tag:blogger.com,1999:blog-5592542.post3996707107033541468..comments2023-11-23T09:51:02.063-08:00Comments on Rondam Ramblings: Are parallel universes real?Ronhttp://www.blogger.com/profile/11752242624438232184noreply@blogger.comBlogger91125tag:blogger.com,1999:blog-5592542.post-86204087910978964512021-01-07T13:19:44.062-08:002021-01-07T13:19:44.062-08:00@HB:
Great questions!
> 1. SR indeed obliged ...@HB:<br /><br />Great questions!<br /><br />> 1. SR indeed obliged us to accept new points of view, but it still reduces to the classical mechanics in the limit of small velocity.<br /><br />QM reduces to classical mechanics as the number of entangled degrees of freedom gets large and decoherence starts to dominate the dynamics. It really is a very good analogy.<br /><br />> 2. QIT tells Ronhttps://www.blogger.com/profile/11752242624438232184noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-47741539495264018502021-01-03T12:20:08.835-08:002021-01-03T12:20:08.835-08:00I like very much your talk, and the QIT interpreta...I like very much your talk, and the QIT interpretation is interesting. But I still do not feel entirely comfortable with it. You claim that people refuse to believe what the mathematics tells them, as happened with Maxwell equations. But then it took ONLY 4 decades to arrive to SR, with QM we are 9 decades after, and the debate still continues for good reasons, as follows:<br /><br />1. SR indeedhuman beinghttps://www.blogger.com/profile/01220494370198170070noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-47653327738718952492018-04-25T20:45:09.467-07:002018-04-25T20:45:09.467-07:00No, of course not.
Then it seems that I'm as ...<i>No, of course not.</i><br /><br />Then it seems that I'm as unable to understand your position as you are to understand mine. So at this point I really am going to bow out.Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-5112150965952571972018-04-25T20:25:07.627-07:002018-04-25T20:25:07.627-07:00"you would refuse to update your internal mod..."<i>you would refuse to update your internal model to make correct predictions because your internal reasoning process is only allowed to use ordinary probabilities?</i>"<br /><br />No, of course not. You're greatly confusing things at very different levels.<br /><br />I can have internal models of all sorts of different things out in the world. I could have a model of a small boyDon Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-75765487122318798932018-04-25T17:53:38.580-07:002018-04-25T17:53:38.580-07:00complex amplitudes do not, in fact, describe my in...<i>complex amplitudes do not, in fact, describe my internal reasoning process</i><br /><br />Hm. So if you were watching qubit measurements instead of coin flips, and the experimenter was applying various quantum logic gates to produce interference effects, you would refuse to update your internal model to make correct predictions because your internal reasoning process is only allowed to use Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-16245024988433294392018-04-25T17:51:50.275-07:002018-04-25T17:51:50.275-07:00Oops, forgot to take the square root at the end
O...<i>Oops, forgot to take the square root at the end</i><br /><br />Oops again, I was right the first time. The square root applies to the vector of amplitudes for all of the possibilities; in this case, it would mean that an amplitude of 0.2 + 0.1i for the sun rising, with a squared modulus of 0.05 (or 5 percent probability for the sun rising) requires that the amplitude for the sun not rising Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-73876402328869912752018-04-25T17:38:17.211-07:002018-04-25T17:38:17.211-07:00"Why does it have to? Your internal reasoning..."<i>Why does it have to? Your internal reasoning process can use any math you like.</i>"<br /><br />It doesn't "have" to. You can make a machine that does any computation you wish. Machines don't have to be "rational", and neither does your reasoning process.<br /><br />The important point is that complex amplitudes do <i>not</i>, in fact, describe my Don Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-58123136814443420422018-04-25T17:24:23.782-07:002018-04-25T17:24:23.782-07:00I don't understand what negative or complex pr...<i> I don't understand what negative or complex probabilities refer to, if applied to my internal reasoning and knowledge.</i><br /><br />Looking at the Scott Aaronson lecture I linked to earlier, I see that it's a bit unclear on this as well. He says " what would it mean to have "probability theory" with negative numbers?", but just a little later, when talking about Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-52688646989765463962018-04-25T17:09:43.748-07:002018-04-25T17:09:43.748-07:00you are (0.2)^2 + (0.1)^2 = 0.05, or 5 percent con...