Presentation ON black holes by mithalesh saini.pptx

In this ppt we've discussed about black holes.

1. PRESENTED BY- MITHALESH SAINI M.Sc phy. 1 st sem . BLACK HOLES

2. INDEX Introduction to Black Holes 2. What are Black Holes? 3. How are Black Holes created? 4. Types of Black Holes 5. Parts of Black Holes

3. The first time the idea of a black hole was suggested was in the late 1790’s by John Michell of England and Pierre-Simon Laplace of France. They both proposed the idea of the existence of an “invisible star” by applying the first Newton Law. They calculated its mass and size, which is now called the “event horizon” that an object would need in order to be faster than even the speed of light. Later, in 1915, Einstein predicted the existence of black holes with his general relativity theory. After that, in 1967, John Wheeler, an American theoretical physicist, applied the term of black holes to what it means now. 1 . INTRODUCTION

4. 2 . WHAT ARE BLACK HOLES? A black hole is a region of space that has so much density, and such a great gravitational pull, that no nearby objects can escape. Scientists can’t directly observe black holes, and the only way to perceive them is by detecting their effect on other matter nearby. As the attracted matter accelerates & heats up, it emits x-rays that radiate into space, emitting powerful gamma rays bursts, which devour nearby stars.

5. 3. HOW ARE BLACK HOLES CREATED Stellar black holes : One way black holes are created is from dying stars. Inside a star, the nuclear fuel of a star and its own gravity collide. This creates stability, but when it runs out of nuclear fuel, gravity compresses the star. The outer layers explode into a supernova, and the centre implodes. After that, a black hole is created. This only occurs in big stars, which are at least 10 times bigger than the sun.

6. 4. TYPES OF BLACK HOLES Astronomers generally divide black holes into three categories according to their mass: stellar-mass,  Supermassive, and intermediate-mass. Stellar-mass black holes : Stellar-mass black holes are born when extremely massive stars collapse and typically weigh between five and 10 times the mass of the Sun. The record-breaking wind is moving about twenty million miles per hour, or about three percent the speed of light

7. Supermassive black holes : fast-moving gas jet; and gravitational forces are equal to 10 billion suns compressed together . These are what we call supermassive black holes. Their even horizon is an imaginary sphere around them which nothing can escape. When matter enter the black hole, it increases in size, reaching other matter which it could not absorb before. Intermediate mass black hole : The intermediate mass black hole is estimated to have a mass between 100 and 1000 solar masses. No single star could ever form such a heavy black hole.

8. 5 . PARTS OF A BLACK HOLE Black holes are really very simple as they have just two main parts – the Event Horizon and the Singularity The Event Horizon : This is the part of the black hole where nothing can get out. It is usually defined as a big sphere that surrounds the black hole, and which absorbs any material including light. Some theories say that only radiation can escape this area.

9. The Singularity : This is the part of a black hole in which all the mass of the black hole has been compressed to a very small space. As a result, the Singularity has almost infinite density.

10. THANK YOU