Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wrecK" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior. Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic “train wreck” between giant galaxy clusters. NASA’s Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior. "These results challenge our...