You are offered a deal in which you are asked to flip a coin ten times. If any one of the flips comes up tails, you are swiftly and painlessly killed. If it comes up heads ten times in a row, you are given a banana. Do you take the deal?
For the purposes of this thought experiment, we may assume it is a perfectly fair coin, and that you like bananas, although not any more so than would generally be considered healthy. We may also assume for simplicity that your life or death is of absolutely no consequence to anyone but yourself: you live in secret on a deserted island, isolated from contact with the outside world, where you have everything you need other than bananas. We may finally assume that we know for certainty that there is no afterlife; upon death, you simply cease to exist in any form. So, there is an approximately 99.9% chance that you will be dead, which by hypothesis implies that you will feel no regrets or feelings of disappointment. And if you survive, you get a banana. What do you think?
Now change the experiment a little. Instead of flipping a coin, you measure the x-component of the spin of an electron that has been prepared in an eigenstate of the y-component of the spin; according to the rules of quantum mechanics, there is an even chance that you will measure the x-component of the spin to be up or down. You do this ten times, with ten different electrons, and are offered the same wager as before, with spin-up playing the role of “heads” for the coin. The only difference is that, instead of a classical probability, we are dealing with branching/collapsing wavefunctions. I.e., if you believe in something like the many-worlds interpretation of quantum mechanics, there will always be a branch of the wavefunction of the universe in which you continue to exist and now have a banana. Do you take the deal?
By the way, my favorite sentence in the paper itself is
“Admittedly, if phi is unsatisfiable, you might be out of luck.”
Here is a question I have formulated sometime ago, as there hs been a few references to:Consciousness-Dreams-and specifically, Quantum Computers.
This is the first time this question has seen the light of day, except for a small number of computer savy whizzkids, and a few friends who I thought would get the first level, but not probe the deeper meaning? which I asked in an informal way.
So next time your close to a Quantum Computer Theorist, who is dazzling you with the AI-ID and other computer related banter, let them finish, then hit them with this:
Out of two choices what would Quantum Computing best define sleep,Unconciousness as an “Offline” or “Online” event?
Think about Computer termonology, think deep!
I personally see no operational difference between collapse of the wave function and MWI in which any observer for some reason is constrained to feel only one branch of the wavefunction after a measurment (and not a superposition). Those other branches, which remain forever inaccessible, are purely a semantic exercise as far as I can tell, so I really don’t see any difference between the two versions of the question. Even for classical probabilities we can pretend those other possibilities “exist” in some number of made-up “universes” we cannot access, should not make any difference.
I guess that just means I don’t believe in the MWI enough…
moshe,
It was a philosophical exercise for Sean? 🙂
I think we are afraid too, and there is some potent force of survival that takes over( try and hold your breathe till your dead?). Letting go, is never easy with matter fixations? 🙂
If we thought for a moment, that we could through some idea of future lives (reincarnation), make amends, what use would there be to fix anything that we might had made by making the wrong choice?
It’s a question about empowering oruselves with the responsibility “now” without invoking some magician, eh?
But lets say you did look to the future, where you might have decided, the choice made was not a good one retrospectively, the possibility might then exist, that altering any new future from that perspective, could have new repercussions?
But wait! Your dead? 🙂
Not possible. If I had everything I needed, other than bananas, the island would not be deserted.
I would have lots of young friends!
And I and my twins in the Multiverse would be content without our bananas, because along with the girls we got mangos. (Assuming that this was a tropical isle, and not a polar one).
Assuming that I put a high value on remaining alive in the near future, then of course I don’t take the deal — the obfuscations are irrelevant. States are superimposed with coin flips just as much as they are with spin measurements — it’s just that the latter are micro-analyzable. And probabilities are calculated by counting the number of worlds in which the event occurs. It doesn’t matter whether the worlds are alternative possibilities or superimposed realities — these are just different models for formally equivalent sysems.
“If you believe in many worlds doesn’t that then mean that in some worlds you will have taken the chance and in others you didn’t? Therefore, you will have taken the chance.”
