An initially spherical silicon oil droplet (0.2 mm) submerged in water gradually deforms into a pendant droplet (red line) after a water-ice solidification front (not shown) advances at a slow rate from right to left to engulf the deformed droplet.

The American Physical Society (APS), publisher of the Physical Review journals, is joining more than 20,000 individuals and organizations across 160 countries in a commitment to improve how researchers and their contributions to the scientific record are evaluated. APS is proud to mark the 10th anniversary of the Declaration on Research Assessment (DORA) by officially signing on to the international initiative.

Positronium, a bound system consisting of an electron and a positron, provides a platform for studying a wide variety of physical effects, ranging from tests of the equivalence principle to diagnostic applications in medicine. This Colloquium gives an overview of the current state of positronium physics, with an equal emphasis on fundamental and applied physics.

View an interview with PRX Life Lead Editor Margaret Gardel and Managing Editor Serena Bradde from the 2023 APS March Meeting for more information on the journal.