tag:blogger.com,1999:blog-22973357.post3694896533941803857..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: Who said it first? The historical comeback of the cosmological constantSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger53125tag:blogger.com,1999:blog-22973357.post-3957159683526463312013-06-17T10:16:54.157-04:002013-06-17T10:16:54.157-04:00@Will: A great summary by someone who lived throug...@Will: A great summary by someone who lived through these exciting times and lived to tell the tale. I agree with all of your points, especially the one directed at me. There were always alternative explanations, but experts in one field couldn't see that their alternative explanation was incompatible with what was going on in other fields (e.g. the structure folks could favour a low HubblePhillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-6278947386522912482013-06-17T10:12:19.043-04:002013-06-17T10:12:19.043-04:00@Will: Great summary of what actually happened (ba...@Will: Great summary of what actually happened (based on the fact that it agrees with my recollection) by someone who lived through these exciting times and lived to tell the tale.<br /><br />I agree on all of your points, especially the last one directed at me. The situation was similar to determining Avogadro's number a hundred years previously: no one measurement was conclusive, but Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-68595065177192178162013-06-16T17:13:48.338-04:002013-06-16T17:13:48.338-04:00(third and last part...)
A few responses to comm...(third and last part...) <br /><br />A few responses to comments above:<br /><br />@Steinn: Re simulations, there is a small LambdaCDM sim actually in ESM (32k particles !) . <br />I think several N-body groups (Durham, Park & Gott, Cen & Ostriker ?) were running <br />big LambdaCDM simulations (and others) by around 1993/4, but I'll have to chase references. <br /><br />@Phillip H: &Will Sutherlandhttps://www.blogger.com/profile/15222963478459876691noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32707643016738339852013-06-16T17:07:24.675-04:002013-06-16T17:07:24.675-04:00(continued from above...)
Several of these were ... (continued from above...) <br /><br />Several of these were fitted in the Wright et al 1992 COBE paper, linked above. <br /><br />All of these had some interest and a significant number of papers; it's hard to be quantitative, <br />but my general recollection is that the most popular was Mixed dark matter, with Lambda-CDM around<br />second or third; while in terms of actually fitting Will Sutherlandhttps://www.blogger.com/profile/15222963478459876691noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-67033990466336404142013-06-16T16:48:51.281-04:002013-06-16T16:48:51.281-04:00Some slightly late comments from the middle author...Some slightly late comments from the middle author of Efstathiou, Sutherland and Maddox 1990 [here ESM], <br />cited in Sabine's original post: <br /> <br />Firstly, ESM did not claim "the data requires a cosmological constant", but did show that <br />observations of large-scale galaxy clustering, (mainly data from the APM Galaxy Survey from <br />http://adsabs.harvard.edu/abs/Will Sutherlandhttps://www.blogger.com/profile/15222963478459876691noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-30000106102161197482013-05-31T17:04:26.677-04:002013-05-31T17:04:26.677-04:00The expanding universe was recognized back in the ...The expanding universe was recognized back in the 1920s, but the big bang theory wasn't really confirmed until radio astronomy was developed in the 1950s & 1960s. In the late 1960s and into the 1970s, the big focus was on completing and nailing down the standard model. Once the micro-theory (the standard model) and the macro-theory (the big bang theory) were in place, the focus turned to Kaleberghttps://www.blogger.com/profile/05283840743310507878noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-31328196315411809282013-05-31T16:51:15.325-04:002013-05-31T16:51:15.325-04:00Btw talking about history, can someone tell me
why...Btw talking about history, can someone tell me<br />why D. Kazanas's 1980 paper on inflation (in ApJ) is not as widely cited as some of the other papers by Guth, Linde etc? In fact it was not cited in the Planck paper on inflation. I think the paper by Kazanas is the first which mentioned that accelerated expansion could solve the horizon problem (although it doesn't mention flatness Shantanuhttps://www.blogger.com/profile/16322812456382858228noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-57890216677203528312013-05-29T11:49:28.826-04:002013-05-29T11:49:28.826-04:00Then in this particular case I'm glad I was th...Then in this particular case I'm glad I was thinking wrong...Erichttps://www.blogger.com/profile/08213251864943443334noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-26772909208058379762013-05-29T03:32:20.273-04:002013-05-29T03:32:20.273-04:00Eric,
"The way the multiverse crowd is think...Eric,<br /><br /><i>"The way the multiverse crowd is thinking, including Bee (I think?)..."</i><br /><br />You're thinking wrong. I've made it clear on this blog numerous times that I think the occurrence of "multiverses" of one way or the other is inevitable, and simply a consequence of us aiming to describe nature by mathematical law. Since I don't believe that Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-64487864784535562012013-05-28T19:49:19.094-04:002013-05-28T19:49:19.094-04:00I should add one more thing and then I'll be q...I should add one more thing and then I'll be quiet. The way the multiverse crowd is thinking, including Bee (I think?)one could go on infinitely adding more universes. Each would be incorporated into the existing universe retroactively as one observes them or gets concrete evidence of them. It's the opposite of reductionist philosophy where as you learn more things become simpler.<br /><Erichttps://www.blogger.com/profile/08213251864943443334noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-81653900310299289922013-05-28T17:05:51.884-04:002013-05-28T17:05:51.884-04:00Actually, contrary to what all the televised pundi...Actually, contrary to what all the televised pundits say, dark matter in combination with dark energy is very theoretically consistent. First one should make a distinction along with an association. "Inflation" seems like it goes with "unitary", while "Inflationary" as used in the common cosmic inflation/multiverse scenario would be associated with "infinite&Erichttps://www.blogger.com/profile/08213251864943443334noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84334553795049420032013-05-28T16:42:52.946-04:002013-05-28T16:42:52.946-04:00"Again, I blame the particle physicists, or a..."Again, I blame the particle physicists, or at least most of them. A bit earlier, the idea of inflation surfaced, which also involves accelerated expansion. Many people believe that the cosmological constant and inflation are somehow related. However, it seemed easier in inflationary models to have a zero cosmological constant NOW."