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Physicists were able to reproduce the so-called «black hole bomb» in the laboratory for the first time, proving the Zeldovich effect proposed 50 years ago.
For the first time, the idea that energy can be obtained from a black hole was proposed by physicist Roger Penrose in 1969. Penrose predicted that particles flying in close proximity to the event horizon of a rotating black hole could receive energy from it due to the fact that the black hole curves and accelerates space-time around it.
In 1971, physicist Yakov Zeldovich discovered that similar processes can be achieved by moving light around a rapidly rotating metal cylinder. According to his calculations, the effect of superradiation should occur when the cylinder rotates at the same speed as the light. However, this is an incredible speed.
Zeldovich noted that if a cylindrical mirror was placed around the cylinder, the energy of the superradiation would be reflected and amplified again by the rotation of the cylinder, and then reflected again. In this way, there would be a rapid accumulation of energy, which would eventually either find a way out or explode.
Moreover, the Zeldovich effect can be triggered even without an initial light source Black hole or a cylinder could amplify tiny, always existing random fluctuations of the electromagnetic field in a vacuum — the so-called quantum fluctuations. Essentially, generating energy from «noise»!
For many decades, physicists have been trying to reproduce the Zeldovich effect. However, this seemed problematic because there was no way to spin the cylinder to the required speed. Finally, a team of physicists led by Hendrik Ulbricht decided to use electromagnetic waves with a significantly lower frequency, which are created by a magnetic field.
The scientists used an aluminum cylinder that rotates with an electric motor, placing three layers of metal coils around it. These coils create a rotating magnetic field and act as a mirror, reflecting the magnetic field back to the cylinder. The rotational speed of the cylinder and the magnetic field meet the Zeldovich conditions for the occurrence of superradiation.
The physicists directed a weak magnetic field at the cylinder and recorded that the outgoing field was indeed more powerful than the one directed at the cylinder. The superradiation effect was confirmed experimentally.
However, the scientists did not stop there and decided to conduct the experiment without the initial magnetic field generated by the coils. The installation began to generate a signal on its own! The rotating cylinder began to amplify this background «noise» — random electromagnetic fluctuations — and the coils-«mirrors» started the avalanche-like process of energy accumulation predicted by Zeldovich.
This experiment allowed scientists to examine in detail the processes that take place in deep space and which scientists cannot see directly. In addition, the study opens the way to a completely new method of searching for hypothetical particles and even dark matter If there are some unknown light particles or fields in the Universe, dark matter, they could also interact with black holes, rotating through the superradiation mechanism.
For example, a huge cloud of such particles forms around a black hole, stealing its rotational energy. What will we see? First, the black hole itself should gradually slow down its rotation. Secondly, this cloud of particles can emit specific gravitational waves that we could detect on Earth.
«Thus, superradiation turns black holes into particle detectors. And for a certain type of dark matter, they may turn out to be much better detectors than the Large Hadron Collider at CERN», — the researchers note.
The results of the study were published on the preprint server Arxiv
Source: IFL Science