. Nothing else jumps between worlds once they have split, why would consciousness? There is already a consciousness in the world you want to jump to with different experiences than yours as you face your last seconds of life, how is there room for your consciousness to pop on over to the other universe to escape death?
Your theory strikes me as the opposite of timeless. Your theory seems to come down to, if I ask my 10,000 year old self about the worlds, I am always going to get an answer in which I lived at least 10,000 years. But if you ask your 20 year old self about the world, then almost all the answers you get are going to be about worlds in which you live less than 100 years, I say that based on the observation that the people other tyan you that you see, way over 99% of them are dying before age 100.
A QI belief in infinite life seems indistinguishable from any other regligious belief in infinite life, at least in regards to conformity with evidence, logical plausibility, and some amount of wishful thinking.
I don’t know if anyone else is conscious, but if they are, and they die in my branch of reality, then in my theory they experience a branch of reality in which they continue living.
seems indistinguishable from any other regligious belief in infinite life
I agree it’s pretty similar. I have to accept the consciousness-causes-collapse interpretation, and it’s a short hop from that to full-on theism.
my consciousness observes exactly one world at once
On macroscopic scale, yes. Trying to observe a particle in the double-slit experiment could change your mind (you might realize you are observing an interaction of multiple worlds, differing only in the trajectory of the observed particle). This is probably irrelevant for everyday life, but using the word “quantum” reminds people that it’s at least technically not true.
It could possibly become more relevant in a very far future, approaching the heat death of the universe, if we take the immortality literally.
my argument is that Quantum Immortality works backward in time, if that makes sense.
Seems to me like an example of selection bias. Some of your future you’s will die, and the rest of them will happily exclaim: “I knew I was immortal!” The question is whether this is a “correct” way to describe reality (and what specifically “correct” means in this context).
If you commit to flipping coins and shooting yourself dead as soon as you get a tail, you will also (in the same sense) “find out” that your coin has an astonishingly large bias towards heads. Are you sure this is a good notion of “finding out”?
(This is just the same point as Viliam’s last paragraph was making, but it seemed worth trying it from a different angle.)
This is false and misleading in various ways.
1) in MWI, splitting events are gradual, in the sense that the relevance of one ‘world’ to another continuously drops from ‘high’ to ‘utterly negligible’ without a sharp cutoff. There is a connection to observation, but it’s a confusing one that MWI ought to be helping one avoid making.
2) splitting events produce thermodynamically large quantities of worlds.
3) the likelihood is indeed a sum over the various paths, but the coefficients on the paths are complex-valued and span many orders of magnitude. I grant that these details might normally not be relevant for such coarse-grained matters as biology, but if you’re going to survive, say, a heavy object smacking into your head at high speed, this is going to be a major issue—all of your survival paths are much smaller than the fatality paths.
4) Nothing is keeping you off of such doomed states, so once you find yourself in one, you’re about to get really lucky (or die). Nothing except going timeless, but...
5) You can’t both take the timeless perspective and invoke quantum immortality. QI is all about the subjective case, and the timeless perspective requires, among other things, not taking the subjective case.
Thanks for the criticism.
summary: If, hypothetically, I tried to catch a terminal-velocity bowling ball with my face, your theory says I would experience the bowling ball doing nonfatal damage and then stopping just before killing me, and my theory says I would experience changing my mind and getting out of the way of the bowling ball. It looks like our key disagreement is whether Quantum Immortality only operates over short timescales. You say it only acts in an instant, and I say it acts over long time intervals as well.
longer argument: I’m not convinced by your argument yet. Specifically:
1) I agree that two worlds may be very similar or very different or many places in between. However, my consciousness observes exactly one world at once. Do we have a disagreement about reality, or only about word definitions?
2) I agree that splitting events produce massive numbers of worlds (I have no idea how many, but I’m guessing no more than the volume of the Universe divided by the cube of the Planck length). Does this invalidate my argument (that I’ll live forever without appearing to get lucky)?
3) I agree that the likelihoods are a sum over various paths whose magnitude ranges from approximately 1 to approximately 0. I also agree with your intuition that if I ended up in a situation with a high-velocity bowling ball partially inside my head then my survival paths are much much less likely than my death paths. However, my argument is that Quantum Immortality works backward in time, if that makes sense. For example, consider all the ways I can walk through a bowling alley—a 10-minute-long time interval. Quantum Immortality means I will not experience death during that 10 minutes. Looking at all of the different worlds in which I don’t die in the bowling alley, it’s most probable I’ll find myself in one where I walk safely and nothing weird happens, and really really improbable that I’ll throw a bowling ball straight up in the air and then try to catch it with my face and then have the bowling ball spontaneously lose its momentum right before impact. This looks like where we disagree. This is clearer in your next point...
