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 ...

Large masses – such as a galaxy – curve space-time. Objects move along a geodesic. If we take into account that space-time itself has quantum properties, deviations arise (dashed line vs. solid line).

Merging Einstein’s theory of gravity and quantum mechanics is one of the main outstanding problems of modern physics. A major challenge is the lack of experimental evidence for quantum gravity, with ...

Hoboken, NJ., January 15, 2026 - Modern physics has a problem. Its two main pillars are quantum theory and Einstein’s theory of general relativity, yet these two frameworks are seemingly incompatible.

A longstanding goal in physics has been to link general relativity with quantum theory and so unify the forces of nature. Theories of quantum gravity, however, are plagued by the weak theoretical ...

As far as we know, our physical world is governed by four fundamental forces: electromagnetism, weak and strong nuclear forces, and gravity. Apart from playing with bar magnets or marveling at the ...

But something else is special about gravity: we have only seen its "classical" version so far, whereas all other forces are explained by quantum theory. One of the holy grails of physics has long been ...

The gauge bosons of the standard model of particle physics are responsible for three of the four known forces in the universe, conveyed through the exchange of virtual bosons. In electromagnetism, the ...

Bottom line: For decades, physicists have been trying to solve one of the greatest mysteries in science: how gravity operates at the smallest scales governed by quantum mechanics. While we have ...

Renormalisation Group (RG) techniques provide a systematic framework to track the behaviour of coupling constants in physical theories as energy scales change. In quantum gravity, RG methods aim to ...

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of "Ask a Spaceman" and "Space Radio," and author of "How to Die in Space." Sutter contributed this article to ...