Magazine

May-June 2021

Current Issue

May-June 2021

Volume: 109 Number: 3

Enormous collections of invisible dark matter are thought to have seeded the formation of galaxies in the early universe. This computer simulation, created by a team led by Hsi-Yu Schive of National Taiwan University in Taipei, maps dark matter based on its density to make its structure obvious. Despite substantial evidence for dark matter, nobody has yet detected it directly. In “Enter the Axion” (pages 158–165), physicist Chanda Prescod-Weinstein explores the increasingly popular idea that dark matter consists of particles called axions. Over large scales, axions could act like waves rather than collections of particles, producing the rippled forms seen on the cover. Prescod-Weinstein is studying the cosmological implications of this phenomenon and assisting efforts to determine whether axions really exist. (Cover image courtesy of H.-Y. Schive et al., with permission from Nature Physics. https://doi.org/10.1038/nphys2996)

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The Chicken, the Egg, and Plate Tectonics

Nicolas Coltice

Environment

Whole-planet models could upend our view of how geophysical forces shape the Earth.

Turning Junk into Us: How Genes Are Born

Emily Mortola, Manyuan Long

Biology Evolution

You are garbage. Don’t feel too bad, though—so is everyone else. Now, geneticists are learning what the junk in your genome has been doing all along.