From ancient night viewing, to thinking about the laws of celestial bodies through telescopes, to relying on science and technology to go to space, human curiosity about the vast universe has never disappeared. Can the naked eye really summarize the law by observing the stars? Why are humans so obsessed with the universe? How has the way the universe been explored over the millennia changed dramatically? The surging Q&B invited Bai Ruixue, founder of Beijing Love Space Technology, to talk about human exploration of space.
How the ancients looked at the stars with the naked eye
@柒星: How did the ancients summarize the law of stargazing with the naked eye?
Bai Ruixue: First of all, naked-eye stargazing needs to determine a series of reference objects and coordinates. Shen Kuo said in the "Mengxi Pen Talk": "Heavenly things are not measured, and those who push the calendar cannot mean their numbers, but it is strange that the day is divided into three hundred and sixty-five degrees." If it is divided, it will be remembered by things, and then it can be counted, so it is remembered by the star of the degree. This means that the movement of celestial bodies is very complex, and the calendar writers use the division of weeks and days to simplify the complex problems, but the division of weeks and days requires references, so it is marked by stars near the ecliptic.
From the ancient Babylonian ancient Greek constellation chart to the ancient Chinese "three walls, four elephants and twenty-eight constellations", almost every ancient civilization has its own constellation division. Based on brighter, unchanging stars, they divide the sky into different regions, each of which is a constellation, and name it after their own imagination of what patterns the stars in that region make up. Constellations, the method of recording the position of celestial bodies by establishing coordinate systems, are an ancient expression of the scope of understanding of the object world by defining the scope of knowledge of the object world through the convention of the dimensions of the reference frame.
Second, since there are great limitations in using the senses, find ways to make indirect observations. Many of the astronomical instruments in ancient and modern China and abroad are tools for indirect observation. The "hips" of the Zhou Dynasty, the oldest Chinese astronomical and mathematical work, are generally believed to refer to a scaled wooden pole used to measure the shadow of the sun. The sun is not easy to observe directly, but it is not difficult to measure the shadow projected by the sun on the ground, and the periodic changes of the sun shadow can be summarized by observing the movement and length of the sun shadow, so as to divide the spring, summer, autumn and winter. In 2016, the "Twenty-Four Solar Terms – A System of Temporal Knowledge and Its Practice formed by observing the annual movement of the Sun by Chinese" was inscribed on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity. From the official name included in the list, it can be seen that "immediate results" as an indirect observation method is the embodiment of the scientific method and scientific spirit of the ancients.
Third, computing, played an important role in the observations of the universe by the ancients. The aforementioned "Zhou Jie Arithmetic Classic" records the method of measuring solar terms using the Pythagorean law, and the astronomical calendar of the past dynasties reflects the calculation basis, conversion relationship and calculation process of the ancients for the space-time calculation of celestial motion. This is a very interesting question. For the development of early mathematical astronomy in ancient China, you can see Christopher Cullen, a paleontologist at Oxford University, "Heavenly Numbers", which is even more interesting if examined in conjunction with the "Needham Mystery".
The above are just examples, not all of them. As we know, scientific activities are the process of discovering laws, summarizing laws, and using laws, and theory, experimentation, and calculation are the three major means of scientific research. Although these means have been raised to new heights in the stage of modern scientific development, they have also had their prototypes in ancient times, and they have played an important role in the era of lack of scientific instruments and the naked eye to see the sky. Whether it is the calendar in the agricultural civilization or the navigation of the marine commercial civilization, the level of stargazing is directly related to the survival of a group, so the wise people of the Eastern and Western civilizations will do their best to observe the stars at night and summarize the law.
What are the advances in space exploration?
@Watermelon Coke Flavor: How much has technology helped to explore the universe? What instruments did we first look at the universe, and what imagination did we have of it?
Bai Ruixue: Human history is the history of continuous use of tools to expand the space of survival and cognition, space exploration not only benefits from technology, but also in turn affects, drives and radiates more technological progress. In the more than half a century since the beginning of the global space industry, space technology has brought thousands of years of human exploration of the universe to a new level.
Using space technology, we can send unmanned probes to the planet for observation, so as to obtain images and data that are not available on the ground; using technology, we can build large radio telescopes deep in the mountains, and even capture the ripples of the universe at the beginning of the universe through satellite arrays in the earth's orbit; and using technology, we can carry out long-term human-involved space science experiments to further reveal the mysteries of the universe and benefit mankind.
