Re: Quantum suicide without suicide
Tim May wrote On Wednesday, January 8, 2003, at 10:58 AM, George Levy wrote: In the original verision of Quantum Suicide (QS), as understood in this list, the experimenter sets up a suicide machine that kills him if the world does not conform to his wishes. Hence, in the branching many-worlds, his consciousness is erased in those worlds, and remains intact in the worlds that do satisfy him. Is it possible to perform such a feat without suicide? What is the minimum attrition that is required and still get the effect of suicide? Hawking had a good line: When I hear about Schrodinger's Cat, I reach for my gun. Good line? I would say it is rather stupid (with all my respect for Hawking). Come on. The Schroedinger's Cat paper is one of the deepest early paper on QM conceptual issues. The notion of entanglement appears in it. It prepares both EPR and quantum computing, which arises from taking seriously the QM superpositions. You can only mock Schroedinger's Cat by taking a purely instrumentalist view of QM, and with such a view quantum computing would not have appear. Slightly modify the QS conditions in another direction: instead of dying immediately, one goes onto death row to await execution. Or one is locked in a box with the air running out. And so on. This removes the security blanket of saying Suicide is painless, and in all the worlds you have not died in, you are rich! In 99....99% of all worlds, you sit in the box waiting for the air to run out. It reminds me a novel I wrote (a long time ago) where computationalist practitioners always wait for complete reconstitution before annihilating the original. It can be consider as a fair practice letting imagine the risk of such immortality use. I don't know if there are other worlds in the DeWitt/Graham sense (there is no reason to believe Everett ever thought in these terms), but if they exist they appear to be either unreachable by us, or inaccessible beyond short times and distances (coherence issues). I disagree. It is only by playing with word that you can suppress the many worlds in Everett. Some of Everett's footnote are rather explicit. See the Michael Clive Price FAQ for more on this. http://www.hedweb.com/everett/everett.htm People like Roland Omnes which agree with pure QM (QM without collapse) and still postulate a unique world acknowledge their irrationality. In particular, it seems to me there's a causal decision theory argument which says that one should make decisions based on the maximization of the payout. And based on everything we observe in the world around us, which is overwhelmingly classical at the scales we interact in, this means the QS outlook is deprecated. You confuse first and third person point of view. If you put yourself at the place of Schroedinger Cat you will survive in company of people which will *necessarily* be more and more astonished, and which should continue to bet you will not survive. Although *where* you will survive they will lose their bets. Consider this thought experiment: Alice is facing her quantum mechanics exam at Berkeley. She sees two main approaches to take. First, study hard and try to answer all of the questions as if they mattered. Second, take the lessons of her QS readings and simply _guess_, or write gibberish, killing herself if she fails to get an A. (Or, as above, facing execution, torture, running out of air, etc., just to repudiate the suicide is painless aspect of some people's argument.) From rationality, or causal decision theory, which option should she pick? It depends of Alice's goal. If she just want the diplom (and not the knowledge corresponding to the field she studies) then QS is ok, but quite egoist and vain at some other level. If she want the knowledge, she will be unable to find a working criteria for her quantum suicide. By the Benacerraf principle we cannot know our own level of implementation code. (I use comp here). All indications are that there are virtually no worlds in which random guessers do well. Of course! From a 3-person point of view quantum suicide is ordinary suicide. Tegmark (and myself before in french) made this completely clear. Also, it is an open problem if some feature in the apparition of life or even matter-appearance does not rely on some quantum guess. (The odds are readily calcuable, given the type of exam, grading details, etc. We can fairly easily see that a random guesser in the SATs will score around 550-600 combined, but that a random guesser in a non-multiple-choice QM exam will flunk with ovewhelming likelihood.) What should one do? What did all of you actually do? What did Moravec do, what did I do, what did Tegmark do? I think the QS point is not practical, and it is highly unethical. It is the most egoist act possible. But QS just illustrate well conceptual nuances in the possible interpretation of QM and MWI. Bruno
Re: Universes infinite in time
At 16:07 -0800 8/01/2003, Hal Finney wrote: The interesting aspect from this list's perspective is how to regard infinite-time cosmologies. Does it make sense to imagine a universe which has had an infinite past? How could we simulate that on a computer, if there were no starting point? We certainly cannot simulate a 3-person infinite past history. But imagine we simulate a society-world of researchers in a computer, and that we would like those researchers never guess anything about our own reality level. Now, the computer is locally finite (i.e. at each time it is finite but it is capable to grow indefinitely) so that those researchers, experimenting their reality, will find little local inconsistencies. For example they will correctly infer some standard model particle theory from they high level experimentations, but as soon they will build particle accelerator to verify their theories, discrepancies will appear (just because we have not simulate the society-world at such a detailed level. So now those researchers can infer that they are simulated at some different reality level. But this is what we don't want. So let us add a subroutine which observes the researchers, and each time reserachers find (serious) discrepancies, the subroutine freezes the researchers and refines their level of reality. Now, it is quite logically possible that the refining need not only to add sub-particles, but need to add past further past-interactions. So, although that past is generated, little by little, in the 3-future, it will happen that from the 1-perspective of the simulated researchers their stories will look as if they are infinite in their past. Is not UD* like that? Open problem. But quite possible once we distinguish the 1-time of the simulated people and the 3-time describing the definite steps of the UD in Platonia. Bruno
