Comments on: Dark Matter Exists http://cosmicvariance.com/2006/08/21/dark-matter-exists/ Random samplings from a universe of ideas Mon, 06 Oct 2008 22:20:30 +0000 http://wordpress.org/?v=2.5.1 By: Astronomy Cast http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-185085 Astronomy Cast Fri, 26 Jan 2007 23:15:11 +0000 http://cosmicvariance.com/?p=950#comment-185085 [...] Cosmic Variance on dark matter. [...] [...] Cosmic Variance on dark matter. [...]

]]> By: Salad Is Slaughter - Thoughts from a “D” List Blogger » Taking the Easy Way http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-182210 Salad Is Slaughter - Thoughts from a “D” List Blogger » Taking the Easy Way Sat, 20 Jan 2007 16:55:21 +0000 http://cosmicvariance.com/?p=950#comment-182210 [...] Meanwhile, the important story this week is the discovery of direct evidence for Dark Matter.  Here is something fundamentally new that expands our understanding the universe and opens up whole areas for research. The news stories dutifully reprinted the press release but the lack of in depth stories was telling. The news media could have written articles that helped educate people about what the discovery means, how it ties in to the Big Bang, Dark Energy, the modified gravity hypothesis, and so on. If any of the big boys were carrying these stories, I missed them. [...] [...] Meanwhile, the important story this week is the discovery of direct evidence for Dark Matter.  Here is something fundamentally new that expands our understanding the universe and opens up whole areas for research. The news stories dutifully reprinted the press release but the lack of in depth stories was telling. The news media could have written articles that helped educate people about what the discovery means, how it ties in to the Big Bang, Dark Energy, the modified gravity hypothesis, and so on. If any of the big boys were carrying these stories, I missed them. [...]

]]> By: Tim Hammond http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-173617 Tim Hammond Thu, 11 Jan 2007 17:28:11 +0000 http://cosmicvariance.com/?p=950#comment-173617 Correction 0f wrong email address on entry 194. Correction 0f wrong email address on entry 194.

]]> By: Tim Hammond http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-173615 Tim Hammond Thu, 11 Jan 2007 17:24:45 +0000 http://cosmicvariance.com/?p=950#comment-173615 From the planetary velocities around the sun and the stellar velocities around the centre of our galaxy, there does not seem to be any dark matter in our solar system or galaxy. Why is this? From the planetary velocities around the sun and the stellar velocities around the centre of our galaxy, there does not seem to be any dark matter in our solar system or galaxy. Why is this?

]]> By: COSMOS Reveals the Cosmos | Cosmic Variance http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-171860 COSMOS Reveals the Cosmos | Cosmic Variance Mon, 08 Jan 2007 18:20:58 +0000 http://cosmicvariance.com/?p=950#comment-171860 [...] It is, needless to say, really cool. The image itself is not where the real science lies, of course; it’s spatially distorted, and very hard to show error bars in a 3-d plot. But there is definitely important science lurking in the details; for example, they seem to find dark-matter concentrations with little or no ordinary matter in the same place. It’ll take some work to figure out whether this is easily compatible with the theoretical models (one could imagine dissipative effects clearing baryons out of a region, leaving dark matter behind, in a mini-version of the Bullet Cluster), or whether we’re going to be challenged. Fun either way! [...] [...] It is, needless to say, really cool. The image itself is not where the real science lies, of course; it’s spatially distorted, and very hard to show error bars in a 3-d plot. But there is definitely important science lurking in the details; for example, they seem to find dark-matter concentrations with little or no ordinary matter in the same place. It’ll take some work to figure out whether this is easily compatible with the theoretical models (one could imagine dissipative effects clearing baryons out of a region, leaving dark matter behind, in a mini-version of the Bullet Cluster), or whether we’re going to be challenged. Fun either way! [...]

]]> By: helena http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-157555 helena Tue, 19 Dec 2006 16:52:31 +0000 http://cosmicvariance.com/?p=950#comment-157555 Ooo very intresting and all, but theres so much to read and such complicated words, i just need a definition :D Good stuff though Ooo very intresting and all, but theres so much to read and such complicated words, i just need a definition :D Good stuff though

]]> By: Coast to Coast | Cosmic Variance http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-145317 Coast to Coast | Cosmic Variance Sat, 02 Dec 2006 03:02:10 +0000 http://cosmicvariance.com/?p=950#comment-145317 [...] Dark Matter Exists [...] [...] Dark Matter Exists [...]

