Obviously, there’s no way to recreate an event as awesome as a black hole merger in a laboratory. But surprisingly, researchers have been considering the problem as far back as 1960, long before we’d ever detected GWs.
One of the first attempts involved rotating masses. However, the rotational speed required to create GWs was impossible to achieve, partly because the materials weren’t strong enough. Other attempts and proposals involved piezoelectric crystals, superfluids, particle beams, and even high-power lasers.
The issue with these attempts is that while physicists understand the theory behind them, they don’t have the right materials yet. Some attempts generated GWs, scientists think, but they aren’t strong enough to be detectable.
“High-frequency gravitational waves, often generated by smaller masses or scales, are feasible for artificial production under laboratory conditions. But they remain undetectable due to their low amplitudes and the mismatch with current detector sensitivities,” the authors explain.
More advanced detection technologies or some method to align generated GWs with existing detection capabilities are needed. Existing technologies are aimed at detecting GWs from astrophysical events.
The authors explain that “Research should focus on designing detectors capable of operating across broader frequency and amplitude ranges.”
While GWs avoid some of the problems that EM communications face, they aren’t without problems. Since they can travel vast distances, GWC faces problems with attenuation, phase distortion, and polarization shifts from interacting with things like dense matter, cosmic structures, magnetic fields, and interstellar matter.
These can not only degrade the signal’s quality but can also complicate decoding.
There are also unique noise sources to consider, including thermal gravitational noise, background radiation and overlapping GW signals.
“Developing comprehensive channel models is essential to ensure reliable and efficient detection in these environments,” the authors write.
In order to ever make use of GWs, we also need to figure out how to modulate them. Signal modulation is critical to communications. Look at any car radio and you see “AM” and “FM.” AM stands for “Amplitude Modulation” and FM stands for “Frequency Modulation.” How could we modulate GWs and turn them into meaningful information?
“Recent studies have explored diverse methods, including astrophysical phenomena-based amplitude modulation (AM), dark matter-induced frequency modulation (FM), superconducting material manipulation, and nonmetricity-based theoretical approaches,” the authors write.
Each one of these holds promise as well as being choked with obstacles.
For example, we can theorize about using dark matter to modulate GW signals, but we don’t even know what dark matter is.
“Frequency modulation involving ultralight scalar dark matter (ULDM) depends on uncertain assumptions about dark matter’s properties and distribution,” the authors write, addressing an elephant in the room.
It might seem as if GWC is out of reach, but it holds so much promise that scientists are unwilling to abandon it. In deep space communications, EM communication is hamstrung by the vast distances and interference from cosmic phenomena. GWC offers solutions to these obstacles.
A better method to communicate over long distances is critical to exploring deep space, and GWC is exactly what we need. “Gravitational waves can maintain consistent signal quality over immense distances, making them suitable for missions beyond the solar system,” the authors write.
Practical gravitational wave communication is a long way off. However, what was once only theoretical is gradually shifting into the practical.
“Gravitational communication, as a frontier research direction with significant potential, is gradually moving from theoretical exploration to practical application,” Wang and Akan write in their conclusion. It will depend on hard work and future breakthroughs.
The pair of researchers know that much hard work is needed to advance the idea. Their paper is deeply detailed and comprehensive, and they hope it will be a catalyst for that work.
“Although a fully practical gravitational wave communication system remains unfeasible, we aim to use this survey to highlight its potential and stimulate further research and innovation, especially for space communication scenarios,” they conclude.
