"The collaboration stopped short of claiming outright detection, opting to describe their results instead as strong evidence of the expected gravitational wave background. That said, "In our statistical analyses, there's a less than 1-in-1,000 chance of nature giving our results without gravitational waves being present," NANOGrav chair Stephen Taylor of Vanderbilt University said during a press briefing." (from the Ars Technica article)<p>That is <i>far</i> short of the usual 5-sigma (1-in-3,500,000) threshold. So I guess interesting results but not really a major discovery?