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If you were asked to define the different stages of human civilization in one word, what would you say?

The Stone Age, the Bronze Age, the Iron Age...and the Silicon Age (Information Age) we are in now. Did you find out? Every giant leap in human history is essentially because we unlocked a new material.

Material science may sound like a boring "discipline of studying stones", but in fact, it is the underlying code of modern society. From the mobile phone screen you touch with your fingertips, to the Voyager flying out of the solar system, to the vascular stents implanted in the human body, materials science is everywhere.

Today, we will talk about this subject called "modern alchemy" and see how scientists change the world by arranging atoms.


1. God’s building blocks: structure determines everything

The core secret of materials science is actually written in junior high school chemistry textbooks, but its profound meaning is often ignored by us: Structure determines properties.

In this world, the most amazing example is "carbon".

Please imagine that you are holding a pencil in your hand. The refill is made of graphite. It is soft and will peel off with just a stroke. Then, if you look at the diamond ring on your ring finger (if you have one), it is diamond, the hardest substance in nature.

Graphite and diamond have exactly the same composition, both are 100% carbon atoms. The only difference is - the arrangement of the atoms.

  • The carbon atoms in graphite are arranged in layers, like a deck of unshuffled playing cards. The layers are loosely bonded and slide apart when pushed, so it can be used for writing and as a lubricant.

    • The carbon atoms in * Diamond are in a pyramid-like three-dimensional network structure, hand in hand and side by side, forming an indestructible fortress.

    The work of a materials scientist is, in a sense, playing with Lego bricks. They try to change the arrangement of atoms and molecules to turn "soft" into "hard", "insulating" into "conductive" and "opaque" into "transparent".

    Once you master the spelling of this building block, magic happens.

    2. Challenging the limits of physics: those counter-intuitive “black technology” materials

    In traditional materials science, we study steel, ceramics, and plastics. But in the 21st century, materials science has begun to look like science fiction. Scientists are no longer satisfied with "finding" materials in nature, but have begun to "create" materials.

    Aerogel: solidified smoke


    Have you ever seen the lightest solid in the world?

    Aerogel looks like a piece of light blue smoke frozen in the air. It is 99.8% air, and the remaining 0.2% is usually a skeleton of silica (the main component of sand).

    How light is it? Place a strawberry-sized piece of aerogel on a flower petal and the petal won't even bend.

    But don't let its fragile appearance fool you. Airgel is the king of insulation. If you put a rose on an airgel plate and spray a 1000°C flame underneath, the rose on top will still be delicate and delicate, and will not feel hot at all. This material has already been used on Mars rovers to protect delicate instruments from the extreme cold of space.

    Memory alloy: a metal with "memory"


    Metal is dead, right? But in the hands of materials scientists, they can be alive.

    Nitinol is a shape memory alloy. You can twist it into twists, roll it into a ball, or even flatten it with a hammer. However, as long as you throw it into hot water or heat it, it will instantly "remember" its original appearance and quickly return to its original shape.

    This property makes it a perfect material for a vascular stent: doctors flatten it and stuff it into a thin catheter and deliver it to the clogged blood vessel. As soon as the body temperature heats up, it "remembers" the shape of its own opening, springs open instantly, and supports the passage of life.

    Topological Insulators and Superconductors: Highways for Electronics


    In this area, we try to tame electrons.

    Ordinary copper wires carry losses because electrons bump around as they travel inside them, generating heat (which is why your computer gets hot). But superconductors are different, at a certain temperature, the resistance is zero. Electrons are like being on a super-light highway, with no traffic lights and no friction, flowing forever.

    Although we currently mainly rely on low temperatures to achieve superconductivity, laboratories around the world are frantically searching for "room temperature superconductors." Once successful, not only will power transmission no longer waste energy, levitating trains will become standard, and even nuclear fusion energy will no longer be far away.

    3. The secret of the invisibility cloak: Metamaterials

    If the above materials are still changing their properties through chemical bonds, then "metamaterials" are completely cheating.

    A metamaterial does not depend on what atoms it is made of, but on its macroscopic geometric structure. Scientists etch microstructures smaller than the wavelength of light waves on the surface of the material to forcibly change the propagation path of light.

    We can see objects because the objects reflect light into our eyes. What would happen if a cloak allowed light to flow around an object like water around a stone, and then continue forward?

    To the observer, the light appears to be coming straight through without any obstruction. The object in the middle "disappeared out of thin air".

    This is no longer the magic in "Harry Potter", but the reality of the combination of optics and materials science. Current metamaterials can already achieve invisibility in the microwave band. In the future, invisibility cloaks for visible light may really be born.

    4. Learn from nature: the rise of bionic materials

    Another great teacher of materials science is nature. After hundreds of millions of years of evolution, nature has long evolved the most perfect material solutions.

  • Lotus Leaf Effect: Why do lotus leaves remain unstained despite being exposed to mud? Under the microscope, the surface of the lotus leaf is covered with micron-sized papillae. The water droplets cannot spread, they can only roll down, taking the dust with them. Scientists imitated this structure and created a "superhydrophobic coating" that can be sprayed on clothes without getting dirty even if coffee is poured on it; sprayed on the windshield, there is no need to turn on the wipers on rainy days.

  • Spider Silk: It is one of the strongest fibers in nature, stronger than steel wire of the same weight. If we could synthesize spider silk (which is already partially possible), we could make body armor lighter than Kevlar and even cables for building space elevators.

  • Abalone Shell: It looks ordinary, but it is actually a natural ceramic composite armor. It is made of calcium carbonate and protein stacked in layers. Although the ingredient is chalk dust, it is very tough and not easily broken due to its special layered structure. This "brick-and-mud" structure is inspiring scientists to design the next generation of tank armor.

    • 5. Conclusion: Ethics and future of materials science

    When we master the ability to rearrange atoms, we are essentially playing God.

    What will the materials of the future look like?
    Perhaps it is self-healing concrete. If the house is cracked, it will heal automatically when exposed to water, and the building life can be as long as hundreds of years;
    Perhaps it is flexible electronic skin that allows prosthetic limbs to have a real sense of touch and even monitor human health;
    Perhaps it is degradable bioplastic that completely solves the white pollution problem plaguing the earth.

    But challenges remain. The bottleneck of lithium batteries restricts the development of electric vehicles, the silicon-based limit of chips is approaching the physical critical point, and the shortage of rare earth resources threatens the high-tech industrial chain.

    Material science is a discipline about "possibility". It tells us that on this planet, nothing is absolute waste, and nothing is absolute limit. As long as you find the right arrangement and combination, the soil under your feet can become wings that fly to the stars.

    Next time, when you swipe across the screen of your mobile phone or see the sunset reflecting off the glass walls of a skyscraper, please remember: you are living amidst the miracles woven by countless materials scientists.


    *Author's note: This article aims to popularize the interest and breadth of science in materials science, and some scientific principles are made popular analogies. *