Black holes in quantum states have surprisingly strange masses: ScienceAlert

For the better part of a century, quantum physics and the general relativity its a marriage on the rocks. Each perfect in their own way, the two just can’t stand each other in the same room.

Now a mathematical proof of the quantum nature of black holes could perhaps show us how the two can reconcile, at least enough to produce a grand new theory of how the universe works on a cosmic and microcosmic scale.

A team of physicists has mathematically demonstrated a strange quirk about how these mind-bogglingly dense objects can exist in a state of quantum superposition, while simultaneously occupying a spectrum of possible features.

Their calculations showed the superpositions of mass in a theoretical type of black hole called the BTZ black hole simultaneously occupying surprisingly different groups of masses.

Usually, each particle of a garden variety can exist in a superposition of states, with characteristics such as spin or momentum not being determined until they have become part of an observation.

Where some qualities, like cargoonly comes in discrete units, mass is usually not quantized meaning the mass of an unobserved particle could be anywhere within a range of maybe.

But as this research shows, the superposition of masses held by a black hole tends to favor certain sizes over others in a pattern that could be useful for modeling mass in a quantized way. This could give us a new framework for investigating the quantum gravity effects of superimposed black holes to reduce the tension between general relativity and quantum theory.

“Until now, we haven’t explored in depth whether black holes exhibit some of the weird and wonderful behaviors of quantum physics,” explains theoretical physicist Joshua Foo. from from the University of Queensland in Australia.

“Such behavior is superposition, where quantum-scale particles can exist simultaneously in multiple states. This is usually exemplified by Schrödinger’s cat, which can be both dead and alive at the same time.”

“But for black holes, we wanted to see if they could have vastly different masses at the same time, and it turns out they do. Imagine you’re both broad and tall, and small and skinny at the same time — it’s a situation that’s intuitively confusing.” because we are anchored in the world of traditional physics. But this is the reality for quantum black holes.”

The extreme gravity that surrounds black holes is an excellent laboratory for probing quantum gravity – the rolling continuum of spacetime according to general relativity coupled with quantum mechanical theory, which describes the physical universe in terms of discrete quantities, such as particles.

Models based on certain types of black holes could lead to a single theory that could explain particles and gravity. For example, some effects observed around a black hole cannot be described in general relativity. For this we need quantum gravity – a unified theory that takes both sets of rules and somehow makes them play nice.

So Foo and his colleagues developed a mathematical framework that would allow physicists to effectively observe a particle outside a black hole that is in a state of quantum superposition.

Mass was the main property they investigated, as mass is one of the few properties of black holes that we can measure.

“Our work shows that the very early theories of Jacob Bekenstein – an American and Israeli theoretical physicist who made fundamental contributions to the creation of a black hole thermodynamics – were on the money,” says quantum physicist Magdalena Zych from the University of Queensland.

“[Bekenstein] argued that black holes can only have masses that have certain values, that is, they must fall within certain bands or ratios – this is how energy levels of an atom work, for example. Our modeling showed that these stacked masses were in fact in certain particular bands or proportions – as predicted by Bekenstein.

“We didn’t expect such a pattern to come in, so the fact that we found this evidence was quite surprising.”

The results, the researchers say, provide a path for future exploration of quantum gravity concepts, such as quantum black holes and superimposed space-time. To develop a complete description of quantum gravity, inclusion of these concepts is crucial.

Their research also allows for more detailed investigations into that superimposed spacetime and the effects it has on particles within it.

“The Universe reveals to us that it is always stranger, more mysterious and more fascinating than most of us could ever have imagined,” Zych says.

The research was published in Physical Assessment Letters.