A viral post claims our galaxy’s black hole, Sagittarius A*, is “completely invisible” and “breaks physics”. It is not invisible: astronomers track stars orbiting its 4.3 million solar masses and imaged its shadow in 2022. But the deeper question is real. In 1976 Stephen Hawking argued that evaporating black holes would erase information, which quantum mechanics forbids. Calculations since 2019 suggest the information does get out, but nobody knows how. Our take: real progress, no final answer, and plenty of hype.
A post that went viral on X this week claims that Sagittarius A*, the black hole at the centre of our galaxy, is “completely invisible” and that black holes “break physics”. Some of it is right, some is wrong, and the core of it is one of the deepest open questions in science: can a black hole destroy information? We checked the claims and explain the puzzle.
Our galaxy’s black hole in numbers
Sagittarius A* holds about 4.3 million solar masses and lies about 27,000 light-years away. Its event horizon, the point of no return, is about 25 million kilometres across (roughly 15.8 million miles), about 18 times the width of the Sun. It is not invisible: astronomers have tracked stars racing around it for decades, work that won Reinhard Genzel and Andrea Ghez the 2020 Nobel Prize, and on 12 May 2022 the Event Horizon Telescope released the first image of its shadow, a dark centre ringed by glowing gas.
Black holeSagittarius A* (Sgr A*)
Mass≈ 4.3 million Suns
Event horizon≈ 25 million km across
Distance≈ 27,000 light-years
Hawking temperature≈ 0.000 000 000 000 01 K
Time to evaporate≈ 10⁸⁷ years
How a black hole evaporates, and the curve that says information escapes
Original Astrometrik animation, not to scale. Left: things fall into the black hole while pairs of particles appear at the horizon and one escapes as Hawking radiation, so the hole slowly shrinks. Right: the entropy of the radiation. Hawking’s 1976 calculation keeps rising (information lost); Don Page showed that if information is kept, the curve must turn over halfway and fall back to zero. Calculations since 2019 reproduce that turn.
Hawking’s problem, now 50 years old
In 1974 Stephen Hawking showed that, once quantum physics is taken into account, black holes are not completely black: they glow faintly and slowly lose mass. In 1976 he drew the unsettling conclusion: the glow seems to be pure heat, carrying no trace of what fell in, so when the hole finally evaporates the information would be gone. Quantum mechanics forbids that: the full state of a system should always, in principle, be recoverable.
This is not a clash between “relativity says destroyed” and “quantum says preserved”, as the viral post puts it. The problem appears only when the two are combined, in Hawking’s own calculation of the radiation. For Sagittarius A* the process is unimaginably slow: its Hawking temperature is about a hundred-trillionth of a degree above absolute zero, colder than the cosmic microwave background, so today it absorbs far more than it emits.
Is it solved? Partly
In 1993 Don Page showed what the radiation must do if information survives: its entropy must rise, peak around halfway through the evaporation and fall back to zero. In 2019 two teams (Ahmed Almheiri, Netta Engelhardt and colleagues, and Geoff Penington) found a way to calculate this “Page curve”, using “islands” inside the black hole and, in a related method, “replica wormholes”. The answer came out right: information does come out. But as physicist Raphael Bousso put it, “We now can compute the Page curve, and I don’t know why.” The mechanism is still unknown, and some physicists doubt these methods.
Fuzzballs, wormholes and other ideas
String theory offers “fuzzballs”: black holes with no singularity at all, just a tangled quantum surface that stores and re-emits everything. The wormholes in the 2019 work are mathematical shortcuts in the calculation of entropy, not doorways you could travel through. Other proposals suggest that evaporation stops and leaves a tiny stable remnant holding the information. Some headlines in 2026 claimed the paradox was “finally solved”, but these are untested theories. The fair summary: there is real progress, no consensus and no experiment yet.
Watch: the black hole paradox in under a minute
Our short animated video explains Hawking’s information paradox with Sagittarius A*.
Fact check: the viral post
Claims from the post, checked:
Correct“15 million miles wide, 4 million solar masses”Close: the event horizon is about 15.8 million miles (25 million km) across, the mass about 4.3 million Suns.
Wrong“Completely invisible”We track stars orbiting it and imaged its shadow in 2022.
Partly right“Relativity says destroyed, quantum says preserved”The clash only appears when quantum effects (Hawking radiation) are added to relativity.
Correct“Physicists have been losing sleep for 50 years”Yes: Hawking’s information-loss paper appeared in 1976.
Wrong“The same principle that stops an LLM hallucinating a token”There is no physical link between language models and black holes.
Partly right“Wormholes suggest black holes are doorways”The wormholes in recent work are mathematical tools for computing entropy, not passages.
Partly right“Nobody has solved it yet”Calculations since 2019 show information gets out; how it does is still open.
Every black hole glows at a temperature set by its mass: the smaller, the hotter. Choose a mass to see its event horizon, Hawking temperature and evaporation time.
Universe’s age: 1.4 × 10¹⁰ years. Background sky: 2.7 K, so heavy black holes are still growing.
See where Sgr A* is
Sagittarius A* lies in the direction of the constellation Sagittarius, in the brightest part of the summer Milky Way. In October it sets in the south-west soon after dark. Our sky map shows where it is from your location.
Hawking showed in 1974 that black holes emit faint radiation and evaporate. In 1976 he argued that this radiation carries no information about what fell in, which would destroy information, something quantum mechanics forbids.
Has the information paradox been solved?
Partly. Since 2019, calculations using islands and replica wormholes show that information can come out of an evaporating black hole, but how it escapes is still unknown and the methods are debated.
How big is Sagittarius A*?
About 4.3 million solar masses, with an event horizon about 25 million kilometres across, about 18 times the width of the Sun.
Is Sagittarius A* invisible?
Not entirely. We see stars orbiting it, and the Event Horizon Telescope imaged its shadow against glowing gas in 2022.
Sources and calculation
Sources: S. W. Hawking, Nature 248 (1974) and Physical Review D 14, 2460 (1976); D. N. Page (1993) on the Page curve; Quanta Magazine, “The Black Hole Information Paradox Comes to an End” (29 October 2020); Space.com on the Event Horizon Telescope image of Sgr A* (12 May 2022); Nobel Prize in Physics 2020; ScienceDaily (2026) on a remnant-based proposal; the viral X post by @0xeronn (October 2026). Horizon size, Hawking temperature and lifetime calculated by Astrometrik from the standard formulas.
Positions and times were recalculated with Astronomy Engine, the sky-calculation library Astrometrik uses; times for Vienna and Istanbul are local time. The artwork on this page was drawn by Astrometrik.