tag:blogger.com,1999:blog-22973357.post8318760332448107350..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: What a burst! A fresh attempt to see space-time foam with gamma ray bursts.Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger17125tag:blogger.com,1999:blog-22973357.post-20130067623951574842017-01-30T03:17:21.470-05:002017-01-30T03:17:21.470-05:00You could start with Bob's own papers on gamma...You could start with <a href="http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&qform=AST&arxiv_sel=astro-ph&arxiv_sel=cond-mat&arxiv_sel=cs&arxiv_sel=gr-qc&arxiv_sel=hep-ex&arxiv_sel=hep-lat&arxiv_sel=hep-ph&arxiv_sel=hep-th&arxiv_sel=math&arxiv_sel=math-ph&arxiv_sel=nlin&arxiv_sel=nucl-ex&arxiv_sel=nucl-th&Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74211357458783701142017-01-25T11:48:16.185-05:002017-01-25T11:48:16.185-05:00Robert: Thanks for the nice explanation. Can you p...Robert: Thanks for the nice explanation. Can you point me to 1-2 references regarding this?Shantanuhttps://www.blogger.com/profile/16322812456382858228noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72408775393668112442017-01-25T10:02:02.998-05:002017-01-25T10:02:02.998-05:00There have been claims of cosmological time dilati...There have been claims of cosmological time dilation in GRBs -- some of which I have been involved with, and some of which I believe (but of course I am therefore biased). The measurement is more difficult than it might seem, though, because the variance is large due to the wide variety in GRB attributes. GRBs can be very different, some being tens of seconds long with multiple peaks, and some Anonymoushttps://www.blogger.com/profile/08016034157445899936noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-37156127271528847552017-01-24T13:13:31.448-05:002017-01-24T13:13:31.448-05:00Can some GRB expert tell me why we haven't yet...Can some GRB expert tell me why we haven't yet seen time-dilation in GRB light curves (similar to that in supernova for example, see<br />astro-ph/9602124)Shantanuhttps://www.blogger.com/profile/16322812456382858228noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36296465811571828322017-01-18T22:00:43.538-05:002017-01-18T22:00:43.538-05:00Hi Dr. H, I am actually the 2nd author of this pap...Hi Dr. H, I am actually the 2nd author of this paper. Thanks for your nice post and all the discussions on our paper and the relevant topics. I enjoyed reading them very much. P.S., we've another comprehensive study on the same GRB: https://arxiv.org/abs/1612.03089. <br /><br /> Anonymoushttps://www.blogger.com/profile/16997020823044383413noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-78935434507817596162017-01-16T13:14:14.306-05:002017-01-16T13:14:14.306-05:00Hello Dr. H. "No ... fundamental frame indepe...Hello Dr. H. "No ... fundamental frame independent of the matter" ok. I get that distinction, thanks. But it still seems to me that the preferred frame "of the matter" still allows us to establish a "standard clock" or "global time". This is the reason why a statement like "the universe is 13.8 billion years old" has any meaning.Matthewhttps://www.blogger.com/profile/03016608637645316849noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24737207081195769262017-01-16T12:58:38.207-05:002017-01-16T12:58:38.207-05:00Matthew,
Yes, there is a preferred frame which is...Matthew,<br /><br />Yes, there is a preferred frame which is defined by the motion of matter. But there is - in ordinary General Relativity - no preferred fundamental frame (independent of the matter). If (local) Lorentz-invariance is broken, there is one. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80747942102830739162017-01-16T11:34:40.953-05:002017-01-16T11:34:40.953-05:00Seems to me there is a "preferred frame"...Seems to me there is a "preferred frame", the equal momentum imparted to everything by the big bang. We even know what motion "in that frame" is, the motion (through the universe) we would have to have to see the CMB coming equally from all directions, a motion now so routinely calculated that most discussion of the CMB doesn't bother to mention it the as early daysMatthewhttps://www.blogger.com/profile/03016608637645316849noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-50299074733641112032017-01-16T07:07:22.252-05:002017-01-16T07:07:22.252-05:00Alexey,
If Lorentz-invariance is broken, you have...Alexey,<br /><br />If Lorentz-invariance is broken, you have a preferred frame. If it's deformed, you don't. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-31031377414900110262017-01-16T06:43:27.404-05:002017-01-16T06:43:27.404-05:00"if Lorentz-invariance is not broken but inst..."if Lorentz-invariance is not broken but instead deformed"<br />Can you please explain the difference betwen broken Lorentz-invariance and deformed Lorentz-invariance?Anonymoushttps://www.blogger.com/profile/11025322357461968539noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-41160222904364334072017-01-14T09:59:20.016-05:002017-01-14T09:59:20.016-05:00Anomalous dispersion snuggles with induced transpa...Anomalous dispersion snuggles with induced transparency (arXiv:1404.5941 and DOI: 10.1126/science.1208066) that could gate a signal versus frequency.<br /><br />http://budker.berkeley.edu/Physics138/Christine_Tsai_Self-Induced%20Transparency.ppt<br /><br />If doubling the pathlength measurably alters observed anomalous dispersion, observe effect versus distance. Local source dimensions are Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-65331179256502142292017-01-13T23:05:31.636-05:002017-01-13T23:05:31.636-05:00The existence of temporal lags between energy chan...The existence of temporal lags between energy channels of GRBs at KeV+ energies has been known since the mid-1990s and is not controversial. Over 100 GRBs clearly show these usually sub-second lags, and lags have been shown correlated with the intrinsic brightness of the GRB (Norris, Marani & Bonnell ApJ 2000): shorter lags correlate with intrinsically brighter GRBs. Likely, all GRBs would Anonymoushttps://www.blogger.com/profile/08016034157445899936noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-76299219970220181172017-01-13T13:01:19.192-05:002017-01-13T13:01:19.192-05:00Another informative and interesting article - Than...Another informative and interesting article - Thank you Louis Tagliaferrohttps://www.blogger.com/profile/16698865662162457632noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-35229635504299616912017-01-13T11:34:32.151-05:002017-01-13T11:34:32.151-05:00Nice article Dr. H. You keep me in touch with inte...Nice article Dr. H. You keep me in touch with interesting and very current work in cosmology and you do it in language (I don't mean English) I can understand!Matthewhttps://www.blogger.com/profile/03016608637645316849noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-83307884159176030712017-01-13T10:52:53.111-05:002017-01-13T10:52:53.111-05:00"if they don’t want you to understand what th..."<i>if they don’t want you to understand what they say</i>" Vacuum refraction, dispersion, dissipation, dichroism, gyrotropy. Noether's theorems leak angular momentum conservation if vacuum is anisotropic in any way. Dark matter is then Milgrom acceleration re the Tully-Fisher relation. "<i>Such quantum gravitational effects are miniscule, but added up over long distances Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84631913811707028742017-01-13T08:39:49.674-05:002017-01-13T08:39:49.674-05:00Phillip,
Thanks, I fixed that. I hope I've di...Phillip,<br /><br />Thanks, I fixed that. I hope I've distributed all sub-burst, time-lag, propagation-delay-dashes correctly :o)Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-85345790086250056552017-01-13T07:19:58.049-05:002017-01-13T07:19:58.049-05:00Pet peeve: " only be compared to themselves&q...Pet peeve: " only be compared to themselves" should be "be compared only to themselves". Otherwise it could mean "they could only be compared; they couldn't be eaten nor seen on television".<br /><br />In German, this mistake is more difficult to make. If one means "konnten nur mit sich selbst verglichen werden", no-one would say "konnten mit Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.com