Look back at how humans used telescopes to observe the universe during the Renaissance 400 years ago. In the Galileo era, telescopes were invented and popularized, and scientists for the first time acquired the instrument to observe the night sky beyond the naked eye — in their time, observing the night sky was to explore the universe. Through the accumulation of observational data, people gradually realized that no matter how fine the theory of the structure of the universe (such as the current-wheel-wheel model) of predecessors, it could not perfectly fit the speed of the movement of planets such as Mars with the Earth as a reference frame. As a result, heliocentrism gradually gained the approval of intellectuals, and the new physics also gained a foothold. Of course, "seeing" is only one way for humans to perceive the world. The contribution of precision instruments based on more principles in the development of the history of astronomy can be consulted in the history of technology, Volume III, Chapter 22, "Precision Instruments Before 1500 Years Ago" when you have time.
The imagination of the universe for each specific era depends on the level of cosmic exploration technology at that time and the mainstream worldview brought about by it. Or take the telescope as an example. For a long time, people observed large places according to their own positions, and the imagination of the world was "round place", and the use of telescopes completely dispelled the idea that human beings thought they were at the center of the universe.
Galileo looked up at the stars
Thinking about the relationship between the Earth and the Moon is also developing on both the scientific and imaginary paths. Since seeing the moon through the telescope for the first time, with its uneven surface and continuous craters, people have come to imagine that it is closer to reality than the myth of Chang'e running to the moon, such as Verne's science fiction novel. Today we are surprised to find that Verne's series of scientific, technological, and engineering ideas from the earth to the moon have many coincidences with the later human moon landing activities.
Commercial aerospace "burns money" or "makes money"
@Little Bunny Rabbit: How much profit can you bring by exploring the universe?
Bai Ruixue: This is an interesting question. For a long period of history, global space exploration has been carried out with the country as the main body, with the purpose of understanding the universe, exploring the future living space of human beings and improving the quality of life of earthlings. In this sense, it is a future-oriented, public welfare work, and it is not profitable. However, at the beginning of this century, countries around the world have introduced policies to encourage the development of commercial spaceflight, and a number of private space companies such as SpaceX have emerged.
Why is this happening? Because business is a kind of driven force that has been proven by practice, sustainable and can greatly stimulate people's creativity, the essence of introducing business in the aerospace field is competition, choice, vitality, entrepreneurship and larger-scale practitioners and beneficiaries, gradually developing aerospace from national behavior into an industrial cluster combined with the country and the market, thus bringing well-being to more people and bringing more possibilities for the future of all mankind.
So the next question is, how to make money in spaceflight? At present, the commercial logic of global commercial spaceflight can basically be summarized into two categories: either useful or fun.
"Useful" includes: selling spacecraft (rocket satellite components, new materials, space infrastructure, etc.), selling spacecraft launch services (rocket carrying, supporting measurement and control insurance, supporting ground facilities and services, etc.), selling spacecraft on-orbit services (on-orbit maintenance and refueling, garbage removal, etc.), selling spacecraft data and applications (communication remote sensing navigation applications, earth-to-sky data, etc.), and selling space resources (space technology experiments and scientific experiments, extraterrestrial mining, etc.). And there is still a lot of room for imagination in the transfer and diffusion of space technology (Americans often call spinoff).
"Traveler's Space Station" space luxury hotel
The second type of business, "fun." This category includes: selling space experience - space tourism from sub-orbit, Earth orbit to lunar orbit has a corresponding route today, for everyone may have a huge market potential for the flying dream, the future development mainly depends on the cost of manned flight can be reduced to what extent; selling feelings - Chinese companies have engaged in DNA in space, the United States has a space funeral company to send human ashes into low Earth orbit (although sooner or later it is going to enter the atmosphere to burn), are representatives of this category, the core of which lies in the cultural concept: selling advertising - Homogeneous advertising fills every corner of the earth today, advertising on space is a good choice. From abroad to the mainland, spacecraft naming logos and even using small satellites to build "space billboards" have been conceived and practiced; selling cultural creations - although the vast majority of people will not be able to go to space for a while and a half, the combination of space concepts, space activities and elements in entertainment, education and other fields with mass consumption behavior is creating a mature business model. After all, Russian movies have all been shot on the space station, and what else can't be imagined?
Of course, most of these profit models are theoretical. The characteristics of long cycle, high cost and complex mechanism determine that it is not easy to make money in space, and it is normal for most commercial space companies in the world to still be in the stage of burning money, and exploration has just begun.