tag:blogger.com,1999:blog-22973357.post2843907671681965547..comments2021-04-18T18:16:05.056-04:00Comments on Sabine Hossenfelder: Backreaction: Infinity Really is DifferentSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger29125tag:blogger.com,1999:blog-22973357.post-30021437871932561472008-11-11T15:21:00.000-05:002008-11-11T15:21:00.000-05:00Hi Thomas,I agree with you. That's why I said a si...Hi Thomas,<BR/><BR/>I agree with you. That's why I said a similar statement, not the same. I don't doubt that reductionism works, the question is whether it is useful. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-15388662872225612932008-11-11T10:13:00.000-05:002008-11-11T10:13:00.000-05:00Prof. Hossenfelder - It would be interesting to se...Prof. Hossenfelder - <BR/><BR/><I>It would be interesting to see whether one could find a possibly weaker statement for large, but finite systems.</I><BR/><BR/>I haven't read the paper yet, but I'll go out on a limb and say 'no'. (I'm often out on a limb - that's why I keep falling out of trees!) The point that allows this model to be Turing-complete (a general computer) is that there are Unknownhttps://www.blogger.com/profile/03518775138865994625noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-65046981215255033702008-11-07T10:27:00.000-05:002008-11-07T10:27:00.000-05:00Hi Anonymous,I believe that the paper you summaris...Hi Anonymous,<BR/><BR/><I>I believe that the paper you summarise does not rule out that we gather information about specific spin systems</I><BR/><BR/>I don't think so either, and I never said that. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-54902110338014611832008-11-07T06:27:00.000-05:002008-11-07T06:27:00.000-05:00Let P be the set of all programs. Consider the fu...Let P be the set of all programs. Consider the function H : P --> {0, 1} such that H(p) = 1 iff the execution of P terminates.<BR/><BR/>Turing proved in ZFC that there is no Turing machine computing H. This result is called "Undidability of the Halting problem". The Church-Turing thesis, at least in my reading, says that there is no physical device in the universe that computes H Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42507878529665487752008-11-07T00:01:00.000-05:002008-11-07T00:01:00.000-05:00Bee,It would be interesting to see whether one cou...Bee,<BR/><BR/><BR/><EM>It would be interesting to see whether one could find a possibly weaker statement for large, but finite systems.</EM><BR/><BR/>Why don't you consider the statement you made about cellular automatons (which can be physically built in a variety of ways) to be this weaker statement?Christophe de Dinechinhttps://www.blogger.com/profile/15212549796119667462noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32903677880556381202008-11-06T10:30:00.000-05:002008-11-06T10:30:00.000-05:00Hi Anonymous,This is still not quite right: there ...Hi Anonymous,<BR/><BR/><I>This is still not quite right: there is no reason to believe that you cannot say anything about these states, all the paper (in your summary) shows is that you cannot mechanically derive what you want to say.<BR/><BR/>Sorry for being pedantic.</I><BR/><BR/>Sorry for being dumb but I don't understand that. What do you mean with 'mechanically derive'? You can either deriveSabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-41436242594559059492008-11-06T06:15:00.000-05:002008-11-06T06:15:00.000-05:00Andrew writes: Whether or not a problem is undecid...Andrew writes: <I>Whether or not a problem is undecidable (or uncomputable) depends on the axiomatic system you choose in mathematics</I>.<BR/>This is correct, but the interesting question is not only the mathematisation of the intuitive notion of computation by Church, Goedel, Post, Zuse and others, but also the empirical content of what is now called the "Church-Turing" thesis. If it were to Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-448491251459244872008-11-06T06:08:00.000-05:002008-11-06T06:08:00.000-05:00You write: "There are of course settings in which ...You write: "<I>There are of course settings in which you can say something about the ground state from knowing the initial conditions and the update rule. The point is there are some in which you can't</I>."<BR/><BR/>This is still not quite right: there is no reason to believe that you cannot <B>say</B> anything about these states, all the paper (in your summary) shows is that you cannot <B>Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28667602882038436712008-11-05T03:53:00.000-05:002008-11-05T03:53:00.000-05:00I think my response to Anonymous yesterday about t...I think my response to Anonymous yesterday about the Halting Problem was misleading. Whether or not a problem is undecidable (or uncomputable) depends on the axiomatic system you choose in mathematics. Excuse me for posting my corrected version as much to get things clearer in my own head as anything else (this is still kind-of on-topic):<BR/><BR/>We're all probably aware of Godel's Andrew Thomashttps://www.blogger.com/profile/03852211910001840777noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32367770463883651212008-11-04T16:27:00.000-05:002008-11-04T16:27:00.000-05:00Phil:I find it somewhat amusing that we believe th...<B>Phil</B>:<I>I find it somewhat amusing that we believe that only now we may become the first to be able to exploit the quantum for the purposes of problem solving when the plants of the world have been doing it for eons.</I><BR/><BR/>There is no doubt on my part that neural point of consideration(tabla rusa) will have been dedicated to "welcher weg?"<BR/><BR/>So this is "beyond once assumed" PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-78869781484907373882008-11-04T09:40:00.000-05:002008-11-04T09:40:00.000-05:00Hi Anonymous,Sorry if my formulation was misleadin...Hi Anonymous,<BR/><BR/>Sorry if my formulation was misleading. There are of course settings in which you can say something about the ground state from knowing the initial conditions and the update rule. The point is there are some in which you can't. