tag:blogger.com,1999:blog-22973357.post7438167528658853387..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: Comments on “Quantum Gravity in the Lab” in Scientific AmericanSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger49125tag:blogger.com,1999:blog-22973357.post-63417425316656021302020-09-15T02:23:00.174-04:002020-09-15T02:23:00.174-04:00Prof.Durgadas Datta published a few papers giving ...Prof.Durgadas Datta published a few papers giving graviton a mass of 750 proton mass in emergent push fermion gravity mechanism. According to him massive graviton is a component of dark matter.D.DUTT.https://www.blogger.com/profile/02801221370018025584noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25786883750832915092020-08-22T01:10:52.221-04:002020-08-22T01:10:52.221-04:00If gravity exists at the quantum level; perhaps it...If gravity exists at the quantum level; perhaps it becomes shared when in a superposition? And in that respect could validate a mechanism of entanglement? Spooky action at a distance.siftinghttps://www.blogger.com/profile/18126421172343686327noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-76107817714450165912019-04-26T10:57:24.950-04:002019-04-26T10:57:24.950-04:00“… can't you tell from the smell before you op...<i>“<a href="https://www.youtube.com/watch?v=Zri9gS1w5ok&t=10m9s" rel="nofollow">… can't you tell from the smell before you open the box …</a>”</i> ;-)<br />Contrary to Smolin I think there is nothing wrong with QM – all we need is a more <i>realistic</i> view how gravity is incorporated in the process. <br />Reimondhttps://www.blogger.com/profile/04669340425105889539noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-88282497213150488982019-04-26T08:19:47.980-04:002019-04-26T08:19:47.980-04:00Fat Man: Question. Is there any reason to think th...Fat Man: <i>Question. Is there any reason to think that additional money spent on physics will produce anything other than higher salaries for tenured professors?</i><br /><br />Sure. <br /><br />1) Additional money doesn't have to be spent on higher salaries, it could be spent on <b>more</b> salaries. It could also be spent funding more experiments, or better educated overseers to prevent Dr. A.M. Castaldohttps://www.blogger.com/profile/17988116835722393503noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-4560166164300786952019-04-26T06:28:17.397-04:002019-04-26T06:28:17.397-04:00Sabine,
In order to distinguish between a dead ca...Sabine,<br /><br />In order to distinguish between a dead cat and a living one there is no need to know "all quantum degrees of freedom". It is enough to determine the mass distribution so that you can conclude if the cat still moves arund, breathe, etc.<br /><br />So, by placing a torsion balance or something like that outside the box you can determine the cat's position and if it Andreihttps://www.blogger.com/profile/05519448415253342448noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-40043936239018787962019-04-25T21:43:05.535-04:002019-04-25T21:43:05.535-04:00Thank you Peter and Sabine!Thank you Peter and Sabine!Jeffhttps://www.blogger.com/profile/06140726210295297492noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-33909089540055371412019-04-25T16:16:27.609-04:002019-04-25T16:16:27.609-04:00Fat Man wrote: Percentage of the Federal Budget is...Fat Man wrote: <i>Percentage of the Federal Budget is a ridiculous metric</i><br /><br />How about percentage of GDP? Do you have a good metric in mind, or a different approach altogether? <br /><br />Fat Man wrote: <i>Is there any reason to think that additional money spent on physics will produce anything other than higher salaries for tenured professors?</i><br /><br />Any discussion about &Steven Masonhttps://www.blogger.com/profile/05140374687362624448noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21980658458369663382019-04-25T10:19:14.166-04:002019-04-25T10:19:14.166-04:00Hi Jeff,
As Peter says, these papers have little ...Hi Jeff,<br /><br />As Peter says, these papers have little to do with "pixelation" and "scrambling." I know that the idea has sometimes been sold as "atoms of spacetime" but really if you look at the math, it has nothing to do with pixels. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32065563865956812122019-04-25T09:36:19.220-04:002019-04-25T09:36:19.220-04:00Dan,
