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The screen you are staring at now, although you can't feel its existence, is most likely made of some kind of aluminosilicate.

If you raise your head and look out the window, it is also what blocks the wind and rain. The glass you drink from, the glasses on the bridge of your nose, even the fiber optic network that delivers this article to you—essentially, it’s all the same thing.

Glass.

In the disdain chain of materials science, glass usually gets mixed up badly. It doesn’t sound hardcore like titanium alloy, nor does it have a sci-fi aura like graphene. It is so common, so common that we often forget: The reason why human civilization can come out of the muddy Middle Ages is entirely because we lit up the technological tree of "glass".

If you erase the glass from history, you will find that the edifice of modern science will collapse in an instant, leaving only a piece of chicken soup.

Today we will talk about how this pile of "burned sand" secretly rules mankind.


1. Is it solid? Or liquid?

Let me first talk about something that subverts three views: from the perspective of the strict definition of physics, glass has an embarrassing identity.

You touch it and it's hard. But if you drill down to the atomic level, it's a mess.
The atoms of metal are like a military parade, neat and orderly; while the atoms of glass are like a subway station during the morning rush hour, packed together irregularly.

This structure is called "amorphous".

Scientists argued for many years, and finally gave a very mysterious definition: it is a "frozen liquid"**. It turns into water at high temperatures and then cools rapidly. Before the atoms can return to their positions and line up, they are forcibly locked in place.

It is this "chaos" that gives it an unparalleled attribute: transparency.
Because there are no regular grain boundaries (Grain Boundaries) in the atomic arrangement to refract light, photons can drive straight in like passing through no man's land.

It took humans thousands of years to figure out this truth: by throwing the most inconspicuous sand (silica), adding soda and lime into a furnace and burning it, you can get this transparent "liquid stone".

2. The first revolution: "Extending life" to mankind

Scholars in ancient times were miserable.

You can think about it, in the era without glass, what will those wise men who have learned a lot face when they are about 40 years old?
Presbyopia.

Before the age of 40, they were elites; after the age of 40, because they could not see the bamboo slips and parchment clearly, they were actually "waste". The inheritance of human wisdom has to be interrupted frequently due to limitations of physiological functions.

It was not until the 13th century that Italian glass craftsmen invented lenses.

The emergence of glasses has directly extended the working life of humans with high IQs by 20 years. These extra 20 years are often the period when a scholar’s ​​thoughts are most mature and his output is richest. The reason why the Renaissance flourished has a lot to do with the fact that these old men put on glasses and continued to create.

This is not over yet. Glass not only allows people to see books clearly, but also allows people to see the "invisible" world clearly.

Grind the two glass lenses and put them into the tube one behind the other.
Looking up into the sky, Galileo saw the satellites of Jupiter, completely shattering the "geocentric theory";
Looking underground, Leeuwenhoek saw bacteria in water droplets. For the first time, humans knew that diseases were not caused by "evils" but by microorganisms.

Without glass, there would be no astronomy and biology. We may still be using magic tricks to treat illnesses.

3. Chemist’s “Transparent Uterus”

If you have the opportunity to go to a museum to see the equipment of ancient alchemists, you will find that they mostly used clay pots and copper tripods.
There's a big pitfall in experimenting with these things: You have no idea what's going on inside.

Did you react? Has the color changed? Has it settled? It's all guesswork.

The popularity of glass containers has changed chemical reactions from "black box" to "white box".
Test tubes, beakers, flasks - these transparent containers are like the womb that breeds modern chemistry. Scientists can watch the liquid change color, accurately measure the volume, and seal danger behind this thin transparent wall.

It can be said that every grid on the periodic table of elements was tried out one by one in a glass bottle.

4. Even the Internet is made of glass

This brings us to the famous joke: What are the three pillars of modern society?
Steel, cement, and sand.

The sand is purified and turned into silicon chips, which are the brain; the sand is burned and drawn into silk, which is the blood vessels.

Optical fiber, this thing is simply the magic of materials science.
You take a glass rod, heat it until it becomes soft, and then stretch it to become thinner than a human hair. In glass of this purity, light travels wildly using the principle of total reflection.

How pure is the current optical fiber glass?
If the sea was also made of this kind of glass, you could see a coin on the seabed thousands of meters deep on the surface of the Pacific Ocean at a glance.
In comparison, our usual window glass, which is about a few meters thick, is already so green that the other side cannot be seen.

The line of words you are swiping now turned into light pulses and ran wildly through the glass fibers on the seabed for half the world before reaching your screen.

5. Why haven’t we found a replacement yet?

Having said all this, you may ask: It’s already 2025, aren’t there any new materials that can kill glass?

plastic? It scratches easily, is not resistant to high temperatures, and will turn yellow over time.
Transparent ceramic? It's hard enough, but the cost is so high that it can bankrupt you.

The scariest thing about glass is its "cost-effectiveness".
The raw material is sand, which is the most abundant on the earth. It can be made by simply adding heat. It is corrosion-resistant, high-temperature resistant, has good light transmission, and can be recycled. It is like a perfect hexagonal warrior. Although every indicator is not the best in the universe, combined it is simply invincible.

Of course, materials scientists are not idle either.
The current "Gorilla Glass" (Gorilla Glass) uses ion exchange technology to replace the small atoms on the glass surface with large atoms, tightening the surface like cotton wool, and literally turning the fragile glass into a shield that can stop bullets.
Today's "flexible glass" can be rolled up like paper, and folding screen mobile phones rely on it to support the scene.


Conclusion

Sometimes I think that if aliens came to Earth, what would surprise them most might not be our nuclear weapons, but our cities.

At night, human cities are like glowing glass forests. We live in a skeleton supported by steel bars, but use glass as our skin. We see the world through glass, record life through glass, and finally shut ourselves behind the glass and watch the joys and sorrows on the screen.

This is a material that is both hard and fragile, both present and void.

Just like in our time: looks crystal clear and everything can be seen clearly, but with just a light tap, it may be shattered to pieces.

This is glass. A transparent liquid that encapsulates human civilization.