A black-hole analogue is a laboratory system whose waves experience an effective horizon resembling the one-way boundary of a gravitational black hole. In an acoustic analogue, a moving fluid reaches a speed greater than the local speed of sound. Sound-like excitations moving against that flow can no longer travel upstream, so they are carried into the supersonic region. In quantum-fluid experiments the excitations are phonons, not ordinary room sound, and the result is an analogy in wave propagation—not a miniature astrophysical black hole.
What a black-hole analogue actually reproduces
An astrophysical black hole is defined by spacetime geometry: beyond its event horizon, every future-directed path leads inward. A black-hole analogue does not recreate a collapsed star, intense gravity or curved spacetime in the laboratory. Instead, it reproduces one mathematical feature that matters for many wave equations: a boundary across which waves can travel effectively in one direction.
As an Amazon Associate I earn from qualifying purchases.
The medium supplies the moving background. Depending on the experiment, that medium may be an ultracold atomic gas, flowing water or an optical system. The waves may be condensate phonons, surface waves or light pulses. Their physical nature differs, but the equations describing propagation can contain a horizon-like point where the background flow outruns the waves trying to move against it.
Recommended Free Tools
How a sonic horizon traps upstream-moving waves
The river-and-swimmer picture
Imagine a swimmer trying to move upstream in a river. When the current is slower than the swimmer, the swimmer can make progress toward the bank upstream. If the current reaches the swimmer’s maximum speed, the swimmer can remain at one location. If the current becomes faster, every effort to swim upstream still results in downstream motion.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Sound in a moving medium behaves in the same broad way. The relevant comparison is not simply whether the medium is moving, but whether its local flow speed is below or above the local speed at which sound propagates through that medium.
Where the horizon forms
A sonic horizon is the location where the magnitude of the flow speed reaches the local speed of sound. The Technion laboratory describes this point in its condensate as analogous to an event horizon. On the subsonic side, a sound wave traveling against the flow can still move upstream. At the horizon, its upstream speed relative to the laboratory falls to zero. On the supersonic side, the flow carries it downstream faster than it can propagate in the opposite direction.
This creates an effective one-way boundary for the relevant excitations. A disturbance outside the supersonic region may approach the horizon, but an upstream-moving disturbance formed inside cannot cross back out against the faster flow. In that limited, wave-mechanical sense, the excitations are trapped.
What “trapped” does and does not mean
- It means the wave packet cannot propagate upstream across the horizon while the flow remains supersonic.
- It does not mean the medium becomes a solid container or absorbs all sound.
- It applies to waves whose propagation speed and direction satisfy the horizon condition; other modes or frequencies may behave differently.
- It does not trap ordinary audible sound in a room, kitchen or concert hall.
The analogy is therefore precise about a propagation rule and limited everywhere else. Gravity is not required to make the horizon; the moving medium creates an effective geometry for its waves.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Why Bose–Einstein condensates are useful acoustic systems
A Bose–Einstein condensate (BEC) is a very cold quantum fluid in which many atoms occupy a common macroscopic quantum state. Its collective disturbances travel as quantized sound modes called phonons. Researchers can shape the condensate’s density and flow, tune the local sound speed and measure correlations between excitations.
That combination makes a BEC attractive for analogue-gravity work. The horizon can be engineered rather than waiting for a naturally occurring astronomical object, and the phonon field can be observed repeatedly under controlled conditions. The experiments discussed by the Technion Steinhauer laboratory use this setting to study Hawking-like radiation, partner excitations and their correlations.
When explaining these experiments, “sound” means a collective excitation of the condensate. A phonon may be mathematically analogous to a sound wave, but it is not a pressure wave traveling through the air at an audible frequency. The laboratory signal is read out from the quantum fluid’s atoms and correlations, not heard with a microphone.
What the condensate experiments have reported
Horizon and approximately thermal emission
The Technion laboratory reports an analogue black hole in an atomic condensate, with the horizon at the point where the condensate flowed at the speed of sound. Its Hawking Radiation page describes an approximately thermal distribution of emitted Hawking phonons and associated partner particles, together with measurements of entanglement. These are findings reported by that laboratory and its papers; they should not be presented as a direct observation of radiation from an astrophysical black hole.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
The phrase “approximately thermal” matters. Hawking’s prediction concerns a characteristic spectrum, but a laboratory condensate has finite size, finite observation time and a specific preparation. The measured distribution belongs to that engineered phonon system.
The 2014 two-horizon experiment
A 2014 Nature Physics experiment created an analogue configuration with an outer horizon and an inner horizon. Together they formed what the authors called a black-hole laser. Waves reflected between the two horizons, and the experiment reported exponential growth of a standing wave. The authors described this as self-amplifying Hawking radiation.
Jeff Steinhauer wrote in the article’s abstract: “We report the observation of Hawking radiation emitted by this black-hole analogue, which is the output of the black-hole laser formed between the horizons.” That sentence is the paper’s claim in the context of its condensate experiment. The amplification mechanism attributed in the report is repeated reflection and growth of waves between the horizons, not an uncontrolled explosion or a gravitational process.
The Tool Desk
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 →The 2016 entanglement paper
A 2016 Nature Physics paper is titled Observation of quantum Hawking radiation and its entanglement in an analogue black hole. When discussing the result, attribute the observation to the paper and its author, Jeff Steinhauer. The title identifies the reported subject; it does not convert the condensate into an astrophysical black hole or establish that every analogue system produces the same signal.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Can sound escape a sonic horizon?
