tag:blogger.com,1999:blog-22973357.post164267382932816187..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: The Cosmological ParametersSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger18125tag:blogger.com,1999:blog-22973357.post-12431569688247982822007-12-22T20:47:00.000-05:002007-12-22T20:47:00.000-05:00Yes, Stefan, it is the same Telegraph article (and...Yes, Stefan, it is the same Telegraph article (and in general, what an interesting e-zine.) It seems the Telly may, however, have done a bad job popularizing that idea, since the title of the arXiv piece doesn't sound like the "nutty" type physo-babble of the Telegraph article, not that I would really know.Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73341217312194307262007-12-22T19:32:00.000-05:002007-12-22T19:32:00.000-05:00Hi Neil',that's the same article from the Telegrap...Hi Neil',<BR/><BR/>that's the same article from the Telegraph that Kelly has mentioned before? Anyway, the reference seems to be to this paper: <I>Is the accelerated expansion evidence of a forthcoming change of signature on the brane?</I> by Marc Mars, José M. M. Senovilla, Raül Vera, <A HREF="http://arxiv.org/abs/0710.0820" REL="nofollow">arXiv:0710.0820v2</A>... no idea what this means and is stefanhttps://www.blogger.com/profile/09495628046446378453noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-53953548664244265182007-12-22T18:58:00.000-05:002007-12-22T18:58:00.000-05:00Try this one from The Telegraph:Time is running ou...Try this one from <A HREF="http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/12/18/scitime118.xml" REL="nofollow">The Telegraph</A>:<BR/><BR/>Time is running out - literally, says scientist<BR/><BR/>By Tom Chivers and Roger Highfield, Science Editor<BR/>Last Updated: 6:01am GMT 18/12/2007<BR/><BR/>[pieces]<BR/><BR/>The idea that time itself could cease to be in billions of years - and Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-46745036760118213942007-12-22T17:15:00.000-05:002007-12-22T17:15:00.000-05:00Hi, plato, I posted similar to the below at Cosmic...Hi, plato, I posted similar to the below at Cosmic Variance and I hope it can explain some terms and things to those who may need it (but I ask a question or two myself):<BR/><BR/>First, the Hubble rule means that right now, or any observer in the past or future, is going to find a galaxy twice as far away moving away at twice the “velocity” (I put in quotation marks since it isn’t a simple Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-40475475947626926862007-12-21T23:09:00.000-05:002007-12-21T23:09:00.000-05:00Is the "current universe" accelerating in expansio...Is the "current universe" accelerating in expansion/contraction?<BR/><BR/><A HREF="http://map.gsfc.nasa.gov/m_uni/uni_101accel.html" REL="nofollow" TITLE="What is a Cosmological Constant?">A cosmological constant term added to the inflationary model, an extension of the Big Bang theory, leads to a model that appears to be consistent with the observed large-scale distribution of galaxies and PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24335890666106835762007-12-21T20:07:00.000-05:002007-12-21T20:07:00.000-05:00ps: I'm much too married to 'look around', and btw...ps: I'm much too married to 'look around', and btw my husband gets all comments cc ;-)Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-89493621353500378942007-12-21T20:06:00.000-05:002007-12-21T20:06:00.000-05:00Hi Neil,Ah. Or maybe I should say 'Oh'? I am defin...Hi Neil,<BR/><BR/>Ah. Or maybe I should say 'Oh'? I am definitely in favor of synchronized orgasms, and I am perfectly sure it will help the world to live in more peace and harmony. Have fun,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-7770940918944211602007-12-21T20:01:00.000-05:002007-12-21T20:01:00.000-05:00Speaking of Cosmic Matters! ;-)Synchronized Global...Speaking of Cosmic Matters! ;-)<BR/><BR/><A HREF="http://global-o.org/" REL="nofollow">Synchronized Global Orgasm for Peace</A><BR/><BR/>(The appointed time grows short, so start looking around ...)Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-78250572560521155122007-12-21T18:05:00.000-05:002007-12-21T18:05:00.000-05:00Hi Neil,Thanks for your interesting comments :-) I...Hi Neil,<BR/><BR/>Thanks for your interesting comments :-) If you fill space with spheres, i.e. have more than one sphere then you don't have spherical symmetry and the conclusions about the gravitational field in the spheres, Newtonian or GR don't apply. Please note, the Bianchi Theorem in GR works if one has a global spherical symmetry - the local one isn't sufficient. Also, if space is Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-90787891700355276542007-12-21T17:20:00.000-05:002007-12-21T17:20:00.000-05:00PS - However, many folks there have patiently put ...PS - However, many folks there have patiently put much work into giving me answers, even though I can be aggravating and keep disagreeing with them! Thanks here, to all of them.Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-58658393273591381122007-12-21T17:19:00.000-05:002007-12-21T17:19:00.000-05:00Here's a thought-experiment of mine (maybe not the...Here's a thought-experiment of mine (maybe not the first instance, of course) that makes we wonder just what concepts properly apply to gravity and space curvature "as a whole" versus local regions: Suppose space is filled with hard spheres, not yet touching, each with a little test particle P in its center. Let this universe contract until the spheres start touching - what happens?<BR/><BR/>In Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-22901413598552419562007-12-21T12:34:00.000-05:002007-12-21T12:34:00.000-05:00Random association: Our time is running outOur tim...Random association:<BR/><BR/><I> Our time is running out<BR/>Our time is running out<BR/>You can't push it underground<BR/>You can't stop it screaming out<BR/>How did it come to this?</I><BR/><BR/><BR/>~ Muse, <A HREF="http://www.lyrics007.com/Muse%20Lyrics/Time%20Is%20Running%20Out%20Lyrics.html" REL="nofollow">Time is Running out</A>Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32265414992633439882007-12-21T12:31:00.000-05:002007-12-21T12:31:00.000-05:00Hi Kelly,Thanks... Well, I could have expected the...Hi Kelly,<BR/><BR/>Thanks... Well, I could have expected the article doesn't actually say anything. I will see if I can find the paper. It doesn't even mention anything about structure formation and the CMB, so far it sounds rather weird to me. A Merry Christmas to you too!<BR/><BR/>Hi Plato,<BR/><BR/>Well, if you allow yourself to temper around with the time coordinates, not even the notion of Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-49331562933962887882007-12-21T11:27:00.000-05:002007-12-21T11:27:00.000-05:00"We do not say that the expansion of the universe ...<A HREF="http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2007/12/18/scitime118.xml" REL="nofollow" TITLE="Time is running out - literally, says scientist-by Tom Chivers and Roger Highfield, Science Editor">"We do not say that the expansion of the universe itself is an illusion," he explains. "What we say it may be an illusion is the acceleration of this expansion - that PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-86360339966992203882007-12-21T10:56:00.000-05:002007-12-21T10:56:00.000-05:00Sure B. Here is the link:ReferenceHave a merry Ch...Sure B. Here is the link:<BR/><BR/><A HREF="http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2007/12/18/scitime118.xml" REL="nofollow">Reference</A><BR/><BR/>Have a merry Christmas!Kellyhttps://www.blogger.com/profile/04132813255298601590noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-89419201600029016282007-12-21T10:40:00.000-05:002007-12-21T10:40:00.000-05:00Hi Kelly,sounds interesting, any chances you have ...Hi Kelly,<BR/><BR/>sounds interesting, any chances you have a reference? I actually don't even know what it's supposed to mean that 'time slows down'. I mean, do they argue the proper time we're sitting in isn't the 't' the scale factor depends on but a rescaled time? And why would that be? I find it hard to believe that this would work for structure formation etc like a Cosmological constant Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25135573519552232502007-12-21T10:32:00.000-05:002007-12-21T10:32:00.000-05:00The Telegraph a couple of days ago posted a rather...The Telegraph a couple of days ago posted a rather radical yet interesting article that time could be slowing down, thus explaining dark energy. <BR/><BR/>"The team's proposal, which will be published in the journal Physical Review D, does away altogether with dark energy. Instead, Prof Senovilla says, the appearance of acceleration is caused by time itself gradually slowing down, like a clock Kellyhttps://www.blogger.com/profile/04132813255298601590noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-43179849638920763232007-12-21T10:28:00.000-05:002007-12-21T10:28:00.000-05:00A Very Merry Christmas Bee and Stefan.The amount o...A Very <A HREF="http://bp3.blogger.com/_cldxKGOzgeM/R2vTL1lfNZI/AAAAAAAAAn4/0K39id01en4/s400/raphael-Plato-Aristotle+and+christmas.JPG" REL="nofollow">Merry Christmas</A> Bee and Stefan.<BR/><BR/><A HREF="http://map.gsfc.nasa.gov/m_mm/mr_content.html" REL="nofollow" TITLE="WMAP Mission-Geometry and Content of the Universe">The amount of dark matter and energy in the universe plays a crucial role PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.com