Does A Black Hole Destroy Information?
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Does a black hole destroy information?
It depends on what the word means. A new philosophy paper uses a famous 2007 thought experiment, in which a black hole behaves like a mirror, to pin the meaning down.
Whether a black hole destroys information depends on the word. In everyday speech information is news, a fact, the contents of a diary: something that means something to someone. Physicists use the same word for at least three other things, and arguments about black holes have often slid between them. A paper posted on 20 October by two researchers at the University of Amsterdam sets out to keep them apart.
Sourced · Corbeel & De Haro, arXiv:2610.28185In 1948 the engineer Claude Shannon made information countable. His unit, the bit, is the answer to one yes-or-no question. Twenty answers pick out one message from 1,048,576 possibilities, whatever the message says. Meaning drops out; only the count remains. The quantum unit is the qubit, which can hold a blend of yes and no and can be linked to other qubits so that their outcomes depend on one another. That link is called entanglement.
Sourced · Shannon, "A Mathematical Theory of Communication" (1948) · Observed · 2²⁰ = 1,048,576In 1973 Jacob Bekenstein argued that a black hole has entropy, a count of the inner arrangements that look the same from outside, and that it grows with the area of the horizon, the boundary past which nothing returns. In bits, a black hole the mass of the Sun holds about 1.5 × 10⁷⁷. Bekenstein read the number as what an outsider does not know. Critics replied that a black hole's physics should not depend on anyone's knowledge. The new paper sides with the critics and grounds the count in physics instead.
Sourced · Bekenstein 1973; Dougherty & Callender 2017, as discussed in arXiv:2610.28185 §2.1 · Observed · the bit count is our calculationThe physicist John Wheeler went further. His 1989 slogan "It from bit" proposed that matter is information at bottom. The philosopher Christopher Timpson argues the opposite: information is abstract and exists only when something physical carries it. A tune is a fair comparison; the same one can be whistled or played on a piano. The same pattern of bits can sit in ink, in light or in a magnet. On this view information has no path of its own through space. Only its carriers do.
Sourced · Wheeler 1989 and Timpson 2013, as cited in arXiv:2610.28185 pp. 7–8, 36 · the tune comparison is oursIn 1974 Stephen Hawking calculated that black holes glow faintly and shrink. In 1976 he argued that the glow, now called Hawking radiation, carries no trace of what fell in. If so, information in Shannon's sense is destroyed. Quantum mechanics says that never happens: any process can, in principle, be run backward to recover where it started. Physicists have argued for fifty years over which gives way. This is the black hole information paradox.
Sourced · Hawking, Nature 248, 30 (1974); Phys. Rev. D 14, 2460 (1976)In 2007 the physicists Patrick Hayden and John Preskill asked a narrower question. Suppose a black hole is an ordinary quantum system, an assumption now called the central dogma. Alice drops a diary of a few qubits into an old black hole, one that has already radiated away about half of what it can hold. Bob, outside, has collected all the radiation it gave off before. How long until Bob can read the diary?
Sourced · Hayden & Preskill, JHEP 0709:120 (2007); arXiv:2610.28185 §4.1First the black hole scrambles the diary. Its internal dynamics spread the qubits' pattern across all its parts, so that no small piece holds any of it. Here entanglement works as protection: losing a few pieces loses nothing. The time this takes grows very slowly with the black hole's size. For one the mass of the Sun it comes to about a thousandth of a second.
Sourced · arXiv:2610.28185 §4.1.2, Eq. 7 · Observed · the millisecond is our calculation from that formulaThen the radiation gives it back. Bob needs only a few more qubits of new radiation than the diary held. Together with what he already collected, they are enough to rebuild the diary. Entanglement does its second job here, as a resource Bob uses up in decoding. Hayden and Preskill wrote that such a black hole "is hardly black at all; it might more accurately be regarded as a kind of information mirror."
Sourced · Hayden & Preskill 2007, Sec. 2; arXiv:2610.28185 Eq. 18The new paper lists the mirror's catches. The copy is approximate. It reflects only for an observer already entangled with the black hole, which is why Bob's collection matters. And the moment the diary becomes readable in principle is not the moment anyone could finish decoding it. A fourth follows from the arithmetic: no black hole is old yet. One the mass of the Sun would take about 2 × 10⁶⁷ years to evaporate; the universe is about 1.4 × 10¹⁰ years old.
Sourced · arXiv:2610.28185 p. 38 · Observed · the evaporation time is our calculation from Hawking's formulaSo which information comes back? Corbeel and De Haro's answer is the measured kind, used as a tool. The model treats the black hole as a channel that stores, processes and sends quantum states, and asks how much, how fast and on what conditions. It needs information to be neither anyone's ignorance nor the stuff of the world. What changes over time is how the diary's pattern is spread, and which pieces, taken together, can rebuild it.
Sourced · arXiv:2610.28185 §§2.2, 4.3, 4.4None of this settles the physics. The central dogma has passed consistency tests but remains unproven, and the authors call Bob's total control of the radiation "clearly unfeasible" for real black holes. Calculations since 2019 that compute the radiation's entropy from gravity have produced results compatible with the central dogma, which keeps it open without proving it. The paper is a preprint, a review written for philosophers, and its physics is nineteen years old.
The modest view has its critics. Readers drawn to Wheeler will say a tool that works this well is a clue to what the world is made of. And the authors' own footnote points to a 2026 paper by De Haro and colleagues arguing that in quantum gravity, information also plays "a substantive semantic and physical role." How modest information should stay is not settled, even among them.
The paper does not solve quantum gravity; it makes one word usable while the physics stays open. When a headline says a black hole destroys or returns information, the first question is which of the four senses the sentence means. The term to search is the Hayden–Preskill protocol.
Sourced — Corbeel & De Haro, "Black Holes are about Quantum Information", arXiv:2610.28185 (preprint, 20 Oct 2026) · Hayden & Preskill, "Black holes as mirrors: quantum information in random subsystems", JHEP 0709:120 (2007) · Hawking, Nature 248, 30 (1974) · Hawking, Phys. Rev. D 14, 2460 (1976) · Bekenstein, Phys. Rev. D 7, 2333 (1973) · Shannon, Bell System Technical Journal 27 (1948) · Wheeler (1989), Timpson (2013), Dougherty & Callender (2017), as cited by Corbeel & De Haro. Observed — the bit count (≈1.5 × 10⁷⁷), scrambling time (≈1 ms) and evaporation time (≈2 × 10⁶⁷ yr) for a black hole of one solar mass are our calculations from the standard formulas. Diagrams are schematic.