Do Dyson spheres represent a feasible technological sign in the search for extraterrestrial intelligence?
The Origin of the Idea
In 1960, the renowned British-American theoretical physicist Freeman Dyson proposed a bold idea that shook the field of the search for extraterrestrial intelligence (SETI). In simple terms, Dyson hypothesized that advanced civilizations (driven by population pressures and the growing need for energy) might eventually have to construct massive structures capable of encompassing their entire star. These structures became known as the “Dyson Sphere” in honor of Dyson. According to Dyson, a structure of this kind could harness all the energy of a star while increasing the living space of the advanced civilization by orders of magnitude. Furthermore, Dyson suggested a method for SETI researchers to search for these structures by looking for their infrared (heat) signatures.
Feasibility
Over time, Dyson’s proposals have faced a mix of criticism and support. On one hand, some scientists agree that there are sufficient materials in the solar system to build these structures. After studying the mathematics related to constructing a Dyson Sphere, theoretical physicist and science communicator Paul Satter concluded that building the shell itself (based on specifications) is not only feasible but would provide a return on investment in a reasonable time frame. On the other hand, critics challenge Dyson’s central claim that Jupiter contains enough materials to build a shell. For example, in his proposed paper, Dyson did not acknowledge that only a portion of the planet’s mass would be suitable for construction purposes. This includes the rocky interior and metallic core, which comprise only 13% of the planet’s mass. Meanwhile, hydrogen and helium account for 87% of the planet’s mass. Between Jupiter’s atmosphere and its rocky/metallic core exists a shell composed of “metallic hydrogen,” where the gravitational pressure compresses hydrogen until it solidifies. Whether this hydrogen can remain in its metallic (stable) state once the pressure is removed remains a contentious issue. In 2016, a team of scientists at Harvard University announced that they had produced metallic hydrogen using a diamond and that the sample was stable. However, these claims were met with skepticism, and the team did not attempt to replicate the experiment. In 2022, another team from Harvard tried to replicate the experiment and found that hydrogen became unstable once the pressure was removed.
Implications for SETI?
In light of the shortcomings and costs, why would an advanced civilization build a Dyson Sphere? Is it likely that Malthusian pressures and the need for energy would compel species to destroy their home worlds and rely solely on expanding the amount of habitable space available? Wouldn’t the development of more advanced technologies – such as fusion energy, nanotechnology, and massive space stations – sufficiently meet their needs?
Dyson was clear in his original paper that this was merely a thought experiment. Although he was a bit sparse on details in the original paper, he later clarified what he meant by “the shell” and “habitable environment,” stating: “The hard shell or ring surrounding the star is mechanically impossible. The form of the habitable environment I envisioned consists of a loose collection or swarm of entities traveling on independent orbits around the star.”
Nevertheless, these considerations may have implications for future SETI research. Should our telescopes look for infrared radiation sources indicative of a “swarm” of artificial structures? Or should they focus on other potential technological signatures, such as leakage from optical transmissions, directed energy, satellite beams around a planet, and traditional radio waves?
All we know for sure is that the search will continue! And whatever we find, once we find it, will have a significant impact. As the famous scientist and orientalist Arthur C. Clarke said in the introduction to his novel 2001: A Space Odyssey, “This is just science fiction. The truth, as always, will be much stranger.”
Source: https://interestingengineering.com/science/time-to-rethink-dyson-spheres
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