How Roger Penrose Found a Way to 'Steal' Energy From Rotating Black Holes — And Why It's Actually Working

How Roger Penrose Found a Way to 'Steal' Energy From Rotating Black Holes — And Why It's Actually Working. In 1969, a 34-year-old young physicist proposed an idea that seemed impossible: a black hole — the darkest and most inaccessible object in the universe — could be a source of energy. Not through explosions or nuclear reactions, but by utilizing the curvature of spacetime itself. How did he manage to avoid violating the law of conservation of energy? And why is direct experimentation still impossible — even though the mathematics has been verified for more than five decades?. The Birth of an Idea Amid the Wave of Relativity Revolution 1969 was not just the year of human travel to the Moon. In Oxford, in a small dusty room filled with notes and hand-drawn graphs, Sir Roger Penrose — who had just been awarded the FRS Fellow of the Royal Society at the age of 34 — was writing a paper that would shake theoretical cosmology. It was not the result of an experiment in a laboratory, but the pure birth of an analysis from Einstein's general relativity mathematics. Penrose was not looking for a way to 'exploit' black holes; he was answering a fundamental question: What is the ultimate limit of the law of conservation of energy in extremely curved spacetime? At that time, black holes were still considered a theoretical concept — even the name 'black hole' was only generally introduced by John Wheeler in 1967. The Kerr solution 1963 , which described a rotating black hole, had not yet fully understood its implications. With his geometric differential sharpness, Penrose began mapping the structure of spacetime around the Kerr object. It was here that he discovered something surprising: outside the event horizon, there exists a region where spacetime itself is forced to rotate — not by force, but by gravity — so that the 'frame-dragging' speed exceeds the speed of light relative to a distant observer . This region, later called the ergosphere , was not just an abstract mathematical concept — it was a physical gateway for processes never before imagined. Ergosphere: A Region Where Spacetime Runs Faster Than Light Imagine you are standing on the edge of a river with such a strong current that no boat — not even waves — can move against it. That is the ergosphere: it is not a place where objects move through space at high speeds, but a place where space itself rotates due to the angular momentum of the black hole. In the Boyer-Lindquist coordinate frame, the Kerr metric shows that the g<sub tφ</sub component becomes dominant outside the horizon, causing all particles — even those initially at rest — to have to rotate in the same direction as the black hole. This is not a friction or pull effect; this is a deep curvature of spacetime so profound that 'rest' becomes impossible. Penrose realized that in this region, the concept of energy is no longer absolute: the energy of a particle can become negative — but only if it is in a specific orbit within the ergosphere. And that is the key. Intentional Contradiction: Negative Energy and Particle Splitting Penrose's process is not a mechanical machine. It is a relativistic drama in three acts: first, an object for example, a hypothetical satellite or a large particle falls into the ergosphere with normal positive energy. Second, at the closest point — where frame-dragging is strongest — the object 'explodes' or splits into two: one fragment is thrown toward the horizon with opposite angular momentum, making its energy negative relative to a distant observer; the second fragment, with the release of angular momentum, shoots out with higher energy than it originally had. Roughly speaking, it is like throwing a ball backward from a moving train — but here, the 'train' is the rotating spacetime, and the 'ball backward' actually falls into the black hole with negative energy, so the black hole loses mass and angular momentum. Mathematics shows: the maximum energy that can be extracted from one process is 20.7% of the original mass of the falling object , provided the black hole is rotating almost at its maximum a → M . Invisible Legacy: From Theory to Modern Astrophysics Although no 'Penrose machine' has ever been built, this process is not fiction. It has become the foundation for understanding real phenomena: relativistic jets from quasars, luminosity of accretion disks around supermassive black holes, and even numerical simulations from LIGO about merging rotating black holes. In 2021, analysis of data from the Event Horizon Telescope showed polarization patterns around M87 consistent with the predicted ergosphere model from Penrose's mechanism. Even more surprisingly: an analogous process — superradiance — has been tested in the lab using sound waves in water vortices and light waves in rotating media, confirming its basic principle: extracting energy from a rotating field is universal, not exclusive to gravity. Why We Haven't 'Harvested It' — And What It Means for the Future Practical questions remain: can humans truly 'mine' energy from black holes? The answer is — not in the near future. The nearest known rotating black hole GRO J1655−40 is 11,000 light-years away. Navigation technology, radiation protection, and orbital precision required are beyond the capacity of the 21st century. However, Penrose's legacy is much deeper: it proves that black holes are not cosmic graves — they are dynamic thermodynamic systems, with temperature, entropy, and even potential work . This idea continues to inspire generation after generation: from string theory to quantum cosmology, from the concept of 'black hole battery' in science fiction to serious proposals about gravitational energy stations in the orbit of hypothetical micro black holes. Penrose did not just find a way to 'steal' energy — he opened the door to understanding that the universe, in its most absolute darkness, still beats with potential yet to be harnessed. --- Rujukan: Penrose process — Wikipedia https://en.wikipedia.org/wiki/Penrose process