Albert Einstein warns President Roosevelt that uranium nuclear chain reactions could produce vast energy and powerful bombs, and recommends the U.S. government maintain contact with physicists working on this research and secure uranium supplies, noting Germany has already halted uranium exports from Czechoslovakia.
Researchers at ETH Zurich and the Paul Scherrer Institute have produced a cold beam of muonium atoms to test whether gravity acts equally on exotic matter as it does on ordinary matter, a fundamental principle of Einstein's theory. By measuring the gravitational behavior of these second-generation particles for the first time, they aim to detect any deviations that could indicate an unknown fundamental force.
Physicist Carlo Rovelli's new book argues that modern physics—relativity and quantum mechanics—reveals we cannot achieve an ultimate, objective understanding of reality independent of observation. Instead, Rovelli proposes that all properties are relational, existing only in connection to other things, fundamentally rejecting the notion that physics can exhaust what can be known about the world.