Researchers warn against doing quantum experiments near a black hole, as it could destroy all quantum states in its vicinity and have implications for future theories of quantum gravity.

Researchers warn against doing quantum experiments near a black hole, as it could destroy all quantum states in its vicinity and have implications for future theories of quantum gravity.

The discovery was made as a result of a thought experiment that pits the laws of quantum mechanics and black holes against one another, according to physicists who presented their findings on April 17 at an American Physical Society meeting.

The researchers discover that any quantum experiment conducted close to a black hole could create a paradox in which the black hole discloses information about its interior, which is against the laws of physics. The team claims that the paradox can be resolved if the black hole simply annihilates any quantum states that approach it.

According to Princeton University theoretical physicist Gautam Satishchandran, “the idea is to use properties of the [theories] that you understand, [which [are] quantum mechanics and gravity, to probe aspects of the fundamental theory,” which is quantum gravity.

Satishchandran, Daine Danielson, and Robert Wald, from the University of Chicago, and their team imagined Alice performing the famous double-slit experiment in a lab orbiting a black hole. If no one observes the particle’s progress, an interference pattern appears on a screen on the other side of the barrier. If someone measures the particle’s path, it will register as having gone through one slit or the other, causing the particle’s quantum state to collapse.

The team then pictured Bob, a different person, sitting just inside a black hole’s event horizon, which is the line beyond which nothing can escape the gravity of a black hole. Bob can still take measurements even though he’s doomed.

Just inside the horizon, the laws of physics operate in the same way as they do outside. Satishchandran claims, “At the horizon, you wouldn’t even know you fell in.”

The quantum state of Alice’s particle will collapse when Bob determines which slit it passed through. That would also inform Alice that Bob is present and causing her experiment to fail. The paradox is that nothing that happens inside a black hole should have any impact on the outside world.

Bob should not be able to communicate with Alice at all according to the laws of physics. Black holes are a one-way street, which Satishchandran claims to be a paradox. Nothing that happens inside a black hole can have an impact on the experiment I conduct outside of it.

However, we’ve just conjured up a scenario that will unquestionably have an impact on the experiment. The team then made an educated guess as to how to resolve that paradox: Whether Bob is present or not, the black hole itself causes the quantum state of Alice’s particle to collapse.

According to Danielson, “There must be an effect that no one has calculated in these theories that comes to the rescue.” The fact that charged particles radiate or emit light when they are shaken provided the solution.

The physicists demonstrated that no matter how meticulously Alice sets up her experiment, her particle will always emit a small amount of radiation as she moves it. Depending on which direction Alice’s particle travelled, that radiation will have a different electromagnetic field.

The black hole will detect this difference when the radiation passes through its event horizon, effectively observing enough of the original particle to cause it to lose its quantum state. Mathematically speaking, the horizon “knows” which direction the particle went, according to Satishchandran. Bob is not to blame for Alice’s experiment failing; the paradox is solved by Alice.

The group advanced the concept. The same thing happens as if Alice’s particle were an electron if it turns out to be a graviton, a particle of gravity. The team also reported at the same meeting that Alice’s particle will still collapse if the horizon in question is not a black hole but rather the cosmic horizon, denoting the edge of the visible universe.

The researchers claim that rather than creating a comprehensive theory of quantum gravity, the goal of this thought experiment is to sketch an outline that a potential future theory would need to fit into. We’re not in the business of developing theories of quantum gravity, claims Satishchandran.

However, the authors state that they “would like to… offer benchmarks, which hopefully tell us something more fundamental about what such theories look like.

” It is unclear how to move on from this point to a full theory, according to physicist Alex Lupsasca of Vanderbilt University in Nashville, who was not involved in the study. The idea that black holes might serve as quantum observers, however, is intriguing in and of itself.

He asserts, “I think it’s a true fact that has to be included in the ultimate theory of quantum gravity.” It is unclear, however, whether this is a significant hint that we are gathering on the way to the definitive theory of quantum gravity or merely an amusing side trip.