No, actually, there are no worlds in which the chance is taken because this is a hypothetical.
Sean writes:
“So I conclude that it’s just not a very probative thought experiment.”
Indeed, this is a straightforward conclusion for anyone who understands probability, modal logic, the nature of models, etc. Apparently, however, few people understand these despite their fundamental simplicity. To determine a probability of an event, count up the number of worlds in which the event occurs. It doesn’t matter whether these are “possible worlds” — mutually exclusive outcomes — or “multiple universes” — superimposed actualities. In either case, 1 out of 1024 worlds contains you holding a banana and 1023 don’t. Whether to take the deal depends upon the relative values that you assign to worlds in which you a) exist and have a banana, b) exist and do not have a banana, c) do not exist — one need not address all the philosophical issues as to what values we should assign in order to address the puzzle; clearly we do assign a much higher value to existing than we do to having bananas.
I should have written “In either case, 1 out of 1024 worlds contains you holding a banana and 1023 don’t if you take the deal, and n out of n worlds containing you not holding a banana if you don’t take the deal.” So we’re comparing (V(alive)+V(have banana) + 1023*V(dead))/1024 to (V(alive)+V(don’t have banana)), where V(s) is the value we assign to state s. If we assign a value of 0 to being dead and to not having a banana, this reduces to
[deal] (V(alive)+V(have banana))/1024 vs. [no deal] V(alive) or
[deal] V(have banana) vs. [no deal] 1023*V(alive)
So you should take the deal only if being alive is worth less than 1/1023 of having a banana.
ah, so we are defining the mathematical framwework around these philosophical points of view? The logic?
While it began as a “thought experiment” the very basis of the question raised(?) were based on what had already come before us?
All the “histories” had already been defined in a “normal distribution.” Now you have to remember how one gets to this point and you place it in perspective, and in context of Bell’s Theorem?
So having encapsulated this history, one leans towards “choices made” and how responsible we are with them? A theoretical position?
Okay, so as an example like Solvay in 1927 makes itself known. The exercise is, “self describing” in process?
No.
Although the “many worlds theory” is a great concept, it falls apart when time is yanked out of the equation.
Worse, the “many worlds” theory states that ANY branching point creates a new
universe. Again, theoretically nice on a limited scale, horrendous on the macro scale (somewhere I got a banana but a meteor slammed into my house and kills me – great).
What I find disturbing about the “many worlds” theory, is that if it holds true for this world, then it must hold true for the alternate world. Do these worlds continue or collapse at some point? Or do they merge back in with the “true” universe?
What I hate about the “many worlds” theory is, if indeed time is not unidirectional, then there can be many pasts as there are many futures. All leading up to you either getting/not getting that banana.
Personally, I fall in the “everything happens at once and time is merely how we perceive things” group. Makes everything nice, neat and tidy.
Feloneous
Although there may be replicates of me in the “other worlds”, I am only aware of my existence in this one. So don’t take the bet (unless bananas can be passed from one world to the next!)
Anthony
As Sean pointed out in a previous comment, it is likely that the quantum suicide thought experiment has more to do with the interpretation of probability theory than with quantum mechanics.
Indeed, when Tegmark says that if you survive the quantume suicide many times you must acknolewdge the truth of the MWI, what he really says is that your subjective probability assignment of the event “the MWI is true” has risen to a value very close to one. This is so only if the a priori probability of the MWI being true is not many times smaller than your probability of surviving the quantum suicide. You have to believe at least a little to the MWI to interpret the experiment in this way. If you don’t, nothing prevent you to interpret it by saying that you are a damn lucky guy. To say the truth, I don’t think assigning a probability to a belief is sensible at all. What probability would you give for the Riemann hypothesis to be true ?
The use of probability is sensible only when there is a randomness generator somewhere.
Amusingly, there seem to be two parallel ‘Anthony’s posting with the same name; comments 14, 17, and this one were not made by the same person as #37.
