Law21 and an even stronger network effect related to the number of communities that can be formed in a network with n participants. He suggested that this effect might be between n2 and 2n. Referring to magnetic storage, he said that Michael Lesk, now at the National Science Foundation, has studied these effects,22 as have Hal Varian and Peter Lyman at Berkeley, 23 and attempted to calculate how much information is produced in a year. They arrived at a number of 2 exabytes24 per year. At a few dollars per gigabyte, the expense of storing all the information produced a year online in magnetic storage would be only a few billion dollars. He said that considering Dr. Aho’s imminent transmission rate of petabits per second, this amount of data could be transmitted quickly as well, which he found quite amazing.

Dr. Ling then raised the topic of microelectromechanical systems (MEMs), saying that MEMs receive the benefit of all the semiconductor technology and will transform the information technology industry. He described the MEMs-based optical switch and MEMs-based displays made by Texas Instruments and other companies. The main idea behind MEMs is to be able to make inexpensive sensors and actuators, including displays, to bring computing into a closer tie with the real world. He cited special MEM devices that could measure structural changes in buildings after an earthquake, describing which sections have been damaged and which have not, and MEM devices for the body, mentioned by Dr. Aho. He said that MEM technology has the potential to bring dramatic change to information technology.

Batteries Do Not Obey Moore’s Law

Dr. Ling turned to technologies that are not increasing exponentially, especially batteries. Many optimistic scenarios are based on the availability of many mobile or isolated devices, all of which require batteries. The amount of power density that can be packed into a battery has not risen fast and for lithium ion batteries will soon approach a theoretical maximum power density of 5652 kJ/l. Portable applications, such as radios, need a certain minimum amount of power. Display applications need a minimum amount of light to be visible to the human eye. Audible signals need a certain volume of sound. In other words some requirements for power do not scale.


Metcalfe’s Law states that the usefulness, or utility, of a network equals the square of the number of users. Robert Metcalfe founded 3Com Corporation and designed the Ethernet protocol for computer networks.


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In the sequence gigabyte, terabyte, petabyte, and exabyte, an exabyte is 1018 bytes.

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