Something in the Dark — Have We Finally Seen Dark Matter?

<p>This episode looks at a science story that proved difficult to set aside: the possibility that dark matter may have been directly detected for the first time — not in space, but 1.5 kilometers underground in South Dakota, inside a facility called LUX-ZEPLIN, surrounded by roughly ten tonnes of ultra-pure liquid xenon.</p><p><br></p><p>The detection itself was a single collision event. One candidate interaction, sitting at 2.6 sigma — well short of the 5 sigma threshold physics requires to call something a discovery. There&#39;s an analogy offered here: someone searching for a Yeti finds a single footprint that looks about right. Worth paying attention to. But one footprint isn&#39;t a Yeti.</p><p><br></p><p>It touches on the sheer scale of what dark matter represents — roughly 85 percent of all matter in the universe, with ordinary matter, everything we can see and touch, accounting for only around 5 percent of everything that exists. The numbers are the kind that don&#39;t quite settle after you read them.</p><p><br></p><p>There&#39;s also a thread running through the episode connecting this to The Three-Body Problem, and to the longer pattern of basic science arriving somewhere unexpected — how people working out electricity couldn&#39;t have imagined a smartphone, and people doing early quantum mechanics couldn&#39;t have foreseen the computer.</p><p><br></p><p>A quiet look at one collision in the dark, and the thought that it might — eventually, if more like it follow — turn out to be the first moment humanity touched a part of the universe it had never reached before.</p>