Information Cannot Be Destroyed

Leonard Susskind’s The Black Hole War tells one of the great intellectual dramas of the twentieth century: a decades long battle between Susskind and Stephen Hawking over whether information swallowed by a black hole is lost forever. The book is brilliant, combative, and honest. It is also, in one crucial respect, incomplete. Because the man who loaded the first round in that war was not a Stanford luminary or a Cambridge icon. He was an unflinching Israeli theorist named Jacob Bekenstein, and the weapon he forged was an equation scribbled in a Princeton doctoral thesis in 1972.

Bekenstein was born in Mexico City in 1947 to Polish Jewish parents who had emigrated from Europe. He grew up in the United States, studied at the Polytechnic Institute of Brooklyn, and arrived at Princeton to work under the legendary John Archibald Wheeler. It was Wheeler who posed the question that would define Bekenstein’s career: what happens to entropy when matter falls into a black hole? The prevailing answer was nothing. Black holes were understood as cosmic drains. Whatever fell in was gone, its information erased from the universe’s ledger.

Bekenstein disagreed. In his doctoral thesis he proposed something radical: that a black hole possesses entropy, and that this entropy is proportional to the area of its event horizon. The idea was elegant and unsettling. It meant black holes were not featureless voids but thermodynamic objects, each one carrying a precise record of everything it had consumed. The universe, Bekenstein argued, keeps its books.

Stephen Hawking thought the idea was wrong. He became, in Bekenstein’s own words, a leader of the vociferous opposition to black hole thermodynamics. Hawking set out to disprove it and, in one of science’s great ironies, ended up confirming it. His 1974 calculation showed that black holes do radiate energy, the phenomenon now called Hawking radiation, which only made sense if Bekenstein’s entropy formula was correct. But that confirmation opened a deeper wound. If black holes radiate and eventually evaporate, what happens to the information encoded on the horizon? Is it destroyed? Hawking said yes. Susskind said no. And so the war began.

It lasted nearly three decades. On one side, Hawking and much of the theoretical establishment, arguing that black holes were furnaces that burned information to ash. On the other, Susskind and a smaller band of dissenters, insisting that the laws of quantum mechanics were inviolable and that information must survive.

The resolution, when it finally came, vindicated Susskind. Information is not destroyed. It is encoded, scrambled, dispersed across the boundary of spacetime, but never annihilated. From this insight came what physicists now call the holographic principle: all the information contained within a volume of space can be described by data on the surface enclosing it. Reality, at its most fundamental level, is a hologram.

And the seed of all of it was planted by a man who, in 1974, immigrated to Israel.

Bekenstein spent four decades at Israeli institutions. First at Ben Gurion University of the Negev in Beersheba, where he became a full professor and led the astrophysics department. Then, from 1990, at the Hebrew University of Jerusalem, where he chaired theoretical physics. He was elected to the Israel Academy of Sciences and Humanities. He received the Israel Prize in 2005 and the Wolf Prize in 2012, the latter often a precursor to the Nobel. The American Physical Society awarded him its Einstein Prize in 2015. He died that same year, suddenly, of a heart attack in Helsinki, where he had travelled to give a lecture. He was sixty eight.

The Nobel committee does not award its prizes posthumously. Bekenstein’s original insight came at Princeton, but his four decades of subsequent work, including the Bekenstein bound and the theoretical architecture that cemented his name alongside Hawking’s in the entropy formula, were done at Israeli institutions. That administrative detail may have cost Israel its first Nobel in physics.

The table below tells its own story. Israel has fourteen Nobel laureates across chemistry, economics, literature and peace, more per capita than Germany or the United States. In physics it has none.

Nobel Prize in Physics: Laureates by Country, 1901 to 2025

Source: NobelPrize.org; dual nationals counted for each country. Totals include 2024 (Hopfield, Hinton) and 2025 (Clarke, Devoret, Martinis).

Bekenstein’s central insight, the one that Susskind spent decades defending and Hawking eventually conceded, carries a weight that reaches well beyond physics. Information cannot be destroyed. Not by a black hole, not by the passage of time, not by those who would prefer certain truths to vanish. The universe is structured so that the record persists. It may be encoded in forms we struggle to read. It may be scrambled across surfaces we cannot yet fully map. But it is there.

In October 2023, cameras and body cameras and dashcams and mobile phones and CCTV footage recorded what happened in southern Israel. In the months and years that followed, efforts to deny, distort, or relativise that record have been relentless. Bekenstein’s physics offers a quiet rebuke to every such effort. The information is encoded. It does not disappear because someone wishes it away. The universe does not permit the erasure of what has been.

Susskind’s book is a marvellous account of a war between titans. But the man who set the terms of that war, who told physics that black holes remember, is absent from its title and largely from its pages. He deserves to be remembered not merely as a footnote to a dispute between more famous men, but as the one who understood, before anyone else, that nothing is truly lost.

Bekenstein’s office at the Hebrew University sits on the Givat Ram campus in Jerusalem. He occupied it for twenty five years. It has been reassigned, as offices are. But the information he put into physics is encoded permanently, written on the boundary of everything we now understand. The room is emptied. The record endures.