The polarization of the cosmic microwave background (CMB) may shed light on the nature of dark matter and dark energy, and on the origin of all structures in the Universe. Discovering a signature of such new physics in the CMB will require new observational and calibration strategies for future CMB experiments.

Living cells use geometric, biochemical and mechanical guiding cues to control intracellular protein patterns that regulate many vital functions. This Review discusses mechanisms of pattern guidance unveiled in living cells and how to study them from a physics perspective.

The standard Hamiltonian approach to quantum field theory violates Poincaré invariance, leading to predictions with artificial dynamical effects and potentially obscuring the fundamental description of a physical system. This Perspective explains how such issues are avoided by using light-front Hamiltonian quantization.

Active matter encompasses various non-equilibrium systems in which individual constituents convert energy into non-conservative forces or motion at the microscale. This Review provides an elementary introduction to the role of topology in active matter through experimentally relevant examples.