tag:blogger.com,1999:blog-9124539381685751273.post3121235477074758281..comments2023-06-19T04:35:06.263-07:00Comments on Skeptic's Play: Multiverses: Is more better?millerhttp://www.blogger.com/profile/05990852054891771988noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-9124539381685751273.post-66834822315779865602010-03-24T11:03:03.447-07:002010-03-24T11:03:03.447-07:00Chris,
That is a very plausible scenario, and I th...Chris,<br />That is a very plausible scenario, and I think some multiverse theories might look like that. Analysis method #2 is best for that scenario.<br /><br />However, I can think of another scenario where analysis #3 seems more appropriate.<br /><br />A mad philosopher has a machine that generates a random integer between 1 and 1,000,000. If it picks anything other than 1, then it kills whatever's inside.<br /><br />The mad philosopher flips a coin, but does not let you, his Frankenstein monster, see its result. If it is heads, then he puts you and nine other monsters through the machine. If it is tails, then he puts you and 9,999,999 other monsters through the machine.<br /><br />If at least one monster survives, then it is most likely that the coin was tails. However, if all you know is that <i>you</i> survived, then there is no reason to think the coin was heads or tails.<br /><br />Does this example make sense?millerhttps://www.blogger.com/profile/05990852054891771988noreply@blogger.comtag:blogger.com,1999:blog-9124539381685751273.post-78892670515688806872010-03-24T10:08:35.443-07:002010-03-24T10:08:35.443-07:00Hey, Miller,
I commented on your blogpost about t...Hey, Miller,<br /><br />I commented on your blogpost about the fine-tuning argument a while back (January maybe?). Sorry for not responding - have only just thought to come back.<br /><br />I agree there's a difficulty (perhaps impossibility?) in establishing the priors for multiverse hypotheses (or, indeed, pretty much any hypothesis). However, in establishing the conditional probabilities, I think it's mistaken to calculate them for each universe. You should calculate them for each multiverse.<br /><br />The reason I say this is that the existence of human beings will be observed as long as they exist somewhere in the multiverse, and not in any one particular universe. We shouldn't look at the likelihood that <i>this</i> universe contains life given H1 or H2; rather, we should look at the likelihood that <i>at least one</i> universe contains life given H1 or H2.<br /><br />For a demonstration of the idea I'm trying to drive at (I hope it's clear, but if not, let me know): A computer is set up to pick a random integer from 1 to 1,000,000. If it picks #1, you're saved. If it fails to pick #1, you're killed. A man tosses a coin. If it comes up heads, the computer goes through the process ten times (and as long as it picks #1 once, you're fine). If it comes up tails, the computer goes through the process ten million times.<br /><br />You are told all these rules, but you do not get to observe the coin toss or the computer. After a while, you're set free, and not killed. Did the coin land heads or tails?<br /><br />Even if you can't know the priors (which maybe you could in this case), you can certainly know the conditionals. The probability of the observation of surviving given heads or tails is not calculated by looking at the probability of each random number being 1 given heads or tails, but rather by looking at the probability that at least one of the random numbers was a 1, given heads or tails. Consequently, p(live|H) < p(live|T).<br /><br />Much the same should apply in the multiverse case. Our observation that there is life in universe alpha will only be observed if there is life somewhere in the multiverse. Neither H1 nor H2 increases the likelihood of universe alpha sustaining life, but H2 does increase the likelihood of <i>some</i> universe sustaining life. The conditional probability should take the whole multiverse into account, not just individual universes. (Though I think I'm right in saying you could take both into account without it making any difference.)<br /><br />I hope I'm being clear. If not, my apologies. Say so and I'll try to rectify.<br /><br />Regarding the usefulness of multiple universe theories, as they stand, I can see two uses: one, opposing design hypotheses, and two, if physicists accept MU hypotheses, they're more likely to incorporate them into their theories; if MU hypotheses are correct, this is good, and maybe this will ultimately lead to increased understanding of reality than would otherwise occur without the belief in MU hypotheses. Maybe.<br /><br />Chris.Chrishttps://www.blogger.com/profile/12623730050401182226noreply@blogger.comtag:blogger.com,1999:blog-9124539381685751273.post-63034989740655892282010-03-02T05:47:18.951-08:002010-03-02T05:47:18.951-08:00I agree. I see some similarity between actual cosm...I agree. I see some similarity between actual cosmologies and astrology, a NEW-astrology.Eduardhttp://baumannatmcnet.chnoreply@blogger.com