Does an evaporating black hole tunnel into a white hole?
In plain words
Some quantum gravity models predict that the collapsed matter bounces back, turning the black hole into a white hole that releases what fell in. The predicted lifetime, and therefore any observable signal, depends on poorly controlled quantum effects.
Precise statement
Loop quantum gravity and related models propose a quantum transition from black hole to white hole (Haggard and Rovelli 2014) with a lifetime scaling between $M^{2}$ and $M^{3}$ in Planck units. Compute the transition amplitude from a well-defined quantum gravity path integral and determine whether this channel dominates over Hawking evaporation. Answer yes or no, with the lifetime as a function of $M$.
What would settle it
A controlled amplitude calculation fixing the tunneling lifetime, compared with the Hawking evaporation time of order $G^{2} M^{3}/(\hbar c^{4})$.
Status in the literature
Unverified note
Lifetime estimates remain model-dependent as of 2026.
Related problems
- Special case of What remains after a black hole evaporates to the Planck scale?