At long last, a unified theory combining gravity with the other fundamental forces—electromagnetism and the strong and weak nuclear forces—is within reach. Bringing gravity into the fold has been the ...

Gravity is one of four fundamental interactions. The most precise description of this force is still provided by Einstein's General Theory of Relativity, published in 1915, an entirely classical ...

The prevailing assumption has been that Einstein's theory of gravity must be modified, or 'quantized', in order to fit within quantum theory. This is the approach of two leading candidates for a ...

A new physics paper takes a step toward creating a long-sought "theory of everything" by uniting gravity with the quantum world. However, the new theory remains far from being proven observationally.

With the help of a new experiment, researchers have succeeded in confirming a ten-year-old theoretical study, which connects one of the most fundamental aspects of quantum mechanics -- the ...

Causal set theory proposes that spacetime is fundamentally composed of discrete elements ordered by a causal relation, replacing the smooth manifold of general relativity with a locally finite ...

The ball rolls across the floor because it was kicked, just as Earth orbits the sun because it is tugged by gravity. The connection between cause and effect is fundamental to how we understand the ...

Quantum theory is fundamentally a probabilistic description of nature in which the outcomes of measurements are governed by the Born rule and encoded in complex amplitudes or density operators. Beyond ...

The original version of this story appeared in Quanta Magazine. In the fall of 2022, a Princeton University graduate student named Carolina Figueiredo stumbled onto a massive coincidence. She ...

Physicists are making new inroads into the world of post-quantum theories, uncovering what reality may look like on a level deeper and stranger than the already infamously odd quantum theory. In the ...

To keep communications secure in a post-quantum world, cryptographers are digging down into the concept of cause and effect.