Research suggests synthetic black holes radiate like real ones | Tech News

Research suggests synthetic black holes radiate like real ones

Understanding black holes is the key to unravelling the most fundamental laws governing the cosmo.

| Updated on: Nov 13 2022, 17:22 IST
Terror in the sky! Black Hole found CLOSE to Earth; it is 10 times BIGGER than Sun
Black hole
1/5 The black hole that is closest to planet Earth has been found by astronomers utilising the International Gemini Observatory, run by the NOIRLab of the NSF. And it is terrifying! It is not only massive, but it is also close to Earth! "It has been confirmed that a dormant stellar-mass black hole exists in the Milky Way for the first time. With only 1600 light-years between it and Earth, it is a fascinating subject for research to improve our knowledge of the development of binary systems," a report by ANI said. (AFP)
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2/5 The closest black hole to Earth has been named Gaia BH1 by astronomers. It is three times closer to Earth than the previous record-holder, an X-ray pair in the constellation of the Monoceros. This dormant black hole is around 10 times as big as the Sun and is situated about 1600 light-years away in the constellation Ophiuchus. (Event Horizon Telescope Collaboration)
Black hole
3/5 The most extreme things in the universe are black holes. All huge galaxies presumably have supermassive versions of these unfathomably dense objects at their centres. There are an estimated 100 million stellar-mass black holes in the Milky Way alone, which are significantly more prevalent and weigh five to one hundred times as much as the Sun. (NASA)
Black hole
4/5 What is a Black Hole? According to NASA, a black hole is an astronomical object with a gravitational pull so strong that nothing, not even light, can escape it. A black hole’s “surface,” called its event horizon, defines the boundary where the velocity needed to escape exceeds the speed of light, which is the speed limit of the cosmos. Matter and radiation fall in, but they can’t get out. (NASA)
Black hole
5/5 Formation of Black Hole: A stellar-mass black hole formation happens when a star with more than 20 solar masses (1 solar mass is the mass of our sun) exhausts the nuclear fuel in its core and collapses under its own weight. The collapse triggers a supernova explosion that blows off the star’s outer layers. But if the crushed core contains more than about three times the Sun’s mass, no known force can stop its collapse into itself and the birth of a black hole. The origin of supermassive black holes is poorly understood, but we know they exist from the very earliest days of a galaxy’s lifetime. Once born, black holes can grow by accreting matter that falls into them, including gas stripped from neighboring stars and even other black holes. (NASA)
Black hole
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Synthetic black holes radiate like real ones. (NASA)

The most extreme objects in the universe are black holes, which are so densely packed into such little space that nothing, not even light, can evade their gravitational attraction once it is sufficiently close to it.

Understanding black holes is the key to unravelling the most fundamental laws governing the cosmos because they represent the limits of two of the best-tested theories of physics: the theory of general relativity, which describes gravity as resulting from the (large-scale) warping of space-time by massive objects, and the theory of quantum mechanics, which describes physics at the smallest length scales.

To fully describe black holes, these two theories need to be stitched together to form a theory of quantum gravity.

Radiating black holes

To achieve this goal, we might want to look at what manages to escape from black holes, rather than what gets swallowed. The event horizon is an intangible boundary around each black hole, beyond which there is no way of getting out. However, Stephen Hawking famously discovered that every black hole must emit a small amount of thermal radiation due to small quantum fluctuations around its horizon.

Unfortunately, this radiation has never been directly detected. The amount of Hawking radiation coming from each black hole is predicted to be so small, it is impossible to detect (with current technology) among the radiation coming from all other cosmic objects.

Alternatively, could we study the mechanism underlying the emergence of Hawking radiation right here on Earth? This is what researchers from the University of Amsterdam and IFW Dresden set out to investigate. And the answer is an exciting "yes".

Black holes in the lab

"We wanted to use the powerful tools of condensed matter physics to probe the unattainable physics of these incredible objects: black holes," says author Lotte Mertens.

To do so, the researchers studied a model based on a one-dimensional chain of atoms, in which electrons can "hop" from one atomic site to the next. The warping of spacetime due to the presence of a black hole is mimicked by tuning how easily electrons can hop between each site.

With the right variation of hopping probability along the chain, an electron moving from one end of the chain to the other will behave exactly like a piece of matter approaching the horizon of a black hole. And, analogous to Hawking radiation, the model system has measurable thermal excitations in the presence of a synthetic horizon.

Learning by analogy

Despite the lack of actual gravity in the model system, considering this synthetic horizon gives important insight into the physics of black holes. For instance, the fact that the simulated Hawking radiation is thermal (meaning the system appears to have a fixed temperature) only for a specific choice of spatial variation of the hopping probability, suggests that real Hawking radiation may also only be purely thermal in certain situations.

Additionally, the Hawking radiation only occurs when the model system starts out without any spatial variation of hopping probabilities, mimicking flat spacetime without any horizon, before being changed into one hosting a synthetic black hole. The emergence of Hawking radiation therefore requires a change in the warping of spacetime, or a change in how an observer looking for the radiation is perceiving this warping.

Finally, Hawking radiation requires some part of the chain to exist beyond the synthetic horizon. This means that the existence of thermal radiation is intricately connected to the quantum-mechanical property of entanglement between objects on either side of the horizon.

Because the model is so simple, it can be implemented in a range of experimental setups. This could include tuneable electronic systems, spin chains, ultracold atoms or optical experiments. Bringing black holes to the lab can bring us one step closer to understanding the interplay between gravity and quantum mechanics, and on our way to a theory of quantum gravity.

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First Published Date: 13 Nov, 17:22 IST