<story><title>No, negative masses have not revolutionized cosmology</title><url>http://backreaction.blogspot.com/2018/12/no-negative-masses-have-not.html</url></story><parent_chain></parent_chain><comment><author>mbell</author><text>I&amp;#x27;m not a physicist, just an interested bystander but some of these arguments don&amp;#x27;t seem to hold water to me:&lt;p&gt;&amp;gt; There’s a more general point to be made here. The primary reason that we use dark matter and dark energy to explain cosmological observations is that they are simple.&lt;p&gt;&amp;gt; A creation term is basically a magic fix by which you can explain everything and anything.&lt;p&gt;Dark matter is an unknown &amp;#x27;substance&amp;#x27; that interacts only through gravity (weakly) and must have a very specific and complex distribution in the universe to &amp;#x27;work&amp;#x27;. That strikes me as neither &amp;#x27;simple&amp;#x27; nor much different than tossing a constant into an equation to make it work. Similarly Dark Energy is an unknown form of energy that in uniformly distributed through the universe, which to me is just a fancy way of saying &amp;quot;we added a constant to make it work&amp;quot;. In both cases I don&amp;#x27;t see how either are implicitly better than adding a &amp;#x27;creation term&amp;#x27;.</text></comment>
<story><title>No, negative masses have not revolutionized cosmology</title><url>http://backreaction.blogspot.com/2018/12/no-negative-masses-have-not.html</url></story><parent_chain></parent_chain><comment><author>duality</author><text>&amp;quot;[T]he gravitational interaction is exchanged by a spin-2 field, whereas the electromagnetic force is exchanged by a spin-1 field. Note that for this to be the case, you do not need to speak about the messenger particle that is associated with the force if you quantize it (gravitons or photons). It’s simply a statement about the type of interaction, not about the quantization. Again, you don’t get to choose this behavior. Once you work with General Relativity, you are stuck with the spin-2 field and you conclude: like charges attract and unlike charges repel.&amp;quot;&lt;p&gt;There was a bit of discussion about this on &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&amp;#x2F;item?id=18609375&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&amp;#x2F;item?id=18609375&lt;/a&gt; as well. Working through the exercise of how spin-2 mediated forces differ from spin-1 is a worthwhile exercise for those who are so inclined.</text></comment>