Posted on by Mark Thompson

This Particle Only Has Mass When Moving in One Direction

The quasiparticle, called a semi-Dirac fermion, was first theorized 16 years ago, but was only recently spotted inside a crystal of semi-metal material called ZrSiS. The observation of the quasiparticle opens the door to future advances in a range of emerging technologies from batteries to sensors, according to researchers who made the discovery. Credit: Yinming Shao / Penn State

Particle physics is not everyone’s cup of tea.  A team of physicists have theorised the existence of a strange type of particle that behaves differently depending on its direction of travel—massless in one direction but possessing mass when moving the other way! This strange, elusive particle, known as a semi-Dirac fermion or “quasiparticle,” has actually been observed in action. To detect it, researchers cooled a semi-metal crystal to near absolute zero, exposed it to a powerful magnetic field and infrared light, and successfully captured the signal of these unusual quasiparticles.

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