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Aliens may be trying to get our attention with beacons synchronized with supernova explosions

The recent Search for Extraterrestrial Intelligence (SETI) has focused on the famous supernova of 1987, with the idea that aliens might use such events to attract attention with synchronized signals. Although nothing was found this time, the study laid the foundation for future searches using the same innovation strategy.


This principle, called the SETI ellipsoid strategy, offers a potential solution to a difficult problem: how do you coordinate with someone when you can’t communicate? This applies to both the search for unknown alien civilizations and communications on Earth.

It seems hopeless, but American economist and theorist Thomas Schelling popularized a solution of sorts, now known as Schelling points, to this problem in his book The Strategy of Conflict. Of course, two unrelated people who want to meet cannot directly coordinate their efforts, but they can still use their brains.

For example, if a man lost his wife at an amusement park and his phone died, he could use rational thinking, social norms, and an understanding of his wife’s tendencies to find her, while also assuming that she was using a similar thought process. So he could head towards the entrance in hopes that she will follow suit, or, if that doesn’t work, towards the car in the parking lot. Here the entrance and the machine serve as Schelling points.

Here’s an example from the US Navy: two Americans in random places wanting to find each other might independently choose New Year’s Eve as a logical date to meet, New York City as the most likely city, and a popular location like the clock at Grand Central Station or somewhere near the ball in Times Square. Of course, the proposed Schelling point does not guarantee success, but it helps in situations where information or communication is extremely limited.

This is the state of SETI researchers, many of whom work under the assumption that alien civilizations are trying to contact us. The problem is knowing where to look. But as Schelling’s concept reminds us, we must use our brains and actively look for obvious ways in which an undetected alien civilization, despite great distance, might be able to contact us, knowing that we have thought similarly about Schelling’s point.


For SETI, potential Schelling points must be something rare, conspicuous, detectable over vast cosmic distances, and of great interest. Fortunately, such a phenomenon exists – supernovae. The idea dates back to the 1990s, when SETI scientist Guillermo Lemarcan proposed that intelligent civilizations could use supernovae—the powerful explosions of stars that signal the final phase of their lives—as focal points for creating Schelling points. Lemarquand even suggested a specific supernova: SN 1987A. This giant supernova, discovered 37 years ago, is located just 168,000 light-years from Earth in our neighboring Large Magellanic Cloud.

Inspired by this research and armed with the necessary data, a research team from the SETI Institute, the SETI Center at Berkeley and the University of Washington attempted to detect an alien optical beacon, or technosignature, emanating from the SETI ellipsoid located between SN 1987A and Earth. And they did this using data from NASA’s ongoing TESS mission to search for exoplanets using the transit method.

The first thing to happen is the supernova itself, which is eventually discovered by an alien civilization. Alerted to the supernova and acting almost immediately, the aliens broadcast a powerful beacon in hopes of attracting the attention of an unknown civilization. The basic idea is that an unknown civilization like ours would naturally look in the general direction of the supernova in hopes of studying the rare celestial event.

But since the aliens (supposedly) have brains and assume that we have brains too, they would also recognize this as an opportunity to use Schelling’s principle, since both parties, although unaware of each other, mutually recognize the supernova as an opportunity to find each other. Of course, the beacon must have signs of artificial origin, that is, something impossible in nature that only alien civilizations could broadcast, so that astronomers on Earth would recognize this signal as an anomaly.

As for the ellipsoid itself, it represents a growing space in which a supernova is theoretically visible to both an alien civilization and the Earth. From our point of view on Earth, we must look for an alien civilization inside this ellipsoid. Or, as the scientists write in their study published in the Astronomical Journal, the SETI ellipsoid “helps select outliers or signals that are of interest and require further analysis or verification from a technosignature perspective.” The animated GIF above, produced by the SETI Institute, clearly demonstrates this concept.

As noted, the researchers used TESS data for their recent scan. “The new sky surveys provide revolutionary capabilities for searching for technosignatures coordinated with supernovae,” said co-author Barbara Cabrales, a scientist at the SETI Institute and the SETI Center at Berkeley, in a press release.

Of course, we are talking about huge time scales, considering the time it takes for a signal to reach a given destination. As noted, SN 1987A is 168,000 light years away, so any potential alien signal likely originated thousands upon thousands of years ago.

The team analyzed one year of data “to be on the safe side,” Cabrales said, using 3D location data from Gaia Early Data Release 3 and identified 32 major targets in TESS’s southern contiguous viewing area associated with the SETI ellipsoid. By closely studying these targets, scientists tried to distinguish normal behavior from potential technosignatures. Unfortunately, this initial scan did not reveal any anomalies, but this initiative now lays the foundation for a similar, more extensive effort.


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