Light Has Transformed into a Liquid Mimicking Spacetime

By shaping light into a liquid-like form, researchers aim to deepen their grasp of black holes and other intriguing phenomena.

Though observing supermassive objects like black holes directly is a challenge, scientists have employed quantum effects to create valuable analogs in laboratory settings. For instance, they have previously simulated space-time with ultra-cold atoms to mimic a black hole’s material.

Now, Kevin Falk from the Kastler-Brossel Laboratory (LKB) in Paris and his team have utilized light to generate highly controlled analogs of space-time.

They achieved this by trapping light within small cavities made of reflective semiconductor materials, allowing it to bounce between layers and interact with the material’s charge. This quantum interaction ultimately converts light into a liquid-like state.

Researchers can manipulate this fluid with lasers to replicate the geometry of space-time, creating structures that correspond to a black hole’s event horizon. The object can fall but will not return.

Their light-based “space” is meticulously controlled, enabling Falk and his colleagues to visualize events and create sudden space-time structures.

They plan to use this unique simulation to investigate how Hawking radiation emitted from black holes varies with abrupt changes in the event horizon. However, achieving this requires cooling and isolating the experiment to amplify the quantum effects involved.

“This work represents a remarkable experimental achievement,” says Juan Ramon Muñoz de Nova from Complutense University in Madrid, who has contributed to initial measurements of Hawking radiation in black hole simulations involving ultracold atoms. He believes these new experiments present opportunities to observe various phenomena, such as how black holes vibrate and produce “ring” effects.

Friedrich Koenig from St Andrews University in the UK notes that this research offers “the most valuable platform” to explore new concepts related to gravity and the complex interplays between gravity and quantum effects.

One striking outcome of this study is the potential to reveal that the observed black holes might not be what they seem. Maxime Jacquet from LKB explains that the first image captured of a black hole by the Event Horizon Telescope may appear authentic, but the visual representation of a black hole may not equate to its true nature.

There could be sizable objects that distort light like black holes, creating a false appearance without an observable event horizon. Theoretical investigations suggest this is feasible, and light-based experiments may allow for further exploration of this possibility, according to Jacquet.

“We must exercise caution. While we have these analogs, fluids and black holes are fundamentally different entities,” warns Falk. “However, this experiment enables us to experiment with testing theories related to black holes.”