When visiting a doctor a few years from now, you can expect to be accompanied by a virtual version of yourself. This so-called digital twin will be a working model of your body that can be summoned onto a physician’s computer screen. Updated with your latest vital signs, it will help the doctor make an accurate diagnosis. It also opens the door for medicines and procedures designed specifically for you, greatly increasing recovery rates.
This might seem like fantasy, but the foundations are being laid. Researchers at Queen Mary University of London already use computer simulations of the hearts of individual patients to evaluate different treatments for atrial fibrillation, a common disorder. It would be far too risky to experiment this way on someone’s real heart. With other organs also being twinned by scientists, it seems likely they will eventually link up to form a virtual body.
As our Science & technology section reports, digital twins are starting to pop up everywhere. Among other things, they monitor the health of jet engines on airliners, keep track of Uber’s network of vehicles and replicate Amazon’s extensive supply chain well enough for the online retailer to accurately forecast sales several years ahead. They are helping local authorities respond to the effects of flooding and letting carmakers shave years off the development of new models by simulating test drives and crashes. Twins are also being developed to help manage factories, companies and entire cities. All this is being turbo-charged by recent progress in artificial intelligence (AI), which gives twins the ability to make predictions about their physical counterparts, and fine-tune themselves on new data.
Digital twins began as basic computer models of physical objects and systems. As computers have become more powerful, twins have become more sophisticated. Complex design and modelling software means many physical objects initially take shape in the virtual world. Small sensors, capable of measuring all sorts of things, feed twins with real-time data, ensuring that they mirror their physical counterparts. A Formula 1 racing car, for instance, may have more than 250 sensors updating its digital twin during a grand prix.
The use of AI takes all this much further, allowing virtual models to become more sophisticated, and to both simulate and optimise activities in the real world. You may worry that this portends a dystopian future; Morpheus, a character in a science-fiction film from 1999 in which a sentient machine subdues humanity through pervasive virtual reality, had a name for it. As he said: “The Matrix is everywhere. It is all around us.”
Reality is more prosaic. The idea of creating symbolic representations of real-world things is centuries old. Many ancient civilisations built architectural models, sometimes to place into tombs but also to work out how to build things. Double-entry book-keeping, developed in the 15th century, was a paper-based representation of a merchant’s finances. The Phillips Machine, a hydraulic computer from the 1940s, created a physical “twin” of national economic flows. Spreadsheets and supply-chain management systems enable companies to log transactions, track inventory, make forecasts and model future scenarios.
Today’s digital twins extend this process, making it easier for humans to tackle complex problems. They can act as virtual crystal balls, allowing people to peer into the future, spot problems before they materialise and test wild ideas without real-world consequences. For businesses, this should mean better designs, more streamlined operations and fewer costly blunders. For society, the promise is equally tantalising: personalised health care, cities that flow and breathe more easily and, thanks to the threats exposed by climate modelling, clues as to how the planet might avoid environmental catastrophe. Digital twins offer the ultimate sandbox in which castles can be built and tested before being made real.
Could these virtual doppelgangers go rogue? They might if they are programmed badly, or hacked into. Avoidable medical conditions could be ignored, corporate systems sent awry and critical power plants compromised. Digital twins will gobble up mountains of data, some of it wrong, some of it prejudiced and much of it raising concerns about privacy and surveillance. There is also the danger of tunnel vision as humans rely more and more on digital twins—and miss things that sensors might not be able to capture. Yet these risks are not specific to digital twins. They apply to all emerging technologies, as they always have and always will. Such concerns need to be considered, as in the current debate over the use of AI. The emergence of the digital mirror world will doubtless raise new questions, but its potential advantages are already plain to see.
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