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Art for "Dark Energy May Be Incompatible With String Theory"
theoretical physics

Dark Energy May Be Incompatible With String Theory

A controversial new paper argues that universes with dark energy profiles like ours do not exist in the “landscape” of universes allowed by string theory.

Photo of the sun
Abstractions blog

What Is the Sun Made Of and When Will It Die?

If and when physicists are able to pin down the metal content of the sun, that number could upend much of what we thought we knew about the evolution and life span of stars.

Illustration of a galaxy simulation.

The Universe Is Not a Simulation, but We Can Now Simulate It

Computer simulations have become so accurate that cosmologists can now use them to study dark matter, supermassive black holes and other mysteries of the real evolving cosmos.

Photo of inside the MiniBooNE tank
Abstractions blog

Evidence Found for a New Fundamental Particle

An experiment at the Fermi National Accelerator Laboratory near Chicago has detected far more electron neutrinos than predicted — a possible harbinger of a revolutionary new elementary particle called the sterile neutrino, though many physicists remain skeptical.

Photo of Large Magellan Cloud rotating clockwise.
Abstractions blog

What Astronomers Are Learning From Gaia’s New Milky Way Map

A roundup of some of the most important discoveries gleaned so far from the Gaia space observatory’s new map of the galaxy.

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 for first stars

Whisper From the First Stars Sets Off Loud Dark Matter Debate

A surprise discovery announced a month ago suggested that the early universe looked very different than previously believed. Initial theories that the discrepancy was due to dark matter have come under fire.

Illustration of a bowl of dark energy on a weighing scale
Abstractions blog

Why the Tiny Weight of Empty Space Is Such a Huge Mystery

The amount of energy infusing empty space seems too small to explain without a multiverse. But physicists have at least one alternative left to explore.

520px illustration of bottle beam
nuclear physics

Neutron Lifetime Puzzle Deepens, but No Dark Matter Seen

Two methods of measuring the neutron’s longevity give different answers, creating uncertainty in cosmological models. But no one has a clue what the problem is.