Last update: January 17, 2024

The Fountains of Creation: The Myth of White Holes

White hole, source of light and matter gushing into the cosmos

The Reverse of the Black Hole

Black holes are now a confirmed cosmic reality. They are gravitational monsters that capture all light and matter.

White holes are imagined as cosmic fountains: their impassable horizon from the inside would spew matter and energy into the cosmos. This concept remains one of the most poetic ideas in physics.

An Idea Born from Equations

The notion of a white hole emerges directly from the solutions to Albert Einstein's (1879-1955) equations. In the 1960s, while exploring the mathematical implications of general relativity, physicists realized that the equations describing a black hole were, from a purely theoretical standpoint, reversible in time.

A black hole is a region where the curvature of spacetime is so extreme that the future of every particle inevitably points toward the central singularity. If one reverses the arrow of time in these equations, one obtains the description of an object whose past points toward a singularity: that is, an object that would "expel" matter and light from a point of infinite density. This is the mathematical definition of a white hole.

The Problem of Real Existence

While white holes constitute a mathematically coherent solution, their physical existence is deemed highly unlikely, if not impossible, given the known laws of physics. The main obstacle is the entropy principle.

A white hole would be born in a highly ordered state (low entropy) and then expel disorder in the form of matter and energy, which seems to contradict the thermodynamic arrow of time, irreversibly oriented toward increasing disorder. Added to this is a fundamental instability: the slightest cosmic dust particle drifting in its direction would suffice to break its theoretical equilibrium and precipitate its collapse into a black hole.

Cosmic Hypotheses and Speculations

Despite these obstacles, white holes fuel fascinating speculations:

The Big Bang itself: Some physicists, such as cosmologist Andrei Sakharov (1921-1989), have suggested that the primordial Universe may have exhibited white hole characteristics, exploding from a singularity.
The "fountains" of quasars: In the 1970s, it was imagined that the immense jets emitted by active galactic nuclei could be linked to white hole-like mechanisms. This idea has largely been replaced by the model of an accretion disk around a supermassive black hole.
The exit of wormholes: In some theories, a traversable wormhole would have a black hole as an entrance and a white hole as an exit. This remains pure science fiction, as traversal would require "exotic matter" with negative energy density to keep the wormhole open.

The Impossible Quest: In Search of White Holes

How to search for an object that most physicists believe is impossible to observe? The search for white holes faces this paradox. It focuses on two fronts: the study of theoretical signatures and the analysis of unexplained cosmic events.

Researchers track unique signals. A genuine white hole would suddenly appear in the sky, emitting a titanic flash of radiation and particles before possibly collapsing. This would resemble a colossal energy explosion, with no apparent cause like a supernova.

Some astrophysicists have hypothesized that short, extremely energetic gamma-ray bursts could fit this profile. The mysterious FRB (Fast Radio Burst) or certain anomalies in the cosmic microwave background have also been considered as candidates. To date, no observation has been convincingly attributed to a white hole.