Particle detector Calculations suggest that millicharged dark matter could be detected by observing its interaction with Earth’s magnetic field. (Courtesy: Shutterstock/Milagli)"> Particle detector Calculations suggest that millicharged dark matter could be detected by observing its interaction with Earth’s magnetic field. (Courtesy: Shutterstock/Milagli) Analysis by physicists in China suggest that if dark matter carries even a tiny electric charge, it will generate a magnetic “hum” in Earth’s geomagnetic field. And what is more, data from existing magnetometer networks can already constrain this effect. Dark matter is one of the biggest open questions in modern physics. Astronomers infer the existence of hypothetical dark-matter particles from their gravitational influence. The invisible presence of dark matter explains why galaxies rotate too rapidly for their visible mass, for example. Also, the gravitational lensing of starlight suggests a similar invisible mass in galaxy clusters.…