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25369546226927758142008-11-04T08:57:00.000-05:002008-11-04T08:57:00.000-05:00Hi Anonymous, yes, you're right considering the Ha...Hi Anonymous, yes, you're right considering the Halting problem and saying that in <STRONG>general</STRONG> it is not possible to say that a computer program will continue forever: that is uncomputable, but individual instances might be calculated. So I think the Halting problem is very misleading in this case. A bit of explanation:<BR/><BR/>According to <A HREF="http://en.wikipedia.org/wiki/Andrew Thomashttps://www.blogger.com/profile/03852211910001840777noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-6633869035148955032008-11-04T08:39:00.000-05:002008-11-04T08:39:00.000-05:00I have not read the paper under discussion, but yo...I have not read the paper under discussion, but your summary is misleading: "<I>without actually running them and looking, thus one can never say anything about the total evolution [...] this then means there are questions about its ground state that can't be answered either [...] There is thus no way to derive this quantity from the Hamiltonian, the question is undecidable.</I>"<BR/><BR/>The Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-81846341033101057492008-11-04T07:38:00.000-05:002008-11-04T07:38:00.000-05:00I've remember doing some work in the past on Hopfi...I've remember doing some work in the past on <A HREF="http://www.learnartificialneuralnetworks.com/hopfield.html" REL="nofollow">Hopfield artificial neural networks</A> which are based on these Ising lattices. Basically a huge network of interconnected elements, with every element connected to every other element (which in this case is supposed to resemble the human brain). And when you run the Andrew Thomashttps://www.blogger.com/profile/03852211910001840777noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18460128978797318972008-11-03T20:43:00.000-05:002008-11-03T20:43:00.000-05:00Hi Plato,“By taking advantage of quantum phenomena...Hi Plato,<BR/><BR/>“By taking advantage of quantum phenomena such as entanglement, teleportation and superposition, a quantum computer could, in principle, outperform a classical computer in certain computational tasks”<BR/><BR/>I find it somewhat amusing that we believe that only now we may become the first to be able to exploit the quantum for the purposes of problem solving when the <A HREF="Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84730961259213894372008-11-03T19:53:00.000-05:002008-11-03T19:53:00.000-05:00Hi Bee,“The development of macroscopic laws from f...Hi Bee,<BR/><BR/>“The development of macroscopic laws from first principles may involve more than, just systematic logic, and could require conjectures suggested, by experiments, simulations or insight.”<BR/><BR/><BR/>Actually after reading the paper of which the above forms to be the conclusion I understand it to more or less agree rather the disagree with Penrose’s position. That is it's Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-8340483154117413092008-11-03T13:45:00.000-05:002008-11-03T13:45:00.000-05:00Dear Stefan,Yes, I would agree the system they con...Dear Stefan,<BR/><BR/>Yes, I would agree the system they consider is far from being natural. I think this is more a proof 'in principle'. As to the groundstate, I think it is relevant that there is this one-dimensional line on which spins are forced into a specific orientation by an external field. This fixes the state of the whole system. Since each line determines the next by construction of Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18580955411616313962008-11-03T13:33:00.000-05:002008-11-03T13:33:00.000-05:00Hi Anonymous,Thanks for the reference, I will give...Hi Anonymous,<BR/><BR/>Thanks for the reference, I will give that a read! Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-30588452468749489942008-11-03T13:31:00.000-05:002008-11-03T13:31:00.000-05:00Hi Phil,There is a subtle point in this example th...Hi Phil,<BR/><BR/>There is a subtle point in this example that I am not sure I made very clear. The state of the system considered is not evolving. It is a static two-dim representation that is analogous to the outcome of running a code. There is thus no sense in which one could think of this case as being a program 'running'. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36639597016498004552008-11-03T13:01:00.000-05:002008-11-03T13:01:00.000-05:00Dear Arun,Yes, exactly that is the point. Best,B.Dear Arun,<BR/><BR/>Yes, exactly that is the point. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-91688689182250412942008-11-03T11:46:00.000-05:002008-11-03T11:46:00.000-05:00I mean sure, what does it look like in terms of co...I mean sure, what does it look like in terms of completion of the standard model to include, and then, you move consideration beyond gamma ray to consider what the universe actually looks like in regards to gravity waves?<BR/><BR/>Are they real?<BR/><BR/>You have to consider the energy valuation of the photon then to think hmmm..... what is this actually representing while one is being so PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42256186325851109992008-11-03T11:38:00.000-05:002008-11-03T11:38:00.000-05:00Unfortunately link has been outdated, yet the prin...Unfortunately link has been outdated, yet the principal I would be considering in context of an information processing centre?<BR/><BR/><I>Physicists have succeeded in entangling five photons for the first time. Although four photons have been entangled before, five is the minimum number needed for universal error correction in quantum computation. Moreover, the same team has demonstrated a PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-88711324221791128562008-11-03T08:27:00.000-05:002008-11-03T08:27:00.000-05:00hi bee!!! just visiting here to your wonderful blo...hi bee!!! just visiting here to your wonderful blog! have a great day!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-91216566188700519522008-11-03T06:41:00.000-05:002008-11-03T06:41:00.000-05:00Dear Bee,thanks for pointing out this interesting ...Dear Bee,<BR/><BR/><BR/>thanks for pointing out this interesting paper :-)<BR/><BR/>But I have to admit, after reading through it, that I a'not so sure what to make of the result. <BR/><BR/>When I've understood it correctly, an important point of the argument (though not discussed explicitely) is that one has to fix the couplings between neighbouring spins in a very special way, so that indeed stefanhttps://www.blogger.com/profile/09495628046446378453noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-82683732833993854302008-11-03T06:17:00.000-05:002008-11-03T06:17:00.000-05:00This seems related ( and neglected)http://www.ph.b...This seems related ( and neglected)<BR/><BR/>http://www.ph.biu.ac.il/data/papers/26/201.pdfAnonymousnoreply@blogger.com