4) I’m kept off of those doomed states by Quantum Immortality. I disagree with you here, and I’ll make two arguments why...
4a) My conscious experience already averages over large lengths of time relative to quantum processes. The brain runs at about 10Hz. In the time it takes for one neuron to fire, many many quantum processes have time to happen. Since my consciousness only collapses the universal wavefunction once every 1/10th second, I see no problem with looking at the problem as if my consciousness only collapses the universal wavefunction once every 10 minutes, or once every lifetime.
4b) When I look at the real world, it looks like I’m kept away from doomed states. Why was I so ridiculously lucky as to be born in the current era, where human immortality is a possibility for the first time in history? Timeless Quantum Immortality provides an answer: because it’s more probable that I’ll live forever from the World I experience now, than it would be for me to live forever from most other worlds. Being born an ancient Sumerian or a dolphin would require many more improbable events to get me to immortality. Being born in a post-Singularity culture where immortality already exists would require a more complicated Universe. My existence looks like it’s one of the most likely ones of the set of all possible Universes in which I don’t die.
4c) I go to sleep (lose consciousness) and wake up again. QI seems to predict that I would never fall asleep, because I stop observing when I’m asleep and so I couldn’t observe that instant. Timeless QI has no problem with me falling asleep and then observing I’m alive and awake hours later.
5) QI is all about the timeless perspective because it requires looking at worlds splitting into other worlds from a perspective outside of time. I’m just doing what regular QI is already doing, just on a longer timescale.
(Rather than start with the main point I’ll follow your responses and conclude)
1 - word definitions. This was one of those that was not wrong, but unclear.
2 - another point that was kind of sketchy-looking. It wasn’t directly wrong, but it looked overly simplified. You’ll see why in a few points.
A better limit would be not more than 2 to the power of that. Hilbert space is very, very large.
3 - this seems to be going out of order.
Regular old Quantum Immortality takes as an axiom that you cannot experience death. If you could, then the whole thing falls to pieces.
As for the universe putting you in a safe place, well then, you are fortunate. How does this argument apply to people who die? Did they not have subjective experiences? What makes them different from you?
4 - the heart of the matter
This is seriously, majorly wrong, and the reason I complained about point 2. Your brain decoheres a zillion times per second. Your consciousness is far, far, far into the classical regime.
Observing does not cause collapse. Events which cause the wavefunction to split into dynamically separate parts do, and those happen at the same rate in a system regardless of how you cut it.
Depends on how you formulate it, doesn’t it? Anyway, arguing against regular QI does not argue for your variant.
That doesn’t look like immortality to me. It looks like you dying eventually. You look at the history of your lifeline and it peters out, little by little, sometimes more at once than other times. Those decreases? Those are dying. The only way QI works is if you ignore the parts that died, and the only justification I’ve seen for doing that is by locking your viewpoint to your subjective experience. That’s what allows you to discard any cases where you don’t survive. If you’re looking from a distance, you see a whole lot of dead you-s out there.
I believe the argument goes that they, too, are immortal… from their own perspective. Your consciousness traces its worldline, taking branches where you stay alive, and theirs does the same, but picking worlds where they stay alive. In other words, you can see them die, and they can see you die, but the consciousness, the qualia of the person who’s supposedly dying is not there; it’s gone down a different worldline.
I think that the theory is cute and quite seductive, but quite clearly wrong. The problem is, for example, brain damage: does quantum immortality allow you to experience Phineas Gage-type brain damage, or doesn’t it?
Also, I’ve been blackout drunk in college, and if quantum immortality is a thing, it’s not clear why my consciousness didn’t trace a path through the universes where I wasn’t blackout drunk. It was, after all, a loss of self, even if it was only temporary. The arguments QI uses for keeping you alive could be used equally easily to prove that you cannot become blackout drunk.
That was my point. The above QI argument broke that by going timeless and universal.
Thank you again for the thoughtful reply.
Eh? Observing is the only thing that causes collapse.
I agree that there are constant tiny thermodynamic events that, if observed, could cause decoherences a zillion times a second. But, usually these events are not observed.
Decoherence is me finding out which world I end up in, and this only happens as quickly as I think, once every ~1/10 seconds when I’m awake.
I’m guessing you would say that decoherence is my brain ending up in some world, and this happens every time any entropy-increasing chemical event happens.
How can I experimentally tell the difference between these? It’s not obvious because even a high-speed detector requires me to read the readout with my (slow) brain. From my perspective, the detector doesn’t collapse any wavefunctions until I look at it. I agree with you that if I looked at another brain I would see that brain decohering / doing thermodynamic stuff all the time. I also agree with you that if I looked at my own brain I would see my own brain doing a bunch of stuff really rapidly. You would say that my brain decoheres as quickly as a detector measures it. I would say that my brain decoheres only as quickly as I notice detector readouts. Until I look at the detector, my brain and the detector are in a superposition of states with different possible detector readouts.
