<story><title>Dark matter nightmare: What if we are just using the wrong equations?</title><url>http://backreaction.blogspot.com/2019/10/dark-matter-nightmare-what-if-we-just.html</url></story><parent_chain><item><author>philwelch</author><text>Yeah, maybe. The thing is, there are a lot of independent observations that match up really really well with the hypothesis, &amp;quot;there&amp;#x27;s a bunch of matter around that only interacts with us via gravity&amp;quot;. If our models are off, they would have to be off in exactly the right way to affect our observations of gravitational forces but not really anything else. Which may very well be the case--or it may be the case that baryonic matter isn&amp;#x27;t really the end-all be-all of the universe and we&amp;#x27;re just a bunch of baryonic chauvinists for thinking so because that&amp;#x27;s what we&amp;#x27;re made of ;)&lt;p&gt;Obviously, nobody knows for sure yet. But I would caution most fellow laymen not to rely too heavily on the intuition that says, &amp;quot;dark matter? pffft!&amp;quot; or even, &amp;quot;but what about all of those observations that didn&amp;#x27;t match Newtonian dynamics?&amp;quot;. Physicists (including the author here!) are generally smart enough to have thought of those objections themselves, which is why they&amp;#x27;ve spent decades trying really hard to disprove the notion of &amp;quot;dark matter&amp;quot; by compiling all of these anomalous observations. Sometimes the universe is just unintuitive, at least to dumb apes like us.&lt;p&gt;I&amp;#x27;m not saying you can&amp;#x27;t have a hunch that we&amp;#x27;re just doing the math wrong somehow; I just wouldn&amp;#x27;t be overly confident that&amp;#x27;s the case just yet.</text></item></parent_chain><comment><author>Certhas</author><text>Hossenfelder is refering to the ongoing discussion in the physicist community on this topic. Some of the giants of the field (Wald, Ellis) semi-regularly exchange papers on this.&lt;p&gt;It&amp;#x27;s not a hunch.&lt;p&gt;Green and Wald tried to proof that the inhomogeneities don&amp;#x27;t matter, others disagree that they proofed anything of the sort. It&amp;#x27;s a fairly robust debate, and I am not qualified to summarize the state of play. Here are some slides:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;cosmoback.sciencesconf.org&amp;#x2F;data&amp;#x2F;program&amp;#x2F;Ostrowski.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;cosmoback.sciencesconf.org&amp;#x2F;data&amp;#x2F;program&amp;#x2F;Ostrowski.pd...&lt;/a&gt;&lt;p&gt;Edit: The rebuttal paper to Green-Wald from three years ago already has 100 citations... &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;1505.07800&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;1505.07800&lt;/a&gt;&lt;p&gt;It&amp;#x27;s possible that the question will be settled in the next years through numerical simulations:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;journals.aps.org&amp;#x2F;prl&amp;#x2F;abstract&amp;#x2F;10.1103&amp;#x2F;PhysRevLett.116.251302&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;journals.aps.org&amp;#x2F;prl&amp;#x2F;abstract&amp;#x2F;10.1103&amp;#x2F;PhysRevLett.11...&lt;/a&gt;&lt;p&gt;Edit 2: All of this is for dark energy, for dark matter I don&amp;#x27;t know if there is a similar discussion on the role of the post-newtonian approximation that is used there.</text></comment>
<story><title>Dark matter nightmare: What if we are just using the wrong equations?</title><url>http://backreaction.blogspot.com/2019/10/dark-matter-nightmare-what-if-we-just.html</url></story><parent_chain><item><author>philwelch</author><text>Yeah, maybe. The thing is, there are a lot of independent observations that match up really really well with the hypothesis, &amp;quot;there&amp;#x27;s a bunch of matter around that only interacts with us via gravity&amp;quot;. If our models are off, they would have to be off in exactly the right way to affect our observations of gravitational forces but not really anything else. Which may very well be the case--or it may be the case that baryonic matter isn&amp;#x27;t really the end-all be-all of the universe and we&amp;#x27;re just a bunch of baryonic chauvinists for thinking so because that&amp;#x27;s what we&amp;#x27;re made of ;)&lt;p&gt;Obviously, nobody knows for sure yet. But I would caution most fellow laymen not to rely too heavily on the intuition that says, &amp;quot;dark matter? pffft!&amp;quot; or even, &amp;quot;but what about all of those observations that didn&amp;#x27;t match Newtonian dynamics?&amp;quot;. Physicists (including the author here!) are generally smart enough to have thought of those objections themselves, which is why they&amp;#x27;ve spent decades trying really hard to disprove the notion of &amp;quot;dark matter&amp;quot; by compiling all of these anomalous observations. Sometimes the universe is just unintuitive, at least to dumb apes like us.&lt;p&gt;I&amp;#x27;m not saying you can&amp;#x27;t have a hunch that we&amp;#x27;re just doing the math wrong somehow; I just wouldn&amp;#x27;t be overly confident that&amp;#x27;s the case just yet.</text></item></parent_chain><comment><author>lonelappde</author><text>I think you misread. Sabine is arguing that maybe dark matter is just the error term in our approximations of real matter, and pointing out that no one yet has actually taken the time to disprove  that Occam&amp;#x27;s Razor theory.</text></comment>