Infrastructure
As we will discuss in Chapter 18 , Cities section, em cities are likely to be big, dense, highly cost-effective concentrations of computer and communication hardware. How might such cities interact with their surroundings? Today, computer and communication hardware is known for being especially temperamental about its environment. Rooms and buildings designed to house such hardware tend to be climate-controlled to ensure stable and low values of temperature, humidity, vibration, dust, and electromagnetic field intensity. Such equipment housing protects it especially well from fire, flood, and security breaches. The simple assumption is that, compared with our cities today, em cities will also be more climate-controlled to ensure stable and low values of temperature, humidity, vibrations, dust, and electromagnetic signals. These controls may in fact become city level utilities. Large sections of cities, and perhaps entire cities, may be covered, perhaps even domed, to control humidity, dust, and vibration, with city utilities working to absorb remaining pollutants. Emissions within cities may also be strictly controlled. However, an em city may contain temperatures, pressures, vibrations, and chemical concentrations that are toxic to ordinary humans. If so, ordinary humans are excluded from most places in em cities for safety reasons. In addition, we will see in Chapter 18 , Transport section, that many em city transport facilities are unlikely to be well matched to the needs of ordinary humans. Higher prices to rent volume near city centers should push such centers to extend both higher into the sky and deeper into the ground, as happens in human cities today. It should also push computers in city centers to be made from denser physical devices, that is, supporting more computing operations per volume, even if such devices are proportionally more expensive than less dense variants. City centers are also less likely to use deterministic computing devices, if such devices require more volume and cooling. It may be possible to make computing devices that use less mass per computing speed supported, even if they cost more per operation computed. Such lighter devices are more likely to be used at higher city elevations, because they reduce the cost of the physical structures needed to hold them at these heights.