tag:blogger.com,1999:blog-22973357.post6961108774102602485..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: What is a singularity?Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger32125tag:blogger.com,1999:blog-22973357.post-67537013740835415792014-08-18T17:39:47.969-04:002014-08-18T17:39:47.969-04:00Interpretation of the physical meaning of r_n
r_...Interpretation of the physical meaning of r_n <br /><br />r_n per se is only a limit geometric, able to enclose the whole mass of the black hole in a volume that always has a constant density equal to half of the density of Planck. However, if we consider a stellar-mass black hole (of any mass), it turns out that this can not happen, and that is that it's not ... 'geometrically' nemohttps://www.blogger.com/profile/07365330980872106443noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-76441486984557406052014-08-18T17:36:57.961-04:002014-08-18T17:36:57.961-04:00This comment has been removed by the author.nemohttps://www.blogger.com/profile/07365330980872106443noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84484669550256882342014-08-09T11:07:08.877-04:002014-08-09T11:07:08.877-04:00The problem is not so much the physics as it is th...The problem is not so much the physics as it is the tools which are currently used to study singularities. General relativity is based on mathematics from 1867, and is not suitable to study quantum gravity. The more proper treatment, these days, is to dispense with the classical manifold concept and study dg categories. Metatronhttps://www.blogger.com/profile/08396427736998362077noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-82810176385568840052014-08-09T02:50:17.034-04:002014-08-09T02:50:17.034-04:00If we assign to ħ, G and c value = 1
the eq. r_n=s...If we assign to ħ, G and c value = 1<br />the eq. r_n=sqrt3(3M ħ G^2 / c^5 2π) becomes r_n=sqrt3(3M/2π) while r_s=2M.<br /><br />So we may rewrite as x=sqrt3(3y/2π) and x=2y<br /><br />x=radius<br />y=mass<br /><br />these the plot:<br /><br />http://www.wolframalpha.com/input/?i=x%3D2y%2C+x%3D%283y%2F%282%CF%80%29%29^%281%2F3%29&a=^_Real<br /><br /><br />nemohttps://www.blogger.com/profile/07365330980872106443noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-65404164851971946642014-08-07T22:59:38.124-04:002014-08-07T22:59:38.124-04:00If only journalism students knew a little complex ...If only journalism students knew a little complex analysis and GR they wouldn't make these mistakes;)<br /><br />Of course the root meaning of singular is unique, and complex analysis did considerable violence to this term by using it for poles and essential singularities. Von Neumann was similarly making an analogy between the so-called technological singularity and the essential CapitalistImperialistPighttps://www.blogger.com/profile/17523405806602731435noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24942845208848474572014-08-07T12:38:44.518-04:002014-08-07T12:38:44.518-04:00Zephir, nemo has an interesting idea and I would ...Zephir, nemo has an interesting idea and I would suggest h can be understood as a middle scale rather than a minimum. The flatland is the sphereland up close, yes? maybe these also are interchanged. So at 8 dimensions the sphere fills the hypercube exactly thence the volume goes the other way in comparison. What are you suggesting but something applying to electrons too, that is the L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-48815916422190660422014-08-07T09:30:14.819-04:002014-08-07T09:30:14.819-04:00@nemo: The similar situation happens with photons ...@nemo: The similar situation happens with photons at the radius = 2 x schwarzschild radius (the relativistic aberration is double of this classical one), i.e. at the surface of <a href="http://i.imgur.com/mBhOpWj.gif" rel="nofollow">photon sphere</a>. It's probable, for heavier particles additional event horizons for another bosons <a href="http://i.imgur.com/bfH4fjP.gif" rel="nofollow">existZephirhttps://www.blogger.com/profile/06010623752049244967noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-20871246574232433992014-08-06T23:47:16.943-04:002014-08-06T23:47:16.943-04:00Sabine, if you believe it is not approriate, feel ...Sabine, if you believe it is not approriate, feel free to remove my comment.<br /><br />There is a strange relationship purely geometric relative to black holes. The mass of a black hole can be determined in function of its Schwarzschild radius (r_s) as follows:<br /><br />[1] M = 1/2 DP r_s lp ^ 2<br />where<br />dp = density of Planck<br />lp=Planck length<br /><br />It’s trivial to prove that nemohttps://www.blogger.com/profile/07365330980872106443noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-13599250374986750032014-08-06T23:39:49.722-04:002014-08-06T23:39:49.722-04:00This comment has been removed by the author.nemohttps://www.blogger.com/profile/07365330980872106443noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-67383355456367369262014-08-06T18:18:44.146-04:002014-08-06T18:18:44.146-04:00Dear Alice,
The Wannabee of Physics is probabilit...Dear Alice,<br /><br />The Wannabee of Physics is probability.<br /><br />All the information you or anyone will ever need to create a universe (or, if you will, to describe all phenomenon) will have a label everyone agrees to: 1.<br /><br />Sounds singular to me.<br /><br />Your truly,<br />simple-minded Bob.hushhttps://www.blogger.com/profile/16176588791118304829noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-15693598439655480302014-08-06T06:02:15.127-04:002014-08-06T06:02:15.127-04:00Also the idea of chaos where the laws of algebraic...Also the idea of chaos where the laws of algebraic operations break down. Where is the chaos in QM theory? Can we observe or explain plasma pinching when the helicity is neutral and successively circular.<br />MarkusM perhaps the ambiguous statement is not strong enough. Stars and planets have shell structures as if the crystalline structures have successive total phase changes.