<i>you are (0.2)^2 + (0.1)^2 = 0.05, or 5 percent confident that the sun will rise tomorrow.</i><br /><br />Oops, forgot to take the square root at the end; that should be sqrt(0.05), or about 22% confident that the sun will rise tomorrow.Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-48126008950138515142018-04-25T16:59:23.046-07:002018-04-25T16:59:23.046-07:00My internal knowledge update process follows ordin...<i>My internal knowledge update process follows ordinary probability</i><br /><br />Why does it have to? Your internal reasoning process can use any math you like. There's no reason why you have to restrict it to "ordinary probability".<br /><br /><i>I don't even know how to meaningfully understand a claimed statement like "I am 0.2+0.1i confident that the sun will rise Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-58805204328310366482018-04-25T16:52:43.332-07:002018-04-25T16:52:43.332-07:00"two possible ways something could happen cou..."<i>two possible ways something could happen could reduce the total probability instead of increase it. We already know this is possible, so why can't your internal reasoning processes allow for it?</i>"<br /><br />Because that's not how internal reasoning works. My internal knowledge update process follows ordinary probability (with some errors, of course), not quantum Don Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-30514274046523157752018-04-25T16:48:22.646-07:002018-04-25T16:48:22.646-07:00@Peter:
> > it is demonstrably false.
>...@Peter:<br /><br />> > it is demonstrably false.<br /><br />> It is if you assume that the quantum state is physically real<br /><br />No, it is not necessary to assume that. Non-unitary collapse is enough to produce FTL communications. It doesn't matter *how* the collapse happens, it is sufficient *that* it happens.Ronhttps://www.blogger.com/profile/11752242624438232184noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-10405075515080733812018-04-25T16:38:12.054-07:002018-04-25T16:38:12.054-07:00The coin was always two-headed. You just didn'...<i>The coin was always two-headed. You just didn't know it, and so you are coming to learn this fact. But this is a change inside of you, not a change in external reality.</i><br /><br /><i>it's certainly the case that people can adopt procedures to more closely align their internal models, with external reality. And in so far as external reality is consistent, we should of course expect Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-75963456682779766522018-04-25T16:33:37.816-07:002018-04-25T16:33:37.816-07:00it is demonstrably false.
It is if you assume tha...<i>it is demonstrably false.</i><br /><br />It is if you assume that the quantum state is physically real, i.e., if you assume that an interpretation in my category #2 is correct.<br /><br />I don't think it is if an interpretation in my category #1 turns out to be correct. Or, to put it another way, it might turn out that whatever more fundamental theory we end up discovering, that has Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-14286139791848930562018-04-25T16:32:33.305-07:002018-04-25T16:32:33.305-07:00"as actual data starts accumulating, my updat..."<i>as actual data starts accumulating, my updated posterior probabilities aren't just about my knowledge any more</i>"<br /><br />But of course they are. The entire evolution of the probability mass that you are describing, is an evolution of your internal model. <i>Nothing</i> in the external objective reality has changed. The coin was always two-headed. You just didn't Don Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-88564234500232754542018-04-25T16:01:35.639-07:002018-04-25T16:01:35.639-07:00But you do have to read my article to know what is...<i>But you do have to read my article to know what is under discussion</i><br /><br />I had to read this article, yes. It already said more than enough for me to know what kind of interpretation you were discussing in the paper. You say at the start of the article that if one has not either watched your video or read your paper, the rest of the article probably won't make a lot of sense; but Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-55989190567241975882018-04-25T15:51:26.431-07:002018-04-25T15:51:26.431-07:00There is a Bayesian interpretation of the math of ...<i>There is a Bayesian interpretation of the math of probability theory, that says that the math describes the evolution of your state of internal knowledge, not any feature of external reality.</i><br /><br />I'm not sure I would describe the Bayesian interpretation that way. For example, say I have a Bayesian model of a coin. My prior is that the coin is fair, so I assign equal probability Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-14274462458151521812018-04-25T15:51:08.248-07:002018-04-25T15:51:08.248-07:00@Peter:
