Heat Flows Backward
Water in a glass cools, ice melts, and a kettle heats the stove: that's how the world works: heat always flows from hot to cold. This is the second law of thermodynamics, a law that has never been broken.
The Invisible Star at the Center of the Galaxy
At the center of the Milky Way lurks something invisible but extremely massive — about four million times heavier than the Sun. It is usually called a black hole and designated Sagittarius A*. But astronomers are not letting their guard down: what if it is not a hole but something more exotic, like a giant ball of ultralight particles — a boson star?
Stellar Mimicry: Boson Stars Pretend to Be Black Holes
The cosmos is full of mimicry. The clearwing moth wears a wasp's mask, a harmless fly buzzes like a bee. And in the world of gravity, the role of impersonator is perhaps played by boson stars — colossal clumps of scalar field, indistinguishable from black holes.
An X-ray flash that heralded a supernova
A massive star ends its life in a spectacular collapse: the core compresses into a neutron star or a black hole, while the outer layers fly off in a dazzling supernova.