  There have been periodic efforts in recent decades to search for
extraterrestrial intelligence (SETI), especially by trying to find an
extraterrestrial (ET) radio signal or other technosignature in space. Yet, no
such technosignatures have been found. Considering the vastness of space,
finding such technosignatures has been described as trying to find a needle in
a cosmic haystack. To help resolve this, two hypotheses are proposed to aid
SETI researchers in narrowing the search for ET technosignatures, based on a
network analysis approach to locate where in space potential ET communication
networks would most likely be. A potential ET communication network can use
exoplanets as communication access points (e.g., placing a communication
satellite into planetary orbit, or an antenna on a planetary surface). The
approach uses a topology where exoplanets are represented as nodes, and the
lines of average distance (generalized communication paths) between adjacent
exoplanets are represented as edges; the nodes and edges form local and wide
planetary networks. Using the approach and data visualization on exoplanet
databases can highlight locations of potential ET communication networks in
space. The first hypothesis posits that an ET technosignature would more likely
appear in a potentially habitable solar system containing a high concentration
of planets, wherein the planets function as communication access points to
facilitate a potential ET communication network. The second hypothesis posits
that an ET technosignature would more likely appear in a highly concentrated
cluster of potentially habitable solar systems. Contributions to the SETI field
can be increased accuracy in finding ET technosignatures, increased accuracy in
reaching a Schelling point (a mutual realization of how we and an ET
intelligence can find each other), and promoting interdisciplinary SETI
research.