Anyway, to those (such as Sean) who ascribe no importance to the ‘other worlds’ in this experiment, it seems to me that this is identical to ascribing no difference between, in my argument of comment #17, having the teleporter’s ‘reassembler’ turned on or off: i.e. you would be equally comfortable stepping into a teleporter that simply disassembled you, then shut down, as one that disassembled you then reassembled you elsewhere. If you are reassued by the fact that ‘you’ will appear on the other side of the room, then surely you will be equally reassured whichever side of the room you reassemble on, and the whole argument goes through. We could also set up the teleporter to reassemble you very far away with no change in the argument. Thus I think dismissing the ‘copy of you’ that continues to exist (somewhere else in the multiverse) as meaningless is only reasonable if you also dismiss your post-teleportation self as meaningless. But this would imply something that you identify as ‘you’ which goes above and beyond the organization of the materials of your body. Perhaps that is the case, but is that what you think?
Anthony (A.?), in my mind there is a difference between “other worlds” which are causally connected to mine, and those which are not. Your teleporter is then not necessarily analogous to either the other branches of the wavefunction or other worlds outside my lightcone, both of which I am having trouble assigning sufficient degree of reality to comfort me in my one tangible universe.
The teleporter example sounds much more concrete, for example presumably I saw it at work before stepping into it… to make it more analogous to the cases above, imagine in contrast someone told you that the person who stepped into the teleporter and vanished “really” keeps on existing in some other branch of the wave function, or somewhere similarly inaccessible (heaven?), I for one would be very suspicious…
Kill the person withholding the banana and take his coin, too. Win-win.
We thus comprehend a fundamental difference between physicists and chemists. Physicists are constrained from discovery by extant theory. Einstein’s annus mirabilis was greeted with years of yawns. Chemists have rules… but we also have waste crocks and are inured to cleaning glassware.
Was a ruined Abbe refractometer too great a sacrifice for discovering SuperGlue? Adam’s catalyst began as burned linoleum. Do we toss back organic metals because the grad student slipped two decimal places in attempting Zieglar-Natta polymerization of acetylene? Do we abandon Zieglar-Natta catalysts because the technician was lazy about cleaning out the autoclave between runs, enabling the discovery? (The boys were 1963 Nobel Laureates. The technician got bupkis.)
Management has alternate universes screwed up, too.
Greg Egan wrote a book around this issue. Quarantine. The main character keep ‘pulling the trigger’ over and over and occasionally freaks out over the idea that there’s all the other versions of himself that are being wiped out every time.
Somewhere years ago i heard this thought problem expressed not in the either/or coin flip metaphor, but in both roulette and craps game constructs. From revisiting it here back in with the coinflip banana version i am reminded that the set and setting we present as first information makes a bit of a difference in the outcomes. When given a craps presentation, the multiple choices and outcomes elicit a wide variety of response choices, and much like Anthony’s “Star Trek” construct. It might be interesting to work this through as a poker game with nine players at the table and each has pretty good hands, mmmmm..
My point (and I do have one) is that the common logic behind the quantum-suicide argument — “you don’t really believe in the many-worlds interpretation, because if you did you’d be willing to die in many branches of the wavefunction to obtain some reward in other branches” — is a little bit faulty, not because of anything about quantum mechanics, but because of how individuals here-and-now go about making decisions for the benefit of their future selves. These thought experiments rely on a certain fungibility in the notion of the univalent “self.” The transporter is the best example — if it makes two copies of me, which is really “me”? I think the strictly correct answer must be that neither is me — they are some future reconstructions based on me. But the implication is that the person I will become in five minutes, even in the real world without any transporters, is also not “me” in some strict sense. And the implication of that is that I shouldn’t be strategizing to necessarily improve the lot of my future self any more than of anyone else in the world. And all of this may be strictly logically true, but it doesn’t reflect the way people actually behave — I do care about my future self, even if I understand that the unique continuity between my present and my future consciousness is just a convenient illusion that would be shattered by a transporter machine operated by a mischievous chief engineer. From this I conclude that my unwillingness to risk quantum death to get a banana doesn’t really count as an argument against the many-worlds interpretation.
