Setting Bounds on SETI
janrinok writes:
https://phys.org/news/2025-10-bounds-seti.html
The Search for Extraterrestrial Intelligence (SETI) has a data scale problem. There are just too many places to look for an interstellar signal, and even if you're looking in the right place you could be looking at the wrong frequency or at the wrong time. Several strategies have come up to narrow the search given this overabundance of data, and a new paper posted to the arXiv preprint server from Naoki Seto of Kyoto University falls nicely into that category-by using the Brightest Of All Time (BOAT) gamma ray burst, with some help from our own galaxy.
When searching for SETI signals, a civilization has to choose three important factors: where to look, what frequency signal to look for, and when to do so. The same problem is faced by the transmitting side-sending signals strong enough to reach other stars coherently in all directions is extraordinarily energy-intensive. In other words, no sane civilization would do that intentionally for long periods of time. And what if you send the wrong frequency? Or worse yet, hop between frequencies? How would a receiving civilization ever know how to find your signal?
[...] To solve these problems, Dr. Seto, who has also published a paper on anchoring events, suggests a "hybrid" strategy. Instead of using only one event, use two-a "spatial" reference and a "temporal" reference. In the paper, he suggests the spatial reference be the center of the Milky Way, while the temporal reference would be an extremely bright event somewhere outside the galaxy.
The underlying idea is to have a "search ring" centered on the event, in the case that your civilization is looking for signals, and a "transmit ring" exactly opposite the event in the case that your civilization is intending to send them. The diameter of each of these rings grows based on the time since the original burst and the distance from the location to the galactic center. Importantly, the angle between the burst and the galactic center is used to "normalize" the time delay at which a signal would be sent to a specific star system.
[...] Unfortunately, all of this spatial and temporal timing doesn't necessarily coordinate the other variable-frequency. There are some theories that a Schelling point for frequency, such as the Hydrogen Line of 1,420 MHz, where hydrogen shines when undergoing a frequency transition, could be used, but realistically, the receiving civilization would still have to search multiple frequencies over that time.
More information: Naoki Seto, Hybrid Strategy for Coordinated Interstellar Signaling: Linking the Galactic Center and Extragalactic Bursts, arXiv (2025). DOI: 10.48550/arxiv.2509.20718
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