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Joy Marcotte, Astronomy & Space Science
Black holes, easily the most mysterious entities in the cosmos. Black holes have destroyed what we thought we knew about physics and the world, quite literally bending the rules of spacetime.
What is a Black Hole?
Black holes are extremely dense cosmic objects with huge concentrations of matter packed into very small spaces. Because they are so incredibly heavy and dense, they bend spacetime to the point where nothing can escape from their gravitational pull.
When particles get too close to a black hole, they undergo a process called spaghettification, where the particle is stretched vertically and squeezed horizontally, making it resemble a noodle (NASA, 2024).
There are two different types of black holes based on mass: stellar-mass and supermassive black holes. Stellar-mass black holes come from the collapse of stars that are twenty to a few hundred times the mass of our Sun. Supermassive black holes, however, have masses that are thousands to millions times the mass of the Sun. The black hole in the center of the Milky Way, for example, is a supermassive black hole (NASA, n.d.).
What is the Event Horizon?
The event horizon is the boundary marking the limits of a black hole. At the event horizon, escape velocity is the speed of light, making it impossible for any particle to escape the black hole’s gravity at that point (Britannica, 2024). The inability of any light or information to escape from that gives black holes its most defining feature: absolute darkness.
What is Hawking Radiation?
Hawking radiation is a theoretical form of radiation emitted from black holes that causes them to eventually evaporate. When subatomic particle pairs approach the event horizon of a black hole, the particles with positive energy are able to escape, while the particles with negative energy are consumed by the black hole. The flow of negative energy into the black hole causes its mass to decrease until it evaporates completely. This process, however, can take billions upon billions of years.
Because nothing within the event horizon can actually escape from the black hole, the particles with positive energy exist just outside the event horizon and escape from there. Hence, hawking radiation does not actually come from within the black hole, but just outside of it (Britannica, 2024).
Conclusion
Black holes cause lots of confusing questions, such as the information paradox, where a black hole’s ability to destroy information goes against scientists’ current understanding of the world. Black holes have forced scientists to reconsider their perspective on modern physics, in order to learn more about these perplexing cosmic objects.
Reference list
Britannica (2024). Hawking radiation | astronomy. [online] Encyclopedia Britannica. Available at: https://www.britannica.com/science/Hawking-radiation [Accessed 30 Nov. 2024].
NASA (2024a). Black Holes - NASA Science. [online] science.nasa.gov. Available at: https://science.nasa.gov/universe/black-holes/ [Accessed 30 Nov. 2024].
NASA (2024b). Types - NASA Science. [online] science.nasa.gov. Available at: https://science.nasa.gov/universe/black-holes/types/ [Accessed 30 Nov. 2024].
Reddy, F. (2020). What Are Black Holes? [online] NASA. Available at: https://www.nasa.gov/universe/what-are-black-holes/ [Accessed 30 Nov. 2024].
The Editors of Encyclopedia Britannica (2017). event horizon | Definition & Explanation. In: Encyclopædia Britannica. [online] Available at: https://www.britannica.com/topic/event-horizon-black-hole [Accessed 30 Nov. 2024].
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