tag:blogger.com,1999:blog-22973357.post6933055742182213483..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: Dear Dr Bee: Can LIGO’s gravitational wave detection tell us something about quantum gravity?Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger31125tag:blogger.com,1999:blog-22973357.post-3403017560608763052016-02-24T14:35:13.129-05:002016-02-24T14:35:13.129-05:00Hello GW afficionados,
check out fig 1 of http://a...Hello GW afficionados,<br />check out fig 1 of http://arxiv.org/pdf/1602.06833v1.pdf<br />if this is right, maybe first evidence of deviation from GR?<br />(of course I don't myself believe and think its detector noise).<br />Shantanuhttps://www.blogger.com/profile/16322812456382858228noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-29812025338961786472016-02-22T02:39:03.108-05:002016-02-22T02:39:03.108-05:00" Rubber sheet spacetime deformation is defec...<i>" Rubber sheet spacetime deformation is defective geometrically (hyperbolic versus elliptic "surface" distortion) and dynamically (arXiv:1312.3893)"</i><br /><br />True but irrelevant. The Bohr model is wrong, but atoms still exist. :-)<br />Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-8451092775302605712016-02-20T07:37:09.874-05:002016-02-20T07:37:09.874-05:00Thank You MarkusM,
BICEP 3 would be an advanceme...Thank You MarkusM, <br /><br />BICEP 3 would be an advancement toward gravitational process understanding in early universe, indeed.<br /><br />Bee and Markus,<br /><br />Regarding Dark Matter and Dark Energy, so indeed, a large part requiring some understanding of the universe in our determinant makeup of "all there is."<br /><br />A couple of things then come to mind about "the PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-23519942868184300732016-02-20T04:23:17.216-05:002016-02-20T04:23:17.216-05:00Noa,
Gravitational waves are disturbances in spac...Noa,<br /><br />Gravitational waves are disturbances in space-time. They are "made of" the same thing, whatever you want to call it. Space-time is not nothing, I don't know why you think so. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-69111638895170616042016-02-20T03:53:11.264-05:002016-02-20T03:53:11.264-05:00This comment has been removed by the author.MarkusMhttps://www.blogger.com/profile/03431499396962852389noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-90115740144721151632016-02-20T03:52:46.314-05:002016-02-20T03:52:46.314-05:00In a context for a search for quantum gravity : Si...In a context for a search for quantum gravity : Since waves need a medium to propagate, and since we have now proven that ripples can be produced, does this imply that space (spacetime) itself must be regarded as a medium, in need of quantisation ? I mean you can't produce ripples from/in 'nothingness'.Koenraad Van Spaendonckhttps://www.blogger.com/profile/15090279727324831109noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-53476923502013428182016-02-19T11:50:48.592-05:002016-02-19T11:50:48.592-05:00This comment has been removed by the author.MarkusMhttps://www.blogger.com/profile/03431499396962852389noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42282931086502985062016-02-18T13:55:54.146-05:002016-02-18T13:55:54.146-05:00MarkusM: Why should it ? My simple answer would be...MarkusM: <i>Why should it ? My simple answer would be "No". Einstein who predicted gravitational waves in 1918 (http://adsabs.harvard.edu/abs/1918SPAW.......154E) had no idea what the Standard Model is.</i><br /><br />No I think it is more about the direction of where we are going today. There needs to be a confirmation regarding quantum theory regarding early universe formation so PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-53849644080684358052016-02-18T13:45:30.258-05:002016-02-18T13:45:30.258-05:00Markus and Bee,
I too am very excited about the c...Markus and Bee,<br /><br />I too am very excited about the confirmation of Gravitational wave detection and I understand we have a long way to go. The finer the detail and the problems with the noise, so what would be the next step regarding early universe understanding of the gravitational waves in the CMB if not with directing attention to the B modes as they are seen and understood?<br /><br /PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9896987152963398252016-02-18T02:54:46.452-05:002016-02-18T02:54:46.452-05:00Plato,
Well, we *do* infer information about the ...Plato,<br /><br />Well, we *do* infer information about the initial state, such as the masses and their orbits and so on. But the finer the detail, the higher the frequency and the weaker the signal. So most of the details get lost in noise. Regarding the question whether GR is part of the SM, that's a question of terminology. SM is normally used to refer to the particle sector. If you Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-44487014517497652502016-02-18T02:50:37.446-05:002016-02-18T02:50:37.446-05:00Voice,
There are no gravitational waves in Newton...Voice,<br /><br />There are no gravitational waves in Newtonian gravity. (A wave-equation requires a local theory.)Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27648884128331183082016-02-18T02:48:28.123-05:002016-02-18T02:48:28.123-05:00Topi,
I think this is a terminology issue. You me...Topi,<br /><br />I think this is a terminology issue. You mean that an electromagnetic wave would also be accompanied by a deformation of space-time. This is correct. This is qua definition not a gravitational wave - a gravitational wave is a ripple in what is otherwise vacuum.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42806286419939202412016-02-18T02:39:38.800-05:002016-02-18T02:39:38.800-05:00This comment has been removed by the author.MarkusMhttps://www.blogger.com/profile/03431499396962852389noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74112812923858960232016-02-18T02:27:43.580-05:002016-02-18T02:27:43.580-05:00This comment has been removed by the author.MarkusMhttps://www.blogger.com/profile/03431499396962852389noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-33046264733794811672016-02-17T17:04:45.961-05:002016-02-17T17:04:45.961-05:00Sabine,
