ARPANET

In American laboratories of the early 1960s, computers lived in autarky. These expensive machines operated in isolation, each jealously guarding its data and programs. But at MIT, Joseph Carl Robnett Licklider saw further. In 1962, this visionary man sketched in his memoranda the outline of a “galactic network” that would radically transform our relationship with machines. He imagined a world where anyone could instantly tap into computing resources scattered across the country. His dream finally found concrete ground when he took charge of ARPA’s computer research program, this Pentagon agency specialized in cutting-edge projects.

Leonard Kleinrock published the first paper on packet switching at MIT in July 1961, an idea he would develop three years later in a complete book. Meanwhile, Paul Baran was working at RAND Corporation on a communication network without a central point, where redundancy would guarantee the survival of exchanges in case of partial destruction. Across the Atlantic, Donald Davies at the British National Physical Laboratory was exploring parallel paths.

In the summer of 1965, Lawrence Roberts and Thomas Merrill managed to connect two computers separated by an entire continent, one in Massachusetts, the other in California. A simple telephone line was sufficient. The experiment worked, certainly, but it also revealed the glaring limitations of the traditional telephone network for this type of use.

Roberts joined ARPA the following year and gave substance to the ARPANET project. His detailed plan, presented in 1967, initially aroused distrust among the researchers involved. The proposed technical architecture seemed too complex to them. Wesley Clark saved the situation by suggesting a solution of genius simplicity: create computers dedicated to routing data, called Interface Message Processors. These famous IMPs immediately won approval. In December 1968, Bolt Beranek and Newman secured the construction contract. The network awakened in September 1969. The first node took up residence at UCLA, where Leonard Kleinrock directed the Network Measurement Center. The second was installed at Douglas Engelbart’s Stanford Research Institute, which housed the Network Information Center. The University of California at Santa Barbara and the University of Utah completed this founding quartet.

October 29, 1969 will remain in history: on that day, the first bits traveled between UCLA and Stanford. Contrary to a widespread idea, ARPANET was not born from a military obsession related to the Cold War. The much more pragmatic objective was to make colossal investments profitable by sharing these prohibitively expensive computers among research centers. ARPA was funding often incompatible machines that sat idle much of the time. Connecting them was simply common economic sense.

Steve Crocker headed the Network Working Group which delivered the Network Control Protocol in December 1970, the first communication protocol between ARPANET host computers. Adoption occurred gradually between 1971 and 1972, allowing the first real applications to emerge. Bob Kahn orchestrated a public demonstration in October 1972 that caused a sensation at the International Computer Communication Conference in Washington. From the basements of the Hilton Hotel, visitors discovered this mysterious network in real time. The success exceeded all expectations. That year also saw the birth of Ray Tomlinson’s electronic mail, the first application that truly won over users.

Growth became exponential. Fifteen nodes by the end of 1971. In 1973, first international connections to University College London and the Norwegian Royal Radar Establishment. ARPANET had just invented the first international packet-switching network.

Vinton Cerf and Bob Kahn achieved a decisive breakthrough in 1973 by designing TCP/IP. They wanted to interconnect networks of different types, such as future radio and satellite networks. Their open architecture allowed each network to retain its specificities while communicating with others via TCP/IP. On January 1, 1983, ARPANET switched to TCP/IP. This technical migration required modifying all the network’s computers simultaneously. To force the transition, the designers progressively deactivated the old NCP protocol in 1982, one day after another, before the final shutdown. The operation succeeded perfectly, demonstrating the maturity of the new architecture.

ARPANET also invented a development method that survives today. Steve Crocker created the Request for Comments in 1969, these informal working documents where researchers shared their thoughts. RFCs became the reference tool for documenting and standardizing the network. This tradition of openness spans decades still. The initial Network Working Group evolved into the Internet Working Group and various structures such as the Internet Activities Board. Researchers and engineers developed protocols together, far from commercial or political pressures.

ARPANET transformed scientific collaboration. It gave birth to an international community united by a common culture of openness and cooperation. The technical and organizational choices of the 1970s influenced the architecture and governance of the contemporary Internet. In 1990, ARPANET quietly faded away, replaced by NSFNET and the first commercial networks that used TCP/IP.