tag:blogger.com,1999:blog-22973357.post116144937893458385..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: Dark MatterSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger45125tag:blogger.com,1999:blog-22973357.post-11097675226457382432011-01-12T17:25:08.450-05:002011-01-12T17:25:08.450-05:00DARK MATTER
-- James Ph. Kotsybar
The universe...DARK MATTER<br />-- James Ph. Kotsybar<br /><br /> <br /><br />The universe is mostly abnormal,<br />if we accept that physicists aren’t wrong<br />and Newton’s gravity’s uniformal,<br />otherwise galaxies couldn’t last long.<br /><br />They’d spin themselves apart, unless, unseen,<br />missing mass resolves the disparity.<br />Dark Matter is needed to intervene.<br />Though not found, it can’t Poeteyehttps://www.blogger.com/profile/09534813243606718999noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-12590184954397238492009-11-13T19:14:45.309-05:002009-11-13T19:14:45.309-05:00I was just thinking just yesterday and before I fo...I was just thinking just yesterday and before I found this excellent page that neutrinos may be the best candidates for Dark Matter among particles that are already known, party because stars have a way of producing quite a bit of them.<br /><br />Then with a few mouse clicks (research) I found there's something called sterile neutrinos, and then this page mentions heavy sterile neutrinos. Steven Colyerhttps://www.blogger.com/profile/10435759210177642257noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1392070836351044872008-03-27T09:48:00.000-04:002008-03-27T09:48:00.000-04:00Hi Rudi,Sure. Rudy Rucker likes to speculate that ...Hi Rudi,<BR/><BR/>Sure. <A HREF="http://www.edge.org/q2006/q06_3.html#rucker" REL="nofollow">Rudy Rucker likes to speculate that dark energy or dark matter (he is somewhat unspecific on the details) is a condensation of the mind</A>. It seems then it's a particularly playful mind that likes to fool us earthly beings. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-26624302956046671512008-03-27T04:12:00.000-04:002008-03-27T04:12:00.000-04:00Bee,All this can also be explained by assuming tha...Bee,<BR/><BR/>All this can also be explained by assuming that General Relativity is wrong by a factor 10 (when it comes to light bending). <BR/>Dark matter has been attributed many strange properties and I would like to add another one: high intelligence! This dark matter has to move and clump in exactly the right way to make the galaxy rotation curves flat. In addition, it constantly find tricksAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-6405730843526088172008-03-26T09:26:00.000-04:002008-03-26T09:26:00.000-04:00Anonymous,There is a long history in which people ...Anonymous,<BR/>There is a long history in which people have tried to explain dark matter with unseen planets, brown dwarfs, or even black holes - i.e. non-luminous but 'normal' matter. One can estimate these contributions by looking at the distribution of such components in our own Galaxy. There is no way they can contribute as much as than ten times more than the visible mass. Besides this, Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73270251359575931822008-03-25T20:10:00.000-04:002008-03-25T20:10:00.000-04:00; if dark matter is confirmed by gravitiation lens...; if dark matter is confirmed by gravitiation lensing, wha t is the effect of angular momentum of planets and sars on gravitional lensing and has this been taken into account. how fo we measure mass of objects diatance from us; estimates of mass and planets, and dust, and angular mementum is sure to add up to more then our estimates based on stars (visable matter alone) how is all this accounted Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-62946540627547392792008-03-17T10:20:00.000-04:002008-03-17T10:20:00.000-04:00Rudi, had you bothered to read this post and other...Rudi, had you bothered to read this post and others I've written and that you find in the sidebar, you'd have noticed I have been very careful with my interpretation of evidence.<BR/><BR/>I do not appreciate that kind of self-advertisement. <BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-50817067793089286192008-03-17T08:01:00.000-04:002008-03-17T08:01:00.000-04:00All this so-called evidence of dark matter is not ...All this so-called evidence of dark matter is not so solid as is often claimed.