By – Naveen SihagB.Tech

BLACK HOLEBLACK HOLE

BLACK HOLES: WHAT BLACK HOLES: WHAT ARE THEY?ARE THEY?

Black holes are the evolutionary Black holes are the evolutionary endpoints of stars at least 10 to endpoints of stars at least 10 to 15 times as massive as the Sun. 15 times as massive as the Sun.

Facts and figuresFacts and figures Black holes are objects so dense that not even Black holes are objects so dense that not even

light can escape their gravity , and since nothing light can escape their gravity , and since nothing can travel faster than light, nothing can escape can travel faster than light, nothing can escape from inside a black hole.from inside a black hole.

For example, if our Sun is magically crushed until For example, if our Sun is magically crushed until it becomes about 1 mile in size, it would become it becomes about 1 mile in size, it would become a black hole, but the Earth would remain in its a black hole, but the Earth would remain in its same orbit. same orbit.

Even back in Isaac Newton's time, scientists Even back in Isaac Newton's time, scientists speculated that such objects could exist.speculated that such objects could exist.

FORMATION OF BLACK FORMATION OF BLACK HOLEHOLE There are two main process constantly There are two main process constantly

going on in massive in stars: nuclear going on in massive in stars: nuclear fusion and gravitation. These two fusion and gravitation. These two dominates, the stars to collapse.dominates, the stars to collapse.

Once the star starts to collapse, it does Once the star starts to collapse, it does not stop, and the star will come inward not stop, and the star will come inward upon itself, resulting in the formation of a upon itself, resulting in the formation of a black hole.black hole.

Only those stars greater than 3 times the Only those stars greater than 3 times the mass of sun that become Black Hole upon mass of sun that become Black Hole upon collapse.collapse.

IF WE CAN’T SEE THEM, IF WE CAN’T SEE THEM, THEN HOW DO WE KNOW THEN HOW DO WE KNOW

THEY ARE THERE?THEY ARE THERE? The X-rays are sent off into space and when they strike the The X-rays are sent off into space and when they strike the matter around the black hole , it can be detected.matter around the black hole , it can be detected.

Binary X-ray sources are placed to find strong black hole .Binary X-ray sources are placed to find strong black hole . Another sign of the presence of a black hole is random Another sign of the presence of a black hole is random

variation of emitted X-rays. And gravitational variation of emitted X-rays. And gravitational lensing ,accretion disks n gas jets .lensing ,accretion disks n gas jets .

EXISTENCE OF BLACK HOLEEXISTENCE OF BLACK HOLE

SIZE OF A BLACK HOLESIZE OF A BLACK HOLE

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Black hole weigh about as much as a star . It would Black hole weigh about as much as a star . It would be aprox 10 times mass of sun .be aprox 10 times mass of sun .

More massive , more space it would require .More massive , more space it would require . The size and mass have a simple relationship, The size and mass have a simple relationship,

which is which is independent of rotationindependent of rotation. According to this . According to this mass/size criterion then, black holes are commonly mass/size criterion then, black holes are commonly classified as :classified as :

Supermassive black holeSupermassive black hole Inter-mediate mass black holeInter-mediate mass black hole Stellar-mass black holeStellar-mass black hole

Micro black holeMicro black hole

HOW BIG IS A BLACK HOW BIG IS A BLACK HOLE?HOLE?

Black holes weigh about as much as a massive Black holes weigh about as much as a massive star. A typical mass for such a black hole would star. A typical mass for such a black hole would be about 10 times the mass of the sun.be about 10 times the mass of the sun.

The more massive a black hole is, the more The more massive a black hole is, the more space it takes up. A typical 10-solar-mass black space it takes up. A typical 10-solar-mass black hole would have a radius of 30 kilometers, and hole would have a radius of 30 kilometers, and a million-solar-mass black hole at the center of a million-solar-mass black hole at the center of a galaxy would have a radius of 3 million a galaxy would have a radius of 3 million kilometers. kilometers.