]]> By: </depesz> » Blog Archive » ciemna materia http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-140561 </depesz> » Blog Archive » ciemna materia Sat, 18 Nov 2006 16:35:30 +0000 http://cosmicvariance.com/?p=950#comment-140561 [...] informacje “po ludzku” (aczkolwiek w jÄ™zyku angielskim) można znaleźć tutaj, natomiast dla chÄ™tnych (i majÄ…cych sporÄ… wiedzÄ™) jest dostÄ™pny oficjalny tekst (nie wiem jak przetÅ‚umaczyć “paper” z angielskiego w tym kontekÅ›cie) napisany przez ludzi którzy wykazali siÄ™ wiedzÄ… i pracÄ… potrzebnÄ… by tÄ™ ciemnÄ… materiÄ™ pokazać (dla pewnych “wartoÅ›ci” sÅ‚owa “pokazać”). [...] [...] informacje “po ludzku” (aczkolwiek w jÄ™zyku angielskim) można znaleźć tutaj, natomiast dla chÄ™tnych (i majÄ…cych sporÄ… wiedzÄ™) jest dostÄ™pny oficjalny tekst (nie wiem jak przetÅ‚umaczyć “paper” z angielskiego w tym kontekÅ›cie) napisany przez ludzi którzy wykazali siÄ™ wiedzÄ… i pracÄ… potrzebnÄ… by tÄ™ ciemnÄ… materiÄ™ pokazać (dla pewnych “wartoÅ›ci” sÅ‚owa “pokazać”). [...]

]]> By: spaceman http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-140278 spaceman Fri, 17 Nov 2006 22:46:53 +0000 http://cosmicvariance.com/?p=950#comment-140278 This post has less to do with the specific observation being discussed and more to do with the issue of when, if at all, dark matter will be found. Ultimately, in my opinion, we will have to directly detect this stuff before we can be dead sure it is exists. Sean and friends, I have been wondering the following: 1). How soon is a WIMP detection predicted to take place? I have heard that a detection may occur during the 2007 CDMSII and Xenon10 runs, as these two experiments are moving into the "favored region" (x-section 10^-44 cm2) of the WIMP parameter space! 2). What will happen if the particles are not found even with the planned 1-ton direct detectors and not produced by the LHC? 3). Will a lack of a detection by 2020 be enough to get the cosmology community to move away from the dark matter particle hypothesis? 4). A lot of pundits say that it is a bad sign for the dark matter idea that the particles have not turned up yet. I am skeptical of these pundits; it took a lot of innovation and huge detectors to find the neutrinos. Does anyone know how long it was from when neutrinos were predicted to exist to when they were actually found? This post has less to do with the specific observation being discussed and more to do with the issue of when, if at all, dark matter will be found. Ultimately, in my opinion, we will have to directly detect this stuff before we can be dead sure it is exists. Sean and friends, I have been wondering the following:

1). How soon is a WIMP detection predicted to take place? I have heard that a detection may occur during the 2007 CDMSII and Xenon10 runs, as these two experiments are moving into the “favored region” (x-section 10^-44 cm2) of the WIMP parameter space!

2). What will happen if the particles are not found even with the planned 1-ton direct detectors and not produced by the LHC?

3). Will a lack of a detection by 2020 be enough to get the cosmology community to move away from the dark matter particle hypothesis?

4). A lot of pundits say that it is a bad sign for the dark matter idea that the particles have not turned up yet. I am skeptical of these pundits; it took a lot of innovation and huge detectors to find the neutrinos. Does anyone know how long it was from when neutrinos were predicted to exist to when they were actually found?

]]> By: sundogseven http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-139759 sundogseven Thu, 16 Nov 2006 17:09:33 +0000 http://cosmicvariance.com/?p=950#comment-139759 If the relative spins of entangled pairs can change instantaneously ie. travel faster than light speeed(or so some bloke down the local told me) then how do we know that the very edge of the universe which maybe did not coallesce and clump together for the supposed time scientists allow but sped apart after the supposed hyper inflation has pulled space-time apart at faster than light speeds and therefore the majority of the universe is and always be unobservable to us.If dark matter can overcome this gravitational connundrum could it not be that this could account for the missing mass? non-scientist. Perhaps the bloke down the pub had already had far too much Guiness If the relative spins of entangled pairs can change instantaneously ie. travel faster than light speeed(or so some bloke down the local told me) then how do we know that the very edge of the universe which maybe did not coallesce and clump together for the supposed time scientists allow but sped apart after the supposed hyper inflation has pulled space-time apart at faster than light speeds and therefore the majority of the universe is and always be unobservable to us.If dark matter can overcome this gravitational connundrum could it not be that this could account for the missing mass? non-scientist. Perhaps the bloke down the pub had already had far too much Guiness

]]> By: sundogseven http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-139756 sundogseven Thu, 16 Nov 2006 16:58:12 +0000 http://cosmicvariance.com/?p=950#comment-139756 and does it matter? and does it matter?

