The discovery of dark matter would mean a major breakthrough in efforts to advance our understanding of the universe. This is why any hint of such a discovery is greeted with mounting excitement. It's also why such hints should be met with scepticism, writes Richard Panek.

An announcement of the possible discovery of dark matter—for instance, the one this past June 15 from the XENON1T collaboration that generated headlines around the world—merits either of two responses.

One is “Big deal.”

The other is “Big deal.”

The actual discovery of dark matter would in fact be a really big deal, one of the biggest in the history of physics. It would solve a mystery that has been plaguing cosmologists for nearly half a century, but more importantly, it would help validate a reinterpretation of the universe that renders everything we’d previously thought to be the cosmos in its entirety (galaxies, stars, planets, people, pixels) only four or five percent of what’s actually out there.