A new paper challenges conventional methods in the hunt for Dyson Spheres, the hypothetical megastructures that could surround a star.
When it comes to spotting advanced civilizations in the galaxy, we might be looking in the wrong place—or rather, the wrong wavelength. A new paper challenges conventional methods in the hunt for Dyson Spheres, the hypothetical megastructures that could surround a star.
Freeman Dyson, the renowned physicist, rocked the scientific community in 1960 with his groundbreaking paper. He suggested that advanced extraterrestrial life could build colossal structures capable of enclosing entire stars. Dyson posited that such ‘Dyson Spheres’ would emit “waste heat,” detectable at mid-infrared wavelengths, thus making them suitable targets for SETI (Search for Extraterrestrial Intelligence).
Past Efforts and New Directions
Despite numerous attempts to find Dyson Spheres by detecting their heat signatures, scientists have so far drawn a blank. This led Jason T. Wright, Professor at the Center for Exoplanets and Habitable Worlds and the Penn State Extraterrestrial Intelligence Center, to propose a change in strategy. Wright’s paper, posted on the arXiv preprint server, advocates focusing on what Dyson Spheres might actually be doing—rather than simply looking for heat emissions.
At the core of Wright’s study is the concept of the Landsberg Limit, which sets an upper bound on the efficiency of solar energy harvesting. Dyson’s initial theory largely rested on the idea that advanced civilizations would tap into ever-larger energy gradients, up to the total energy output of their parent star. Wright uses this thermodynamic principle to offer a more nuanced way to detect these elusive structures.
Infrared Studies and Their Limitations
To date, researchers have conducted only three comprehensive mid-infrared sky surveys, namely IRAS, WISE, and AKARI. Wright clarifies, “Generally, we look for infrared emissions from stars to identify orbiting material. But the challenge has been that we lack a foundational theory on what the heat emissions from a Dyson Sphere would even look like, given that their material properties are unknown.”
Wright is among those who have attempted to create theoretical models for the thermal signatures of Dyson Spheres, but these models often rely on many assumptions. They tend to focus on shell symmetry and orbital distance but fall short in predicting other critical factors like temperatures or radiative interactions.
Megastructure Functions and Observable Consequences
Besides energy capture, Wright discusses alternative motivations for constructing Dyson Spheres, such as utilizing them as gigantic supercomputers (Matrioshka brains) or stellar engines (Shkadov thrusters). He also delves into the engineering practicalities of constructing these megastructures and then applies radiation thermodynamics to understand what scientists might observe.
Wright concludes that smaller, hotter Dyson Spheres would be the most efficient in terms of mass usage. He suggests widening search parameters to temperatures above 300K, as it’s more efficient to extract starlight closer to the star, where temperatures are higher.
Project Hephaistos: The Latest Search Efforts
Mathias Suazo, a Ph.D. student in astrophysics at the University of Uppsala, recently presented his team’s work as part of Project Hephaistos. Utilizing combined data from various observatories, they identified around 20 candidates for future, more focused investigations.
While the search for Dyson Spheres has yet to yield definitive evidence, the hunt continues. As Freeman Dyson once put it, the sheer possibility that even one in a million advanced civilizations might engage in such cosmic engineering keeps the quest alive.
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