Time travel has shifted from pure fantasy to a serious, if highly constrained, topic in modern physics. The equations that describe gravity, quantum fields and the structure of spacetime now allow ...

Imagine a thread so thin it's invisible to the naked eye but packed with the mass of thousands of stars. This isn't science fiction—it's the theoretical description of cosmic strings, structures that ...

From H. G. Wells's The Time Machine to Christopher Nolan's Interstellar, the possibility of travelling through time has fascinated people for centuries. But, although it sounds like pure science ...