Physics and Technology – Technology – Computer Networks
Our modern world has been shaped by linking computers and therefore people together. Networks allow data to flow from machine to machine- across a room or around the globe.
With only a little effort, computers can be linked together in small networks. In turn. these Local Area Networks (LANs) can form the links and nodes of broader or even global network structures. Printers and other devices can also be included in networks. allowing multiple users to access them.
Thus, computers can exchange information, a printer can be shared by several computers, and data of interest to all users can be stored on a common server. A server is a computer or program that offers services within a network. For instance, a mail server distributes personal messages (e-mails) to recipients.
Local area networks
The computers in a LAN are usually located in the same building and connected to the network via network cards. Applications pass data to the network card and receive external data from it. An operating system, such as Windows, Mac OS, or Linux, is required to organize this data exchange. The network card feeds data into the network in the form of packets.
Data packets are exchanged according to set technical rules, called protocols. Likewise, computer networks are constructed using particular technical standards. Ethernet is widely used for wired networks, while Wireless LAN (WLAN) is most common for wireless networks. The interface between a WLAN and a wired network is managed by a special device, a Wireless Access Point.
Broader networks
A Metropolitan Area Network (MAN) connects computers and entire LANs, typically within a city. It usually relies on fiber optic cables and radio links to enable rapid data exchange.
A Wide Area Network (WAN) covers an even larger territory. WANs may be linked via satellite or undersea cable to a Global Area Network, or GAN.
DISTRIBUTED COMPUTING
Scientific research often requires large amounts of computing power. Instead of using a supercomputer, the tasks can be split up and divided among many ordinary computers working at the same time. In the SETI@ home project of the University of California at Berkeley, for example.
Internet users download radio telescope data to their home computers. When the computer is not in use. a screen saver software package searches the data for possible signals from alien civilizations.
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