]]> By: sundogseven http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-139755 sundogseven Thu, 16 Nov 2006 16:55:39 +0000 http://cosmicvariance.com/?p=950#comment-139755 what is the speed of dark? what is the speed of dark?

]]> By: Out-Einsteining Einstein | Cosmic Variance http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-135833 Out-Einsteining Einstein | Cosmic Variance Wed, 08 Nov 2006 13:41:28 +0000 http://cosmicvariance.com/?p=950#comment-135833 [...] And here it is. You can see the slides from the talk, as well as hear what I’m saying. I started somewhat lethargically, as it’s hard to switch gears quickly from one talk to another, but we built up some momentum by the end. I started quite broadly with the idea of different “gravitational degrees of freedom,” and worked my up to Bekenstein’s TeVeS model (a relativistic version of Milgrom’s MOND), explaining the empirical difficulties with clusters of galaxies, the cosmic microwave background, and most recently the Bullet Cluster. We can’t say that the idea is ruled out, but the evidence that dark matter of some sort exists is overwhelming, which removes much of the motivation for modifying gravity. [...] [...] And here it is. You can see the slides from the talk, as well as hear what I’m saying. I started somewhat lethargically, as it’s hard to switch gears quickly from one talk to another, but we built up some momentum by the end. I started quite broadly with the idea of different “gravitational degrees of freedom,” and worked my up to Bekenstein’s TeVeS model (a relativistic version of Milgrom’s MOND), explaining the empirical difficulties with clusters of galaxies, the cosmic microwave background, and most recently the Bullet Cluster. We can’t say that the idea is ruled out, but the evidence that dark matter of some sort exists is overwhelming, which removes much of the motivation for modifying gravity. [...]

]]> By: Company Blueprints » Blog Archive » The Complete Money Science http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-129555 Company Blueprints » Blog Archive » The Complete Money Science Tue, 31 Oct 2006 14:38:56 +0000 http://cosmicvariance.com/?p=950#comment-129555 [...] Dark Matter Exists. [...] [...] Dark Matter Exists. [...]

]]> By: The Trouble With Physics | Cosmic Variance http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-122903 The Trouble With Physics | Cosmic Variance Tue, 03 Oct 2006 07:08:33 +0000 http://cosmicvariance.com/?p=950#comment-122903 [...] Smolin does mention a number of experimental results that have already been obtained, but none of them is naturally explained by LQG any more than by string theory, and most of them are, to be blunt, likely to go away. He mentions the claimed observation that the fine-structure constant is varying with time (against which more precise data has already been obtained), certain large-angle anomalies in the cosmic microwave background anisotropy, and the possibility of large-scale modifications of general relativity replacing dark matter. (Bad timing on that one.) I don’t know of any approach to quantum gravity that firmly predicts (or even better, predicted a head of time) that any of these should be true. That’s the least surprising thing in the world; gravity is a weak force, and most of the universe is in the regime where it is completely classical. [...] [...] Smolin does mention a number of experimental results that have already been obtained, but none of them is naturally explained by LQG any more than by string theory, and most of them are, to be blunt, likely to go away. He mentions the claimed observation that the fine-structure constant is varying with time (against which more precise data has already been obtained), certain large-angle anomalies in the cosmic microwave background anisotropy, and the possibility of large-scale modifications of general relativity replacing dark matter. (Bad timing on that one.) I don’t know of any approach to quantum gravity that firmly predicts (or even better, predicted a head of time) that any of these should be true. That’s the least surprising thing in the world; gravity is a weak force, and most of the universe is in the regime where it is completely classical. [...]