" an electromagnetic wave doesn'...Sabine,<br /><br />" an electromagnetic wave doesn't deform space-time"<br /><br />Why? Em wave is carrying energy, ie mass, away from source. During the course the mass (photons or em field energy) is deforming space-time similar way any other mass does? I don't see why this should be different from more tangible mass.<br /><br />Or is the deformation due gravitational waves Topi Rinkinenhttps://www.blogger.com/profile/10274807062102966219noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72001876615860193602016-02-17T13:26:11.962-05:002016-02-17T13:26:11.962-05:00Sabine,
Thanks for the article. I'm excite...Sabine,<br /><br /> Thanks for the article. I'm excited to find this site and I've always had a layman's interested in these topics. I do have a question regarding the LIGO's results which are interpreted as validating Einstein's theory. Without getting into the fine details, do the LIGO results differentiate between Einstein's theories wrt gravitational waves and whatVoice Of Reasonhttps://www.blogger.com/profile/17450518752501867971noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-6985853640512275122016-02-17T13:18:02.680-05:002016-02-17T13:18:02.680-05:00Bee Said: "A most excellent question! Yes, th...<br /><b>Bee Said</b>: "<i>A most excellent question! Yes, they can, and they do. They must carry away all information that deforms the initial configuration away from the rotational symmetry that it must have at the end because of the no-hair theorem. At last that's what General Relativity predicts (leaving aside some loopholes in these theorems).</i>"<br /><br />Okay.....then not PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-66443221895265648182016-02-17T13:11:48.231-05:002016-02-17T13:11:48.231-05:00Plato,
A most excellent question! Yes, they can, ...Plato,<br /><br />A most excellent question! Yes, they can, and they do. They must carry away all information that deforms the initial configuration away from the rotational symmetry that it must have at the end because of the no-hair theorem. At last that's what General Relativity predicts (leaving aside some loopholes in these theorems). Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-4271177119165043702016-02-17T13:11:01.914-05:002016-02-17T13:11:01.914-05:00 Second follow up question.
Is Gravity now part o... Second follow up question.<br /><br />Is Gravity now part of the standard model?PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-12395225506749476932016-02-17T13:07:14.434-05:002016-02-17T13:07:14.434-05:00Charlie,
Please see these references
http://arxi...Charlie,<br /><br />Please see these references<br /><br />http://arxiv.org/abs/gr-qc/0702079<br />http://arxiv.org/abs/gr-qc/0511083<br /><br />The brief answer is 3) the light (being light-like) is not affected the same as the arms of the interferometerSabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28977123178118579772016-02-17T12:54:56.858-05:002016-02-17T12:54:56.858-05:00Dear B,
Is it possible that gravitational waves c...Dear B,<br /><br />Is it possible that gravitational waves carry a type of "information" away from it's source? <br /><br />Best,PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-22562967866426249192016-02-17T11:48:08.148-05:002016-02-17T11:48:08.148-05:00Thanks Sabine! Your blogs and articles are really ...Thanks Sabine! Your blogs and articles are really wonderful to read. If you will forgive me, I'd like to ask a very basic question about LIGO (and similar systems to measure gravitational waves). Apology due to the fact that this has been asked before by others, but the answer still eludes me:<br /><br />How can LIGO measure changes in space-time when the "ruler" itself (light) is Charliehttps://www.blogger.com/profile/04163738909524521887noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-10104970821747765372016-02-17T11:11:38.551-05:002016-02-17T11:11:38.551-05:00That's around 4miliWatt. 4 millionth of the su...That's around 4miliWatt. 4 millionth of the sun. https://en.wikipedia.org/wiki/Magnitude_(astronomy)<br />Around the brightness of the full moon.<br />Daniel de França MTd2https://www.blogger.com/profile/01281817409696805377noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-15936143453762260342016-02-17T11:05:16.222-05:002016-02-17T11:05:16.222-05:00Your Forbes exposition of gravitons and photons is...Your Forbes exposition of gravitons and photons is attractive and lucid. Rubber sheet spacetime deformation is defective geometrically (hyperbolic versus elliptic "surface" distortion) and dynamically (arXiv:1312.3893). The Earth as a strain gauge gravitational wave detector via temblors and geophone outputs is unreported. Has anybody looked?<br /><br />"<i>violations of the Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-26584314244999243442016-02-17T10:40:22.064-05:002016-02-17T10:40:22.064-05:00Sabine: slightly offtopc to this. but just wanted ...Sabine: slightly offtopc to this. but just wanted to point to readers to free online proceedings of 1957 chapell hill conference proceedings where there were lots of discussions of reality of gravitational waves and many of the doubts were clarified by <br />Feynmann, Bondi, Dewitt etc<br />http://www.edition-open-access.de/media/sources/5/Sources5.pdfShantanuhttps://www.blogger.com/profile/16322812456382858228noreply@blogger.com