BLACK HOLES: A frightening event                                                

These holes exist only in deep space and fortunately for us, they are far, far away from Earth—at least for the time being.

A black hole is where the gravity of the hole pulls so much material inward that even light cannot escape it. This comes about because all the matter of a star that is dying is caving in on itself and becomes a tiny area about the size of the dot at the end of this sentence. That small dot which is at the bottom of the black hole also includes the planets, moons, asteroids and  space debris that were next to the dying star. 

Imagine if you will; a  very large round magnet on your table and you sprinkle specks of metal all over the table. The metal specks will head directly to the magnate until all the specks cling to the surface of the magnet. This is similar as to what occurs when matter is moving into a black hole.  

Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. Such black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter in any object. Light is caused by a star so if the star is drawn to a large black hole, so does the star’s light waves.

Another kind of black hole is called "stellar." Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth's galaxy which is included in the Milky Way.

Scientists think the smallest black holes formed when the Universe began which incidentally, the Universe at one time was a small dot when it began to expand.     

I know that is hard to believe so I will explain. Astronomers have known for some time that everything in space—stars, moons, asteroids etc., are moving away from each other. Imagine that you have a black balloon and you spatter white spots of paint on it. When you blow air into the balloon and the balloon expands, the dots will expand outwards and away from each other. That is what is happening in space.

Based on the astronomer’s observations, the nebulae are really faraway galaxies that are fleeing from the Milky Way at speeds of approximately  600 miles (1,000 kilometers) an hour.  

Eventually, if new life-forms come to occupy Earth's surface millions of centuries later, all evidence of other galaxies—and thus an expanding universe—will have disappeared from their views.

This raises an interesting question. Will space stop expanding?

Scientists believe that in time—perhaps a hundred billion years from now, the Universe as we know it, will stop expanding and will look like a vast, empty space at a standstill because all the stars and galaxies will be so far from one another, the light from these stars and galaxies won’t be seen from other galaxies. In fact, anyone on Earth won’t even see stars in our own galaxy. But then, Humans and all wildlife on Earth wouldn’t exist because the sun would also be out of sight.

The astronomers have radio instruments that allows them to determine how quickly distant stars are moving away from each other thereby giving hints to the forces acting on the galaxies they belong to. The farther away the supernovas are, the longer their light has been traveling and the further back in time the explosions occurred. To date astronomers have detected 23 such explosions from about 9 billion years ago.

Here is my theory as to what will happen next. Everything in space will begin to close in on one another just as the white spots on your black balloon will when you let out the air of the balloon. Eventually, everything in space will deflate until everything in space, I mean everything will end up in size similar to the small dot at the end of this sentence.

Before that happens in the far-flung future, Earth will most likely be a distant memory because the entire planet will be destroyed when the sun expands into its red giant phase in about ten billion years from now. Billions of years later, the sun will begin to shrink, drawing everything in the sun’s sphere in which everything else together will also shrink into the size of a dot.  When that happens, there will be an enormous explosion and then everything in the sun’s sphere will be in a black hole. How long would that take?

Scientists have detected a black hole that's taken a record-breaking decade to devour a star and it's still chewing away. The food fest is happening in a small galaxy 1.8 billion light-years from Earth.

German, U.S. and Canadian scientists have stumbled upon one of the largest supermassive black holes discovered to date in a place they never would have expected to find such a monster.

The new black hole is located at the centre of the galaxy NGC 1600 in the constellation Eridanus and is 17 billion times the mass of the sun. That makes it only a little smaller than the biggest black hole on record, which is 21 billion times the mass of the sun.

While all other giant supermassive black holes bigger than 10 billion times the mass of the sun are in parts of the universe crammed with hundreds of large galaxies, NGC 1600 is in "a cosmic backwater" with just 20 or so galaxies. The position of the stars surrounding the black hole suggested it was once a pair of black holes that later merged.

The discovery may mean that the mass of extremely massive black holes may not be related to the mass of the stars near the centre of their host galaxy, and there may be far more monster black holes in the universe than astronomers had expected, in other small galaxy clusters. 

The newly discovered black hole is currently dormant and it's not actively gobbling up the dust and gas around it  so it's not emitting any radiation. Scientists discovered it by measuring its influence on the velocities of nearby stars using the Gemini North 8-metre telescope on Mauna in Hawaii.

