Sustainable mobility #1: think more, move less

We once hoped that the Internet would replace trips to the mall; that air travel would give way to teleconferencing; and that digital transmission would replace the physical delivery of books and videos. In the event, technology has indeed enabled some of these new kinds of mobility – but in addition to, not as replacements for, the old kinds. Roads built to relieve congestion increase total traffic, and the Internet has increased transport intensity in the economy as a whole. The rhetoric of a “weightless” economy, the “death of distance”, and the “displacement of matter by mind” sound ridiculous, in retrospect. The fundamental problem with the car and the plane is not that they burn too much of the wrong kind of fuel. The problem is that they enable, and perpetuate, patterns of land use, transport intensity, and the separation of functions in space and time, that render the whole way we live unsupportable. Rather than tinkering with symptoms – such as inventing hydrogen-powered vehicles, or turning gas stations into battery stations – the more interesting design task is to re-think the way we use time and space. Distributed computing is an inspiration, I believe, because it’s the information equivalent of sending the acorn, not the tree. There is an alternative way: reduce the movement of matter – whether goods or people – by changing the word faster, to closer. The speed-obsessed computer world, in which network designers rail against delays measured in milliseconds, are years ahead of the rest of us in rethinking space-time issues. They can teach us how to rethink relationships between place and time in the real world, too. Embedded on microchips, computer operations entail carefully accounting for the speed of light. The problem geeks struggle constantly with is called latency – the delay caused by the time it takes for a remote request to be serviced, or for a message to travel between two processing nodes. Another key word, attenuation, describes the loss of transmitted signal strength as a result of interference – a weakening of the signal as it travels further from its source – much as the taste of strawberries grown in Spain weakens as they are trucked to faraway places. The brick walls of latency and attenuation prompt computer designers to talk of a “light-speed crisis” in microprocessor design. The clever design solution to the light-speed crisis is to move processors closer to the data. In ecological terms, to re-localise the economy. Network designers, striving to reduce geodesic distance, have developed the so-called storewidth paradigm or “cache and carry”. They focus on copying, replicating and storing Web pages as close as possible to their final destination, at content access points. Thus, if you go online to retrieve a large software update from an online file library, you are often given a choice of countries from which to download it. This technique is called “load balancing” – even though the loads in question, packets of information, don’t actually weigh anything in real-world terms. Cacheand- carry companies maintain tens of thousand of such caches around the world. By monitoring demand for each item downloaded and making more copies available in its caches when demand rises, and fewer when demand falls, operators can help to smooth out huge fluctuations in traffic. Other companies combine the cache-andcarry approach with smart file sharing, or “portable shared memory parallel programming”. Users’ own computers, anywhere on the Internet, are used as shared memory systems so that recently accessed content can be delivered quickly when needed to other users nearby on the network.

The law of locality
My favourite example of decentralisation of production concerns drinks. The weight of beer and other drinks, especially mineral water, trucked from one rich nation to another is a large component of the freight flood that threatens to overwhelm us. But first Coca-Cola, and now a boom in microbreweries, demonstrate a radically lighter approach: export the recipe, and sometimes the production equipment, but source raw material and distribute locally. People and information want to be closer. When planning where to put capacity, network designers are guided by the law of locality; this law states that network traffic is at least 80 per cent local, 95 per cent continental, and only 5 per cent intercontinental. This is not the “death of distance” once promised by Internet pioneers. Communication network designers use another rule that we can learn from in the analogue world: “The less the space, the more the room.” In silicon, the trade-off between speed and heat generated improves dramatically as size diminishes: Small transistors run faster, cooler and cheaper. Hence the development of the socalled processor-in-memory (PIM) – an integrated circuit that contains both memory and logic on the same chip. So, too, in the analogue world: radically decentralised architectures of production and distribution can radically reduce the material costs of production. We need to build systems that take advantage of the power of networks – but that do so in ways that optimise local-ness. This design principle – “the less the space, the more the room” – is nowhere better demonstrated than in the human brain. The brain, in Edward O. Wilson’s words, is “like one hundred billion squids linked together...” An intricately wired system of a nerve cells, each a few millionths of a metre wide, that are connected to other nerve cells by hundreds of thousands of endings. Information transfer in brains is improved when neuron circuits, fulfilling specialised functions, are placed together in clusters. Neurobiologists have discovered an extraordinary array of such functions: sensory relay stations, integrative centres, memory modules, emotional control centres, among others. The ideal brain case is spherical, or close to it, Wilson observes, because a sphere has the smallest surface relative to volume of any geometric form. A sphere also allows more circuits to be placed close together; the average length of circuits can thus be minimised, which raises the speed of transmission while lowering the energy cost for their construction and maintenance. The mobility dilemma is not as hard as it looks. I have tried here to look at the issue through a fresh lens and to borrow from other domains such microprocessor design, network topography and the geodesy of the human brain. The biosphere itself is the result of 3.8 billion years of iterative, trial-and-error design – so we can safely assume it’s an optimised solution. As J anine Benyus explains in her wonderful book Biomimicry, biological communities, by and large, are localised or relatively closely connected in time and space. Their energy flux is low, distances covered are proximate. With the exception of a few high-flying species, in other words, “nature does not commute to work”.