A 50-year-old theory begins with how to use alien civilization Black hole The energy generation has been verified by the first experiment in the Glasgow Research Laboratory.
Penrose predicts that objects will gain negative energy in this unusual region of space. By dropping the object and dividing it into two halves so that half falls into the black hole and the other half is recovered, the recoil will measure the loss of negative energy – effectively, the other half of the recovery will obtain energy from the rotation of the black hole. The scale of the engineering challenge required by this process is so large, but Penrose believes that only very advanced, perhaps foreign civilizations can complete the mission.
Two years later, another physicist named Yakov Zel’dovich suggested that a more practical and practical experiment could be used to verify the theory. He proposed that the “twisted” light wave hits the surface of a rotating metal cylinder rotating at the correct speed. Due to the weirdness of the rotating Doppler effect, it will eventually be reflected by the extra energy extracted from the rotation of the cylinder.
But Zel’dovich’s idea has only been in the theoretical field since 1971, because to conduct experiments, the metal cylinder he proposed needs to rotate at least one billion times per second, which is another insurmountable current ergonomic limit Challenge.
Now, from University of GlasgowThe School of Physics and Astronomy finally found a way to prove the effect proposed by Penrose and Zel’dovich through experiments, that is, by distorting sound instead of light (a signal source with a much lower frequency), in the laboratory To demonstrate in practice.
In a new paper published on June 22, 2020, Natural physicsThe team described how they constructed a system that uses a small circle of speakers to produce sound wave distortions similar to those of Zel’dovich’s.
These distorted sound waves are directed to a rotating sound absorber made of foam disk. A group of microphones on the back of the disc picked up the sound when passing the disc from the speaker, thereby steadily increasing the rotation speed.
In order to know that Penrose and Zel’dovich’s theory is correct, the team hopes to hear a significant change in the frequency and amplitude of sound waves as they propagate through the disc. This is caused by the Doppler effect.
The main author of the paper is Marion Cromb, a doctoral student in the College of Physics and Astronomy. Marion said: “The linear form of the Doppler effect is familiar to most people, because this phenomenon occurs as the pitch of the ambulance siren rises as it approaches the listener and decreases as it approaches. Because sound waves reach the listener more frequently when the ambulance approaches, but less often when the ambulance passes, it seems to increase the sound wave.
The rotating Doppler effect is similar, but the effect is limited to circular space. When measured from the angle of a rotating surface, the distorted sound wave changes its pitch. If the surface rotates fast enough, the sound frequency may do something very strange-it can change from a positive frequency to a negative frequency, and doing so will steal some energy from the surface rotation. “
During the researchers’ experiments, as the turntable speed increased, the pitch of the sound from the speakers decreased until it became too low to be heard. Then the tone rises again until it reaches its previous tone-but louder, its amplitude is 30% greater than the original sound from the speaker.
Marion added: “What we heard in the experiment was extraordinary. What happened was that as the rotation speed increased, the frequency of the sound wave was positive Doppler shifted to zero. When the sound recovered again, it was because the wave It has been converted from a positive frequency to a negative frequency. These negative frequency waves can absorb some energy from the rotating foam disk and become larger in the process-just as Zeldovic proposed in 1971.”
Professor Daniele Faccio, who is also the School of Physics and Astronomy at the University of Glasgow, is the co-author of the paper. Professor Faccio added: “We are very pleased to be able to verify some very strange physics through experiments half a century after the theory was proposed. Strangely, we have been able to confirm that half of the The theory of the origin of the universe in the history of the century, but we think it will open up many new avenues for scientific exploration. We are eager to see how we can investigate the impact on different sources, such as electromagnetic waves, in the near future.”
References: Marion Cromb, Graham M. Gibson, Ermes Toninelli, Miles J . Padgett), Ewan M. Wright and Daniele Faccio, “Amplification of Rotating Waves”, June 22, 2020, Natural physics.
The research group’s paper titled “Amplification of Waves from Rotating Bodies” was published on Natural physics. This research was supported by the Engineering and Physical Sciences Research Council (EPSRC) and the European Union’s Horizon 2020 program.