Re: Quantum suicide without suicide
Thanks Bruno, for your comments, I fully agree with you. Let me add a few comments for Tim and Scerir Tim May wrote: Consider this thought experiment: Alice is facing her quantum mechanics exam at Berkeley. She sees two main approaches to take. First, study hard and try to answer all of the questions as if they mattered. Second, take the lessons of her QS readings and simply _guess_, or write gibberish, killing herself if she fails to get an "A." (Or, as above, facing execution, torture, running out of air, etc., just to repudiate the "suicide is painless" aspect of some people's argument.) What should one do? What did all of you actually do? What did Moravec do, what did I do, what did Tegmark do? Tim, this example is completely inapplicable to the case of QS just like you would not set up a relativistic experiment to measure the slowing of a clock in which the clock travels one mile per hour. To get significant results you must travel a significant fraction of the speed of light. QS decisions are significantly different from "classical" decisions when the life of the experimenter is at stake, (or as I pointed out earlier the memory of the quantum suicide machine in the mind of the experimenter must be at stake). The amount "at stake" does not have to be 100% as I shall explain below. Even intentional death (suicide) is not necessary. The incoming death may be entirely unintentional! This reminds me of a science fiction story I read about 30 years ago in which the end of the world was forecasted for midnight. A zealous journalist was faced with preparing a story to be published the next day (after the world ended.) He accomplished the task by stating in the story that the forecast was in fact in error and that the world had not ended. In the branch of the manyworld, in which he remained alive, his story was right, and he therefore, astonished the public with his prescience. He made the right QS decision. As you can see, suicide is not necessary. One could be on death row - in other words have a high probability of dying - and make decisions based on the probability of remaining alive. Being on death row, dying of cancer, travelling on an airline, or sleeping in our bed involve different probability of death... These situations only differ in degrees. We are all in the same boat so to speak. We are all likely to die sooner or later. The closer the probability of death, the more important QS decision becomes. The guy on death row must include in his QS decision making the factor that will save his life: probably a successful appeal or a reprieve by the state governor. The person flying in an airline should include in his QS decision process the fact that the plane will not have a mechanical failure or be hijacked. The person dying of cancer must include the possibility of finding a cure to cancer, or of being successfully preserved somehow by cryogenic means. As you see, suicide is not necessary for QS decisions. In addition the whole issue of "measure" is in my opinion suspect as I have already extensively stated on this list. See below. Scerir wrote Lev Vaidman wrote that we must care about all our 'successive' worlds in proportion to their measures of existence [Behavior Principle]. He does not agree to play the 'quantum Russian roulette' because the measure of existence of worlds with himself dead is be much larger than the measure of existence of the worlds with himself alive and rich! I agree that QS is unethical. Yet, the reasons given by Vaidman could be unjustified because maximizing measure may not be possible if measure is already infinite - a clue that measure is infinite is that the manyworld seem to vary according to a continuum since schroedinger function is continuous. George
Re: Quantum suicide without suicide
From: Tim May [EMAIL PROTECTED] Date: Thu Jan 9, 2003 1:22:32 PM US/Pacific To: [EMAIL PROTECTED] Subject: Re: Quantum suicide without suicide On Thursday, January 9, 2003, at 12:32 PM, George Levy wrote: As you can see, suicide is not necessary. One could be on death row - in other words have a high probability of dying - and make decisions based on the probability of remaining alive. Being on death row, dying of cancer, travelling on an airline, or sleeping in our bed involve different probability of death... These situations only differ in degrees. We are all in the same boat so to speak. We are all likely to die sooner or later. The closer the probability of death, the more important QS decision becomes. The guy on death row must include in his QS decision making the factor that will save his life: probably a successful appeal or a reprieve by the state governor. No, this is the good news fallacy of evidential decision theory, as discussed by Joyce in his book on Causal Decision Theory. The good news fallacy is noncausally hoping for good news, e.g., standing in a long line to vote when the expected benefit of voting is nearly nil. (But if everyone thought that way, imagine what would happen! Indeed.) The guy on death row should be looking for ways to causally influence his own survival, not consoling himself with good news fallacy notions that he will be alive in other realities in which the governor issues a reprieve. The quantum suicide strategy is without content. As you see, suicide is not necessary for QS decisions. No, I don't see this. I don't see _any_ of this. Whether one supports Savage or Jefferys or Joyce or Pearl, I see no particular importance of quantum suicide to the theory of decision-making. It would help if you gave some concrete examples of what a belief in quantum suicide means for several obvious examples: -- the death row case you cited -- the airplane example you also cited -- Newcomb's Paradox (discussed in Pearl, Joyce, Nozick, etc.) -- stock market investments/speculations --Tim May
