Jongjin Park
In 1969, humans finally set foot on the moon. Six billion people on Earth watched TV and cheered. We thought we were going to go on a trip to the moon soon, and we knew that sooner or later we would do manned Mars exploration and extrasolar interstellar travel. And following half a century, there has been no such thing. Why?
We underestimated the universe as it is said that overnight dogs are not scary. When he left footprints on celestial bodies outside the Earth, he treated the universe as if he might reach anywhere just by reaching out. However, I have come to realize that the universe is not as accommodating as I thought.
First of all, astronomical resources were needed to deal with an astronomical number of stars at an astronomical distance. Growing crops can earn you income by investing only one year of hard work. After four years of college, you can graduate and get a job. However, since space exploration did not know when and how the results of the investment would come back, it was not easy to jump in with the exception of the very rich countries. It was only natural that space exploration, a risky business, was delayed, requiring a lot of money, requiring advanced science and technology, and taking a long time to recoup the investment.
Today we know a lot regarding the universe. That the beginning of the universe was the Big Bang, that there was a rapid expansion of the universe following the big bang, that the universe continues to expand, that among the galaxies scattered in the universe, our Milky Way galaxy and neighboring Andromeda galaxy, every corner of the solar system, dark matter, dark energy And we know the future of our universe.
But the problem is the size of the universe. We seem to have had the naive imagination that one day we might go to Mars and to the North Star, just like the Apollo spacecraft went to the moon.
For reference, it is now possible to travel to the moon in three days on a high-tech spacecraft. However, it takes 7 months each way to reach Mars, the closest planet to Earth. Moreover, it has been 45 years since Voyager left Earth. It takes half a hundred years to leave our solar system. And it is said that the closest star to our star, the Sun, will have to fly regarding 20,000 more years to reach it. There are regarding 400 billion such stars in our galaxy, and there are regarding 1 trillion stars in the neighboring Andromeda galaxy. It is said that hundreds of billions of such galaxies come together to form the universe.
The observable universe is said to be regarding 93 billion light-years in diameter, but for us who live at most 100 years, it is an infinite distance and infinite time. Such a universe is divided into three categories in Roman (English) notation.
First, Space has the meaning of space, but it also refers to the universe in a narrow sense, and generally refers to the outer space of the Earth’s atmosphere.
Second, Universe generally refers to the universe referred to in physics, and the universe we usually refer to is this Universe. So, when translating the universe into English, you can write Universe.
Third, there is also the word Cosmos. It is a word used when talking regarding the universe in a philosophical sense. It is easy to think that the universe in a science book is a Universe, and the universe in a philosophy book is Cosmos. (Writer)
Jongjin Park
