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Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Physicists did create a black-hole analogue in a laboratory, but not a miniature object with the gravity of a real black hole. They used an ultracold atomic condensate flowing fast enough to trap sound-like waves: inside the analogue horizon, those waves could not travel upstream. That is what it means to say the system “swallowed sound.”
What did the physicists actually build?
The experiment used a Bose–Einstein condensate, an ultracold state of matter that behaves like a fluid. The researchers created a flow with regions moving at different speeds. In the 2019 experiment, the condensate consisted of 8,000 rubidium-87 atoms, according to a contemporaneous Nature News & Views commentary.
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This was an analogue black hole: a laboratory system designed to reproduce some of the wave behavior associated with a black-hole horizon. It had no astrophysical black hole’s mass or gravitational field, and it did not capture light or matter through gravity.
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The sonic horizon
Sound travels through the condensate as collective, sound-like excitations. Where the fluid’s speed reaches the local speed of sound, those excitations can no longer move against the flow. The boundary between the slower and faster-flowing regions is the sonic analogue of an event horizon. The Steinhauer Atomic Physics Laboratory at Technion puts it this way: “The point where the condensate flowed at the speed of sound was analogous to the event horizon.”
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Why sound cannot escape
On the subsonic side, a sound wave can travel upstream, against the fluid’s motion. On the supersonic side, the flow carries it downstream faster than it can propagate back. A wave that crosses into that region cannot get back out against the flow. The system traps sound-like waves relative to the condensate; it does not trap sound in empty space or reproduce the gravitational capture of an astronomical black hole.
What did the experiment report about Hawking radiation?
In a 2019 Nature paper, Juan Ramón Muñoz de Nova, Katrine Golubkov, Victor I. Kolobov and Jeff Steinhauer reported observing thermal Hawking radiation and measuring its temperature in the analogue system. The result concerns Hawking-like radiation in the condensate, not radiation detected from an astronomical black hole.
A 2021 follow-up reported observations of the analogue system’s spontaneous Hawking radiation at six different times and said those observations confirmed that the radiation was stationary—that is, its reported behavior persisted over those measurements rather than appearing only at one selected moment.
How does this differ from the earlier 2014 experiment?
Steinhauer’s 2014 work reported a black-hole-laser setup with both an analogue black-hole horizon and an inner horizon. In that arrangement, the reported phenomenon was self-amplifying Hawking radiation. The 2019 paper addressed a different question: whether the analogue radiation was thermal and what its temperature was.
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| Experiment | Setup or question | Reported result |
|---|---|---|
| 2014 | Analogue black-hole laser with a black-hole horizon and an inner horizon | Self-amplifying Hawking radiation |
| 2019 | Analogue system used to examine the radiation’s thermal character and temperature | Thermal Hawking radiation and its temperature |
What the laboratory result does—and does not—show
The experiment shows how a horizon-like boundary can arise for sound-like waves in a flowing quantum fluid, and it reports Hawking-like thermal radiation from that analogue system. It is not a direct observation of Hawking radiation from an actual black hole. The available evidence also does not establish the extent of independent replication or settle published criticism of the 2019 interpretation, so the result should be described as the authors’ reported analogue-system finding rather than as a universally settled detection.
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