Black Holes present a lot of mysteries in our understanding of the Cosmos. The properties of Black Holes are so extreme that the laws of physics start to break down around them. However, to confidently proclaim that we have understood the Universe, we need to square the current laws of Physics with that of the effects of Black Holes. The current explanations leave a lot to be desired. However, we do not need a comprehensive understanding of Black Holes to be able to employ a certain trick to gain an advantage.
In 1971, English Mathematical Physicist and Emeritus Rouse Ball Professor of Mathematics at Oxford University, Sir Roger Penrose, suggested one such trick. The Penrose process is a means by which energy can be extracted from a rotating Black Hole. This was a ground-breaking idea as extracting anything from the all-devouring clutches of a Black Hole seemed impossible till then.
The Penrose process only works on rotating black holes whose rotational energy is located outside the event horizon. This region, known as the Kerr spacetime (ergosphere), is very interesting as any particle in this region gets propelled in concurrent motion with the rotating black hole.
The full details of the idea involve lowering and then releasing a mass from a structure that is co-rotating with the black hole. This idea is feasible, perhaps for those civilizations that can build superstructures required for this feat.
Later on, some physicists translated this idea into the extraction of energy from a rotating absorber, such as a metallic cylinder. The experiment involves hitting the rotating cylinder with ‘twisted’ light waves, which then get propelled outwards with more energy than they came in with. The operating principle behind this is the rotational Doppler effect.
The experiment seemed unfeasible as it required a rotating absorber rotating at a Billion rpm. This was resolved recently when some physicists created sound waves that were twisted in the same sense as the light waves that were required. The experiment was carried out on rotating foam to see whether the Penrose process could work.
The results of the experiment were astonishing. As the rotation of the foam disc was increased, the pitch of the sound dropped until it was too low to hear. Then it rose back again with an amplitude 30% greater than the original one.
The results have conclusively verified the half-century-old brilliant idea that was thought up by an equally incredible personality. What the implications of this experiment are is still unclear. However, it would be interesting to keep tabs on this potentially revolutionary venture.
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