The nature of dark matter is one of the leading mysteries in modern astronomy

The name "dark matter" is essentially a placeholder for something astronomers know is there but can't yet thoroughly investigate.

Dark matter doesn't interact electromagnetically, so it doesn't absorb or give off light.

It doesn't seem to interact with ordinary matter or radiation at all, except through its gravitational influence.

Dark energy is a whole other story, involving the expansion rate of the universe, and we won't get into it here.

Scientists are using similar instruments and methods as a starting point for dark matter detectors.

The amount of background radiation has declined since the mid-20th Century but it's still higher than it was before we built those first bombs.

Modern metals are contaminated with nuclear fallout that lingers to this day .

Low-background steel is commonly recovered from shipwrecks at the bottom of the oceans.

Some scientific instruments, one in the U.S. and one in Europe are constructed in part from metal ingots recovered from the shipwreck.

The Cryogenic Dark Matter Search (CDMS) in Minnesota is constructed from lead ingots retrieved from an 18th Century wreck.