"Stuff Matters"

Aerogel: (my favorite)

• I remembered it as being transparent, yet strangely opalescent—like a hologram of a jewel: a ghost material.
• What was jelly? he asked. He knew that it wasn’t a liquid, but it wasn’t really a solid either. It was, he decided, a liquid trapped in a solid prison, but one in which the prison bars were like an invisibly thin mesh. In the case of edible jelly, the mesh is made from long molecules of gelatin, which is derived from the protein, collagen, that makes up most connective tissues, such as tendons, skin, and cartilage.
• It’s also why jelly feels so amazing when you eat it: it’s almost 100 percent water, and with a melting point of 35°C the internal gelatin network promptly melts, freeing the water to burst in your mouth.
• “Mr. Charles Learned and I, with the kindly assistance and advice of Prof. J. W. McBain, undertook to test the hypothesis that the liquid in a jelly can be replaced by a gas with little or no shrinkage. Our efforts have met with complete success.” Their cunning idea was to replace the liquid with a gas while it was still inside the jelly, and so use the pressure of the gas to keep the skeleton from collapsing. First, though, they found a way to replace the water in the jelly with a liquid solvent (they used alcohol), which would be easier to manipulate.
• “Mere evaporation would inevitably cause shrinkage. However, the jelly is placed in a closed autoclave with an excess of liquid and the temperature is raised above the critical temperature of the liquid, while the pressure is maintained at all times at or above the vapor pressure, so that no evaporation of liquid can occur and consequently no contraction of the gel can be brought about by capillary forces at its surface.”
• But when he raises the temperature of the whole jelly above the “critical temperature”—the point at which there is no difference between a gas and a liquid because both have the same density and structure—the whole liquid becomes a gas without going through the destructive process of evaporation.
• The jelly has had no way of ‘knowing’ that the liquid within its meshes has become a gas.”... So it was that he engineered a jelly in which the internal skeleton was made of the mineral silicon dioxide: the main constituent of glass.
• This Raleigh scattering, as it is called, is very slight indeed, so you need an enormous volume of gas molecules to see it: the sky works but a room full of air doesn’t. Put another way, any one bit of the sky doesn’t look blue but the whole atmosphere does. But if a small amount of air happens to be encapsulated in a transparent material that happens to contain billions and billions of tiny internal surfaces, then there will be sufficient Raleigh scattering off these surfaces to change the color of any light that passes through it. Silica aerogel has exactly this structure, and this is where its blue hue comes from. So when you hold a piece of aerogel in your hand, it is, in a very real way, like holding a piece of sky.
• Enter aerogel. Because it is a foam, it has within it the equivalent of a billion billion layers of glass and air between one side of the material and the other. This is what makes it such a superb thermal insulator.
• What NASA needed, then, was a way to slow the dust down from eighteen thousand kilometers per hour to zero without damaging the dust or the spacecraft—ideally a material with a very low density, so that the dust particles would be slowed gently without being damaged; ideally one that could do so within the space of a few millimeters; and ideally one that would be transparent, so that scientists could find the tiny specks of dust once they were buried in it. That such a material existed was a minor miracle. That NASA had already used it in space flights was extraordinary. It was, of course, silica aerogel... NASA built an entire space mission around the ability of aerogel to gently collect stardust.
• Aerogels seem to have the ability to compel you to search your brain for some excuse to be involved with them. Like an enigmatic party guest, you just want to be near them, even if you can’t think of anything to say.

Celluloid & glass:

