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theoretical physics

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Questioning Truth, Reality and the Role of Science

In an era when untestable ideas such as the multiverse hold sway, Michela Massimi defends science from those who think it hopelessly unmoored from physical reality.

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

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.

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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.

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

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

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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.

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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.

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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.