Scientists all over the world are searching for dark matter: an invisible, untouchable substance that holds our universe together. But they haven't found it. Are they chasing a ghost?For further reading, sign up for our newsletter here: http://vox.com/unexplainable-newsletterShow transcript and articles (including one about why we made this show now): http://vox.com/unexplainableEmail us! [email protected] read every email.Learn more about your ad choices. Visit podcastchoices.com/adchoices