> I don't have to read your articl...@Peter:<br /><br />> I don't have to read your article to know what the interpretations you are talking about say.<br /><br />But you do have to read my article to know what is under discussion because, as you yourself just pointed out:<br /><br />> there is no universally accepted definition of the term "Copenhagen interpretation"<br /><br />Also:<br /><br />> The Ronhttps://www.blogger.com/profile/11752242624438232184noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-57129951556298744522018-04-25T15:50:58.134-07:002018-04-25T15:50:58.134-07:00"the wave function describes what can be know..."<i>the wave function describes what can be known about the system. There is no claim that it is the physically real state of the system</i>"<br /><br />I disagree with your epistemology here. "What can be known" is a statement about objective reality, independent of any particular observer. It is very, very different, than a Bayesian probability interpretation describing Don Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-88522478698987806972018-04-25T15:40:56.549-07:002018-04-25T15:40:56.549-07:00"there is no universally accepted definition ..."<i>there is no universally accepted definition of the term "Copenhagen interpretation"</i>"<br /><br />There may be some minor variations of interpretation that all get labeled "Copenhagen". That does <i>not</i> mean that any arbitrary variation is acceptable. All correct "Copenhagen" interpretations of QM posit that "wavefunction collapse" is Don Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-76160153013305795392018-04-25T15:37:15.815-07:002018-04-25T15:37:15.815-07:00This thing you are describing certainly doesn'...<i>This thing you are describing certainly doesn't seem to be the standard Copenhagen interpretation.</i><br /><br />Since you gave Wikipedia as a source, here is an excerpt from the Wikipedia page on the Copenhagen interpretation:<br /><br />A wave function Ψ represents the state of the system. It encapsulates everything that can be known about that system before an observation; there are noPeter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-84050570798231177302018-04-25T15:29:53.617-07:002018-04-25T15:29:53.617-07:00Even in standard cosmology, there is nothing in th...<i>Even in standard cosmology, there is nothing in the theory that explains why the universe began in the exact state it did at the big bang, in precisely that size, with precisely that amount of energy. It's just taken as a given: that was the (arbitrary) starting state, and then the universe evolved according to our known physical laws after that.</i><br /><br />No, that's not what Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-2180716034968432642018-04-25T15:18:40.833-07:002018-04-25T15:18:40.833-07:00You began commenting in this thread by making some...<i>You began commenting in this thread by making some incorrect claims about the Copenhagen interpretation.</i><br /><br />No, we were using the term "Copenhagen interpretation" to refer to different things. Since there is no universally accepted definition of the term "Copenhagen interpretation" (as the Wikipedia page on that interpretation, which is linked to in the page on Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-90252235237726205202018-04-25T15:08:19.589-07:002018-04-25T15:08:19.589-07:00@Peter: "I don't have to read your articl...@Peter: "<i>I don't have to read your article to know what the interpretations you are talking about say. I've already mentioned that I've been studying QM for many years.</i>"<br /><br />I don't think that's accurate. You began commenting in this thread by making some incorrect claims about the Copenhagen interpretation. When called on it, you retreated by saying Don Geddishttps://www.blogger.com/profile/04214642122689048677noreply@blogger.comtag:blogger.com,1999:blog-5592542.post-41939642714732160562018-04-25T15:01:09.520-07:002018-04-25T15:01:09.520-07:00You appear to want to make some analogy with proba...<i>You appear to want to make some analogy with probability</i><br /><br />I should clarify this as well: it's just a reference to the idea that quantum mechanics is a generalization of ordinary probability theory in which probabilities can be negative. A good quick exposition by Scott Aaronson is here:<br /><br />https://www.scottaaronson.com/democritus/lec9.html<br /><br />A more Peter Donishttps://www.blogger.com/profile/09122769947782402203noreply@blogger.com