Compare · Black Holes

ER = EPR vs Hawking's Information Loss

Black Hole Information Paradox · within family

	ER = EPR Frontier	Hawking's Information Loss Historical
Proposed	2013	1976
Key figures	Juan Maldacena, Leonard Susskind	Stephen Hawking
In one sentence	Every pair of quantum-entangled particles is connected by a microscopic Einstein-Rosen wormhole. Spooky-action-at-a-distance entanglement and the gravitational geometry of bridges through spacetime are the same phenomenon in two different languages. Applied to the firewall paradox: the late Hawking radiation is entangled with the black hole interior, and that entanglement IS a wormhole geometry behind the horizon, so the infalling observer passes through smoothly.	Hawking argued in 1976 that an evaporating black hole destroys the information about what fell in, which limits prediction beyond ordinary quantum uncertainty.
Predictions	Every quantum-entangled bipartite system is connected by a microscopic wormhole geometry; the wormhole is non-traversable (you cannot send signals through it) but is geometrically real An infalling observer crosses the horizon of an old black hole smoothly; no firewall is encountered; the smooth horizon is supported by the entanglement-as-geometry structure The Page curve of an evaporating black hole's radiation can be reproduced from a gravitational path integral with replica wormhole saddle points, without any modification of standard semiclassical gravity The black hole interior is in some sense not an additional independent quantum system; it is encoded in the entanglement of the radiation, accessible to a sufficiently capable outside observer through quantum operations	A black hole that forms and then evaporates completely turns a pure quantum state into a mixed one, so [[unitarity]] fails for the process as a whole The outgoing radiation carries no record of what fell in beyond the black hole's mass, angular momentum and charge No S-matrix exists for black hole formation and evaporation. A superscattering operator, which maps density matrices to density matrices, takes its place The entropy of the radiation never turns back down as the black hole shrinks, so the radiation does not follow the [[Page curve]] Gravitational collapse sets a limit on prediction that is fundamental and comes on top of quantum uncertainty
Where it breaks	ER=EPR is still labelled a conjecture by Maldacena and Susskind themselves; a precise definition that lets you check it for an arbitrary entangled state, not just thermofield-double states, has not been given The connecting wormhole for a generic EPR pair (two particles in a typical Bell state) is at sub-Planckian scales where general relativity is not under controlled approximation; the geometric picture is suggestive rather than calculable in this regime Some authors (Harlow, Hayden, Susskind himself in subsequent work) have pointed out that ER=EPR requires the infalling observer to perform exponentially complex quantum operations to actually probe the interior, raising the question of whether the geometric interior is operationally distinguishable from a non-geometric encoding Whether ER=EPR is a precise physical claim, a useful heuristic, or a slogan attached to the more careful replica-wormhole technical story is contested in the post-2020 literature	Banks, Susskind and Peskin argued in 1984 that any evolution law of this kind violates either locality or energy-momentum conservation Page estimated in 1993 that information may leak out so slowly at first that a calculation expanded in the ratio of Planck mass to black hole mass would miss it Hawking argued in 2005 that information is preserved, using a Euclidean path-integral argument restricted to asymptotically anti-de Sitter spacetimes. It was not a microscopic account of how the information gets out Penington derived the Page curve in 2019 within a semiclassical gravity calculation for an evaporating black hole in [[anti-de Sitter space]]. It shows how information can escape in that framework; it is a calculation, not an observation
Key unresolved problem	The no-general-definition problem: the ER=EPR idea, that entangled particles are linked by a tiny wormhole, has only been made precise for one special case, so it cannot yet be checked or applied to ordinary entangled states.	The locality problem: no one has written down an evolution law for information loss that keeps both locality and energy conservation, the obstacle Banks, Susskind and Peskin raised in 1984.
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ER = EPR

2013 · Frontier

Hawking's Information Loss

1976 · Historical

Proposed

2013

1976

Key figures

Juan Maldacena, Leonard Susskind

Stephen Hawking

In one sentence

Every pair of quantum-entangled particles is connected by a microscopic Einstein-Rosen wormhole. Spooky-action-at-a-distance entanglement and the gravitational geometry of bridges through spacetime are the same phenomenon in two different languages. Applied to the firewall paradox: the late Hawking radiation is entangled with the black hole interior, and that entanglement IS a wormhole geometry behind the horizon, so the infalling observer passes through smoothly.

Hawking argued in 1976 that an evaporating black hole destroys the information about what fell in, which limits prediction beyond ordinary quantum uncertainty.

Predictions

Every quantum-entangled bipartite system is connected by a microscopic wormhole geometry; the wormhole is non-traversable (you cannot send signals through it) but is geometrically real
An infalling observer crosses the horizon of an old black hole smoothly; no firewall is encountered; the smooth horizon is supported by the entanglement-as-geometry structure
The Page curve of an evaporating black hole's radiation can be reproduced from a gravitational path integral with replica wormhole saddle points, without any modification of standard semiclassical gravity
The black hole interior is in some sense not an additional independent quantum system; it is encoded in the entanglement of the radiation, accessible to a sufficiently capable outside observer through quantum operations

A black hole that forms and then evaporates completely turns a pure quantum state into a mixed one, so [[unitarity]] fails for the process as a whole
The outgoing radiation carries no record of what fell in beyond the black hole's mass, angular momentum and charge
No S-matrix exists for black hole formation and evaporation. A superscattering operator, which maps density matrices to density matrices, takes its place
The entropy of the radiation never turns back down as the black hole shrinks, so the radiation does not follow the [[Page curve]]
Gravitational collapse sets a limit on prediction that is fundamental and comes on top of quantum uncertainty

Where it breaks

ER=EPR is still labelled a conjecture by Maldacena and Susskind themselves; a precise definition that lets you check it for an arbitrary entangled state, not just thermofield-double states, has not been given
The connecting wormhole for a generic EPR pair (two particles in a typical Bell state) is at sub-Planckian scales where general relativity is not under controlled approximation; the geometric picture is suggestive rather than calculable in this regime
Some authors (Harlow, Hayden, Susskind himself in subsequent work) have pointed out that ER=EPR requires the infalling observer to perform exponentially complex quantum operations to actually probe the interior, raising the question of whether the geometric interior is operationally distinguishable from a non-geometric encoding
Whether ER=EPR is a precise physical claim, a useful heuristic, or a slogan attached to the more careful replica-wormhole technical story is contested in the post-2020 literature

Banks, Susskind and Peskin argued in 1984 that any evolution law of this kind violates either locality or energy-momentum conservation
Page estimated in 1993 that information may leak out so slowly at first that a calculation expanded in the ratio of Planck mass to black hole mass would miss it
Hawking argued in 2005 that information is preserved, using a Euclidean path-integral argument restricted to asymptotically anti-de Sitter spacetimes. It was not a microscopic account of how the information gets out
Penington derived the Page curve in 2019 within a semiclassical gravity calculation for an evaporating black hole in [[anti-de Sitter space]]. It shows how information can escape in that framework; it is a calculation, not an observation

Key unresolved problem

The no-general-definition problem: the ER=EPR idea, that entangled particles are linked by a tiny wormhole, has only been made precise for one special case, so it cannot yet be checked or applied to ordinary entangled states.

The locality problem: no one has written down an evolution law for information loss that keeps both locality and energy conservation, the obstacle Banks, Susskind and Peskin raised in 1984.

Reader vote

No votes yet