In the middle of the Milky Way, there is an enormous black hole that keeps growing as it sucks in nearby stars after they have exploded. Eventually (and I won’t hazard a guess) every star, planet, moon and asteroid in the Milky Way will be sucked into that huge black hole until, our galaxy won’t exist anymore.  If there is anything you have left undone, you better finish it before you and everyone on Earth exist no more. (That statement is what is called gallows’ humor)

When the Universe is a black dot again, what will follow is what is called the “Big Bang”—an enormous explosion. Then billions of centuries later, Man will probably emerge again. One of the key indicators of the big bang—the cosmic explosion that kicked off the expansion of the universe—is a type of energy called cosmic microwave background energy, which is still observable by radio telescopes.

Here is an interesting question to ponder. Will each of us also be reborn again like we actually were before we died? If so, then history will repeat itself. If not, maybe Earth as we know it and its new inhabitants will have a better life the next time around.

Scientists believe that dark energy makes up about 70 percent of the substance of the universe. Scientists can measure the strength of dark energy by looking at distant galaxies for a type of exploding star known as a Type 1A supernova.  (a mammoth explosion)

Because these supernovae release known amounts of energy, measuring the amount of light arriving on Earth serves as a convenient distance marker to any galaxy in which one is observed.

The surroundings of a supermassive black hole is typical of that found at the heart of many galaxies. The black hole itself is surrounded by a brilliant accretion (ever expanding) disc of very hot, with falling material and, further out, a dusty torus. (a torus is a surface of revolution generated by revolving a circle in three-dimensional space within the circle.) If the axis of revolution does not touch the circle, the surface has a ring shape and is called a “torus of revolution”.

Astrophysicists agree that once a black hole is in place in the center of a galaxy, it can grow by accretion of matter and by merging with other black holes. There are, however, several hypotheses for the formation mechanisms and initial masses of the progenitors, or "seeds", of supermassive black holes.

One hypothesis is that the seeds are black holes of tens or perhaps hundreds of solar masses that are left behind by the explosions of massive stars and grow by accretion of matter

A vacancy exists in the observed mass distribution of black holes. Black holes that spawn from dying stars have extremely large masses.  The minimal supermassive black hole is approximately a hundred thousand solar (sun) masses. Mass scales between these ranges are dubbed intermediate-mass black holes. Such a gap suggests a different formation process. However ultraluminous X-ray sources may be black holes that haven’t been found yet. 

Astrophysicists agree that once a black hole is in place in the center of a galaxy, it can grow by accretion (the gradual collection of something over time) of matter by merging with other black holes. There is, however, an upper limit to how large supermassive black holes can grow. So-called ultramassive black holes which are at least ten times the size of supermassive black holes, appear to have a theoretical upper limit of around 50 billion solar masses, as anything above this slows growth down to a crawl (the slowdown tends to start around 10 billion solar masses) and causes the unstable accretion disk surrounding the black hole to coalesce (come together) into stars that orbit it.

This is bad news because if black holes could actually continue  to grow, then the Universe would end up as one huge super massive black hole and that would be the end of the Universe.

Astronomers have discovered a super-size black hole going back to almost the dawn of creation. It's the farthest black hole ever found.

Now back to ordinary black holes.

There are also often high-speed jets of material ejected at the black hole’s poles that can extend huge distances into space. Observations with radio telescopes have detected a very strong magnetic field close to the black holes at their base of the jets and this is probably involved in jet production.

The event horizon of a black hole is like the rim of a whirlpool. It   is inversely proportional to the square of the mass. For example;  a person on the surface of the Earth and one at the event horizon of a large black hole would experience about the same tidal force between their head and feet. Unlike with stellar mass black holes, humans would not experience significant tidal force until very deep into the black hole. However, if a space craft or even a planet were somewhere within the event horizon, the space craft and the planet would be sucked downward into the black hole. Once anything begins heading deeper into the black hole, the atoms of everything would slowly begin to separate until all the atoms mingle with the atoms of everything else. For humans, it would be a weird way to die. It is conceivable that such an occurrence may occur in the very very far future. The good news is that none of us alive today will suffer that experience.

What does worry me is the existence of extremely small black holes moving about in space and perhaps even in our own solar system. If they are in our solar system, how long will it be before they arrive on Earth?  WOW. That would be great material for a very scary movie.

“Hey. what is that small round black thing coming towards me?  OH NO OOOO00OO.......”   You have just read a line from the script of such a scary movie.