Chapter 6: Black Holes

The term black hole was developed by John Wheeler in 1969. However, the idea of black holes started nearly 200 years ago. The theory about light that was favored by Newton was that light was made up of particles. The other theory about light implies that light is made of waves. Since these early times, we have concluded that both hypotheses are correct. Many people believed that gravity could not influence the speed of light. But gravity does play a key role in the speed of light. John Mitchell, who wrote the Philosophical Transactions of the Royal Society of London, said that light could not escape a large, compact star that had a strong gravitational field. Any light that escaped the star would be pulled back by the star's gravitational field. These absent-lighted stars are what we call black holes. We can not see them because they do not emit light, but you know they exist. We can learn more about black stars by observing the life cycles of a star. A star is born when hydrogen atoms as well as other atoms are drawn together by a gravitational field. The atoms heat up and continually collide with one another to form helium. The pressure increases to form a balance between the atom repulsion and the gravitational attraction. These two forces hold stars together. The star also releases hydrogen atoms, which makes them light up in the universe. These now stable stars will remain in tact for many years. The life time of a star depends solely on the quantity of energy used in the first stages of the star's life cycle. If the energy input is very high, the star will die sooner then it would have if it had used less energy to start with.



Black holes are formed when stars run out of hydrogen and begin to cool off. The balance between the repulsion of the atoms in the star and the gravitational field comes to an end. This caused the star to cave in, pulling particles close with its gravitational attraction. A once thriving star becomes a black hole that pull light and matter towards it. The fact that black holes do not emit light make them hard to detect with even our best technology. But was can predict that black holes exist by examining the movement of other objects in the universe. When stars are close enough to each other, the orbit abound each other, eventually colliding due to the gravitational attraction. But sometimes we can see stars orbiting around something that is invisible to our eyes. Although it could be a star that is too faint to see from here, it could also be a black hole. We can only assume that black holes exist due to the orbiting pattern of other stars as well as other celestial bodies. Many scientists believe that their could be a large black hole at the center of our galaxy. Such large black holes would need a lot of energy to exist, but it is not impossible. For now, we can only base our ideas of scientific observations and calculations.