I don’t know how to test this.
That isn’t the relationship between decoherence and observation.
Decoherence events are when a quantum system splits into multiple parts that are no longer dynamically accessible to each other. At this point, they are in different worlds.
Observation events have to be decoherence events. Observation has no other role in quantum mechanics other than that in order to observe, you must decohere.
So, whether or not you observe things, you are in some world of dynamically mutually accessible states, and this will evolve into many dynamically inaccessible components with or without your observing it. By the time you’ve observed anything, it’s way too late to get from one to another.
In that case, it seems like Quantum Immortality doesn’t work.
And here I thought I was safe. Dammit.
Well, the nice form you described here doesn’t work. The kind of lousy usual form does, with the usual caveats.
I agree provided the many-worlds interpretation is correct, which seems likely.
If the consciousness-causes-collapse interpretation is correct (which seems less likely), then the special form I described might still work. But I can’t count on it.
This also explains why you find yourself in a world that has already perfected immortality technology.
… Oh, wait.
[EDITED to add: I see that you sort-of addressed this ”… would require a more complicated Universe”. But I don’t understand that at all. How would it require a more complicated universe?]
It’s a flawed argument but if for some reason there was a high complexity penalty to being born in an older Universe then it could be more likely to be born in a younger Universe where immortality technology has not quite been invented yet.
How sure of that are you, anyways?
So from the perspective of a you that I can talk to after the near miss with the bowling ball, your description makes sense. But it also makes sense to me. We are both in the universe where you changed your mind before the bowling ball hit you and you got out of the way.
But from the perspective of me in the world where you got hit by the bowling ball and died in pain, your consciousness did whatever consciousnesses do when people die. Presumably it felt the fear when it noticed he inevitability, felt the impact and then the pain, and then stopped working as the neurons in the brain stopped working, some from immediate injury, others more slowly form loss of viable environment.
The worlds in which people die exist. I am in a world where billions, of people have died. A small number I have seen die with my own eyes, a larger number I have seen soon after they died, a much larger number I know of by reliable report.
This immortality you speak of: if there are identical twins and a the age of 5 they are crossing the street and one is hit by a bus,has not some individual died? If you live in a world with MWI, and at the age of 5 for one conscious version of you the universe splits, and in one of those branches EVERY new universe generated ends in your death at a finite age at least 20 years later, while in the other branch there are some branches where you go on forever, than have there not been at least one conscious version of you which will last 20 or more years, but not infinitely, that will die?
This idea that your consciousness jumps from the dying world to somehow mystically join with the version of you in a different world is anti-intuitive at best, and non-scientific or religious at worst. Nothing else jumps between worlds once they have split, why would consciousness? There is already a consciousness in the world you want to jump to with different experiences than yours as you face your last seconds of life, how is there room for your consciousness to pop on over to the other universe to escape death?
Your theory strikes me as the opposite of timeless. Your theory seems to come down to, if I ask my 10,000 year old self about the worlds, I am always going to get an answer in which I lived at least 10,000 years. But if you ask your 20 year old self about the world, then almost all the answers you get are going to be about worlds in which you live less than 100 years, I say that based on the observation that the people other tyan you that you see, way over 99% of them are dying before age 100.
A QI belief in infinite life seems indistinguishable from any other regligious belief in infinite life, at least in regards to conformity with evidence, logical plausibility, and some amount of wishful thinking.
I don’t know if anyone else is conscious, but if they are, and they die in my branch of reality, then in my theory they experience a branch of reality in which they continue living.
I agree it’s pretty similar. I have to accept the consciousness-causes-collapse interpretation, and it’s a short hop from that to full-on theism.
On macroscopic scale, yes. Trying to observe a particle in the double-slit experiment could change your mind (you might realize you are observing an interaction of multiple worlds, differing only in the trajectory of the observed particle). This is probably irrelevant for everyday life, but using the word “quantum” reminds people that it’s at least technically not true.
It could possibly become more relevant in a very far future, approaching the heat death of the universe, if we take the immortality literally.
Seems to me like an example of selection bias. Some of your future you’s will die, and the rest of them will happily exclaim: “I knew I was immortal!” The question is whether this is a “correct” way to describe reality (and what specifically “correct” means in this context).
The “Wigner’s Friend” experiment has some interesting examples that physicists already thought about.
I’ll find out in about 100 years.
If you commit to flipping coins and shooting yourself dead as soon as you get a tail, you will also (in the same sense) “find out” that your coin has an astonishingly large bias towards heads. Are you sure this is a good notion of “finding out”?
(This is just the same point as Viliam’s last paragraph was making, but it seemed worth trying it from a different angle.)