Astronaut Charles Conrad Jr, commander of the Apollo 12 mission, on the surface of the moon. He has lunar soil on his spacesuit, especially around the knees and below (Image: Johnson Space Center Collection, NASA)

EVER since a 1998 space shuttle experiment saw what appeared to be an anomalously heavy variety of matter, the hunt has been on for more of the same. Now, a search of lunar soil for so-called “strange matter” has come up short, casting doubt on whether it exists at all.

The standard model of particle physics describes six types of quark, including the up and …