Former Secretary of Energy and Nobel Laureate Steven Chu gave a wide-ranging and engaging talk at Lindau about science innovation and a realistic appraisal of problems. There were two main messages in his presentation: first, that scientific innovation has often thwarted doom and gloom prognostications, and second, that an accurate recognition of the nature of our most pressing problems is key to bringing innovation to bear on them. Chu began by listing what are probably the two most important scientific and technological innovations of the twentieth century. The first one was the agricultural revolution started by the Haber-Bosch process of nitrogen fixation which is today keeping a third of the world alive. An equally important revolution was engineered by Norman Borlaug in the 70s, right after the doom-and-gloom prognosticator Paul Ehrlich of Stanford University predicted that no crash programs could possibly keep the world from starving in the 80s and 90s. Borlaug’s repudiation of Ehrlich’s dire prognosis taught us, firstly, that prediction is always difficult, especially about the future, and secondly, that scientific innovation can quell fears of imminent doom almost overnight. The pertinent question about the agricultural revolution though was, can innovation truly solve our problems or does it simply postpone them? Chu pointed out that the world’s population actually promises to level off because of increased wealth and literacy, so the benefits of growth that we have been enjoying may indeed be here to stay for the foreseeable future. The one factor that could derail this state of affairs is climate change, as Chu mentioned later in his talk. The second revolution was the communication revolution that was initiated by Edison and others in the late nineteenth century but which reached its full potential through the invention of the vacuum tube, transistor and integrated circuit in the 1950s. This revolution led directly to the information revolution whose fruits we are still sampling. Chu then moved on to climate change and said that it is the single-biggest problem that could thrown a wrench in the works, that could impact us disproportionately so that all our innovative capability is stretched to its limits. He ran through a quick summary of the major pieces of evidence for increased CO2 emissions and temperature including data from ice cores, satellite measurements of melting ice in Greenland and heat waves. I liked Chu’s overall take on climate change: He said, “I prefer to take a very epidemiological view of climate change, similar to the link between cigarette smoking and cancer. Even if we don’t know all the gory details and the exact mechanisms, the trends are clear and ask us that we act”. How can scientific innovation help us act? This was a half hour talk after all so Chu could not go through all possible solutions. But he started by noting two cases – that of clothes washers and refrigerators – where innovation guided by government mandated efficiency standards led to cost reduction, efficiency and size reduction. He talked about a car from Tesla Motors which his friend owns which can go 300 miles on a single charge. The problem: the cost – $80,0000. This is of course a problem with most electric vehicles and it will have to be addressed by a combination of solutions including government taxes and better technology. The most promising battery technology currently available depends on lithium ion batteries. The problem with lithium batteries is that in terms of energy density they are quite lousy. Chu showed a revealing graph in which he compared the energy density of lithium batteries with that of a variety of other substances. Pound for pound body fat and sugar provide some of the highest energy density around (indeed, there is much more energy in a Snickers bar than in an equivalent stick of dynamite). From the graph the situation looks hopeless since we seem to need at least an improvement of a factor of ten. But as Winston Churchill once said, “It is not enough to do our best, we should do what is necessary”. What is necessary in this case is to ramp up the energy density of lithium just enough to provide us with a cost-effective and reasonably efficient technology. For lithium that sweet spot turns out to be an improvement of a factor of about four. With that improvement we can get electric cars which can go 400-500 miles on a single charge, potentially enough for most homes. Since he was speaking in Germany Chu spent some time talking about solar energy. He praised Germany’s extensive solar energy infrastructure but did not point out the limitations including cost, long-term feasibility and government support. He also pointed out new potential methods for solar cell fabrication that avoid the wastage of silicon. Solar energy is a promising technology whose long-term and large-scale use needs to be validated before it can serve to power the world. But there is no doubt that there is innovative research taking place on this front. Overall Chu’s message was quite clear: whenever people have projected doom-and-gloom scenarios for the future of humanity, some unexpected and often relatively simple scientific development has revolutionized the solution to the problem. The most important challenge in front of us is how to engage the brightest people in the world and provide them with enough funds so that they can generate potentially game-changing ideas by the truckload.