Scientists mimic black hole environments in groundbreaking quantum vortex experiments

Using superfluid helium, scientists have created quantum vortices in the laboratory that mimic black holes. Such experiments could enhance our understanding of black holes' interaction with their surroundings.

When helium is cooled to just a few degrees above absolute zero, it enters a superfluid state where quantum phenomena dominate matter behavior. In this state, viscosity—or internal friction—is nonexistent, allowing the fluid to move without losing kinetic energy. Consequently, matter can circulate indefinitely in a closed circuit without extra energy.

Researchers from the University of Nottingham, in partnership with King's College London and Newcastle University, have developed a pioneering experimental platform to study black holes. The vortex created in the superfluid helium so closely resembles the environment around black holes that it offers unprecedented insight into their interaction with the environment.

The findings and study details were published in the journal "Nature" ([DOI: 10.1038/s41586-024-07176-8](https://dx.doi.org/10.1038/s41586-024-07176-8)).

**Quantum Tornado**

"Superfluid helium has enabled us to examine small surface waves with far greater detail and accuracy than in previous water experiments. The incredibly low viscosity of superfluid helium allowed us to closely analyze the interaction of waves with the superfluid tornado and compare the outcomes with our theoretical predictions," stated Patrik Svancara from the University of Nottingham, the lead author of the publication.

A specialised cooling system was constructed to hold a few litres of superfluid helium. Scientists cooled the helium to a temperature of about -271 degrees Celsius. At this threshold, liquid helium presents unique quantum properties, making it easier to create and stabilize vortices compared to other superfluid substances.

Svancara disclosed that in superfluid helium, tiny quantum vortices tend to repel each other. "In our setup, we managed to contain tens of thousands of these quanta within a small tornado-like object, reaching a record strength of quantum fluid vortex flow," he explained.

**Studying Black Holes**

Black holes, which neither emit nor reflect light, are so dense that, beyond a certain threshold (the event horizon), the escape velocity surpasses the speed of light, rendering them invisible and challenging to study directly. Scientists can only infer their presence through their interaction with nearby matter and light.

The researchers observed fascinating parallels between the quantum movement of their vortices and the gravitational interaction of spinning black holes with the surrounding spacetime, opening up new avenues for black hole simulation and interaction studies.

"Observing clear signs of black hole physics in our 2017 experiment was a pivotal moment for grasping some of the elusive phenomena that are often hard, if not impossible, to investigate by other means," commented Professor Silke Weinfurtner, a co-author. "Our advanced experiment now propels these studies forward, potentially leading to a deeper understanding of how quantum fields behave in the curved spacetime around astrophysical black holes," he added.

Source: University of Nottingham, photo by Leonardo Solidoro