<story><title>A Jewel at the Heart of Quantum Physics</title><url>https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics</url></story><parent_chain><item><author>gruseom</author><text>Is anyone here familiar with this work? I would like to hear more about it. At a minimum, this article is very much better than the usual science blog filler—it contains signs of a genuine conceptual breakthrough. For example:&lt;p&gt;&lt;i&gt;“You can easily do, on paper, computations that were infeasible even with a computer before.”&lt;/i&gt;&lt;p&gt;That doesn&amp;#x27;t happen very often! Or this:&lt;p&gt;&lt;i&gt;[T]he new geometric approach to particle interactions removes locality and unitarity from its starting assumptions. The amplituhedron is not built out of space-time and probabilities; these properties merely arise as consequences of the jewel’s geometry. The usual picture of space and time, and particles moving around in them, is a construct.&lt;/i&gt;&lt;p&gt;That is exactly the kind of thing that happens when one model is replaced with a deeper one.</text></item></parent_chain><comment><author>ssivark</author><text>I&amp;#x27;ve been keenly following this area of research and have heard some of the talks and read some papers. I concur with the sketch given by @gaze.&lt;p&gt;1. The notion of &lt;i&gt;unitarity&lt;/i&gt; is a &amp;quot;common sense&amp;quot; rule that implies that you can consistently assign probabilities to possible outcomes in a quantum mechanical experiment (&lt;a href=&quot;http://en.wikipedia.org/wiki/Unitarity_%28physics%29&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Unitarity_%28physics%29&lt;/a&gt;)&lt;p&gt;2. The notion of &lt;i&gt;locality&lt;/i&gt; states that what happens on Jupiter better not affect how fast your code compiles this morning (or how experiments run on earth). This is an important postulate, because if this weren&amp;#x27;t true, we might as well give up on doing science as there would be arbitrarily many external influences we couldn&amp;#x27;t take into account.&lt;p&gt;All our experiments so far are perfectly consistent with these two principles. Quantum field theory is the brainchild of the marriage of unitarity  (from quantum mechanics) and the idea of locality (in field theory). Our world view today (&amp;quot;Standard model of particle physics&amp;quot;) is based on this.&lt;p&gt;In practice, calculating answers using this theory is painfully difficult. YOu will add up thousand pages worth of algebraic terms and then your answer will &amp;#x27;miraculously&amp;#x27; reduce to a few terms. This and other observations have inspired researchers to search for underlying structure... leading to what is now being called the &amp;#x27;amplitude revolution&amp;#x27; by some people.</text></comment>
<story><title>A Jewel at the Heart of Quantum Physics</title><url>https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics</url></story><parent_chain><item><author>gruseom</author><text>Is anyone here familiar with this work? I would like to hear more about it. At a minimum, this article is very much better than the usual science blog filler—it contains signs of a genuine conceptual breakthrough. For example:&lt;p&gt;&lt;i&gt;“You can easily do, on paper, computations that were infeasible even with a computer before.”&lt;/i&gt;&lt;p&gt;That doesn&amp;#x27;t happen very often! Or this:&lt;p&gt;&lt;i&gt;[T]he new geometric approach to particle interactions removes locality and unitarity from its starting assumptions. The amplituhedron is not built out of space-time and probabilities; these properties merely arise as consequences of the jewel’s geometry. The usual picture of space and time, and particles moving around in them, is a construct.&lt;/i&gt;&lt;p&gt;That is exactly the kind of thing that happens when one model is replaced with a deeper one.</text></item></parent_chain><comment><author>ISL</author><text>Physicist here: This has a higher probability of being important than your usual science blog material. The Simons Foundation is a serious entity, backed with serious funds.&lt;p&gt;Arkani-Hamed had some compelling things to say recently at a talk and colloquium at our university; looking forward to learning more.</text></comment>