tag:blogger.com,1999:blog-22973357.post2719530363194351955..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: The Causal Diagram of the Black HoleSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger78125tag:blogger.com,1999:blog-22973357.post-50050741382112379682010-05-03T02:52:27.800-04:002010-05-03T02:52:27.800-04:00Err, I meant blueshifted, sorry.Err, I meant blueshifted, sorry.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-91792874857835324772010-05-03T02:48:53.751-04:002010-05-03T02:48:53.751-04:00Hi Topi,
1) There's no radial distances drawn...Hi Topi,<br /><br />1) There's no radial distances drawn in the diagram. The horizon remains timelike, but that doesn't mean the radial coordinate at the horizon remains constant when the black hole's mass is shrinking.<br /><br />2) The rest mass of a particle is a conserved quantity, it never decreases. In GR, there's no such thing as a gravitational potential, there's only Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-26168026336960460372010-05-02T16:53:33.599-04:002010-05-02T16:53:33.599-04:00Hi Bee,
I'm hundred persent sure I didn't...Hi Bee,<br /><br />I'm hundred persent sure I didn't see all the fine details of the causal diagram of radiating BH, but I'd like to understand few details:<br /><br />1. if the BH is first growing, and then radiating away it's mass; is it so that in two different (horizontal lines on the diagram) hypersurfaces, the solution of EH is equal? Meaning that the area of EH finally getsAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-37152353631137971932009-12-17T10:49:26.015-05:002009-12-17T10:49:26.015-05:00Hi Bee. Thanks for maintaining a blog where an ex...Hi Bee. Thanks for maintaining a blog where an ex-CM experimentalist with some educational gaps can learn something about modern GR. (The jargon-dropping at Reference Frame really put me off, by the way).bnachumihttps://www.blogger.com/profile/02680088142970303268noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-37715987407163803312009-12-11T07:21:40.143-05:002009-12-11T07:21:40.143-05:00Hi Phil,
Thank you for your interest. It is a coi...Hi Phil,<br /><br />Thank you for your interest. It is a coincidence that my last two papers were finished almost at the same time. They both came about rather short notice, though the general topic in both cases is certainly something that's been on my mind for a longer time. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-49609670705799304482009-12-11T06:43:31.905-05:002009-12-11T06:43:31.905-05:00Hi Bee,
Also to make the observation that as of l...Hi Bee,<br /><br />Also to make the observation that as of late you seem to be more prolific with your papers and to wonder what might be the cause as being resultant of more ideas of late, more time to express them,some consequence of your new enviroment or you in having reached some kind of flash point in regards to what has been on your mind for some time.<br /><br />Best,<br /><br />PhilPhil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-6321313554902548652009-12-11T06:30:30.705-05:002009-12-11T06:30:30.705-05:00Hi Bee,
Just to make comment on your most recent ...Hi Bee,<br /><br />Just to make comment on your most recent paper you coauthored with some Perimeter researchers, being I found it to be quite interesting. However I find it most interesting, not so much as it denies the existence of both singularities and an actual event horizon, rather it carries as a consequence that while there being no end for a black hole in regards to time with its end Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-11796536997073847442009-12-06T21:51:02.504-05:002009-12-06T21:51:02.504-05:00"I know that sometimes the surface is picture..."I know that sometimes the surface is pictured as hitting the singularity on the horizontal line. I'm not sure this is uniquely specified without R(t), or is it?"<br /><br />Well, the surface of the star can be represented by a particle falling freely. Where that particle hits the singularity depends on the initial conditions. [Think of particles falling into an ordinary black hole:Pope Maledict XVInoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-38724553428604222102009-12-06T08:06:28.892-05:002009-12-06T08:06:28.892-05:00Hi Steven,
The session you mention sounds intrigu...Hi Steven,<br /><br />The session you mention sounds intriguing and yes it’s certainly something I wished I could have attended. Perimeter Institute in the past offered a similar thing where the researchers there would approach topics in general or at times even what they were currently working on. You might find it interesting they called them “Black Hole Sessions”. Unfortunately they Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-5463026742817298472009-12-06T07:41:51.270-05:002009-12-06T07:41:51.270-05:00Thanks for your responses, Phil.
