This blog post presents an interesting perspective by exquisitely comparing college students registering for classes with the birth of stars in the universe.
Only one hour left! Message notifications keep coming in on my phone. Today is the day to register for classes. It is a battle for countless college students whose fate for the semester hangs in the balance. Some are greedy for a better schedule, while others wait patiently. This is happening in a small country on a small planet called Earth, but even the stars in the distant universe are also registering for classes that will determine their entire lives.
Course registration day is a fierce battle for college students. Countless clicks and fast internet speeds determine victory or defeat, and all their attention is focused on securing the classes they want. One mistake can ruin their schedule, but with a little luck, they can get the perfect schedule. The tension and excitement that naturally arise during this process are reminiscent of the process by which stars determine their own destinies.
Just as countless lectures await our choices, there are things in space that await the choices of stars. These are called “interstellar matter.” Interstellar matter is mostly composed of hydrogen and helium. Stars begin to pull interstellar matter toward themselves with all their might to spend their entire lives with it. From stars that greedily attract large amounts of interstellar matter to stars that modestly attract small amounts, their world seems similar to ours.
The interstellar matter that gathers in this way moves and collides with other interstellar matter, soon generating heat. This is called “gravitational contraction,” and it heralds the birth of stars. The process of star formation is very dramatic and as exciting as the tension of registering for classes. Interstellar matter is compressed by gravity, and stars are born under that pressure. This process is similar to clicking on the class you want to take and registering for it. However, stars go through this process over millions of years, while we complete the click in a matter of seconds.
In order for newly born stars to continue shining, they need their own food. The food of stars is not miso soup or chicken, but the gases that make up their bodies. “They live by eating their own bodies?” It sounds very strange, but let’s calm down and continue reading. Most of the interstellar matter attracted by stars is hydrogen. When this hydrogen reaches extremely high temperatures, four hydrogen nuclei combine to form the next element, helium. This is called “hydrogen fusion.”
However, there is an interesting point to note here. Although four hydrogen nuclei have clearly combined to form a helium nucleus, when comparing their masses, the helium nucleus is slightly smaller! It is as if the laws of physics are wrong. If you ask a star about this, it will answer as follows. “Decreased mass? I ate it!” Even if the mass is very small, when it is converted into energy, an unimaginably large amount of energy is released. In other words, stars live by emitting light with the energy converted from the decreased mass.
Friends who are greedy and try to enroll in too many classes are more likely to fail. What is the life of a greedy star like? Greedy stars attract a lot of interstellar matter and maintain their large size. Such large (or massive) stars eat faster than anyone else in order to maintain high temperatures. Stars that eat quickly, that is, stars where hydrogen fusion reactions proceed rapidly, produce helium fusion, carbon fusion, and so on, until they finally produce iron, the final element.
Eventually, greedy stars that have no more elements to create explode with tremendous energy. This is called a “supernova explosion,” which is like a greedy college student dropping a class after only a few days. The remnants of the supernova explosion scattered throughout space await the selection of new stars. And at the center of the supernova explosion, a large scar called a black hole remains.
On the other hand, stars with moderate mass enjoy a stable diet for about 10 billion years. After that, they go through a red giant phase, where they become brighter and larger, and then become white dwarfs, which seem to exist and not exist in this universe, shining faintly in a corner of space. The sun we see every day is a star with moderate ambition, which has been eating a stable meal for 5 billion years and is expected to live a stable life for another 5 billion years.
The world of stars seems very similar to our world. Stars gather interstellar matter, and stars with large masses die quickly, while stars with small masses die slowly. They feed on their own bodies, and when they die, they scatter their bodies throughout the universe for the next generation. However, this process always follows strict natural laws. The only difference is that stars live their lives according to the laws of nature without anyone watching over them. I think this is honest and fair. We, who live our lives looking at the sun and the night sky every day, also need to emulate the honesty and fairness of these stars.