• The game of pool evolved from billiards, a fifteenth-century Northern European game that started in royal palaces and was essentially an indoor version of croquet. This is why the table surface was colored green, to simulate grass. One of the results of the Industrial Revolution was to make billiard tables much cheaper to produce. As in our day, it was found that the game could increase the income of bars and public taverns,
• Ivory has a unique combination of materials properties: it is hard enough to endure the thousands of high-speed collisions between the balls without denting or chipping; it is tough enough to not crack; it can be machined into the spherical shape of a ball; and like many organic materials it can be dyed into different colors.
• Many inventors were operating from their homes—and, in the case of Goodyear, from debtors’ prison.
• You can melt and freeze water repeatedly, and the crystals will re-form. With SiO2 things are different. When this liquid cools down, the SiO2 molecules find it very difficult to form a crystal again...  The result is a solid material that has the molecular structure of a chaotic liquid: a glass.
• the brown color is a dreaded sign in chemistry, a clue that you have a mixture of impurities.
• creating shafts of glass called fulgurites.... They can be up to fifteen meters long and are fragile, since much of their bulk is made of lightly fused sand. Until recently, they were thought of only as strange curiosities. However, because they trap bubbles of air inside themselves when they form, ancient fulgurites provide scientists studying global warming with a handy record of the desert climates of previous eras.
• For instance, they invented the glass window (the word means “wind eye”).
• The Romans realized that the addition of a layer of transparent glass would protect this metal surface from scratches and corrosion while at the same time allowing them to reduce the metal surface to a thickness of a mere fraction of a millimeter. This dramatically reduced the cost of the mirror
• Wherever there is a bubble or crack, the atoms have fewer neighboring atoms to hold them in place and with which to share the force, and so these atoms are more prone to being ripped from position. When a glass smashes, it is because the force is so great that a chain reaction occurs within the material, with the failure of each atom causing the failure of its neighbor.
• The Chinese were experts in paper, wood, ceramic, and metals, but they pretty much ignored glass.
• The lack of glass technology in the East meant that, despite their technical sophistication, they never invented the telescope nor the microscope, and had access to neither until Western missionaries introduced them.
• Similarly, without the microscope, it is impossible to see cells such as bacteria and to study systematically the microscopic world, which was essential to the development of medicine and engineering.
• This idea of electrons not being able to move between rows (or energy states, as they are called) unless the energy exactly matches is the theory that governs the atomic world, called quantum mechanics.
• The way these quanta are arranged in glass is such that moving to a free row requires much more energy than is available in visible light. Consequently, visible light does not have enough energy to allow the electrons to upgrade their seats and has no choice but to pass straight through the atoms.
• Higher-energy light, on the other hand, such as UV light, can upgrade the electrons in glass to the better seats, and so glass is opaque to UV light. This is why you can’t get a suntan through glass,
• Opaque materials like wood and stone effectively have lots of cheap seats available and so visible light and UV are easily absorbed by them.
• Pyrex is a glass with boron oxide added to the mix. This is another molecule that, like silicon dioxide, finds it hard to form crystals. More importantly, as an additive it counteracts the tendency of glass to expand when heated or contract when cooled.
• This new generation of toughened glass has a layer of plastic in its middle, which acts as a glue keeping all the shards of glass together. This layer, known as a laminate, is also the secret behind bulletproof glass, which is essentially the same technology but with several layers of plastic embedded at intervals within the glass.
• When a bullet hits this material, the outermost layer of glass shatters, absorbing some of the bullet’s energy and blunting its tip. The bullet must then push the glass shards through the layer of plastic beneath it, which flows like tough treacle, thus spreading the force over a wider area than the point of impact.
• There is nothing special about our scale, about our cities, about our civilization, except that we have a material that allows us to transcend our scale—that material is glass.

Graphite:

• As I weighed the heavy disk in my hand I found it almost obscenely metallic: gold is the full-fat cream of the metal world.
• Instead, these layers are held together by the universal glue of the material world, a weak set of forces generated by fluctuations in the electric field of molecules, called van der Waals forces. This is the same force that makes Blu-Tack sticky. The upshot is that when graphite is put under stress, it is the weak van der Waals forces that break first, making graphite very soft.
• Meanwhile, the sea of electrons also acts as an electromagnetic trampoline for light, and this reflection of light is what makes it appear shiny like other metals. This neat explanation of graphite’s metallic properties is
• He heated diamond in a vacuum so that there, with no air to react with the diamond, it might survive to higher temperatures. It’s one of those experiments that is easy to propose but much harder to carry out, especially in the eighteenth century, when vacuums themselves were not so easy to produce. What happened next astounded Lavoisier: the diamond still wasn’t impervious to red heat, but this time it turned into pure graphite—proof that these two materials were indeed made of the same stuff, carbon.
• Carbon fiber, as they named it, was made by spinning graphite into a fiber. By rolling sheets of this material up, with the fibers running lengthwise, they could take advantage of the huge strength and stiffness within the sheets. The weakness, as with pure graphite, still lay in the material’s structural dependence on van der Waals forces, but this was overcome by encasing the fibers in an epoxy glue. A new material was born: carbon fiber composite.
• In 1985 Professor Harry Kroto and his team discovered that inside a candle flame carbon atoms were miraculously self-assembling in groups of exactly sixty atoms to form super-molecules of carbon. The molecules looked like giant footballs and were nicknamed “buckyballs” after the architect Buckminster Fuller,
• another type of carbon emerged, a carbon that could form tubes that are only a few nanometers wide. Despite the complexity of their molecular architecture, these carbon nanotubes had a peculiar property: they could self-assemble. They needed no outside help in order to form these complex shapes, nor did they need high-tech equipment. They could do it in the smoke of a candle. It was a moment on a par with the discovery of microscopic bacteria; the world suddenly seemed a much more complex and extraordinary place than we had imagined. It wasn’t just living organisms that could self-assemble into complex structures; the non-living world could do it too. An obsession with the production and examination of nanoscale molecules gripped the world, and nanotechnology became fashionable.
• Carbon nanotubes are like miniature carbon fibers except that they have no weak van der Waals bonding.
• Just for starters, graphene is the thinnest, strongest, and stiffest material in the world; it conducts heat faster than any other known material; it can carry more electricity, faster and with less resistance, than any other material; it allows Klein tunneling,

