Pau Amaro Seoane

An ordinary black hole is the perfect devourer: everything that crosses its horizon disappears forever. But in recent decades, this picture has been cracking at the seams. The information paradox, singularities, firewalls: theorists are looking for a way out, and one candidate replacement is the black mirror.

In the early universe, just a few hundred million years after the Big Bang, astronomers see strange objects — little red dots. They are compact, red, and in their spectra, broad Balmer lines scream the presence of supermassive black holes. But how did the hole manage to accumulate millions of solar masses in such a short time?

At the very heart of the Milky Way, stars whirl around an invisible supermassive black hole. One of them, S301, completes an orbit in just 8.7 years. Its path is a highly squashed ellipse: sometimes it grazes the black hole, sometimes it shoots far away. At closest approach, the distance to the black hole is tiny by cosmic standards.