tag:blogger.com,1999:blog-22973357.post2526847402913022959..comments2017-12-12T21:25:03.484-05:00Comments on Backreaction: Dear Dr B: What do physicists mean by “quantum gravity”?Sabine Hossenfelderhttps://plus.google.com/111136225362929878171noreply@blogger.comBlogger32125tag:blogger.com,1999:blog-22973357.post-87883133619703263672016-11-15T10:10:56.135-05:002016-11-15T10:10:56.135-05:00Hi,
I have a question on black hole evaporation. S...Hi,<br />I have a question on black hole evaporation. So the idea is that once a pair of virtual particles appears, one escapes away while the other one (with a negative energy) falls into a black hole and decreases its energy. So, it is possible that in the end a black hole evaporates. While it all makes sense, is it not as likely that a virtual pair has an opposite fate: positive energy Je Klhttps://www.blogger.com/profile/05108293373680019307noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42431269451542941602016-10-31T16:54:32.788-04:002016-10-31T16:54:32.788-04:00Thanks BThanks BNeil Southallhttps://www.blogger.com/profile/09235857510622600554noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-68089227205228597662016-10-31T06:46:56.985-04:002016-10-31T06:46:56.985-04:00Sorry. The mass-dimension of Newton's constant...Sorry. The mass-dimension of Newton's constant depends on the number of space-time dimensions.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-40090772054221983782016-10-31T04:55:35.887-04:002016-10-31T04:55:35.887-04:00Sorry dimension does what?Sorry dimension does what?Neil Southallhttps://www.blogger.com/profile/09235857510622600554noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18002120493393746682016-10-31T00:37:39.159-04:002016-10-31T00:37:39.159-04:00The value doesn't, the dimension does.The value doesn't, the dimension does.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-3381599183230536752016-10-30T15:19:40.653-04:002016-10-30T15:19:40.653-04:00B
In your paper you express Newton's constant...B<br /><br />In your paper you express Newton's constant in terms of the Planck mass saying this is in 3 dimensions. Is the value dimension dependent?Neil Southallhttps://www.blogger.com/profile/09235857510622600554noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-68979160374221111832016-10-13T01:09:10.520-04:002016-10-13T01:09:10.520-04:00MP,
You can either submit it here in the comments...MP,<br /><br />You can either submit it here in the comments, or send me a note on twitter or on facebook, or an email. Just as advance warning: I take on very few of the questions I get. A good question should fulfill the following criteria: a) of interest for many readers b) a question I can answer c) be clearly phrased and d) not a question that Google can answer in 2 seconds. Best,<br /><br /Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-47441512937134722002016-10-12T16:37:30.327-04:002016-10-12T16:37:30.327-04:00What is the best way to officially submit a "...What is the best way to officially submit a "Dear Dr B" question?M*P*Lockwoodhttps://www.blogger.com/profile/11740436901803793444noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9821874213119717212016-10-12T11:33:53.618-04:002016-10-12T11:33:53.618-04:00http://www.mazepath.com/uncleal/qzdense.png
Quan...http://www.mazepath.com/uncleal/qzdense.png<br /> Quantitative geometric chirality divergence of single crystal alpha-quartz given <br /> doi:10.1063/1.532988, doi:10.1063/1.1484559 and QCM software.<br /> Theoretical slope is -2 exactly.<br /><br />CHI = 1 is perfectly divergent. The "fuzz" is sampling artifact. A sample sphere cannot perfectly symmetrically encapsulate the Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28728727897494452642016-09-30T09:14:40.965-04:002016-09-30T09:14:40.965-04:00Rob,
Hawking radiation is not created at or nearb...Rob,<br /><br /><a href="http://backreaction.blogspot.de/2015/12/hawking-radiation-is-not-produced-at.html" rel="nofollow">Hawking radiation is not created at or nearby the horizon.</a> <br /><br />Having said that, your explanation is pretty confused. The particles that are created in the Hawking radiation are always entangled across the horizon. You can *not* get the inside particle out (Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-54264575688765681732016-09-30T08:49:56.505-04:002016-09-30T08:49:56.505-04:00Perekatifield
"Black hole evaporation however...Perekatifield<br />"Black hole evaporation however seems to violate unitary which is incompatible with quantum mechanics."<br /><br />I understood it was more complex. <br /><br />Looked at from the outside, nothing ever crosses the horizon. The evaporation is seen as originating from a thin layer of material completely outside of the horizon. Unitarity is not violated.<br /><br />From Rob van Son (Not a physicist, just an amateur)https://www.blogger.com/profile/12611755507524401026noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24477706236935173302016-09-30T08:03:29.515-04:002016-09-30T08:03:29.515-04:00Perekatifield,
