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A complete classification could lead to a wealth of new materials and technologies. But some exotic phases continue to resist understanding.
The mother of all string theories passes a litmus test that, so far, no other candidate theory of quantum gravity has been able to match.
Updated results from a Japanese neutrino experiment continue to reveal an inconsistency in the way that matter and antimatter behave.
It weighs as much as 780 million suns and helped to cast off the cosmic Dark Ages. But now that astronomers have found the earliest known black hole, they wonder: How could this giant have grown so big, so fast?
Edward Witten reflects on the meaning of dualities in physics and math, emergent space-time, and the pursuit of a complete description of nature.
A number of high-energy anomalies raised hopes that astrophysicists had seen their first direct glimpses of dark matter. New studies suggest a different source may be responsible.
Astronomers are mystified by a strange star explosion in a distant galaxy that might be a relic from an earlier cosmological era.