Porcelain:

• Clay is a mixture of finely powdered minerals and water. Like sand, these mineral powders are the result of the eroding action of the wind and water on rocks, and are in fact tiny crystals.
• prowess. From that moment on in Chinese history, different royal dynasties were associated with different types of imperial porcelain.
• Then, as the temperature increased further still to 1300°C and the whole kiln became white hot, the magic would have started to happen: some of the atoms flowing between their crystals would have turned into a river of glass. Now they were mostly solid, but also part liquid. It would have been as if the cups had blood running through their veins in the form of liquid glass. This liquid would have flowed into all the small pores between the crystals and coated all the surfaces.
• The ringing sound of a cup is the clearest and surest way to know whether it is fully formed inside. If there are any defects within it, any holes that were never filled by the river of glass that flowed while they were white hot, then these will absorb some of the sound and prevent it from reverberating.
• A plaster cast is stiff and strong enough to take the weight of a person and to withstand the knocks that occur when walking about on crutches, while allowing a perfect recovery. Until this material innovation, a broken leg often resulted in permanent lameness.
• The invention in 1840 of an alloy comprised mainly of silver, tin, and mercury, called amalgam, was the turning point.
• It is the ligaments’ job to connect one bone to another. They are viscoelastic, which means that they will stretch immediately a certain amount, but then if that stretch is held, they will flow and lengthen. It is part of the reason why athletes do stretching exercises
• have a look at how people walk. It is kneeled—meaning that you push your knee out ahead of you, positioning it above the point where you wish to plant your next step, allowing the lower leg and foot to swing into place underneath it. Once planted, the foot has to adjust its angle to the terrain, twisting or tilting it,

Scales:

• Structurally, any material is like a Russian doll: it is made up of many nested structures, almost all of which are invisible to our eyes, each one smaller and fitting exactly into the one before. It is this hierarchical architecture that gives materials their complex identities—and, in a very literal sense, it also gives us our identities too.
• These structures are not arbitrary—you cannot create any structure—but are governed by the rules of quantum mechanics, which treat atoms not as singular particles but as an expression of many waves of probability. (This is why it makes sense to refer to the atoms themselves as structures, as well as their formation when they bond with one another.) Some of these quantum structures create electrons that can move, and this results in a material that can conduct electricity.
• “Nano” means “a billionth,” and this world of the nanoscale features things that are roughly a billion times smaller than us. .. These include the proteins and fats in our bodies. They also include the molecules at the heart of plastics, such as the cellulose nitrate used to make celluloid, or the lignin that is removed from wood to make paper.
• The possibilities seem limitless, but what is more interesting is that many of the structures at this scale self-assemble. The crucial difference between the car motor and a nano-motor is that in the case of the nano-version the physical forces that dominate at that scale, such as electrostatic and surface tension forces, which can pull things together, are very strong,
• microscopic structures, which are ten to a hundred times bigger, but nevertheless still invisible. This is the scale at which we encounter one of the greatest technological triumphs of the twentieth century: the silicon chip. ... This is also the scale of biological cells, of iron crystals, of the cellulose fibers of paper and the fibrils of concrete. At the same scale still we find another remarkable man-made structure: the chocolate microstructure.
• The macroscale binds together the atomic structures, the nanostructures, and the microstructures. It is just on the edge of what we can see. The touch screen of a smartphone is a good example of such a structure.
• But as the scale chart shows, living matter is, in some sense, no different conceptually from non-living matter. What dramatically distinguishes the two is that in living materials we find there is an extra degree of connectivity between the different scales: living materials actively organize their internal architecture. They do this by setting up communication between the different scales of the organism.