New microsoft office power point presentation

Black Holes

Presented by:

Salman AhmadIU14S6MA046

Department of Physics, The Islamia University of Bahawalpur.

Starting as one should!

Don’t let the name FOOL you!

A black hole is a great amount of matter packed in a very small area.

A black hole is a region of space in which the gravitational field is so powerful that nothing, including electromagnetic radiation such as visible light, can escape its pull - a kind of bottomless pit in space-time.

The strong gravity occurs because matter has been pressed into a tiny space. This compression can take place at the end of a star's life. Some black holes are a result of dying stars.

It is "black'' in the sense that not even light can escape. Another way to say it, is that a black hole is an object for which the escape velocity (the velocity required to break free from an object) is greater than the speed of light -- the ultimate "speed limit'' in the universe.

History of ideas about Black Holes

1686-87 - Sir Isaac Newton described laws of gravity in his publication, "Principia.“

November, 1783 - John Michell conjectured that there might be an object massive enough to have an escape velocity greater than the speed of light.

1796 - Simon Pierre Laplace predicted the existence of black holes.

November 25, 1915 - Albert Einstein published the Theory of General Relativity, which predicted spacetime curvature.

1916 – German astronomer and military officer Karl Schwarzchild used Einstein's Theory of General Relativity to define a black hole. Defined gravitational radius of black holes, later called the Schwarzchild radius.

1926 - Sir Arthur Eddington, a relativity expert who, along with Einstein, opposed black hole theory.

1939 - Robert Oppenheimer and Hartland Snyder predicted that massive stars can collapse into black holes.

1967 – American astronomer John Archibald Wheeler coined the term, "black hole.“

1970 - Cygnus X – 1, the first good black hole candidate that astronomers found.

1974 – Prof. Stephen Hawking showed that black holes may not be black after all: They may emit a form of radiation that will eventually cause them to evaporate.

Types of Black Holes According to theory, there might be several

types of black holes, but two of them are more common: stellar black holes and supermassive black holes – depending on their mass.

The smallest ones are known as primordial black holes. Scientists believe this type of black hole is as small as a single atom but with the mass of a large mountain.

How Black Holes are formed?

A black hole is usually formed when a massive star – about 8-10 solar masses collapses or dies under its own gravity.

Stellar Black Holes: It forms when a massive star runs out of nuclear fuel and collapses under its own weight or gravity (supernova).

An Intermediate-mass black hole: Mass of such hole varies from a few tens to a few millions of the mass of the Sun. It is not clear how such a black hole would form. 

Supermassive Black Holes: These types are the biggest of them all. Scientists believe that these black holes, which occupy the center of a galaxy, increase in size as they pull in more and more material from the dense core of the galaxy. Unlike the outer parts of the galaxies, the inner region is crowded with stars, and this creates favorable conditions for the supermassive black holes to grow. The size of these black holes are in the order of hundred thousand solar masses.

Miniature Black Holes: It is believed to have formed during the Big Bang and there is no evidence to substantiate its possible existence during the evolution of the universe. The mass of such black holes would have been considerably smaller than that of the Sun and they only formed due to the extreme external pressures during the Big Bang that compressed the mass to create the singularity.

Structure of a Black Hole

5.PARTS OF A BLACK HOLE:

The singularity: This is the region of the black hole where all the mass of the black hole has been compressed down to nearly zero volume. As a result the singularity has almost infinite density and creates an enormous gravitational force.

The Event Horizon: This is the "point of no return".  Any object, even light, that is within this radius cannot escape the gravitational pull of the black hole.

The Schwarzschild Radius: This is the event horizon's radius. It is the radius at which the escape velocity is equal to the speed of light, This radius depends on the mass of the black hole. For a black hole as massive as the Sun, the radius is about two miles (3 km). For every extra solar mass, the radius increases by two miles.

R = 2GM/c2 R= Schwarzschild radiusG= Gravity constantM= Mass of black holeC= Speed of light

The Accretion Disk:  This is a disk composed of stellar material that is spiraling towards that black hole.