<br />A BH in a L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-33498620899367987812014-08-06T05:48:24.455-04:002014-08-06T05:48:24.455-04:00or better to define our ignorance:-)or better to define our ignorance:-)Giotishttps://www.blogger.com/profile/03594944884584261018noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-70455248512442386862014-08-06T05:40:39.595-04:002014-08-06T05:40:39.595-04:00For me at least and for space-like (cosmological) ...For me at least and for space-like (cosmological) singularities in the context of GR the term “Singularity” is used more as a way to parameterize our ignorance than to describe any Physics in a meaningful way.Giotishttps://www.blogger.com/profile/03594944884584261018noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-8348580543336860772014-08-06T05:12:20.639-04:002014-08-06T05:12:20.639-04:00"Singularity is a term derived from physics, ..."Singularity is a term derived from physics, where it means the point at the unknowable centre of a black hole where the laws of physics break down."<br />A very strong statement to my taste.<br />When you put water into your freezer you also go through a singularity in a certain sense (phase transition).MarkusMhttps://www.blogger.com/profile/03431499396962852389noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-62247549279867759652014-08-05T23:40:34.360-04:002014-08-05T23:40:34.360-04:00Zephir etc al,
perhaps a little humility is in ord...Zephir etc al,<br />perhaps a little humility is in order for scientists still learning, especially where physics comes to the frontier of issues we call non-linearity.<br />For me questions of arithmetic and visualization of geometries seem all important but even this may be too simple for new generalizations. Praise then to whom may stumble on new deep yet simple foundational principles by L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28150819854457201312014-08-05T22:09:35.227-04:002014-08-05T22:09:35.227-04:00Yes, nice blog post. Complex analysis is fascinati...Yes, nice blog post. Complex analysis is fascinating. Also, for an essential singularity, the function takes on all values in the complex plane as it approaches the singularity.GWhttps://www.blogger.com/profile/16309914321843947595noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-2379556218494536892014-08-05T18:53:52.473-04:002014-08-05T18:53:52.473-04:00I dunno about technological singularity, but the c...I dunno about technological singularity, but the current evolution in physics already exhibits many signs of conceptual singularity in similar way, like the physics before one hundred of years. The situation, when the originally coherent description of nature becomes fragmented into many mutually inconsistent phenomenological descriptions is just what the energy does at the proximity of Zephirhttps://www.blogger.com/profile/06010623752049244967noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-88494654553263298292014-08-05T07:18:44.660-04:002014-08-05T07:18:44.660-04:00Maybe you should make it clear that you're jok...Maybe you should make it clear that you're joking....Rastus Odinga Odingahttps://www.blogger.com/profile/09615544434035028500noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-45931803061812069512014-08-05T06:01:05.029-04:002014-08-05T06:01:05.029-04:00Ghonada,
No, the word itself does not come from V...Ghonada,<br /><br />No, the word itself does not come from Von Neumann. I wrote he was the first to use it to describe the (alleged) breakdown of predictability in technological development. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-274032251977494492014-08-05T04:24:19.708-04:002014-08-05T04:24:19.708-04:00Hi Sabine,
does the word singularity origin...Hi Sabine,<br /> does the word singularity originates from von neumann ? I thought the concept comes from calculus of complex variable, as you mention in the post. In that case, may be Cauchy or Reimann used it ? It is interesting to note that the concept of singularity is central to mathematics of Navier-Stokes equations and also for blast waves. Two subjects, von neumann made fundamentalghonadahttps://www.blogger.com/profile/01739730402827699973noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-11652874020642805822014-08-05T00:51:48.909-04:002014-08-05T00:51:48.909-04:00Rastus,
Yeah, you lost that battle. The singulari...Rastus,<br /><br />Yeah, you lost that battle. The singularity is at R=0, which is as good as you can make a definition of "center" in spherical coordinates. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-19540447782306028902014-08-05T00:49:24.636-04:002014-08-05T00:49:24.636-04:00Xerxes:
If your theory of technological progress ...Xerxes:<br /><br />If your theory of technological progress diverges, it just means you've left its regime of applicability. You're not seriously trying to tell me you believe there is indeed anything diverging at finite time? Besides this, I'm not "uncharitable" to the idea, but to the word. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27042039865743930652014-08-05T00:46:11.593-04:002014-08-05T00:46:11.593-04:00Giotis,
Well, to me a final condition is the same...Giotis,<br /><br />Well, to me a final condition is the same as an initial condition. I would prefer calling them boundary conditions, but people might mistake it for being about space only. Yes, you're right of course that one better not speak about the black hole singularity as a point, but for the present purpose and without wanting to draw diagrams I think it's good enough. Best,<br /Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-6389836900622588722014-08-05T00:44:48.893-04:002014-08-05T00:44:48.893-04:00Zephir, one does not need to say high or low dim...Zephir, one does not need to say high or low dimensions for the illusion of event horizons and singularies. It can be a shifting of adjacent dimensions in these matters of continuity and discreteness, for Newton defined continuity as continuous, contiguous, and consecutive. So things can be superimposed or totally separate or "touch" in a sense. Not all of the connections may be L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-48215508655127694942014-08-05T00:44:32.327-04:002014-08-05T00:44:32.327-04:00Sabine, the term singularity certainly needs to be...Sabine, the term singularity certainly needs to be better defined. I myself use the term "spacious singularity" which I now imagine makes little sense to readers. I need to follow your links to know what your take on it is as I do not find it apparent as in "No one these days imagines there is a singularity inside a black hole."<br />A simple analogy is the Earth with poles.L. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.com