What's up in

theoretical physics

Illustration for "Mathematicians Explore Mirror Link Between Two Geometric Worlds"
geometry

Mathematicians Explore Mirror Link Between Two Geometric Worlds

Decades after physicists happened upon a stunning mathematical coincidence, researchers are getting close to understanding the link between two seemingly unrelated geometric universes.

520px illustration for black hole echoes
Quantized Columns

Black Hole Echoes Would Reveal Break With Einstein’s Theory

Gravitational waves have opened up new ways to test the properties of black holes — and Einstein’s theory of gravity along with them.

Photo of Stephen Hawking in 1979 in Princeton, New Jersey.
Abstractions blog

Why Stephen Hawking’s Black Hole Puzzle Keeps Puzzling

The renowned British physicist, who died at 76, left behind a riddle that could eventually lead his successors to the theory of quantum gravity.

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.

An illustration of gravity as particles
gravity

Physicists Find a Way to See the ‘Grin’ of Quantum Gravity

A recently proposed experiment would confirm that gravity is a quantum force.

520px photo of Joe Polchinski
Quantized Columns

Physicists Mourn Joe Polchinski, Developer of Deep Ideas and Paradoxes

The theoretical physicist Joe Polchinski, who died Feb. 2, left a tremendous professional and personal legacy, says a friend and collaborator.

520px illustration for the bounce model theory
cosmology

How the Universe Got Its Bounce Back

Cosmologists have shown that it’s theoretically possible for a contracting universe to bounce and expand. The new work resuscitates an old idea that directly challenges the Big Bang theory of cosmic origins.

520 Illustration for Quantum Gravity
Quantized Columns

Why an Old Theory of Everything Is Gaining New Life

For decades, physicists have struggled to create a quantum theory of gravity. Now an approach that dates to the 1970s is attracting newfound attention.

520px illustration of classification of phases
condensed matter physics

Physicists Aim to Classify All Possible Phases of Matter

A complete classification could lead to a wealth of new materials and technologies. But some exotic phases continue to resist understanding.