The Ergosphere: If the black hole is rotating, then as it spins, its mass causes the space-time around the black hole to rotate as well. This region is called the ergosphere. 

How are Black Holes detected?

Black holes don't give off light, so we can't just look for them. However, astronomers can find black holes by observing the gravitational effects on other objects nearby.

Rotating stars: Many stars rotate around each other, much as the planets orbit our Sun. When astronomers see a star circling around something, but they cannot see what that something is, they suspect a black hole or a neutron star.

X-rays: Astronomers can discover some black holes because they are sources of X-rays. The intense gravity from a black hole will pull in dust particles from a surrounding cloud of dust or a nearby star. As the particles speed up and heat up, they emit X-rays. So the X-rays don't come directly from the black hole, but from its effect on the dust around it. Although X-rays don't penetrate our atmosphere, astronomers use satellites to observe X-ray sources in the sky.

Falling Matter: Astronomers can observe matter falling into a black hole for additional evidence of its existence. When matter is pulled into a black hole, it forms a disk shape around the black hole that can become incredibly hot. This energy can be detected by traditional observation methods like X-rays.

Do Black Holes die/finish off?

Yes, they do! Perhaps “evaporate” is a more suitable word in this case. The process by which black holes evaporate is called Hawking radiation, or sometimes, Bekenstein-Hawking radiation.

Since nothing can escape from the gravitational force of a black hole, it was long thought that black holes are impossible to destroy. But we now know that black holes actually evaporate, slowly returning their energy to the Universe. The well-known physicist and author Stephen Hawking proved this in 1974 by using the laws of quantum mechanics to study the region close to a black hole horizon.

What if you fell into a Black Hole?You will die! It's safe to say you wouldn't survive the  trip, so stay on the

side of the Event Horizon if you ever want to be seen again.

Death will happen even before hitting the singularity which is at center of Black Hole. Strong gravitational field around Black Hole will stretch and squeeze your body (described in picture below) such that you fall apart dramatically!

What does The Holy Qur’an say about Black Holes?

"Soon We will show them Our Signs in the (furthest) regions (of the earth), and in their own souls, until it becomes manifest to them that this is the Truth. Is it not enough that thy Lord doth witness all things?" - (Al-Qur’an)

Among the many scientific miracles that are mentioned in The Holy Quran is the black hole.

Allah says in The Holy Qur’an:“I swear by the (stars)

receding/invisible/veiled, the running, sweeping (stars).” – (Qur’an 81:58)

The Holy Qur’an mentions the black holes in the following holy verse by its very specific characteristics; these are:

They are running stars. They are veiled or receded. They are sweeping stars.

The star receding or invisible here is the black hole, because light can’t escape the gravity of the black hole, so it is invisible or black as scientifically known.

The Holy Quran describes this star by the word “running”. It’s scientifically known that the black star rotates around itself more than one thousand times a second. Also in the same the black hole is described by the word “sweeping”.

Black holes are “black,” i.e. veiled from direct observation. As well as depictions of the Day of Judgment, the verse below may also be pointing to this scientific discovery about black holes:

“When the stars are extinguished” - (Qur'an, 77:8)

"Consider the LOST STARS“ - (Qur’an, 56:75)

In Surah At-Tariq, Allah says – “And [I swear] by Heaven and the Tariq! And what will convey to you what the Tariq is? The Star Piercing [the darkness]!” (Qur'an, 86:1-3)

It is well known that stars change their nature as they age till they die, among the endpoints of stars is the black hole. Allah says in the Holy Qur’an what means:

  “And call not, besides God, on another god. There is no god but He. Everything (that exists) will perish except His own Face. To Him belongs the Command, and to Him will ye all be brought back.“ - ( Al-Kasas:88)

The Holy Qur’an (The Main Book) holds every bit of information about everything:

“Certainly there is no hidden thing in either heaven or earth which is not in The Clear Book.” - (Qur’an, 27:75)

That’s it! THANK YOU.Any question(s)?