<br /><br />I too blame the particle physicists. But I Erichttps://www.blogger.com/profile/08213251864943443334noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-7659154554100842122013-05-28T16:14:48.031-04:002013-05-28T16:14:48.031-04:00This comment has been removed by the author.Erichttps://www.blogger.com/profile/08213251864943443334noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-35999523226328162922013-05-28T09:24:59.150-04:002013-05-28T09:24:59.150-04:00I think that's a good assessment. It's a ...I think that's a good assessment. It's a gradual process, of course, and some people saw it coming more quickly than others. What is definitely not the case, though, is that someone saw hints <i>in the supernovae data</i> already in 1995.<br />Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-81976328212656142252013-05-28T06:47:19.560-04:002013-05-28T06:47:19.560-04:00Hi Phillip,
Sure, it wasn't clear really what...Hi Phillip,<br /><br />Sure, it wasn't clear really what the data showed. All I was saying is that there were hints already. Maybe the word "evidence" that I used is too strong, if that's what you mean. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-2443979690894698322013-05-28T04:05:22.503-04:002013-05-28T04:05:22.503-04:00"there was evidence in the data well before t...<i>"there was evidence in the data well before the supernova results from 98"</i><br /><br />Now I'm confused. It depends on what you mean by "evidence". Before the SNIa stuff, many people suggested (Krauss and Turner, Ostriker and Steinhardt etc)---and in prominent journals---that a positive cosmological constant would be a natural interpretation of the data. On the Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-55991729439083944292013-05-28T03:38:05.417-04:002013-05-28T03:38:05.417-04:00coraifeartaigh,
Yes... but that's not what I ...coraifeartaigh,<br /><br />Yes... but that's not what I meant. The interesting thing for me is not that there were theoreticians who never stopped believing in the CC, but that there was evidence in the data well before the supernova results from 98. Best,<br /><br />B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-38740723291698375332013-05-27T13:51:01.096-04:002013-05-27T13:51:01.096-04:00Hi Bee, I spent a bit of time on this a while ago,...Hi Bee, I spent a bit of time on this a while ago, and the answer given in most of the history books is that, at least for theoreticians, the cc 'never really went away', partly because of the age problem, and partly because it arises naturally as a constant of integration.<br />References for this are North's 'the measure of the universe, Kragh's 'cosmology and Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-15668087253195342372013-05-27T04:58:13.431-04:002013-05-27T04:58:13.431-04:00It's just my impression from talking to people...<i>It's just my impression from talking to people, listening to talks, etc, that pre 1995 we "didn't know" of the CC.</i><br /><br />Check out <a href="http://adsabs.harvard.edu/abs/1966MNRAS.132..379S" rel="nofollow">this paper from the 1960s</a>. This shows that the cosmological constant was certainly considered among cosmologists back then. By the way, this is probably my Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-69498476963220329612013-05-27T04:54:16.722-04:002013-05-27T04:54:16.722-04:00"dark energy is a more general expression tha...<i>"dark energy is a more general expression than cosmological constant. The CC is one type of dark energy, but there are other types of dark energy that look similar and have similar effects and we're waiting for experiments to distinguish between them"</i><br /><br />Right. However, there is no observational evidence--and <i>not</i> because no-one has looked---that "dark Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-5917128557021134282013-05-27T04:52:01.727-04:002013-05-27T04:52:01.727-04:00"It's just my impression from talking to ...<i>"It's just my impression from talking to people, listening to talks, etc, that pre 1995 we "didn't know" of the CC."</i><br /><br />You were talking to the wrong people. :-)Phillip Helbighttps://www.blogger.com/profile/12067585245603436809noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74986573004682072022013-05-26T08:47:51.885-04:002013-05-26T08:47:51.885-04:00This comment has been removed by the author.PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-12356602350921659752013-05-25T18:13:18.283-04:002013-05-25T18:13:18.283-04:00If you'd rather see the cosmological constant ...If you'd rather see the cosmological constant go away, then you might want to check out my very modest "Tiny Alice" theory, circa 1975, in which the same evidence of accelerated expansion is explained rather elegantly (if I say so myself) by positing a situation in which the universe finds itself expanding into a black hole. It is the gravitational pull of the black hole that is theDocGhttps://www.blogger.com/profile/17359004200002936544noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-79171273357964614952013-05-25T13:13:16.864-04:002013-05-25T13:13:16.864-04:00What about this 1986 paper by C. Sivaram:
"U...What about this 1986 paper by C. Sivaram: <br />"Uncertainty Principle Limits on the Cosmological Constant" ?<br />(If you don't have access to this paper, there several others by the author restating the results).<br /><br />BestMarkusMhttps://www.blogger.com/profile/03431499396962852389noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-10532722174724218862013-05-25T09:13:15.906-04:002013-05-25T09:13:15.906-04:00Hi Phillip,
I knew there were others because of t...Hi Phillip,<br /><br />I knew there were others because of the information that was developed.<br /><br />It was a way of saying that the quest even after Einstein proposed the CC <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/astro/fried.html#c1%20target=_blank%3E" rel="nofollow">the mathematical language</a> was being developed lead to the issues of the cosmological constant being <a href=PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.com