Funny thing, for...Thanks for your responses, Phil.<br /><br />Funny thing, for the first time since I started re-learning all this Math and Physics stuff 14-1/2 months ago, I FINALLY met my first real Scientist in flesh and blood rather than on the internet last night, asked him my question, and he responded in the negative.<br /><br />The Scientist in question is <a href="http://www.amnh.org/exhibitions/einstein/Steven Colyerhttps://www.blogger.com/profile/10435759210177642257noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36329843488260906242009-12-05T13:33:25.425-05:002009-12-05T13:33:25.425-05:00Hi Steven,
Just as a follow up is to say a more p...Hi Steven,<br /><br />Just as a follow up is to say a more plausible explanation as to why there are no quasar like galaxies close at hand is that its consistent with the evolution of such structure. For instance the supermassive black hole that is suppose to exist at the center of our galaxy has long since swept up much of the readily available surrounding matter and thus is less active in Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73887955732480190652009-12-05T12:53:07.025-05:002009-12-05T12:53:07.025-05:00Hi Steven,
The evaporation for even a stellar mas...Hi Steven,<br /><br />The evaporation for even a stellar mass black hole in accordance with Hawkings’ proposal is many times the current age of the universe so a supermassive one is much longer than that. What Hawkings’ referred to as primordial black holes having masses about that of a mountain have been calculated to have a lifetime of about 13 billion years and were speculated to perhaps Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84300592497917894052009-12-05T10:18:21.398-05:002009-12-05T10:18:21.398-05:00Go, Go Germany! Click here to see what I'm tal...Go, Go Germany! Click <a href="http://www.sciencenews.org/view/generic/id/50372/title/Black_hole_may_construct_its_own_galactic_home" rel="nofollow">here</a> to see what I'm talking about.<br /><br />Bee, I have a simple question: Are quasars real in our time, or an evolutionary development in the history of our Universe?<br /><br />My thinking (possibly wrong ... which is why I'm asking)Steven Colyerhttps://www.blogger.com/profile/10435759210177642257noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-45164135646027784952009-12-05T10:05:01.900-05:002009-12-05T10:05:01.900-05:00This comment has been removed by the author.Steven Colyerhttps://www.blogger.com/profile/10435759210177642257noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42557064922627608802009-12-05T04:20:33.131-05:002009-12-05T04:20:33.131-05:00Hi Pope,
Yes, I agree with you regarding the surf...Hi Pope,<br /><br />Yes, I agree with you regarding the surface/radius relation. I think we extensively commented on that in our paper too. Either way, in my diagram the surface doesn't hit r=0 before it hits the singularity, they all meet in the same point. I know that sometimes the surface is pictured as hitting the singularity on the horizontal line. I'm not sure this is uniquely Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-19602244581821739772009-12-05T02:27:26.616-05:002009-12-05T02:27:26.616-05:00I just meant that Hsu's work is an example of ...I just meant that Hsu's work is an example of the fact that there is no simple relation between area and volume --- as you said in your article about monsters, "In flat space-time the relation between the volume of an area and its surface is trivial, it's just Euclidean geometry. But not so if space-time is strongly curved!"<br /><br />So the fact that a the surface area of the Pope Maledict XVInoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25675651200043753492009-12-04T07:34:48.419-05:002009-12-04T07:34:48.419-05:00Put another way from my perspective in terms of di...Put another way from my perspective in terms of dimension when we rotate time one has a line. Rotate a line one has a circle. Rotate a circle one has a sphere. The question then being is time the primal dimension or is it also simply the result of rotating something more primal?Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80039856618788494062009-12-04T07:03:24.572-05:002009-12-04T07:03:24.572-05:00Hi Bee,
How about if we consider this passing thr...Hi Bee,<br /><br />How about if we consider this passing through zero from a reductionist’s perspective, beginning with having only a four dimensional universe of which one being time. So to begin, if a sphere being the greatest amount of volume for the least amount of surface, then a negative sphere would be the least amount of volume for the greatest amount of surface, this being a circle. Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73524293792140401582009-12-04T04:25:29.171-05:002009-12-04T04:25:29.171-05:00Hi Pope & Bee,
I think it would be fair to sa...Hi Pope & Bee,<br /><br />I think it would be fair to say that no one knows what r=0 means when it relates to time or space as we usually consider it, other than perhaps if one compares it to the perspective of a photon to say in terms of SR such conditions could be considered as its natural environment from the standpoint of any sub c entity (observer). In fact it could be used as an Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32605482523311987562009-12-04T01:51:14.507-05:002009-12-04T01:51:14.507-05:00Pope: While it is correct that one best thinks of ...Pope: While it is correct that one best thinks of r in terms of surface, for all I can recall the geometries Hsu et al consider are not singular, thus I'm not sure what you're trying to say. Best,<br /><br />B.<br /><br />PS: <a href="http://backreaction.blogspot.com/2009/01/monsters.html" rel="nofollow">see also</a>Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-89020012588328899372009-12-03T22:42:05.045-05:002009-12-03T22:42:05.045-05:00I'd just like to point out that the coordinate...I'd just like to point out that the coordinate "r" is *not* a measure of radial distance, not even outside the black hole. What it measures is the *area* of the sphere at a given point in the diagram. The advantage of thinking in this way is that you can still make sense of r even inside the event horizon where it is actually a time coordinate and not a spatial coordinate at all. <Pope Maledict XVInoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-50362726131848666472009-12-01T11:55:22.972-05:002009-12-01T11:55:22.972-05:00Yeah, I'd have thought the black hole came fir...Yeah, I'd have thought the black hole came first. Then the gas started swirling and plunging into the hole like water going down a plughole! Which lead to the formation of the galaxy structure. I mean, it seems pretty obvious you're not going to get something like a spiral galaxy without something pretty enormous in the middle around which everything spirals.<br /><br />So note, Steven Andrew Thomashttps://www.blogger.com/profile/03852211910001840777noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73862733776400597182009-12-01T09:01:31.738-05:002009-12-01T09:01:31.738-05:00Which came first, the chicken or the egg?
Or in P...Which came first, the chicken or the egg?<br /><br />Or in Physics-speak, the Galaxy or the Black Hole at the (Spiral) Galaxy's center?<br /><br />Click <a href="http://www.space.com/scienceastronomy/091130-black-hole-galaxies.html" rel="nofollow">here</a> to see was writer Claire moskowitz at space.com reports: the Black Hole.<br /><br />I wish I could dig into this stuff more, but my Steven Colyerhttps://www.blogger.com/profile/10435759210177642257noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-33332705376963344992009-12-01T02:11:28.089-05:002009-12-01T02:11:28.089-05:00Giotis: I have B&D, but not with me (currently...Giotis: I have B&D, but not with me (currently traveling). I'll check when back to see what you mean. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-22346747441769360102009-11-30T22:27:18.097-05:002009-11-30T22:27:18.097-05:00Hermann Weyl once commented:
'While topology ...Hermann Weyl once commented:<br /><br />'While topology has succeeded fairly well in mastering continuity, we do not yet understand the inner meaning of the restriction to differentiable manifolds. Perhaps one day physics will be able to discard it. '<br /><br />We are now ready to do that. In fact it has been done and the results are so amazing that most theoretical physicists cannot Anonymousnoreply@blogger.com