Oh, I see, it does look like the issues to do with continuity of the self get conflated with the interpretation of QM. To design a better diagnostics of one’s faith in MWI any scheme that trades worldly comfort for the some promised heavenly bliss can be used, where the unseen and inaccessible heaven can stand for unseen and inaccessible branches of the wave function if one wishes. There are lots of such schemes around…
(It is clear by now I am not playing this game in good faith, as I mentioned above I see no problems getting solved by postulating this ontological monstrosity, just an opinion…)
Actually, it can’t be ‘strictly logically true’ — you logically can’t get an ought from an is, so logic doesn’t tell us what we should do, it only allows us to logically manipulate “shoulds”, or values, that are already determined. And to do that, two issues must be addressed:
1) The value of surviving. There is no logical basis for the survival ‘instinct’, or urge — this is something that is built into us, as a matter of our evolutionary history. While the urge is much more malleable in us than in, say, cockroaches, because the processing mechanism is much more complex in us, it is still a matter of our nature. No matter how we have reasoned about it, if we see someone walk into a ‘teleportation’ booth, be scanned, and then be destroyed, we’re going to balk about being put into the booth — it’s an emotional reaction.
2) The notion of identity over time. This is a convention of sorts; there is no logical basis for the claim that the me of a second from now is the same as the me of now — they certainly aren’t in identical configurations, or even composed of identical materials. And by the time I wake up tomorrow morning, “I” will be considerably different. Suppose that, every night while asleep, I am scanned, duplicated, and then the the original is destroyed and replaced with the duplicate, which later wakes up unaware of the difference. Does this “matter”? Suppose I find out that this happens every night — should I be afraid to go to sleep? Logic is of little help here. And likewise it is of little help in deciding whether we should care about ‘alternate’ selves — our emotional reactions to these scenarios tells us nothing about MWI — MWI logically cannot be distinguished from another model for the same data, so we shouldn’t be sucked into thinking that poorly formed intuitions and faulty analysis can serve as a test.
Indeed and of course. It’s really rather pathetic that anyone imagines that their personal fear has any bearing on metaphysical truth.
By this I mean that it’s a matter of logic that no empirical test (such as whether some scenario scares us) can distinguish between models for the same data — else they wouldn’t be models for the same data. Branching vs. superposition with collapse are different ways of conceptualizing the exact same phenomena.
I like this experiment, and the statement “we are dealing with branching/collapsing wavefunctions.”
#6:”we should decrease the survival probability substantially — if you perform a quantum Russian Roulette experiment with a survival probability of 10^10 or so, and you survive, then you at least will have a pretty strong conviction of the truth of the MWI.”
After 10^10 trials of quantum suicide, I am still alive? Then I will abandon QM theory, not believe MWI.:-)
I mean, I measure spins of 10 electrons, at t=0. I found 10 spin-ups and get my banana. Then I will start to think that “|+x>=|+z>?, is there really quantum uncertainty?” Or I will think “did the world change abruptly at t=0?”
Yeah, 10 electrons aren’t enough to doubt validity of QM.
Will to use 10^10 electrons change the story? I guess not…
What if the half-life of proton is actually 1s, instead of 10^35 years? Because our universe is particular branch.(10^35 years is what physicists calculated and what they are believing.)
We found QM. —> Adopted MW interpretation. —> Arrived at non-QM’al world.
“We found QM. —> Adopted MW interpretation. —> Arrived at non-QM’al world”
No, we found QM, performed experiments, arrived at non-QM’al world. How we interpret an experiment doesn’t alter its actual outcome.
Just because in one world I get a banana doesn’t make the other 2^10-1 worlds any less deprived of my gestalt, my Me-ness. That’s a pretty big loss for just a banana, even taking in consideration my ego.