<BR/><BR/>1) Galaxy rotation curves:<BR/><BR/>These do not demonstrate the presence of dark matter. They show that the stars do not follow Newton's law of gravitation. Newton's law has been obtained by observations on a very small scale (our solar system) and it is no surprise that it breaks down when extrapolating theAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1165482507198456212006-12-07T04:08:00.000-05:002006-12-07T04:08:00.000-05:00Bee remarks:“And isn't that a nice way to model ou...Bee remarks:<BR/><BR/>“And isn't that a nice way to model our universe, where the present day cosmological data lets us conclude that.…23% [of the universe] is non-baryonic dark matter….”, <BR/>The foundation of the model that Bee is marveling about has an unflattering similarity to the foundation of the model of the universe that Scholastics extolled. No one then and now has been able to come Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1162161146553513522006-10-29T17:32:00.000-05:002006-10-29T17:32:00.000-05:00Hi Arun,Thanks for your comments. You are right th...Hi Arun,<BR/><BR/>Thanks for your comments. You are right that in many cases the so-called experimental evidence is much more involved than it appears at first sight. There are many factors and assumptions that often aren't explicitly pointed out. Your concern might be one, but one way or the other there would be something left open to explain. <BR/><BR/>In the case of dark matter the evidence Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1162048393020007502006-10-28T11:13:00.000-04:002006-10-28T11:13:00.000-04:00Dear Bee,A quick disclaimer - I don't disbelieve t...Dear Bee,<BR/><BR/>A quick disclaimer - I don't disbelieve the astronomers. I just want to understand how they do their observations.<BR/><BR/>A long ago, when first the He/H ratio of the primordial universe was a marker of how many generations of particles we had, I ventured to read a astronomer's article on a measurement of this all-important ratio. Sorry, I won't be able to find the Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1162044526528574612006-10-28T10:08:00.000-04:002006-10-28T10:08:00.000-04:00Dear B,Please take a look at this galactic rotatio...Dear B,<BR/><BR/>Please take a look at this galactic rotation curve:<BR/><BR/><A HREF="http://astrosun2.astro.cornell.edu/academics/courses//astro201/rotcurve.htm" REL="nofollow">http://astrosun2.astro.cornell.edu/academics/courses//astro201/rotcurve.htm</A><BR/><BR/>How did they get the detail around 30 arcseconds? Or is the illustration of the spectral image schematic only?Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161982214433972412006-10-27T16:50:00.000-04:002006-10-27T16:50:00.000-04:00Paul,I think one has to look for similarities from...Paul,<BR/><BR/>I think one has to look for similarities from QGP if it is ever held to <A HREF="http://eskesthai.blogspot.com/2006/10/probing-perfect-liquid.html" REL="nofollow">relativistic conditions?</A><BR/><BR/>Some of our talks have been leading in that perspective, with some image links supplied.PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161981360794774442006-10-27T16:36:00.000-04:002006-10-27T16:36:00.000-04:00If the reversal of Time is applied to the Aero cho...If the reversal of Time is applied to the Aero chocolate bar, then it starts of as a Liquid, the bubbles are introduced, Airated?..then left to solidify.<BR/><BR/>Heat causes the naturally "cold" solid chocolate to "melt".<BR/><BR/>One can state that a chololate Universe is initially "cold_solid" ,then heats up to boiling liquid point "bubbled" ,then cools back down to a stable solid temperatureAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161953025823120512006-10-27T08:43:00.000-04:002006-10-27T08:43:00.000-04:00Beisdes the bubble creations, some may like a "spe...Beisdes the bubble creations, some may like a "special brand of <A HREF="http://eskesthai.blogspot.com/2006/10/probing-perfect-liquid.html" REL="nofollow">molasses</A>" in Europe too?PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161862874617283272006-10-26T07:41:00.000-04:002006-10-26T07:41:00.000-04:00Hi Bee,in case you haven't seen itlink from PPARC ...Hi Bee,<BR/>in case you haven't seen it<BR/>link from PPARC <A HREF="http://www.pparc.ac.uk/Nw/bbaryon.asp" REL="nofollow">Baryon</A>QUASAR9https://www.blogger.com/profile/00593390598251093182noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161860148661711032006-10-26T06:55:00.000-04:002006-10-26T06:55:00.000-04:00Arun said... Is the simulation code "open-source"?...<I>Arun said... <BR/>Is the simulation code "open-source"? </I><BR/><BR/>Hi Arun,<BR/><BR/>sorry for the late answer, I had to find out myself: No, it's not open source.