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The amazing world of black holes: Why do their energy disappear?
In the vastness of the universe, black holes attract countless matter and light with their mysterious and powerful gravity. With the continuous advancement of science and technology, astronomers have gradually gained a deeper understanding of black holes, but one question continues to trouble physicists: How do black holes lose their energy? This question involves the concept of negative energy, which is closely linked to the nature of black holes.
Negative energy is a concept used in physics to explain the properties of certain fields, including gravitational fields and various quantum field effects.
Gravity energy and black holes
Gravitational energy or gravitational potential energy refers to the potential energy possessed by a massive object due to being in a gravitational field. In classical mechanics, there is always gravitational potential energy between two or more masses. According to the principle of conservation of energy, this gravitational field energy must be negative, so its value is zero when the object is infinitely far away. When two objects come close to each other, gravity accelerates their motion, which results in an increase in the positive energy of the system.
In a universe dominated by positive energy, it will eventually fall into a big collapse; while in an "open" universe dominated by negative energy, it will expand infinitely or eventually disintegrate.
Black hole rotation and energy conversion
For a classical rotating black hole, its rotation creates a region called an "energetic phosphor" outside the event horizon, where spacetime also begins to rotate, a phenomenon known as frame drag. In this region, the particle's energy may transform into negative energy, i.e. under the relativistic rotation of its Kilnin vector. When negative energy particles cross the event horizon and enter a black hole, according to the law of energy conservation, the same amount of positive energy must escape.
In the Penrose process, an object splits into two parts, one of which gains negative energy and falls into the black hole, while the other part gains the same amount of positive energy and escapes.
Negative energy in quantum field effects
Negative energy and negative energy density are also fairly consistent in quantum field theory. In quantum theory, the uncertainty principle allows virtual particle-antiparticle pairs to spontaneously appear in a vacuum and exist for a brief period of time. Some virtual particles may carry negative energy, and this property plays a key role in several important phenomena.
In the Casimir effect, the spacing between two flat plates limits the wavelength at which quantum particles can exist, which results in a reduction in the number and density of virtual particle pairs, resulting in negative energy density.
Black hole radiation and energy disappearance
Beside the event horizon of a black hole, part of the virtual particle pair will be sucked into the black hole, and the energy of one of the particles may become negative due to this sucking. Positive particles can escape and form Hawking radiation, while the presence of negative energy particles will reduce the net energy of the black hole. This creates an interesting phenomenon: over time, the black hole may slowly radiate energy, eventually causing it to disappear.
Future possibilities: wormholes and faster-than-light flight
In some theories, negative energy is considered to be the core element of wormholes. Wormholes can directly connect two locations extremely far apart in space and time, making it possible to achieve near-instantaneous travel. However, some physicists think these ideas are too unrealistic.
The idea of using the theoretical principles of negative energy to design a faster-than-light (FTL) aircraft is also a fascinating idea. The most representative of this idea is the Alcubierre capsule.
The exploration of these theories not only challenges our understanding of the universe, but also makes us rethink the relationship between energy, time and space. In this universe full of mysteries, black holes and negative energy continue to drive scientific progress, but we still have to face a fundamental question: How deep do we understand black holes?
