Transistor
The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Julius Edgar Lilienfeld patented a field-effect transistor in 1926 but it was not possible to actually construct a working device at that time. The first practically implemented device was a point-contact transistor invented in 1947 by American physicists John Bardeen, Walter Brattain, and William Shockley. The transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The transistor is on the list of IEEE milestones in electronics, and Bardeen, Brattain, and Shockley shared the 1956 Nobel Prize in Physics for their achievement.
Carver Mead
Stimulated by Moore's question, Mead and his students began a physics-based analysis of possible materials, trying to determine a lower bound for Moore's Law. In 1968, Mead demonstrated, contrary to common assumptions, that as transistors decreased in size, they would not become more fragile or hotter or more expensive or slower. Rather, he argued that transistors would get faster, better, cooler and cheaper as they were miniaturized. His results were initially met with considerable skepticism, but as designers experimented, more and more results supported his assertion. In 1972, Mead and graduate student Bruce Hoeneisen predicted that transistors could be made as small as 0.15 microns. This lower limit to transistor size was considerably smaller than had been generally expected. Despite initial doubts, Mead's prediction influenced the computer industry's development of submicron technology. When Mead's predicted target was achieved in actual transistor development in 2000, the transistor was highly similar to the one Mead had originally described.