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Hubble constant

Lede art for "A Radically Conservative Solution for Cosmology’s Biggest Mystery": This Hubble image shows RS Puppis, a type of variable star known as a Cepheid variable. As variable stars go, Cepheids have comparatively long periods— RS Puppis, for example, varies in brightness by almost a factor of five every 40 or so days. RS Puppis is unusual; this variable star is shrouded by thick, dark clouds of dust enabling a phenomenon known as a light echo to be shown with stunning clarity. These Hubble observations show the ethereal object embedded in its dusty environment, set against a dark sky filled with background galaxies.
Abstractions blog

A Radically Conservative Solution for Cosmology’s Biggest Mystery

Two ways of measuring the universe’s expansion rate yield two conflicting answers. Many point to the possibility of new physics at work, but a new analysis argues that unseen errors could be to blame.

Illustration: man using rulers stacked on a compass as a telescope
insights puzzle

Solution: ‘Triangulation and Motion Sickness’

A method for estimating distances in sailing and astrophysics helps explain why riding on buses and boats can make us nauseous.

Illustration: man using rulers stacked on a compass as a telescope
insights puzzle

How Triangulation Leads to Knowledge

What does measuring distances in sailing and astrophysics have to with motion sickness?

Artist’s rendering of merging neutron stars.
cosmology

Colliding Neutron Stars Could Settle the Biggest Debate in Cosmology

Newly discovered “standard sirens” provide an independent, clean way to measure how fast the universe is expanding.