Dyson Sphere: Reality or Science Fiction?

“Could this be a Dyson Sphere?”. These are the words spoken by Captain Picard as he encounters a mysterious object in the 130th episode ("Relics") of Star Trek: The Next Generation. While the series often delves into fantastical spaceships and creatures, the Dyson Sphere has been theorized in our world and recently made the headlines in the scientific community, causing excitement and debate among scientists and Trekkers. But what exactly is a Dyson Sphere? And where does the line between fiction and reality lie?¹

In a world facing challenges in energy use and management, the total quantity of material is limited on Earth, and our generation is already pushing the transition from fossil fuels to renewable energy sources. Nowadays, the energy consumption linked to fossil fuels is estimated to be $138{,}000\,\mathrm{TWh}$ per year. Renewable energy has the potential to generate an immense amount of power, limited only by our capacity to capture it through means like wind turbines and solar panels. Both methods rely on the influence of the Sun, which emits about $3.3 \times 10^{18}\,\mathrm{TWh}$ per year. This is actually sufficient to sustain our current fossil fuel consumption for about 24.1 trillion years, for only one year of our Sun’s lifetime. This staggering comparison underscores the virtually unlimited energy reservoir that our star offers. To put it in perspective, the fraction of the Sun's energy that reaches Earth represents only 0.0000000453% of its total output.²

Now, imagine an advanced civilization capable of capturing and redirecting the full energy output of our Sun to the Earth. Could this involve massive solar panels orbiting the Sun in space? Or a giant sphere obscuring the star? As this might sound like fiction, the reader will not be surprised that this concept first appeared in a science‑fiction novel, Star Maker, by Olaf Stapledon (1937). It is 23 years later, in 1960, that the physicist Freeman Dyson (after whom the concept is named) established the scientific foundation for this structure.

In his article, Search for Artificial Stellar Sources of Infrared Radiation, Dyson described a shell‑like structure or a swarm of small satellites orbiting the Sun to capture a significant portion of its emitted energy. Although Dyson does not actually describe how such a structure works in his paper, his arguments lie in the potential needs of energy from an advanced civilization after a period of several thousands of years. In fact, only assuming the actual electricity needs—which show a growth rate of 2.7% per year—our needs for energy would increase by a factor of roughly 300 billion (assuming a constant rate over time) after thousands of years. By then, Earth's energy resources would be depleted, compelling humanity to look towards space for solutions.

Dyson's argument emphasizes the inevitability for any advanced civilization to harness the energy of their star. In our case, assuming the current electricity needs, the previous growth rate, and the current efficiency of our solar panels, approximately $10^{22}$ solar panels would need to be deployed around the Sun. This immense number illustrates the scale of infrastructure required to meet the future energy demands of an advanced civilization. The reader might reach the same conclusion as Dyson: if such advanced civilizations do exist and build such enormous structures, they should be visible from Earth!

As we know, an object that receives energy emits a fraction of it as radiation. A simple everyday example is a hot stovetop. Following Dyson’s thought experiment, this gigantic installation should emit a signature located in the infrared band—an anomaly to careful observers. Therefore, a significant deviation from standard stellar expectations could indicate the presence of advanced extraterrestrial engineering.

From 1960 and Dyson’s paper, it is only in 1983 that the Infrared Astronomical Satellite (IRAS) was launched and observed many stellar systems, providing spectra to analyze for researchers. Although it was a pioneer effort, no conclusive evidence of Dyson Spheres was found. From the 2000s, the Wide‑field Infrared Survey Explorer (WISE), a NASA mission, was also used to look for Dyson‑Sphere‑like structures. Although some intriguing results were found, no significant confirmations emerged. More recently, the European Space Agency’s mission, Gaia, included a dedicated program to search for Dyson Sphere candidates. After an extensive campaign, with observations of millions of systems, only seven possible star candidates were obtained. In each case, an unusual obscuration or infrared excess was observed that could indicate the presence of a megastructure. Even though, to date, no significant results were observed, all of them were consistent with the presence of clouds of dust. Thus, investigations are still required.

As readers can see, the Dyson Sphere remains at the boundary of science and science fiction, fitting neatly into the plot of a Star Trek episode. Despite the lack of concrete evidence and the challenges in observing the radiation signatures of Dyson Spheres, scientific programs continue to monitor thousands of stellar systems. Future programs are even on their way, like the James Webb Space Telescope (JWST), promising more precise infrared observations that could enhance the search. Until then, our generation must rely on innovation and efficiency, hoping that one day a scientist might look at their data and ask, “Could this be a Dyson Sphere?”.

References

• Energy consumption — Our World in Data
• Dyson sphere — Wikipedia
• Freeman Dyson (1960), "Search for Artificial Stellar Sources of Infrared Radiation" (Science)
• Star Trek: The Next Generation — "Relics" (episode)