Physics in a New Era An Overview (2001) / Chapter Skim
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9. The Economy and the Information Age
9. The Economy and the Information Age
Pages 131-148
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From page 131... ...
From wireless telephones and handheld GPS units to video games, DVD, and digital television; to genetic engineering, decoding of the human genome, and combinatorial drug design; to MRls, CT scans, laser eye surgery, and robotic hip replacement surgery; to polymeric materials for inline skates, tennis rackets, and skis; to superalloys for jet engine turbine blades; to lightweight, fuel-efficient automobiles and aircraft; to computers, the Internet, and the World Wide Web technology is everywhere and touching all of us in ever more pervasive ways (see sidebar "The Woricl Wicle Web". All of this technology does not just happen.
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From page 132... ...
In the process, HTTP (Hypertext Transfer Protocol) , which allows the client and server to communicate, was invented, along with HTML (Hypertext Markup Language, based on SGML)
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From page 133... ...
databases at the Stanford Linear Accelerator Center, containing a wide range of information on high-energy physics experiments, institutes, publications, and particle data, that sold the Web to that community. Subsequently, the Mosaic browser developed in early 1993 at the National Center for Supercomputing Applications at the University of Illinois set the Web on the path to the broad role it plays today.
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From page 134... ...
The physics discoveries shown in this figure have enabled breakthrough technologies in virtually every sector of the national economy. The most recent fundamental advances leading to new foundations and discoveries have yet to realize their potential.
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From page 135... ...
The key foundations of the modern silicon semiconductor industry are the discovery of the electron in 1897, the concept of the fieldeffect transistor (FET) in 1926, the first demonstration of the metal oxide ra~:mo ° Vacuum tube Disco Integrated circuit a- ~ v vie v _' ~ v ., to FIGURE 9.2 Computational power that $1000 has bought over the last 50 years.
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From page 136... ...
In 2000, the Nobel Prize in physics was awardecl in part for basic and applied research lead i ng to the i ntegratecl ci rcu it. For the past 30 years, semiconductor technology has been described by Moore's law, an empirical observation that the density of transistors on a silicon integrated circuit doubles about every 18 months.
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From page 137... ...
Moreover, the performance of complex integrated circuits with tens of millions of transistors may be degraded because of nonuniform operating characteristics. In time, continued decreases in device dimensions may result in the information being carried by an ever-decreasing number of charge carriers; ultimately, simple statistical fluctuations wil l l imit the uniformity of device characteristics as the number of charges used to convey information decreases.
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From page 138... ...
Optical-fiber communication is based on a number of developments in basic physics and materials science. They include the purification and processing of tiny pipes of glass, called optical fibers, that efficiently guide light over long distances with so little absorption or scattering that the light can travel for hundreds of kilometers without being absorbed; the invention of the laser and its realization in tiny, efficient semiconductor chips, which gives us a suitable source of the light; and, finally, the invention of the erbium-doped fiber amplifier, which allows efficient amplification of the optical signals.
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From page 139... ...
This has made possible the fiber gratings that are now used to combine and separate the different colors of light that make up the different WDM channels. Also, basic research on atoms and molecules that involved precisely measuring the color of light that they absorb is now used to stabilize the color of light used for each WDM channel, allowing even closer spacing of channels that do not interact, called dense WDM (DWDM)
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From page 140... ...
· /. 1 1 1 1 1 1 1 1 1 1 1 ~ ~ ' l · ~ Experimental · Single Channel (ETDM)
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From page 141... ...
The ultimate information theory limit to the amount of data that can be transmitted over a single fiber is estimated to be on the order of 20 Tbps and is currently a subject of intense study by physicists. As with silicon technology, it is also the dramatic reduction in cost that has ciriven fiber technology development so rapidly.
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From page 142... ...
Because compound semiconductors have two or more different atomic constituents, they can be tailored by selecting materials that have the desired optical and electronic properties. Exploiting decades of basic research in materials such as gallium arsenide and indium phosphide, we are now beginning to be able to understand and control all aspects of compound semiconductor structures, from mechanical through electronic to optical, and to grow devices and structures with atomic layer control.
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From page 143... ...
. storeinlorma110nin the torm ofphysicalslruc~ ture on a sud~ce~ which ~ read out es ones snd zeros w~hanAF~.ln the example below st the right,the structure takes the ~rm of dlmples that are ther~0mechanica~y~rT1en ln af~m ~kh the same AF~ 1hat does the readlng.A drawbackof this approach ~tha1 theread#~rkebandwlUthofaslngieAF~ blow owingloksrelativelyslow~carrate.Toovercomethb~m~adon,ana~ayof103 or even lO6AF~s,aHintegratedona~ngle~E~Schlp, ~ beinginves~galed.The chip ~scannedas en array oftlryphonograpE needles overthe medJa,w~haLlheAF~:operatinginparahe~ 1O read out the data.This approach holds prom~eofachievingstoragedensklesofseveralterabits per squareinch or more w~h ~ i I' 1 1~ : ~I1 IilI
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From page 144... ...
In the past decade, our growing understanding of condensed matter and materials led to important advances in our ability to deposit materials with atomic-level control, enabling production of the GMR heads that were introduced in workstations in late 1997. This increased understanding, made possible by our growing computational ability coupled with atomic-level control of materials, has led to exponential growth in the storage density of magnetic materials.
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From page 145... ...
. 90 95 2000 2005 Availability Year FIGURE 9.6 Hard disk drive (HDD)
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From page 146... ...
Given that quantum mechanics sets bounds on the lifetime of any magnetic state, how do such bounds ultimately establish limits on the size of the smallest possible magnetic entities useful for technological applications? The applications focus provided by GMR has helped to stimulate and invigorate the search for new magnetic heterostructures and nanostructures and new magnetoresistive materials.
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From page 147... ...
Their potential value has recently been demonstrated in magnetic recording studies. The lower left panel shows state-of-theart CoPtCrB magnetic recording media, while the lower right shows a self-assembled FePt nanocrystal superlattice at the same magnification.
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From page 148... ...
In storage, for example, various scanning probe techniques have been proposed as follow-one to hard disk cirives, and computer logic gates made of biological entities or even individual molecules are possible. In optical communications, the use of miniaturized silicon technology or microelectromechanical systems to produce tiny arrays of switches will enable new, low-cost optical networks that do not require translation from optical to electronic and back to optical for regeneration.
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