]]> By: Dark Matter Breakthrough « Information that Sometimes Matters http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-122748 Dark Matter Breakthrough « Information that Sometimes Matters Mon, 02 Oct 2006 07:04:38 +0000 http://cosmicvariance.com/?p=950#comment-122748 [...] It’s common nowadays to throw theories such as Dark Matter and String Theory. However, this is a pretty interesting read about some pretty solid evidence on Dark Matter’s existance. [...] [...] It’s common nowadays to throw theories such as Dark Matter and String Theory. However, this is a pretty interesting read about some pretty solid evidence on Dark Matter’s existance. [...]

]]> By: Norwegian Wood » interesting news this week http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-122231 Norwegian Wood » interesting news this week Fri, 29 Sep 2006 03:19:38 +0000 http://cosmicvariance.com/?p=950#comment-122231 [...] - and finally, they say dark matter exists. cv 1, 2 Filed under: science — [...] [...] - and finally, they say dark matter exists. cv 1, 2 Filed under: science — [...]

]]> By: Dark Energy Exists « View From a New Vrindaban Ridge http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-122103 Dark Energy Exists « View From a New Vrindaban Ridge Thu, 28 Sep 2006 12:43:00 +0000 http://cosmicvariance.com/?p=950#comment-122103 [...] Dark Matter Exists [...] [...] Dark Matter Exists [...]

]]> By: Norwegian Wood » Blog Archive » dark matter http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-121776 Norwegian Wood » Blog Archive » dark matter Wed, 27 Sep 2006 04:12:07 +0000 http://cosmicvariance.com/?p=950#comment-121776 [...] 听完报告后想起前不久在cv上看到的一篇证实dark matter存在的文章, 很值得一读. 不过看后感觉给dark matter所赋予的性质太玄乎了, 很有点像当年发现电磁波时的以太… [...] [...] 听完报告后想起前不久在cv上看到的一篇证实dark matter存在的文章, 很值得一读. 不过看后感觉给dark matter所赋予的性质太玄乎了, 很有点像当年发现电磁波时的以太… [...]

]]> By: Simonomics » Blog Archive » Dark Matter http://cosmicvariance.com/2006/08/21/dark-matter-exists/#comment-121008 Simonomics » Blog Archive » Dark Matter Sun, 24 Sep 2006 02:29:27 +0000 http://cosmicvariance.com/?p=950#comment-121008 [...] So for my first proper post I would like to talk about a recent development in science that I have read a few articles about recently: the finding of concrete proof for the existence of Dark Matter. For those who don’t know, the concept of Dark Matter arose in response to a long-standing cosmological problem. Essentially, the large star clusters known as galaxies do not seem from observation to contain enough mass to produce the gravity required to keep the galaxies themselves bound together. In other words, the amount of observable matter in these galaxies is not nearly high enough to keep the galaxies from dissolving (as more mass creates higher gravitational pull). However, the fact that the galaxies do not in fact drift apart means that either gravity must work differently over long distances (alternative gravity theory) or that the galaxies are in fact filled with huge amounts of invisible matter (Dark Matter). Neither theory had ever had much evidence to support it, until very recently. By studying the gravitational interactions between stars in far off galaxies (using a technique called gravitational lensing) scientists believe that they have found proof of the existence of Dark Matter. A good explanation of the experiment can be found here. What is also interesting is the response issued by proponents of the special gravity theory, which can be viewed here. The technical details of it is still a bit beyond me, but its a very interesting topic that has been a mystery for a long time, and I have found it fascinating to read about over the past few weeks. [...] [...] So for my first proper post I would like to talk about a recent development in science that I have read a few articles about recently: the finding of concrete proof for the existence of Dark Matter. For those who don’t know, the concept of Dark Matter arose in response to a long-standing cosmological problem. Essentially, the large star clusters known as galaxies do not seem from observation to contain enough mass to produce the gravity required to keep the galaxies themselves bound together. In other words, the amount of observable matter in these galaxies is not nearly high enough to keep the galaxies from dissolving (as more mass creates higher gravitational pull). However, the fact that the galaxies do not in fact drift apart means that either gravity must work differently over long distances (alternative gravity theory) or that the galaxies are in fact filled with huge amounts of invisible matter (Dark Matter). Neither theory had ever had much evidence to support it, until very recently. By studying the gravitational interactions between stars in far off galaxies (using a technique called gravitational lensing) scientists believe that they have found proof of the existence of Dark Matter. A good explanation of the experiment can be found here. What is also interesting is the response issued by proponents of the special gravity theory, which can be viewed here. The technical details of it is still a bit beyond me, but its a very interesting topic that has been a mystery for a long time, and I have found it fascinating to read about over the past few weeks. [...]

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