The exciting news coming out of the Lawrence Livermore Laboratory in California has immediately brought to mind the futuristic omens of some of the world’s most insightful and imaginative physicists. American researchers have marked a milestone in the development of fusion energy, the other nuclear energy, which neither emits CO₂ nor generates long-term radioactive waste that will complicate the lives of generations to come for ever and ever. The Livermore experiment is a long way from industrial applications, but it clears a major hurdle by showing that fusing two hydrogen atoms into one helium can generate more energy than it requires. This means that fusion energy will not arrive in the short term, but in the medium term. A clean, cheap and inexhaustible energy seems like a dream, but there is no doubt that it will come true.
And will that be all? Is nuclear fusion the energy of the future and that’s the end of the story? That is unlikely. Since the fusion of hydrogen into helium is the very nuclear reaction that makes the Sun shine, this type of process is sometimes described as a taming of our star’s innermost secret, as if we were bringing a miniaturized version of our star to the planet. It is a correct and inspiring image, but it reveals to us on second reading what the great source of energy that feeds us really is, which is none other than the Sun itself. As Albert Einstein said, imagination reaches beyond knowledge, so let’s let it fly.
Russian physicist Nikolai Kardashov, who headed the Institute for Space Research of his country’s Academy of Sciences and died a few months before the pandemic, classified the degree of development of a civilization into three types of growing ambition. A Type I civilization, according to this scale, is one that uses the energy resources of its entire planet. This includes all the energy sources that we use today and also those that we intend to use in the medium term, such as nuclear fusion. A planet’s resources are sufficient, in theory, to work wonders like controlling the weather, farming the oceans, and exploring its entire solar system. We don’t do that because we haven’t even reached type I yet. We’ll go more for type 0.6 or something similar. Fusion energy will play a very important role here.
But sooner or later we will have to turn our gaze to the Sun again. Even if we turned the entire Earth into a nuclear fusion power plant, we could not achieve even a tiny fraction of the energy that the Sun produces in a single day. Hence, a type II civilization, always on the Kardashov scale, is the one that takes advantage of all the energy of its sun. Not only the one that falls on the planet, but all of it, with large displays such as the Dyson sphere, a swarm of satellites that would completely surround the star to suck all its energy. Finally, type III would be a galactic civilization of the type Star Wars. We will return to the Sun sooner or later.
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