Topic Cluster

Black Holes

From the laboratory that glimpsed Hawking radiation to the question of whether the observable universe is itself one — a complete reading list on the strangest objects in physics.

A black hole is the simplest object in the universe — defined entirely by three numbers: mass, electric charge, and angular momentum. It is also, by every measure that matters, the strangest. Inside the event horizon, the geometry of spacetime is so warped that time itself behaves as a spatial dimension. No information escapes. No light returns. And yet, slowly and inevitably, every black hole evaporates.

The mathematics of black holes was worked out by Karl Schwarzschild in 1916, weeks after Einstein published general relativity and while Schwarzschild was dying of an autoimmune disease on the Russian front. For nearly fifty years afterward, most physicists assumed the singularity he had described was a mathematical artifact rather than a physical object. It is not. The Event Horizon Telescope has now imaged the photon ring around two of them — M87* and Sagittarius A* — and the predictions of general relativity hold to better than five percent.

What follows is what we currently know, and what we are still arguing about. How does a black hole die? Stephen Hawking proved in 1974 that an event horizon must radiate a faint thermal spectrum, slowly losing mass until the entire object evaporates. In 2025, a laboratory in Israel observed the analog of that radiation in a system of ultracold atoms — the first direct confirmation. What lives inside the singularity? Possibly another universe: a one-page 1972 paper by Raj Kumar Pathria proposed that our entire observable cosmos sits inside the event horizon of a larger one, and the idea has matured into a serious branch of theoretical cosmology. And how do black holes form in the first place? The collapsing cores of massive stars — the same supernovae we now observe in real time, with polarized spectra revealing the shape of the blast.

The articles below cover each of these threads, with sources traced back to peer-reviewed papers in Nature, Physical Review Letters, and the Astrophysical Journal. They can be read in any order.

6 Articles
Event Horizon Telescope image of Sagittarius A*, the supermassive black hole at the centre of the Milky Way Astrophysics · Black Holes · Quantum Gravity

How Black Holes Eventually Die — And the Lab That Glimpsed It Happening

In 1971, Stephen Hawking proved a theorem stating that the surface area of a black hole's event horizon can never decrease. Three years later, he proved himself wrong. The mechanism that makes black holes die has now been observed — not in the sky, but in a chilled laboratory in Israel.

April 30, 2026 14 min read
Event Horizon Telescope reconstruction of the black hole at the centre of M87 Cosmology · Black Holes · Theoretical Physics

What If Every Black Hole Contains a Universe?

In 1972, the Indian-American physicist Raj Kumar Pathria published a one-page paper in Nature with a single audacious suggestion: the observable universe and a black hole may, mathematically, be the same kind of object. Half a century later, the idea has matured into a serious branch of theoretical cosmology.

April 28, 2026 14 min read
SN 2024ggi supernova in NGC 3621 observed by VLT and ATLAS Astrophysics · Supernovae · Stellar Evolution

We Caught a Star Exploding — and Saw the Shape of the Blast for the First Time

On April 11, 2024, ATLAS detected a supernova within hours of explosion. A Beijing team raced to commandeer the VLT in Chile to measure its geometry — and what they found may rewrite 50 years of theory about how stars die.

May 17, 2026 16 min read
Bow shock around dead star RXJ0528+2838 imaged by ESO VLT Signals & Anomalies · ESO Discovery

The Dead Star That Shouldn't Be Breathing — And Is

According to everything physicists know, RXJ0528+2838 should not have a shock wave around it. It does — and 12 institutions across seven countries cannot explain why.

April 20, 2026 13 min read
Artist's impression of two black holes in the final inspiral phase before merger, emitting gravitational waves across spacetime Astrophysics · Black Holes · Gravitational Waves

The Day Two Black Holes Released More Energy Than Every Star in the Observable Universe Combined

On September 14, 2015, LIGO recorded the final 0.2 seconds of a collision that had been a billion years in the making. The peak luminosity exceeded the combined light output of every star in every galaxy in the observable cosmos by a factor of fifty.

May 25, 2026 14 min read
Artist's impression of Betelgeuse and its newly discovered companion star, Betelbuddy, orbiting within the red supergiant's outer atmosphere Astrophysics · Stellar Evolution · Red Supergiants

The Closest Star About to Explode Has a Hidden Companion

Betelgeuse is 650 light-years away, one thousand times the diameter of the Sun, and visibly twinkling above your head every clear winter night. For decades it has confused astronomers with cycles no one could explain. In 2024, two teams finally found why — and it is a small star, hidden in the glare.

May 27, 2026 15 min read