WHAT HAPPENS IF YOU FALL WHAT HAPPENS IF YOU FALL INTO A BLACK HOLE?INTO A BLACK HOLE?

FALLING INTO A BLACK HOLEFALLING INTO A BLACK HOLE

A black hole is a place where the force of gravity is so A black hole is a place where the force of gravity is so powerful that you would need to be travel at a speed powerful that you would need to be travel at a speed faster than the speed of light to escape its pull. Since faster than the speed of light to escape its pull. Since nothing in the universe is faster than the speed of light, nothing in the universe is faster than the speed of light, nothing that falls into a black hole can ever escape. nothing that falls into a black hole can ever escape.

The pulling force would increase as you moved toward the The pulling force would increase as you moved toward the

center, creating what's called a "tidal force" on your body. center, creating what's called a "tidal force" on your body. If you fell into a large enough black hole, no one outside If you fell into a large enough black hole, no one outside

would be able to see you, but you'd have a view of them. would be able to see you, but you'd have a view of them. Meanwhile, the gravitational pull would bend the light Meanwhile, the gravitational pull would bend the light weirdly and distort your last moments of vision. weirdly and distort your last moments of vision.

IF A BLACK HOLE EXISTED, WOULD IF A BLACK HOLE EXISTED, WOULD IT SUCK UP ALL THE MATTER IN THE IT SUCK UP ALL THE MATTER IN THE

UNIVERSE?UNIVERSE? A black hole has a horizon," which means a A black hole has a horizon," which means a

region from which you can't escape. As long region from which you can't escape. As long asyou stay outside of the horizon, you can asyou stay outside of the horizon, you can avoid getting sucked in .avoid getting sucked in .

WHAT IF THE SUN BECAME A WHAT IF THE SUN BECAME A BLACK HOLE?BLACK HOLE?

SUN AS A BLACK HOLESUN AS A BLACK HOLE Only stars that weigh considerably more Only stars that weigh considerably more

than the Sun end their lives as black holes. than the Sun end their lives as black holes. The Sun is going to stay roughly the way it The Sun is going to stay roughly the way it is for another five billion years or so.is for another five billion years or so.

If the Sun *did* become a black hole for If the Sun *did* become a black hole for some reason? The main effect is that it some reason? The main effect is that it would get very dark and very cold around would get very dark and very cold around here. The Earth and the other planets would here. The Earth and the other planets would not get sucked into the black hole; they not get sucked into the black hole; they would keep on orbiting in exactly the same would keep on orbiting in exactly the same paths they follow right now.paths they follow right now.

BLACK HOLE HUBBLEBLACK HOLE HUBBLE

HUBBLE BLACK HOLE HUBBLE BLACK HOLE PHOTOPHOTO

The strikingly geometric disk -- The strikingly geometric disk -- which contains enough mass to which contains enough mass to make 100,000 stars like our Sun -- make 100,000 stars like our Sun -- was first identified in Hubble was first identified in Hubble observations made in 1992.observations made in 1992.

BLACK HOLE SEEN IN BLACK HOLE SEEN IN CLOSEST LOOK EVERCLOSEST LOOK EVER

September 4, 2008September 4, 2008—A super massive black —A super massive black hole at the center of the Milky Way has wound hole at the center of the Milky Way has wound up in the crosshairs of a virtual telescope up in the crosshairs of a virtual telescope spanning 2,800 miles (4,506 kilometers). spanning 2,800 miles (4,506 kilometers).

Though unproven, there is strong evidence for Though unproven, there is strong evidence for the existence of black holes. the existence of black holes.

JOURNEY TO THE BLACK JOURNEY TO THE BLACK HOLEHOLE

NASA create a NASA create a three-dimensional three-dimensional simulation of simulation of merging black merging black holes. This was the holes. This was the largest largest astrophysical astrophysical calculation ever calculation ever performed on a performed on a NASA NASA supercomputer. supercomputer.

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