June 25, 2022
Nothing escapes the massive gravitational pull of black holes, explains professor

Nothing escapes the massive gravitational pull of black holes, explains professor

Nothing in the universe is more terrifying than a Buraco Nigers. Black holes – regions in space where gravity is so strong that nothing can escape – is a hot topic in the news these days. Half of the 2020 Nobel Prize in Physics has been awarded to Roger Penrose for his mathematical work showing that black holes are an inevitable consequence of Einstein’s theory of gravity.

Andrea Geis and Reinhard Genzel shared the other half to prove the existence of a supermassive black hole at the center of our galaxy.

Black holes are scary for three reasons. If you fall into a black hole left by a star, it will be torn apart. Moreover, the massive black holes seen at the center of all galaxies have an insatiable appetite. Black holes are places where the laws of physics are forgotten.

I’ve been studying black holes for over 30 years. In particular, I focused on the supermassive black holes that lie at the center of galaxies. They are often inactive, but when they are active and eat stars and gas, the region near the black hole can cast a shadow over the entire galaxy it hosts. Galaxies in which black holes are active are called quasars. With everything we’ve learned about black holes over the past few decades, there are still many mysteries to solve.

black hole death

Black holes are expected to form when a massive star dies. After a star runs out of nuclear fuel, its core collapses into the densest state of matter imaginable, a hundred times denser than the nucleus of an atom. It is so dense that protons, neutrons, and electrons are no longer distinct particles. Because black holes are dark, they are found when they orbit an ordinary star. The properties of a normal star allow astronomers to deduce the properties of its dark companion, the black hole.

The first confirmed black hole was Cygnus X-1, the brightest X-ray source in the Cygnus constellation. Since then, about 50 black holes have been discovered in systems where an ordinary star orbits a black hole. They are the closest examples of about 10 million that should be spread across the Milky Way.

Black holes are graveyards of matter. Nothing can escape from it, not even light. The fate of anyone falling into a black hole would be agonizing “spaghettitation,” an idea promoted by Stephen Hawking in his book A Brief History of Time. In the process of spaghetti transformation, the intense gravity of the black hole will separate it from its bones, muscles, tendons, and even its particles. As the poet Dante described the words about the gates of hell in his poem The Divine Comedy: Abandon hope, you all enter here.

Hungry monster in all galaxies

Over the past 30 years, Hubble Space Telescope observations have shown that all galaxies have black holes at their centers. Larger galaxies contain larger black holes.

Nature knows how to create black holes in an astonishing range of masses, from the corpses of stars a few times the mass of the Sun to monsters tens of billions of times more massive. This is the difference between the apple and the Great Pyramid of Giza.

Last year, astronomers published the first image of a black hole and its event horizon, a 7 billion solar-mass monster at the center of elliptical galaxy M87.

It is more than a thousand times larger than the black hole in our galaxy, and its discoverers won this year’s Nobel Prize. These black holes are dark most of the time, but when their gravity attracts nearby stars and gas, they go into intense activity and release a great deal of radiation. Supermassive black holes are dangerous in two respects. If you get too close, the sheer gravity will suck you in. And if they are in the active quasar phase, they will be exposed to high-energy radiation.

How bright is the quasar? Imagine that you are hovering over a large city like Los Angeles at night. Nearly 100 million lights in cars, homes, and city streets correspond to the stars of the galaxy. In this analogy, a black hole in its active state is like a 1-inch light source in downtown Los Angeles that dazzles the city by a factor of hundreds or thousands. Quasars are the brightest things in the universe.

Supermassive black holes are ‘strange’

The largest black hole yet discovered weighs 40 billion times the mass of the Sun, or 20 times the size of the Solar System. While the outer planets of our solar system rotate once every 250 years, this most massive object rotates once every three months. Its outer tip moves at half the speed of light.

Like all black holes, massive holes are shielded from view by the event horizon. At its center is a singularity, a point in space where the density is infinite. We can’t understand what’s inside a black hole because the laws of physics don’t work. Time freezes on the event horizon and gravity becomes infinite at the singularity.

The good news about massive black holes is that you can survive falling into a single hole. Although its gravity is stronger, the expansion force is weaker than that of a small black hole and it wouldn’t kill it. The bad news is that the event horizon marks the edge of a cliff. Nothing can escape from inside the event horizon, so you can’t escape or report your experience.

According to Stephen Hawking, black holes evaporate slowly. In the distant future of the universe, long after all the stars have died and galaxies have been wiped out of view by the accelerating cosmic expansion, black holes will be the last surviving bodies.

The most massive black holes would take an unimaginable number of years to evaporate, estimated at 10 to 100 powers, or 10 to 100 zeros later. The scariest things in the universe are almost eternal.

Chris Embi Professor of Astronomy at the University of Arizona.

(Translated text, read the original text in English Here)