Physicists recreate "black holes" in the laboratory with surprising simplicity

Black holes are the best kept secrets of the universe. We all want to know what's happening in such exclusive space clubs, but the best we can do is stay out and listen to the rhythm.

To do this, scientists organize their own parties. Of course, these are not as fun as twisted space-time pits, but they are as close as we can have a VIP treatment on the dance floor of a black hole.

The Black Hole Laboratory at the University of Nottingham in the UK contains no authentic black holes. What's he is a cistern filled with colored water with green dye and a hole to return it

Physicists from the laboratory and the Universidade Federal do ABC in Brazil have recently used this setup to identify wave patterns in the water surrounding a sewer, which could help us understand the crisp tones of the water. a newborn hole screaming.

When black holes merge and form larger black holes, the whole Universe hears about it: the space hums a melody called quasi-normal mode that contains clues to the characteristics of the new black hole, such as its mbad and its angular momentum.

These modes have become fashionable in physics with the steady progress of gravitational wave astronomy, and physicists are keen to extract as much detail as possible from how space was shaking after these cosmic crashes.

To extract information in an almost normal fashion, it is necessary to know some notions about how energy dissipates in a field and about how some features of the wave patterns change or persist in the weather.

Whirlwind is an element that can affect the characteristics of a wave. This is the curved flow of its underlying medium, driven by competing forces.

For most simple models describing the oscillations of a black hole, it is badumed that the space is a little more than a calm background through which waves wave, which means that its whirlwind is not normally taken into account.

It might not make much difference. Or it could be important. It's not like we can look closely at these space-time swirls to discover.

But we can examine near-normal modes in other media and look for signs of interference.

Water is not necessarily the perfect metaphor of space-time, certainly, but the fundamentals work perfectly. The badogy also relies on theoretical work by the Canadian physicist William "Bill" Unruh, almost 40 years ago, who proved that the hydrodynamic equations fit perfectly with the description of gravity around sufficiently large mbades.

Away from sewers, waves on a surface tend to move faster than the current, allowing them to wave in virtually any direction. But when the water flows to the equivalent of a black hole, it picks up speed, causing with it the waves disorder.

"The velocity of the fluid is much higher than the speed of the waves, so the waves are driven by the water current even when they are propagating in the opposite direction," said physicist Maurício Richartz to José Tadeu Arantes of Agência FAPESP.

Oscillation measurements revealed patterns that stuck for long periods near the edge of the vortex, states reflecting the characteristics of the hole, such as its size and angles.

"Our main finding is that some oscillations very slowly disintegrated or, in other words, remained active for a long time and located in the area near the drain," Richartz told Agência FAPESP.

"These oscillations are no longer quasi-normal modes, but a different scheme called" quasi-linked states. "

Researchers hope to intentionally create more of these long-term "quasi-linked" energy states, under different conditions, to investigate their implications for black hole rotation.

It has been more than a century since Einstein's field equations gave rise to curious objects called singularities: strange distortions of space that give birth. to the monsters of gravity we call black holes.

Yet despite decades of research, we are a little closer to understanding the physics of black holes.

Fortunately for us, black holes are not as quiet as they are dark. We just need to learn how they play their music.

This research was published in Letters of physical examination.