Once upon a time, people looked up at the sky and thought that the sun and the moon were the same size. After all, to the naked eye, they hang on the canopy, and they seem to be the same disc, and it is really unclear who is big and who is small. However, today we all know that the sun is much bigger than the moon, just because the sun is incredibly far away and the moon is relatively much closer, so they look about the same. It's like if you put a ping-pong ball in front of you and a basketball in the distance, the two objects may seem similar in size, but the difference is huge.

It takes a full eight minutes for sunlight to travel from the sun to the earth, while the moon's light takes just over a second to arrive. The speed of light is so fast that it still reflects the distance between the two. The human eye images a scene like the lens of a camera, where distant objects are compressed by the depth of field and appear to be similar to those near them. This is why, even by the end of the 19th century, mankind has more advanced astronomical telescopes, but it is still unable to accurately measure the specific distance of distant stars.

Scientists can only draw a flat constellation map of the stars visible to the naked eye into various shapes, but in reality, these stars are very different from each other. The universe is never a simple two-dimensional picture, but a huge three-dimensional or even four-dimensional space.

What's even more interesting is that in the middle of the last century, scientists thought that galaxies in the universe were randomly and evenly distributed, like grains of salt sprinkled on the table. However, with the improvement of observation methods, more and more astronomical data surfaced, and people discovered that the galaxies of the universe are not scattered randomly, but arranged regularly, like a huge network of countless silk threads.

為了形象理解這個結構，我們可以看看銀河系在宇宙中的位置。科學家發現，銀河系是一個更大星系群的一部分，而這個龐大的星系群被稱為“拉尼亞凱亞超星系團”。它的形狀像是一片羽毛，而銀河系就棲息在其中的一根“羽絲”上。這個超星系團包含了大約十萬個星系，科學家直到2014年才勾勒出它的完整結構。

In fact, the entire universe is filled with such superclusters of galaxies, which are like an incomparably large cosmic cobweb, each of which is connected by thousands of galaxies. This is the so-called large-scale filamentous structure of the universe. In other words, the universe is not a mass of chaos, but an intricately woven web, and the galaxy in which we live is just a speck of dust in this net.

This begs the surprising question: why does the universe have such a network-like structure? The answer may come down to the "invisible" – dark matter.

In addition to the glittering stars that we are able to see, there is also a vast amount of invisible matter hidden in the universe. Scientists have discovered that it is these mysterious dark matter that weave an invisible web in the universe that allows galaxies to line up along these invisible silk threads.

Imagine a giant bunch of grapes, each galaxy is a grape, and the vines that support these grapes are invisible to us. The mass of this dark matter is even far greater than that of the visible matter we know it well. Scientifically estimated, the ratio of dark matter to ordinary matter is about 1:0. This means that in the universe, there is a world that is far larger than the world we know and cannot be directly detected.

What's even more striking is that this dark matter is not just suspended in the distant starry sky, but is everywhere, and may even be all around us. Inside our bodies, in the spaces we live in, dark matter is always there, but we can't perceive it. They don't emit light, they don't reflect light, and even the most sophisticated detectors can't catch their tracks directly.

Scientists speculate that it is this dark matter that maintains the stability of the Milky Way. Without their gravitational support, the Milky Way might have fallen apart, and the Earth might not have been able to orbit the Sun as safely as it does now.

Life is extremely rare in the universe, and despite the vastness of the universe, only the Earth is the only one we can be sure of at the moment. So, is the emergence of life also related to some "invisible factors"?

Life itself is beautiful, but its origins come from a dark and chaotic world. The first beings were insignificant single-celled organisms that survived tenaciously in harsh environments. Even today, there are countless "invisible" lives around us, such as viruses and bacteria.

Take, for example, the bacteria in our gut and stomach, which number in trillions, silently helping us break down food and provide nutrients. Although they are invisible to the naked eye, they are closely related to our survival. The laws of life are never just what we see with our eyes.

科學家發現，人類的大腦同樣隱藏著一個驚人的網路。我們的大腦里有超過1000億個神經細胞，它們通過錯綜複雜的神經網路連接在一起，形成了思維、記憶和意識。這些神經網路的結構，與宇宙的絲狀結構驚人地相似。

Perhaps, one day in the future, when we uncover the secrets of dark matter, we will also solve the mystery of life at the same time. At that time, we may discover that the entire universe is actually a truly "living" existence.