<BR/>Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161859693175174372006-10-26T06:48:00.000-04:002006-10-26T06:48:00.000-04:00Hi Quasar,glad you liked my post :-) I find the to...Hi Quasar,<BR/><BR/>glad you liked my post :-) I find the topics dark matter and dark energy as annoying as fascinating. One way or the other, for the theoretician it's a huge challenge, and admittedly kind of addictive. Over the last years (since WMAP or so), I've talked to so many colleagues, and almost everybody has his/hers interpretation of how to explain the observations, many of which are Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161856436276715712006-10-26T05:53:00.000-04:002006-10-26T05:53:00.000-04:00Hi Sabine, great post!I quite like aeroes even if ...Hi Sabine, great post!<BR/>I quite like aeroes even if they have low (the real thing) cacao content, and the holes are produced by a guarded secret and allergy causing additives. To date I have not encountered any allergies to food additives. lol!<BR/>Mint aeroes are a little bit over the top, like menthol cigarrettes.<BR/>But have you thought of a giant honeycombed malteser wrapped in thick QUASAR9https://www.blogger.com/profile/00593390598251093182noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161744733024186102006-10-24T22:52:00.000-04:002006-10-24T22:52:00.000-04:00Hi Bee,do we know anything of the origin of DM?a r...Hi Bee,<BR/><BR/>do we know anything of the origin of DM?<BR/><BR/>a residue from the earilest moments?<BR/><BR/>is DM as old as the universe- meaning produced at the BB event, and does the universe treat DM equal to normal matter i.e. does DM obey the accelerated expantion?<BR/><BR/>what if DM is purely a manifestation of gravity "curled up" upon itself? like a black hole with extremely low Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161642877536310372006-10-23T18:34:00.000-04:002006-10-23T18:34:00.000-04:00Hi Island,Thanks for your explanation, which is ve...Hi Island,<BR/><BR/>Thanks for your explanation, which is very helpful indeed. I have some questions though. <BR/><BR/>1) What do you do with ultrarelativistic matter? <BR/><BR/>2) Where goes Baryogenisis?<BR/><BR/>3) If you keep spacetime flat by producing pairs via the mechanism you described, how come spacetime isn't flat? What you propose would not only affect Cosmology but also astrophysics.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161641829660366522006-10-23T18:17:00.000-04:002006-10-23T18:17:00.000-04:00Dear Stefan,yes, that's about correct, though I th...Dear Stefan,<BR/><BR/>yes, that's about correct, though I think the mass of the smallest halos is closer by mass of Mars than of Earth (I dropped some factors of order one). That makes a very thin medium if it travels through our solar system, indeed. <BR/><BR/>I am not sure but maybe one would be able to find traces of the time-dependence? I mean, given that such an event would happen with Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161639945710325852006-10-23T17:45:00.000-04:002006-10-23T17:45:00.000-04:00Dear Bee, a very interesting post :-), and I alway...Dear Bee, <BR/><BR/>a very interesting post :-), and I always wanted to know a little bit about Stefan's work on cold dark matterand structure formation.<BR/><BR/>So, the concentrations of CDM Stefan has investigated correspond to roughly the mass of the Earth, which is about 3x10e-6 solar masses, distributed over the volume of the whole solar system? Did I get that right?<BR/><BR/>If I use for stefanhttps://www.blogger.com/profile/09495628046446378453noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161629590922037132006-10-23T14:53:00.000-04:002006-10-23T14:53:00.000-04:00Hi Klaus,yes, sure, there are collider constraints...Hi Klaus,<BR/><BR/>yes, sure, there are collider constraints on the existence of dark matter candidates as well. See eg. the <A HREF="http://pdglive.lbl.gov/listings1.brl?exp=Y" REL="nofollow">Particle Data Booklet</A> (the new life-sites are pretty cool!), constraints on Neutralinos and Axions. Thus, yes you could say that we would <I>produce</I> these things in the collider should they exist. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-1161608971190721112006-10-23T09:09:00.000-04:002006-10-23T09:09:00.000-04:00Hi Bee,Do you think it possible to produce artific...Hi Bee,<BR/><BR/>Do you think it possible to produce artificial,/manmade dark matter in colliders?<BR/><BR/>maybe its lifespan will be extremely short, nevertheless it is established that the newest colliders can produce micro black holes... so why not consider the possibility of DM production..?<BR/><BR/>greetings<BR/><BR/>KlausAnonymousnoreply@blogger.com