Indeed, thanks for pointing out!Perekatifield,<br /><br />Indeed, thanks for pointing out!Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-53394404826961514002016-09-30T06:22:51.083-04:002016-09-30T06:22:51.083-04:00In your article (https://arxiv.org/abs/1208.5874) ...In your article (https://arxiv.org/abs/1208.5874) there seem to be a typo, "unitary" instead of "unitarity":<br /><br /> Black hole evaporation however seems to violate unitary which is<br />incompatible with quantum mechanics.Perekatifieldhttps://www.blogger.com/profile/05666643415120929616noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-82877670993459766412016-09-29T17:30:50.409-04:002016-09-29T17:30:50.409-04:00"when gravity is strong, both gravity and mat..."when gravity is strong, both gravity and matter aren't quantum"<br /><br />This statement bothered me because it seemed to mean that black-body radiation in strong gravity would produce the "ultraviolet catastrophe", but I guess by strong you mean infinite? If not, this idea might be testable by comparing frequency spectra of large stars to quantum predictions.<br /><br /JimVhttps://www.blogger.com/profile/10198704789965278981noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-20783550067907050872016-09-29T02:04:47.683-04:002016-09-29T02:04:47.683-04:00asnant,
In general relativity the gravitational f...asnant,<br /><br />In general relativity the gravitational field can't be in a quantum superposition because the mathematical apparatus doesn't contain any such structures. It's just the wrong theory for that. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-8798622123059701712016-09-29T01:57:33.695-04:002016-09-29T01:57:33.695-04:00Dear Dr B,
Why is it such that "the gravitat...Dear Dr B,<br /><br />Why is it such that "the gravitational field can’t be in a quantum superposition"? <br /><br />Thanks<br />asnanthttps://www.blogger.com/profile/03824003267539409944noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-91123986273747793932016-09-28T06:58:45.772-04:002016-09-28T06:58:45.772-04:00Dear Dr. B.,
Thank you for the link to your paper...Dear Dr. B.,<br /><br />Thank you for the link to your paper, this was very interesting. While I'm not in a position to scientifically judge your idea - I'm neither physicist nor mathematician - it does make intuitive sense to me.<br /><br />But even while I like myself be guided by intuition, what I eventually need is someone telling me "well, it might make sense to you, BUT ...&Herr Wehhttps://www.blogger.com/profile/12475580610867971789noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-45107609225525576632016-09-28T00:48:26.595-04:002016-09-28T00:48:26.595-04:00Do you have thoughts on Diosi-Penrose and related ...Do you have thoughts on Diosi-Penrose and related ideas about gravity and collapse in QM?David Duffyhttps://www.blogger.com/profile/12142997170025811780noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18616752223774156822016-09-28T00:22:02.811-04:002016-09-28T00:22:02.811-04:00No, it's not my daughter. I tried to take a vi...No, it's not my daughter. I tried to take a video of her trampoline jumping at some point, but every time I pointed the phone at her, she stopped because she thought I was making a photo... Also, we don't have a cat. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9796093908734261582016-09-27T16:25:17.165-04:002016-09-27T16:25:17.165-04:00Hi Bee,
Great video! Is that your daughter Lara?...Hi Bee,<br /><br />Great video! Is that your daughter Lara?<br /><br />Cheers, KrisKris Kroghhttps://www.blogger.com/profile/07340827856086381459noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-57974203870498625832016-09-27T12:51:30.627-04:002016-09-27T12:51:30.627-04:00 Déborah And Kitten - Playing In Trampoline (24 s... Déborah And Kitten - Playing In Trampoline (24 seconds long)<br />http://www.dailymotion.com/video/xgg3b3_deborah-and-kitten-playing-in-trampoline_animalsUnknownhttps://www.blogger.com/profile/01874452998675783899noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-4451862033732719222016-09-27T10:54:00.177-04:002016-09-27T10:54:00.177-04:00"without running into difficulties (except fo..."<i>without running into difficulties (except for me, but nobody listens</i>" New theory is politics. Beautiful symmetries require parameterization versus observation[1]. The universe is emergent not intrinsic[2]. Breaking time reversal symmetry demonstrably creates strong arrow of time chirality[3]. <br /><br />"<i>problem with the singularities</i>" Black holes are (2 +Uncle Alhttps://www.blogger.com/profile/05056804084187606211noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18972539103736663952016-09-27T09:19:05.867-04:002016-09-27T09:19:05.867-04:00Matthew,
Sorry, I don't know what you mean.Matthew,<br /><br />Sorry, I don't know what you mean.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21894912714574972962016-09-27T08:58:40.716-04:002016-09-27T08:58:40.716-04:00Haven't we got a virtual quantization of space...Haven't we got a virtual quantization of space-time in the various Planck values? Matthew Rapaporthttps://www.blogger.com/profile/03016608637645316849noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-86528865432548801912016-09-27T05:32:38.849-04:002016-09-27T05:32:38.849-04:00Richard,
This should make sense if you read the f...Richard,<br /><br />This should make sense if you read the full paper. "Phase" refers to "phase" not as in a complex exponent but as in "phase-transition". The point of the model in the paper is that "quantumness" is a phase of matter/fields (anything in the Lagrangian), and that when gravity is strong, both gravity and matter aren't quantum, hence theySabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.com