<story><title>The Case Against Dark Matter</title><url>https://www.quantamagazine.org/20161129-verlinde-gravity-dark-matter/</url></story><parent_chain><item><author>bambax</author><text>&amp;gt; &lt;i&gt;Physicists do not like magic; when other cosmological observations seemed far easier to explain with dark matter than with MOND, they left the approach for dead.&lt;/i&gt;&lt;p&gt;But how is &amp;quot;dark matter&amp;quot; not magic?&lt;p&gt;To my untrained and pretty ignorant eye, dark matter looks like filler: the observation does not match the theory, and so, instead of looking for a better theory, we decided the observation was wrong and couldn&amp;#x27;t see what was there (and not just a little bit, but the greatest part of it).&lt;p&gt;Isn&amp;#x27;t that the definition of superstition? Invisible forces that explain events, in mysterious ways?</text></item></parent_chain><comment><author>raattgift</author><text>&amp;quot;Invisible forces that explain events, in mysterious ways&amp;quot;&lt;p&gt;The cold dark matter component of the standard cosmology is not the first time anomalous momentum was attributed to invisible (as in, does not experience electromagnetism) matter.&lt;p&gt;Twenty-six or so years from proposal (which incidentally was about two years before the discovery of the neutron) to direct detection:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.wikiwand.com&amp;#x2F;en&amp;#x2F;Neutrino#&amp;#x2F;History&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.wikiwand.com&amp;#x2F;en&amp;#x2F;Neutrino#&amp;#x2F;History&lt;/a&gt;&lt;p&gt;Note that neutrinos are hot dark matter; hot because they move quickly compared to the speed of light.&lt;p&gt;While neutrinos are definitely part of the dark matter sector, they cannot be the sole component because their hotness would smear out galaxies.   A colder neutrino would work very well to match all the observations associated with observed anomalous momentum that strongly suggests dark matter, and hunts are on for direct detections of a cold (implying high rest-mass) neutrino-like particle.&lt;p&gt;There are other options, of course, but the four key things are: there is non-ignorable anomalous momentum; matter generates momentum (in this case, through gravitation); there is no visible matter associated with the momentum in question (that&amp;#x27;s why it&amp;#x27;s anomalous); and we have discovered non-visible matter in the past while trying to explain other cases of anomalous momentum.</text></comment>
<story><title>The Case Against Dark Matter</title><url>https://www.quantamagazine.org/20161129-verlinde-gravity-dark-matter/</url></story><parent_chain><item><author>bambax</author><text>&amp;gt; &lt;i&gt;Physicists do not like magic; when other cosmological observations seemed far easier to explain with dark matter than with MOND, they left the approach for dead.&lt;/i&gt;&lt;p&gt;But how is &amp;quot;dark matter&amp;quot; not magic?&lt;p&gt;To my untrained and pretty ignorant eye, dark matter looks like filler: the observation does not match the theory, and so, instead of looking for a better theory, we decided the observation was wrong and couldn&amp;#x27;t see what was there (and not just a little bit, but the greatest part of it).&lt;p&gt;Isn&amp;#x27;t that the definition of superstition? Invisible forces that explain events, in mysterious ways?</text></item></parent_chain><comment><author>sidek</author><text>But the motivation behind dark matter is deeper than its gravitational observations. For instance, almost all particles physicists believe the standard model of particles is incomplete. No one is really sure exactly what we need to add to the standard model, but it turns out that if you add things to it in any sensible way, you almost always get things that look like they could explain dark matter.&lt;p&gt;So, it&amp;#x27;s more: particle physicists all believe the real theory has this aspect; when we look at gravity it looks like it had this aspect; therefore we should probably find a way to modify our theory so it has this aspect.&lt;p&gt;The major reason we haven&amp;#x27;t been able to go further than this is because we haven&amp;#x27;t been able to pin down exactly what these new particles are. Particle experiments are &amp;#x2F;hard&amp;#x2F; (see:LHC), and it might take a long time.</text></comment>