I would never dare to ask for UV completion....Dan,<br /><br />I would never dare to ask for UV completion. What I meant was far more modest and would take place in flat spacetime. From [1] (figure 8) I got the impression that CWL mimics classical behavior in a double slit once the object exceeds m_CWL. This is good news. <br />What I worried about was that if also the internal QM structure of the object would become classical, then this is Reimondhttps://www.blogger.com/profile/04669340425105889539noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36636592198654332462019-04-25T07:57:12.642-04:002019-04-25T07:57:12.642-04:00Hello Jeff,
You're misinterpreting these two ...Hello Jeff,<br /><br />You're misinterpreting these two papers. From the abstract: <br /><br /><br />... can be used to test the violation of the Lorentz invariance (LIV), predicted by <b>some</b> quantum gravity theories ... (boldface mine)<br /><br />So there are other theories involving pixellation of space-time that satisfy Lorentz invariance.<br /><br />Peter Shorhttps://www.blogger.com/profile/13823970640202949073noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-79542373778500854932019-04-25T06:19:44.576-04:002019-04-25T06:19:44.576-04:00Andrei,
What you say is wrong because the gravita...Andrei,<br /><br />What you say is wrong because the gravitational field is not a faithful copy of all quantum degrees of freedom. You can see this easily by noting that the source is bi-linear. (If it did, the information loss problem wouldn't exist.)Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-79650355727893803342019-04-25T06:17:41.624-04:002019-04-25T06:17:41.624-04:00drl,
I wrote about this here: Why doesn't ant...drl,<br /><br />I wrote about this here: <a href="http://backreaction.blogspot.com/2017/04/why-doesnt-anti-matter-anti-gravitate.html" rel="nofollow">Why doesn't antimatter antigravitate?</a> And, yes, there are experiments.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-42420131182561708972019-04-25T06:08:21.765-04:002019-04-25T06:08:21.765-04:00Andrei,
Depends on exactly what you measure, of c...Andrei,<br /><br />Depends on exactly what you measure, of course. Ideally you would want to measure something like a Bell-inequality violation that demonstrates entanglement (of the gravitational field), which would be proof of a quantum phenomenon. The point that was made by Bose et al is that if you can create entanglement through the gravitational interaction, then that too would require Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-76865049740517574002019-04-25T05:59:53.750-04:002019-04-25T05:59:53.750-04:00neo,
They don't. I commented on this in my ea...neo,<br /><br />They don't. I commented on this in my earlier blogpost. There are no theoretical predictions. As I said, theoreticians have not been very interested in actually making contact to the real world. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-67885915665559332392019-04-24T23:53:06.748-04:002019-04-24T23:53:06.748-04:00Hello Sabine,
How can anyone make those statement...Hello Sabine,<br /><br />How can anyone make those statements about pixelation and the scrambling of spacetime continuity in the face of https://arxiv.org/abs/1106.1068 and the more recent https://arxiv.org/abs/1710.08432? Am I completely misinterpreting these two papers? Or does actual science just not matter to scientists anymore? :-(Jeffhttps://www.blogger.com/profile/06140726210295297492noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24342737442894823222019-04-24T01:39:07.770-04:002019-04-24T01:39:07.770-04:00Quite ok, I figured that something along those lin...Quite ok, I figured that something along those lines was the case.John Fredstedhttps://www.blogger.com/profile/14392519442398073571noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-52380005371301685792019-04-24T00:40:13.808-04:002019-04-24T00:40:13.808-04:00The real problem with the idea of quantum gravity ...The real problem with the idea of quantum gravity IMO is that GR has serious problems all by itself that are more or less ignored. Until those get fixed there doesn't seem to be much point in pressing forward. Classical electromagnetism of point particles of course has huge problems, and surprise, these are not fixed by quantum electrodynamics, and in some ways are made even worse. Dirac'drlhttps://www.blogger.com/profile/05424774416249451584noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-44818278733703612612019-04-24T00:18:18.422-04:002019-04-24T00:18:18.422-04:00@Philip, of course Weyl was right! Only it wasn...