Composed of countless stars
Composed of countless stars, dust, and gas and held together by gravitational attraction, galaxies are systems which are so vast, a total number of them in existence cannot be determined. Some of these distant systems are similar to our own Milky Way galaxy, yet others are completely different. Small Galaxies are referred to as such when they have less than a billion stars. In our own galaxy, the sun is just one of about 100 billion stars. For illustrative purposes, consider that stars are collected into galaxies, which are then collected into groups of galaxies, and the groups are collected into clusters. Galaxy superclusters are the largest structures in the Universe and contain millions of galaxies. While galaxies are not living objects, they can in fact evolve. When looking into the night sky, we can reflect on the fact that galaxies have been in existence for billions of years. Some of the changes that occur result from being disturbed by the gravity of other galaxies. In the further exploration of what the Universe has to offer, there is a phenomenon which has the constant attention of scientists and laypeople alike: The Black Hole.
The oddest and mysterious objects in outer space are Black Holes. Space and time are so warped where these dense objects exist that virtually nothing can escape their gravitational grasp. According to Theoretical Physicist Kip Thorne, Black Holes can be understood as “objects made wholly and solely from curved spacetime.” These unusual objects result from the ashes of dead stars. Following a Supernova, small parts of the remains of stars are left behind. The equations of general relativity, developed by Albert Einstein, predict that if the remains of any given star have three times the mass of the sun, then the powerful gravitational force will overwhelm everything else. In this case, the material that it is made of will be crushed into an infinitely small point with infinite density.
The reality of these objects was first introduced in the late 1700s. Karl Schwarzschild, a German astronomer, established black holes and the current understanding of their existence. Applying Einstein’s theory of general relativity, Schwarzschild made fascinating discoveries. Most notably that matter, when compressed to a certain point, would be enclosed by a section in space from which nothing could escape. The limit of this section is referred to as the event horizon, indicating that it is impossible to observe what takes place inside of a black hole.
Locations of black holes have been identified by Astronomers. For instance, the Milky Way contains about a hundred million black holes, which were formed by the collapse of extremely massive stars. Each stellar black hole weighs about ten times as much as the Sun. Few of these black holes are closely orbited by a normal star that is slowly bleeding matter into the black hole. As this gas falls toward the black hole, it is heated by strong gravity and friction and reaches a standard temperature of ten million degrees.
Black holes can be categorized into different types: including Stellar, Intermediary, and Supermassive. The origins of Stellar black holes can be explained by considering the life cycle. A star may collapse when burning through the last of its fuel. For smaller stars, up to about three times the mass of the sun, the new core will become a neutron star or a white dwarf. When a large star collapses, however, it continues to compress and forms a Stellar black hole. After they are formed by the collapse of individual stars, these black holes are small but extremely dense. In fact, they pack at least three times the mass of the sun into a size that could be like that of a city. This leads to a large amount of gravitational force pulling on objects around black holes. Black holes grow in size when consuming the dust and gas from surrounding galaxies. Additionally, scientists have introduced research revealing Intermediate black holes, which are medium sized. Prior to this research, black holes were believed to only have existed in small and large sizes. In 2014, however, Astronomers found what appeared to be an Intermediate-mass black hole within a spiral galaxy. Lastly and although small black holes fill the universe, Supermassive black holes dominate. These black holes are millions, perhaps even billions, of times as massive as the Sun. Supermassive black holes are thought to exist at the center of virtually every galaxy. The way these black holes form has not been explicitly explained by scientists. Some theories suggest that Supermassive black holes may have resulted from hundreds or thousands of tiny black holes that joined, or as a result of stellar clusters collapsing.
On the surface, scientific theories can be considered arguments. So, research on black holes can produce explanations that vary. Black holes are a phenomenon; however, advancements in research and technology have resulted in conflicting information. For example, black holes are often compared to a vacuum, pulling anything within reach into the abyss with no possibility of an exit. There are also theories which suggest black holes do not act as vacuums, stating that “the gravity around a black hole remains normal unless you get extremely close. (Hubblesite.org). This prompts many to question black holes: Will we ever know the full story on the inner workings of these cosmic objects?