The Secret of Glass

Hi everyone, welcome to Cold-Knowledge Blind Box. I'm your host, Qiao Yulan.

Today we're talking about something that's everywhere in our lives, something we see every time we walk or drive: glass.

It is bright and clear, and comes in many beautiful colors. But who would have thought that such a simple piece of glass has made an everlasting contribution to the history of science? Thanks to glass, Newton, Galileo and other scientists could observe physics through lenses, and do precise measurements with test tubes.

Its existence also deepened humanity's understanding of optics, all the way to the invention of the lithography machine, which lets us carve complex, intricate chips into an area the size of a fingernail, and so build the smart life we have today.

In this episode of Cold-Knowledge Blind Box, let's get to know glass all over again!

The origins of glass can be traced back several thousand years BC, which means glass appeared even earlier than Jesus. Some records suggest glass first appeared in ancient Egypt five or six thousand years ago. Their pottery craftsmen occasionally found shiny glass fragments while heating pottery. After repeated experiments, they finally managed to fire a shaped glass vessel from a mixture of sand and soda.

The main chemical component of glass is silicon dioxide. Yes, silicon dioxide is also the main component of sand and of semiconductor chips. The melting point of sand is as high as 1700 degrees Celsius. When making glass, you need to add soda to lower the melting point, and then add lime for firing. After cooling, you get the shining glass.

The Yue king Goujian's sword, excavated in China, also has glass inlaid in its hilt. Back then, we didn't call glass "boli." We called it liuli. The word lili in the idiom guang guai lu li ("strange and dazzling") is also glass, so that idiom means something with a strange shape and colorful, brilliant hues.

Oh, so we came into contact with glass this early? Then why did most Chinese buildings still use paper windows? In TV dramas, assassins can poke a tiny hole and see what's going on inside the room. The reason is that ancient Chinese buildings were mostly wooden structures, and a room could not bear the weight of so many glass windows. On top of that, in the hot days before air conditioning, paper windows were much more comfortable than glass, and far more practical. So when we hear the word "glass," our first reaction is that it must have been invented in modern times.

Ancient European buildings, on the other hand, were mostly made of stone, so adding glass put much less pressure on them. Medieval cathedrals still preserved in Europe use glass extensively for their windows, and some even have glass roofs. The windows are printed with many pictures, dazzling with all the colors of the rainbow.

However, history quietly said hello here. From this simple object, the paths of development in East and West began to fork.

One obvious difference is in painting. I wonder if any of you feel the same as I do: looking at Eastern ink painting, it feels very artistic. With a few brush strokes it outlines a mountain, a sea. Early Western painting was similar. When depicting God, artists simply added a halo over his head to set him apart, and the paintings were not full of detail, and their handling of perspective was rather plain.

But right after the Renaissance began, Western realistic painting suddenly made an incredible leap forward. Paintings like the Mona Lisa and Girl with a Pearl Earring look as if they had been rendered by a physics engine in 3D. My first reaction was that Leonardo da Vinci was practically a human camera. And not only da Vinci: in some other paintings, you can even see a series of background blurs. How could that be seen with the human eye? It is obviously shot with a camera. Did they cheat?

Indeed, these masters were less painters than "engineers" who were skilled at operating optical instruments and well versed in the science of the human body. There is now much evidence that when painting portraits, these artists would sit in a separate little room, use a glass lens to project the sitter's image onto the canvas, and then simply trace the projected image to produce a lifelike portrait.

From roughly the fifteenth to the nineteenth century, these Western painters commonly used optical instruments such as the "perspective drawing device," the "camera obscura" and the "concave mirror" to assist their painting.

This was truly a great watershed. A seemingly unremarkable little item, glass, became a tool for humanity to understand optics, and offered a new angle from which to re-examine the world. When you can naturally observe and understand the world through tools, you are less easily fooled by the church and by authority.

Someone once counted that among the twenty greatest experiments in history, sixteen were verified and carried out with the help of glass instruments. Take Newton's mechanics, which laid the scientific foundation. How could one calculate and discover the gravitational attraction between celestial bodies? It is not something you can write a paper about just because an apple fell on your head. You have to propose a hypothesis and verify it before a conclusion holds. Since you have to verify the connections between celestial bodies, and observe the motions of the stars in the sky, wouldn't you need astronomical telescopes fitted with glass?

The same goes for chemistry and biology. Observations of experimental results must be made through transparent containers. Take the steam engine, which set off the first Industrial Revolution. Essentially it was about studying the motion of air pressure, and that required barometers made of glass. In the Age of Discovery, there was no GPS. At sea, sailors used sextants to determine their position, and there was a piece of glass in those as well.

So the tool of glass, to put it plainly, is about deconstructing this world. It presents things that were once invisible in a form we can see with our eyes. If you want to measure one centimeter, you first have to make a ruler that can measure one millimeter. If you cannot observe the facts with independent tools, you have no way to carry out correct practice.

From then on, the way humanity understood the world no longer relied on the mind, but shifted to the eyes. Observing the heavens, observing bacteria, inspecting everything. Humanity suddenly had the instrument to interrogate nature, and that instrument was glass.

When people had powerful tools to observe natural phenomena themselves, and these tools were not a monopoly of royalty and nobles, and their cost was not high enough that many ordinary merchants couldn't afford them, the seeds of a scientific mindset that respects facts were planted, step by step.

After the Renaissance came the Enlightenment. This little piece of glass carried Western civilization forward, opening one technological branch after another in chemistry, astronomy and physics. And among the branches of this technology tree, the most dazzling is modern semiconductor chip technology. The lithography machine is one of its most important links. It is fair to say that without mature lithography machines, we could not have such an abundance of affordable smart chips, nor could we keep unlocking the peaks of computing power, and thus make artificial intelligence possible.

In the field of lithography, glass once again takes center stage at a new height. You have to know that these glass lenses account for 40% of the cost of a lithography machine. Simply put, a lithography machine is a giant camera for manufacturing chips. We take photos to seal the world we see into a picture. The job of the lithography machine is to use exposure and development to reproduce an integrated circuit design onto a silicon wafer coated with photoresist. A good camera lets you take photos of extremely high resolution, and a powerful lithography machine can make very precise chips in the same way.

We may have heard about camera resolution: some manufacturer's camera has 200 megapixels. On a lithography machine, the resolution value is the process node, such as 90 nanometers or 45 nanometers. The smaller the nanometer value, the more powerful the chip's computing power. It's like a small city the size of a fingernail: if you can build more tall buildings in it, it can house more computing units, and the corresponding chip has more computing power.

This is also why Carl Zeiss, besides being a world-famous lens maker, has also become the leader in the Dutch lithography machine industry, and a supplier to ASML. When people master the technology of glass lenses, they effectively also master the scientific understanding of optics, and so form a specialized discipline.

Who would have thought that a little piece of glass could run through human history in this way? It has enabled us to make the high-tech products we depend on today: smartphones, computers, and even the car you're driving now, with its intelligent driving capabilities. From the microscopic world to the edge of the universe, glass keeps extending humanity's horizons. More importantly, it has pushed humanity away from knowing the world with the mind, and toward understanding and reshaping reality through observation and scientific thinking.

Well, the secret story of glass ends here. If you have any other cold knowledge you'd like to hear, you can also open the NIO app, go to the Friends screen, find the community NIO Radio Shenzhen City Branch, and share the cold knowledge you like with us.

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