A black hole analogue could tell us a thing or two about elusive radiation theoretically emitted by the real object.
Using a single-file string of atoms to simulate the event horizon of a black hole, a team of physicists observed in 2022 the equivalent of what we call Hawking radiation – particles born from disturbances in the quantum fluctuations caused by the break-in of the black hole. space-time.
This, they say, could help resolve the tension between two currently irreconcilable frameworks for describing the Universe: the theory of general relativity, which describes the behavior of gravity as a continuous field called space-time; and quantum mechanics, which describes the behavior of discrete particles using the mathematics of probability.
For a unified theory of quantum gravity to be universally applied, these two immiscible theories must find a way to get along in some way.
This is where black holes come into play – perhaps the strangest and most extreme objects in the Universe. These massive objects are so incredibly dense that, at a certain distance from the black hole’s center of mass, no velocity in the Universe is sufficient to escape. Not even the speed of light.
This distance, which varies depending on the mass of the black hole, is called the event horizon. Once an object crosses its boundary, we can only imagine what happens, since nothing sends us back vital information about its fate. But in 1974, Stephen Hawking proposed that interruptions in quantum fluctuations caused by the event horizon result in a type of radiation very similar to thermal radiation.
If this Hawking radiation exists, it is far too weak for us to detect. We may never be able to extract it from the hissing static of the Universe. But we can probe its properties by creating black hole analogues in the laboratory.
This had been done before, but in November 2022, a team led by Lotte Mertens from the University of Amsterdam in the Netherlands tried something new.
A one-dimensional chain of atoms served as a path for electrons “jump” from one position to another. By adjusting the ease with which these jumps can occur, physicists could make certain properties disappear, creating a kind of event horizon that would interfere with the wave nature of electrons.
The effect of this false event horizon produced an increase in temperature that matched theoretical expectations of an equivalent black hole system, the team said: but only when part of the chain extended beyond the event horizon.
This could mean that the entanglement of particles that straddle the event horizon plays a key role in generating Hawking radiation.
The simulated Hawking radiation was only thermal for a certain range of jump amplitudes, and in simulations that began by imitating a kind of spacetime considered “flat.” This suggests that Hawking radiation can only be thermal in certain situations and when there is a change in the warping of spacetime due to gravity.
It’s unclear what this means for quantum gravity, but the model offers a way to study the emergence of Hawking radiation in an environment that is not influenced by the wild dynamics of hole formation. black. And because it’s so simple, it can be used in a wide range of experimental setups, the researchers said.
“This may pave the way for exploring fundamental aspects of quantum mechanics, as well as gravity and curved spacetimes in various condensed matter contexts,” the researchers wrote.
The research was published in Physical examination research.
A version of this article was first published in November 2022.