Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

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    CARBON NANOTUBES
    One preview of the power of nanotechnology is carbon nanotubes. In principle, carbon nanotubes are stronger than steel and can also conduct electricity, so carbon-based computers are a possibility. Although they are enormously strong, one problem is that they must be in pure form, and the longest pure carbon fiber is only a few centimeters long. But one day, entire computers may be made of carbon nanotubes and other molecular structures.
    Carbon nanotubes are made of individual carbon atoms bonded to form a tube. Imagine chicken wire, where every joint is a carbon atom. Now roll up the chicken wire into a tube, and you have the geometry of a carbon nanotube. Carbon nanotubes are formed every time ordinary soot is created, but scientists never realized that carbon atoms could bond in such a novel way.
    The near-miraculous properties of carbon nanotubes owe their power to their atomic structure. Usually, when you analyze a solid piece of matter, like a rock or wood, you are actually analyzing a huge composite of many overlapping structures. It is easy to create tiny fractures within this composite, which cause it to break. So the strength of a material depends on imperfections in its molecular structure. For example, graphite is made of pure carbon, but it is extremely soft because it is made of layers that can slide past each other. Each layer consists of carbon atoms, each of which is bonded with three other carbon atoms.
    Diamonds are also made of pure carbon, but they are the strongest naturally occurring mineral. The carbon atoms in diamonds are arranged in a tight, interlocking crystal structure, giving them their phenomenal strength. Similarly, carbon nanotubes owe their amazing properties to their regular atomic structure.
    Already, carbon nanotubes are finding their way into industry. Because of their conductivity, they can be used to create cables to carry large amounts of electrical power. Because of their strength, they can be used to create substances tougher than Kevlar.
    But perhaps the most important application of carbon will be in the computer business. Carbon is one of several candidates that may eventually succeed silicon as the basis of computer technology. The future of theworld economy may eventually depend on this question: What will replace silicon?
    POST-SILICON ERA
    As we mentioned earlier, Moore’s law, one of the foundations of the information revolution, cannot last forever. The future of the world economy and the destiny of nations may ultimately hinge on which nation develops a suitable replacement for silicon.
    The question—When will Moore’s law collapse?—sends shudders throughout the world economy. Gordon Moore himself was asked in 2007 if he thought the celebrated law named after him could last forever. Of course not, he said, and predicted that it would end in ten to fifteen years.
    This rough assessment agreed with a previous estimate made by Paolo Gargini, an Intel Fellow, who is responsible for all external research at Intel. Since the Intel Corporation sets the pace for the entire semiconductor industry, his words were carefully analyzed. At the annual Semicon West conference in 2004, he said, “ We see that for at least the next fifteen to twenty years, we can continue staying on Moore’s law.”
    The current revolution in silicon-based computers has been driven by one overriding fact: the ability of UV light to etch smaller and smaller transistors onto a wafer of silicon. Today, a Pentium chip may have several hundred million transistors on a wafer the size of your thumbnail. Because the wavelength of UV light can be as small as 10 nanometers, it is possible to use etching techniques to carve out components that are only thirty atoms across. But this process cannot continue forever. Sooner or later, it collapses, for several reasons.
    First, the heat generated by powerful chips will eventually melt them. One naive solution is to stack the wafers on top of one another, creating a cubical chip. This would increase the processing power of the chip but at the expense of creating more heat. The heat from these cubical chips is so intense you could fry an egg on top of them. The problem is simple: there is not enough surface area on a cubical chip to cool it down. In general, if you pass cool water or air across a hot chip, the cooling effect is greater if you have more surface contact with the chip. But if you have a cubical chip, the surface