The Universe of Black Holes

Abstract

Black holes are some of the strangest and most fascinating objects found in outer space. They are objects of extreme density, with such strong gravitational attraction that even light cannot escape from their grasp if it comes near enough. Albert Einstein first predicted black holes in 1916 with his general theory of relativity. The term “”black hole”” was coined in 1967 by American astronomer John Wheeler, and the first one was discovered in 1971.

Stellar-mass black holes are formed when a massive star runs out of fuel and collapses. These stars are made up of basically, stars are big exploding balls of gas, mostly hydrogen and helium. Our nearest star, the Sun, is so hot that the huge amount of hydrogen is undergoing a constant star-wide nuclear reaction, like in a hydrogen bomb. Even though it is constantly exploding in a nuclear reaction, the Sun and other stars are so large and have so much matter in them that it will take billions of years for the explosion to use all the “”fuel”” in the star. The huge reactions taking place in stars are constantly releasing energy into the universe, which is why we can see them and find them on radio telescopes such as the ones in the Deep Space Network.

Introduction

Stars, including the Sun, also send out a solar wind and burst out occasional solar flares. They are found scattered throughout the galaxy, in the same places where we find stars, since they began their lives as stars (Smaller stars become dense neutron stars, which are not massive enough to trap light.) If the total mass of the star is large enough (about three times the mass of the Sun), it can be proven theoretically that no force can keep the star from collapsing under the influence of gravity. However, as the star collapses, a strange thing occurs. As the surface of the star nears an imaginary surface called the “”event horizon,”” time on the star slows relative to the time kept by observers far away. When the surface reaches the event horizon, time stands still, and the star can collapse no more – it is a frozen collapsing object. According to theory, there might be three types of black holes: stellar, supermassive, and miniature black holes – depending on their mass. These black holes would have formed in different ways.

Even bigger black holes can result from stellar collisions. Soon after its launch in December 2004, NASA’s Swift telescope observed the powerful, fleeting flashes of light known as gamma ray bursts. Chandra and NASA’s Hubble Space Telescope later collected data from the event’s “”afterglow,”” and together the observations led astronomers to conclude that the powerful explosions can result when a black hole and a neutron star collide, producing another black hole.

Although the basic formation process is understood, one perennial mystery in the science of black holes is that they appear to exist on two radically different size scales. On the one end, there are the countless black holes that are the remnants of massive stars. Peppered throughout the Universe, these “”stellar mass”” black holes are generally 10 to 24 times as massive as the Sun. Astronomers spot them when another star draws near enough for some of the matter surrounding it to be snared by the black hole’s gravity, churning out x-rays in the process. Most stellar black holes, however, lead isolated lives and are impossible to detect. Judging from the number of stars large enough to produce such black holes, however, scientists estimate that there are as many as ten million to a billion such black holes in the Milky Way alone.

On the other end of the size spectrum are the giants known as “”supermassive”” black holes, which are millions, if not billions, of times as massive as the Sun. Astronomers believe that supermassive black holes lie at the center of virtually all large galaxies, even our own Milky Way. Astronomers can detect them by watching for their effects on nearby stars and gas.

Stellar Black Holes Massive black Holes Miniature Black Holes

What are black holes made up of?

A scientist answered the question, he said, “”The simple answer is that we don’t know. A black hole is defined as a region of spacetime from which extremely strong gravity prevents anything, including light, from escaping. We know that matter falling into black holes is no different from the matter which can be found lurking around the rest of the Universe. However, the closer we get to the centre of a black hole, the faster our understanding of physics breaks down. Thanks to General Relativity, we think we understand what happens in this extreme gravity and with the help of Quantum Mechanics, we can make an intelligent estimate as to what happens at smaller, microscopic scales. But if the two theories are combined – like they would be at the centre of a black hole – they break down, leaving us with no idea as to what’s going on!

To get around the problem, astrophysicists need a theory of gravity that is compatible with Quantum Mechanics that might just describe the physics inside a black hole. At the moment though, no such model exists but physicists are working on it.

How Do Humans Observe Black Holes?

Scientists can’t directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby. If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion.

A similar process can occur if a normal star passes close to a black hole. In this case, the black hole can tear the star apart as it pulls it toward itself. As the attracted matter accelerates and heats up, it emits x-rays that radiate into space. Recent discoveries offer some tantalizing evidence that black holes have a dramatic influence on the neighborhoods around them – emitting powerful gamma ray bursts, devouring nearby stars, and spurring the growth of new stars in some areas while stalling it in others.

Can Humans Create A Black Hole?

Unlike a natural black hole in space which draws matter in through its intense gravitational pull, even scientists can create a black with only lasers. The scientists’ black hole attracted electrons with its electrical charge. The black hole was created as the X-ray laser fired bright, fast flashes at iodomethane molecules. As a result, a void was left which started attracting electrons over the course of a fraction of a second before it blew up.

Another scientists said, “”In theory, to make a black hole all we would need to do would be to compress a huge amount of matter and energy into a tiny amount of space. In practical terms, however, this is incredibly difficult. There is much disagreement about the minimum size a black hole can be, and standard physics offers different answers to more exotic ‘multi-dimensional’ physics. Einstein said that mass and energy are equivalent – you can turn mass into energy and energy into mass – so very high energy particles smashing together could potentially lead to the creation of a black hole. However, the energy required for this would be the equivalent to taking the mass of a mountain range and converting it into energy. For reference, a nuclear weapon only releases the energy of a few grams worth of matter. So even the Large Hadron Collider at CERN, with its particles traveling at close to the speed of light will not, under standard physics, be able to create a black hole.

Conclusion

When we look into the universe today, we see that pretty much every large galaxy has a supermassive black hole in its heart. Even the Milky Way has a black hole in it’s core with a mass of four million times that of the Sun.

Black holes are a long way off at least 26,000 light years

It’s mass is still very small compared to the 200 billion solar masses of our galaxy so it can’t really harm us.

Unless it starts actively feeding, which it isn’t. But it might start sometime, if something falls into it. Though we don’t anything that can fall into it soon.

Even though black holes can cause death and destruction on a major scale they also help galaxies themselves form.

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