48 SMArT ThIngS: UBIqUITOUS COMpUTIng USer experIenCe DeSIgn any known user needs or desires? If so, where will the light sensor go? If the lamp reacts to the weather, how will it know what the weather is like? Whether or not to include any of these functions becomes less a question of technological capability or expense, since both are relatively minor compared to other components in the lamp. Instead, it becomes a point of team negotia- tion around the use of a single (if critically important) material: information. 4.3 the propertieS of informAtion If information processing is a new design material, what are its properties? What can designers do with it and how can they do it? 4.3.1 InformatIon requIres a medIum Although digital information can be described in isolation, it requires other materials to be experienced. 6 In this format it resembles electricity. Just as we cannot experience electricity without employing conductors, information requires other media to be used in design. Vallgårda and redström (2007) proposed "computational composite" as a term to describe the melding of information with a traditional material "to become a material we can use in design practice." For example, glass that is coated with a film that changes color in response to electrical signals sent by an attached processor 7 is fundamentally different than just coated glass that has no processor attached. Similarly, a simple electric motor is a different design material than a servo, which is an electric motor that has processors and sensors permanently attached to it and controlling it. Motors are controlled electroni- cally or mechanically, while servos must be controlled digitally. This effect is so strong that the combination of the two materials, the computational composite, becomes a design material in its own right, just as reinforced concrete (which couples steel rods with concrete) is treated as a single material. The study of smart materials (see Sidebar: Smart Materials) is based on this fundamental capability of information as a material. As with all physical materials, new properties and applications continuously emerge. Designers regularly create new uses for old material, and new materials appear with such regularity that material libraries (Figure 4-2) exist to familiar- ize designers with them. Traditional materials (steel, plastic, or cotton) have properties such as elas- ticity, strength, resistance to corrosion, etc., but digital information has none of these inherently. Löwgren and Stolterman (2004) described information as a "material without qualities," with few inherent attributes that can be used in design, but which acquires attributes as part of the design practice. 7 Electrochromic glass (Ritter, 2007). 6