Cross-scale turbulence in space plasmas: old concepts, recent findings, and future challenges

Turbulence, a fascinating and intricate phenomenon, has captivated scientists over different domains, mainly for its complex cross-scale nature spanning a wide range of temporal and spatial scales. Despite significant advances in theories and observations in the last decades, some aspects of turbulence still remain unsolved, motivating new efforts to understand its underlying physical mechanisms and refine mathematical theories along with numerical models. This topical review explores recent findings from the Parker Solar Probe mission, providing a distinctive opportunity to characterize solar wind features at varying heliocentric distances. Analyzing the radial evolution of magnetic and velocity field fluctuations across the inertial range, a transition has been evidenced from local to global self-similarity as proximity to the Sun increases. This behavior has been reconciled with magnetohydrodynamic theory revising an old concept by emphasizing the evolving nature of the coupling between fields. This offers inspiration for novel modeling approaches to understand open challenges in interplanetary plasma physics as the heating and acceleration of the solar wind, as well as, its evolution within the inner Heliosphere.