Free Astronomy Magazine September-October 2024

11 SEPTEMBER-OCTOBER 2024 ASTRO PUBLISHING billions of years by intense flows of radiation and lethal particles, capa- ble of stripping those planets of their possible atmospheres. Even if they managed to retain their atmosphere, the tidal forces of the red dwarf would almost certainly force these planets to always turn the same hemisphere towards the star (the length of the day and the year are then the same), with the result being the powering of devastating winds. If the arguments against the seven candidates found by Suazo’s team are not convincing enough, even more convincing are those argu- ments against the very existence of Dyson spheres. Firstly, their existence was hypothesized in a historical con- text characterized by an exponential acceleration of global energy con- sumption, mainly due to rapid tech- nological-industrial development and the increase in the world population. Extrapolating these trends to some distant future, it was reasonable to expect in the 1960s that Earth’s re- sources would sooner-or-later no longer be sufficient and that human- ity would have to then exploit the solar system’s main source of energy more and more intensely. Today, we know that the growing efficiency of technologies, the miniaturization of components, and the development of nanotechnologies allow for in- creasing energy savings. The growth trend of the world population is also expected to slow significantly by the end of this century. In addition to the historical context, Dyson may have been misled by his approximate calculations on the amount of material needed to make the spheres. More recent assess- ments reveal that to collect just 10% of the solar energy at the Earth’s distance, it would be necessary to build a megastructure with a surface area equal to 1 billion Earths. If that megastructure, to make it habitable, were 10 km thick, the equivalent of one million Earths of solid material would be needed to build it. Our own solar system contains approxi- mately 100 Earths of solid material − it would therefore be necessary to dismantle another 10,000 planetary systems similar to ours and transport all the material here! By giving up habitability and accepting the sacri- fice of “only” our planets, the mate- rial available might be enough for a sphere with a radius of 1 astronomi- cal unit and a thickness of just 1 me- ter. We are clearly in the realm of technological fiction. The search for Dyson spheres does not seem to be the best path to demonstrate that there is intelligent life in the universe. Perhaps its exis- tence (as Bill Watterson points out above in Calvin & Hobbes) can be demonstrated by the fact that no one has contacted us yet. !