tag:blogger.com,1999:blog-22973357.post2019922560145580823..comments2021-05-17T15:38:47.485-04:00Comments on Sabine Hossenfelder: Backreaction: Can we test quantum gravity with gravitational bremsstrahlung? Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-22973357.post-86500184010384929562013-09-06T19:29:35.105-04:002013-09-06T19:29:35.105-04:00Sabine,
While the phenomenology of quantum gravit...Sabine,<br /><br />While the phenomenology of quantum gravity is outside my area of study, I couldn't help but be surprised that a paper about <i>gravitational bremsstrahlung</i> didn't reference the well-worn results from classical GR.<br /><br />"Relativistic Gravitational Bremsstrahlung" Phys. Rev. D 1, 1559–1571 (1970) by P.C.Peters. This is the first hit on google...<br /><Unknownhttps://www.blogger.com/profile/15235866457505580221noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-56146338119306079042013-08-30T21:09:52.492-04:002013-08-30T21:09:52.492-04:00The quantum gravity can be tested with whatever ph...The quantum gravity can be tested with whatever phenomena at the dimensional/energy density scale between quantum mechanics and general relativity, which involves the painting and farming of bees.Zephirhttps://www.blogger.com/profile/06010623752049244967noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-8430913352434362202013-08-30T04:16:58.079-04:002013-08-30T04:16:58.079-04:00John,
I have no clue what you're trying to sa...John,<br /><br />I have no clue what you're trying to say or what you see in quantum gravity papers. The tensor bundle is a fibre bundle too. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-16693598806935403282013-08-29T15:23:17.774-04:002013-08-29T15:23:17.774-04:00I think there's maybe some kind of issue here ...I think there's maybe some kind of issue here Sabine. Can you see my comment 4 on this physicsworld article?<br /><br />http://physicsworld.com/cws/article/news/2012/nov/06/highly-charged-ions-could-make-better-atomic-clock<br /><br />See the second lattice picture, where the cells are all rectangular but the cell volume changes? That's your Riemann curvature. The curvature in the first Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-550181792812182592013-08-29T02:49:23.155-04:002013-08-29T02:49:23.155-04:00John,
The statement that spacetime is curved has ...John,<br /><br />The statement that spacetime is curved has a clear technical meaning. The existence of a graviational field means that spacetime has a curvature (a nonvanishing curvature tensor). Yes, there's a similar tensor in electrodynamics but the non-vanishing of that tensor is not referred to as space-time curvature. (It is a source for gravity though.) Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-52021299426360770752013-08-28T13:29:02.231-04:002013-08-28T13:29:02.231-04:00Interesting stuff. I see you got a nice mention, S...Interesting stuff. I see you got a nice mention, Sabine. Can I mention this on page 3?<br /><br /><i>"In this sense, it is correct to discuss virtual gravitons as a signature of non-zeroth curvature itself, like virtual photons as a signature of a non-zero Coulomb field as a development of the quantum treatment of the mediating forces".</i><br /><br />A gravitational field is "Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-88394573170345733082013-08-28T12:35:02.836-04:002013-08-28T12:35:02.836-04:00"charged particles passing by large charged o..."<i>charged particles passing by large charged objects in conceivable distance.</i>" Muon cascade into (high-Z) nucleus ground state orbit. Are spectra not fully explained? U(91+) has good spectroscopy for Lamb shift and hyperfine structure. Is there anomalous graininess?<br /><br />"<i>the cross-section becomes comparable to that of other cross-sections in the standard model<Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.com