For the upstream-moving phonon modes that define the horizon, the answer is no while the flow remains faster than their propagation speed. A phonon generated in the supersonic region is swept with the flow and cannot cross outward through the horizon against it. This is the acoustic counterpart of the one-way character of an event horizon.
That answer needs three qualifications. First, the statement concerns a particular medium and its modes, not every possible disturbance. Second, the horizon is a region of changing flow, so its behavior depends on how the flow is prepared and maintained. Third, analogue Hawking radiation is not ordinary sound escaping from inside. In Hawking-like descriptions, correlations can involve an exterior phonon and an interior partner, while the horizon condition still prevents a conventional upstream signal from crossing outward.
One horizon, two horizons and changing flows
| Configuration | How it works | Typical signature or claim |
|---|---|---|
| Single sonic horizon | The flow crosses from subsonic to supersonic, creating an effective one-way boundary for upstream phonons. | Phonon emission with an approximately thermal distribution and correlations reported by the Technion condensate work. |
| Outer and inner horizons | A supersonic region is bounded so waves can reflect between two horizon-like boundaries. | The 2014 condensate report described exponential standing-wave growth and self-amplifying Hawking radiation. |
| Time-dependent flow approaching a sonic regime | The background changes in time and asymptotically approaches a sonic condition rather than requiring a permanently trapped region. | A 2006 theoretical paper argued that stationary Planckian quasiparticle emission can arise in this setup. |
The 2006 result is theoretical. It shows that a permanently trapped region is not a universal prerequisite for every Hawking-like analogue calculation; it does not negate the condensate demonstrations that use a trapped or bounded supersonic region.
How other analogue systems differ
“Hawking analogue” is a family of experiments, not one device. The medium determines the wave excitation, how a horizon is formed and which observable can be measured.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
| Medium | Wave excitation | Horizon arrangement or preparation | Reported observable |
|---|---|---|---|
| Atomic Bose–Einstein condensate | Phonons, the condensate’s quantized collective sound modes | Engineered stationary or bounded flows; experiments include single- and two-horizon arrangements | Spectral distribution, phonon correlations, partner modes and reported entanglement |
| Water waves | Surface waves | Flow over a region where the current changes the waves’ ability to travel upstream | Mode conversion was observed in water-wave studies noted by the Technion laboratory |
| Fibre-optical systems | Optical waves or pulses in a nonlinear fibre | Dynamic optical background that can create a horizon for selected wave components | Stimulated response and other optical signals; interpretations differ between experiments |
The Technion laboratory notes that an optical-fibre result discussed on its site was attributed to effects other than Hawking radiation. Separately, a 2026 Nature article reported evidence concerning stimulated radiation and backreaction in a fibre-optical analogue. Those reports involve optical excitations and observables, not condensate phonons, so their conclusions should not be merged automatically with the BEC results.
What these experiments can test
- Wave propagation near an effective horizon: they let researchers test how disturbances behave when a background flow changes from subsonic to supersonic.
- Mode conversion: an incoming wave can be transformed into different outgoing or partner modes, a feature shared by several analogue proposals.
- Correlation and entanglement predictions: condensate experiments can compare paired phonon measurements rather than looking only at average intensity.
- Effects of horizon geometry: adding an inner horizon allows tests of repeated reflection and amplification, as in the reported black-hole-laser configuration.
- Time-dependent backgrounds: theoretical work can examine whether Hawking-like spectra require a long-lived trapped region or can emerge as a flow approaches a sonic state.
What they cannot establish about real black holes
A laboratory analogue does not directly detect Hawking radiation from an astrophysical black hole. It does not reproduce the gravitational field of a collapsed object, the curvature of spacetime or the full range of high-energy physics near an astronomical horizon. Its evidence concerns an effective field in a specified medium.
Analogue experiments are valuable precisely because they isolate the horizon part of the problem. A measured phonon spectrum or correlation can test predictions about quantum fields near an effective one-way boundary. It cannot by itself settle every question about quantum gravity, astrophysical black-hole interiors or the origin of radiation in space.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Interpretation also depends on the system. Surface waves, fibre-optical waves and condensate phonons have different dispersion relations, temperatures, losses and measurement methods. A signal described as Hawking-like in one medium is not automatically proof that another medium has produced the same phenomenon.
How to read a claim about a “sonic black hole”
- Identify the medium. Ask whether the experiment uses a condensate, water, an optical fibre or another system.
- Identify the excitation. In a BEC, it is a phonon; in other systems it may be a surface or optical wave.
- Locate the horizon condition. Check where the background flow reaches the relevant wave speed and whether the boundary is stationary or dynamically created.
- Check the measured signature. A thermal spectrum, mode conversion, correlations, entanglement, stimulated response and backreaction are different observables.
- Separate observation from interpretation. Read whether the authors report an analogue effect, attribute it to Hawking radiation or discuss competing explanations.
- Keep the scale in view. No laboratory result described here is a direct observation of an astrophysical event horizon.
The bottom line
A black-hole analogue traps sound-like waves by making the medium’s flow faster than those waves can travel upstream. In a Bose–Einstein condensate, the trapped excitations are phonons. The point where condensate flow reaches the local sound speed acts as a sonic horizon, and reported experiments have examined thermal-like emission, correlations, entanglement and two-horizon amplification. The result is a powerful test bed for horizon physics, but it remains an analogue: it does not turn ordinary sound into a gravitational black hole or directly observe Hawking radiation from space.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