@Philip, of course Weyl was right! Only it wasn't the Lorentz spacetime "gauge", length standard, that was changing place to place, it was the phase of the wave function.<br /><br />-drldrlhttps://www.blogger.com/profile/05424774416249451584noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-46726452522560126402019-04-24T00:16:23.266-04:002019-04-24T00:16:23.266-04:00@Sabine, does anyone really know if antimatter fal...@Sabine, does anyone really know if antimatter falls up or down? Has that experiment ever been done? I'd say you'd have to do that experiment first, if for no other reason than to get warmed up. If you think about it, it's a hard experiment to do.<br /><br />-drldrlhttps://www.blogger.com/profile/05424774416249451584noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24093186809601829292019-04-24T00:14:22.060-04:002019-04-24T00:14:22.060-04:00@Bill - Of course it was considered testable. In f...@Bill - Of course it was considered testable. In fact Einstein shot down Weyl's unification in its original form in spite of the fact that Weyl's solution was of extraordinary mathematical beauty. He pointed out that sharp spectral lines could not exist because the electron would have a mass dependent on its spacetime history. That's a testable phenomenon - broadening of spectral drlhttps://www.blogger.com/profile/05424774416249451584noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-90466040902243595112019-04-23T20:51:54.337-04:002019-04-23T20:51:54.337-04:00The statement What happens in the known approaches...The statement <i>What happens in the known approaches to quantum gravity instead is that quantum uncertainties increase when space-time curvature becomes large. </i> is interesting. This interplay between curvature and quantum uncertainty is something I have thought interesting. I just did a back of the envelope calculation to find<br /><br />ΔpΔx ≈ √(⟨p^2⟩ - ⟨p⟩^2)√(⟨x^2⟩ - ⟨x⟩^2) + R^i_{00j}(⟨Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27503782027564952002019-04-23T12:39:53.618-04:002019-04-23T12:39:53.618-04:00Phillip wrote: The English word "consequent&q...Phillip wrote: <i>The English word "consequent" means "resulting from" and is not applied to a person.</i><br /><br />I'll comment on this as a matter of interest, not as a nitpick. In English, "consequence" can be applied to a person. If Freeman Dyson is consequential, or a person of consequence, it means he's important. Conversely, if a person is of little Steven Masonhttps://www.blogger.com/profile/05140374687362624448noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-35641780509652512782019-04-23T12:27:55.436-04:002019-04-23T12:27:55.436-04:00Hi Reimond,
"Are there any activities to ins...Hi Reimond,<br /><br />"Are there any activities to install this kind of experiment?" -- yes, see the review [1] for a bunch of links, or also you can check out the excellent review by Bassi Ulbricht and Grosshardt https://arxiv.org/abs/1706.05677<br /><br />As to your path bunching question, if I understand what you are after, the statement would be that we only really worked out how Danhttps://www.blogger.com/profile/09480680527150522129noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28766700409323556042019-04-23T11:41:29.562-04:002019-04-23T11:41:29.562-04:00The second part is one comment on the first part a...The second part is one comment on the first part and a question to Dr. Hossenfelder.<br /><br />Comment: Percentage of the Federal Budget is a ridiculous metric. In 1965, half of the Federal Budget was for defense. Medicare, Medicaid and other Federal health spending was in its infancy. The Federal Budget is now largely medical care and pensions.<br /><br />Question. Is there any reason to think Fat Manhttps://www.blogger.com/profile/09554029467445000453noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-58846802503559756702019-04-23T11:39:36.670-04:002019-04-23T11:39:36.670-04:00I apologize. I tried to post this in an old thread...I apologize. I tried to post this in an old thread you had linked.<br /><br />It is the first of two parts. The first part is excerpts from an op-ed from Saturday's Wall Street Journal. Note that the lead author is best known as the architect of Obamacare.<br /><br />"How the U.S. Surrendered to China on Scientific Research: Washington could show its seriousness about key technologies Fat Manhttps://www.blogger.com/profile/09554029467445000453noreply@blogger.com