Halloween is a time of ghosts, goblins and ghouls, but nothing in the universe is as scary as a black hole.
In recent news, black holes (areas where gravity is so strong that they cannot escape) have been talked about. Half of the 2020 Nobel Prize in Physics was awarded to Roger Penrose for his mathematical work showing that black holes are an unavoidable result of Einstein’s theory of gravity. Andrea Ghez and Reinhard Genzel shared the other half to show that a huge black hole is in the center of our galaxy.
Black holes are scary for three reasons. If you fall into a black hole that remains when a star dies, you will be shredded. Also, the huge black holes found in the center of every galaxy have an insatiable desire. And a black hole is where the laws of physics disappear.
I have been studying black holes for over 30 years. In particular, we focused on the supermassive black hole hidden in the center of the galaxy. In most cases, they are inactive, but when they are active and eat stars and gas, areas close to black holes can surpass the entire galaxy that hosts them. The galaxy in which the black hole is active is called a quasar. I’ve learned everything about black holes over the last few decades, but there are still many mysteries to solve.
Death from a black hole
It is expected that a black hole will be formed when a giant star dies. After the star’s nuclear fuel is exhausted, the nucleus collapses into the densest state of matter imaginable, 100 times denser than the nucleus. Protons, neutrons, and electrons are no longer discrete particles because they are so dense. Black holes are dark and are found when orbiting a normal star. The characteristics of ordinary stars allow astronomers to infer the characteristics of their dark companion, the black hole.
The first black hole identified was Cygnus X-1, which was the brightest source of X-rays in Cygnus. Since then, about 50 black holes have been discovered in a system in which ordinary stars orbit black holes. They are the closest example of about 10 million expected to be scattered in the Milky Way.
A black hole is a tomb of matter. Even the light cannot escape from them. The fate of a black hole will be the painful “spaghettification” that Stephen Hawking spread in his book “A Brief History of Time.” In spaghettification, the strong gravity of black holes pulls you apart, separating bones, muscles, muscles, and even molecules. As the poet Dante explained in his poem “Divine Comedy” the words beyond the Gates of Hell: Give up hope, all you who enter here.
Hungry beast in all galaxies
Over the last three decades, Hubble Space Telescope observations have shown that all galaxies have a black hole in their center. Larger galaxies have larger black holes.
Nature knows how to create black holes over an astonishing range of masses, from corpses of stars that are several times the mass of the Sun to monsters that are tens of billions of times the mass. It’s like the difference between an apple and the Great Pyramid of Giza.
Just last year, astronomers published the first-ever photo of a black hole and its event horizon, a 7 billion solar-mass beast in the center of the M87 elliptical galaxy.
It’s more than 1000 times larger than the black hole in our galaxy where the discoverer stole this year’s Nobel Prize. These black holes are mostly dark, but when gravity draws in nearby stars and gases, they flare violent activity and emit large amounts of radiation. Huge black holes are dangerous in two ways. If you get too close, huge gravity will suck you in. And if they are in the active quasar stage, you will be blown up by high-energy radiation.
How bright is the quasar? Imagine hovering over a big city like Los Angeles at night. Approximately 100 million lights from the city’s cars, houses and streets correspond to the stars of the galaxy. In this analogy, an active black hole is like a one-inch diameter light source in downtown Los Angeles, shining hundreds or thousands of times over the city. Quasars are the brightest objects in the universe.
Supermassive black holes are strange
The largest black hole ever discovered is 40 billion times the mass of the Sun, or 20 times the size of the solar system. The exoplanets of our solar system orbit once every 250 years, but this much heavier object rotates once every three months. Its outer edge moves at half the speed of light. Like all black holes, huge black holes are protected from view by the event horizon. At their center is a singularity, which is a point in space of infinite density. You can’t understand the inside of a black hole because the laws of physics are broken. Time freezes on the event horizon and gravity becomes infinite at the singularity.
The good news about huge black holes is that you can fall into one and survive. Gravity is strong, but it is less stretchable than a small black hole and does not kill people. The bad news is that the event horizon points to the edge of the abyss. You cannot escape from inside the event horizon, so you cannot escape or report on your experience.
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According to Stephen Hawking, black holes are slowly evaporating. In the distant future of the universe, black holes will be the last surviving objects long after all stars die and are destroyed from sight by the galaxy’s accelerated cosmic expansion.
The largest black hole takes an unimaginable number of years to evaporate and is estimated to be 10 with 10 to the 100th power, or 10 with 100 zeros after it. The scariest objects in the universe are almost eternal.
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