The idea is to communicate with extraterrestrial civilizations using gravitational waves.

When supermassive black holes or neutron stars merge, distortions in spacetime generate gravitational waves that propagate through the Universe at the speed of light. These waves have been detected using the LIGO and Virgo detectors, thereby confirming one of the key predictions of Einstein's General Theory of Relativity.

Since the 1960s, physicists have raised the possibility of using gravitational waves for communication, including communication with extraterrestrial civilizations, long before their actual discovery.

The essence of the matter is that gravitational communication is not merely science fiction. It pertains to the creation of a new data transmission technology based not on electromagnetic waves but on gravitational waves generated in laboratory conditions: if successful, gravitational-wave communication could become a vital tool for exploring deep space, providing stable interstellar communication with spacecraft.

Traditional communication methods based on electromagnetic waves have several limitations: as distance increases, signals weaken and are distorted by atmospheric phenomena, while solar activity creates interference. In contrast, gravitational waves possess unique properties: they interact with matter much less than electromagnetic signals, lose almost no energy (propagating over vast distances), are resistant to interference, and are unaffected by the atmosphere or cosmic dust.

This is why the authors of a new study, published on the Cornell University preprint server, Houtianfu Wang and Ozgur B. Akan from the University of Cambridge (UK), thoroughly examined the fundamentals, current state, and future of gravitational-wave communication.

To utilize the "ripples" of spacetime as a means of communication, two key challenges must be addressed: generating gravitational waves in laboratory conditions and detecting them. Solving the first challenge requires the development of new materials and methods, particularly superconducting devices and powerful lasers; however, even with these, it is impossible to create waves of sufficient amplitude and frequency for subsequent detection and propagation through the Universe.

However, the same is true for the second, equally distant challenge. The fact is that current detectors, such as LIGO and Virgo, are designed to detect gravitational waves from astrophysical events (i.e., they are oriented towards low-frequency astrophysical signals — hertz to kilohertz), meaning they cannot be used to receive artificial signals.

Although the creation of such technology is not feasible today, the situation may change in the future: not long ago, gravitational waves themselves were considered a purely theoretical consequence of Einstein's equations.

This work is interesting from a scientific perspective as the proposals for creating new technologies outlined in it may assist in the development of superconductors and prove useful in experiments with high-frequency detectors. The researchers hope that their review will inspire colleagues to pursue further investigations.