Scientists Deciphering Alien Signals Make Breakthrough Discovery

Searching for alien signals is central to the Search for Extraterrestrial Intelligence (SETI) initiative. However, the challenge lies in distinguishing these signals from the natural noise of the cosmos and the interference caused by exoplanets as they move in their orbits around their parent stars. A better grasp of this noise will enable scientists to refine their search for genuine alien transmissions.

“This work gives deeper insight into what extraterrestrially transmitted signals may look like if they come from exoplanets, informing not only the parameter space of techno signature searches but also possible interpretations of detected signals,” research leader Megan Grace Li, a Ph.D. student at UCLA and a National Science Foundation intern for the Research Experience for Undergraduates at the Berkeley SETI Research Center’s Breakthrough Listen project, said.

To decipher alien signals from the noise of exoplanets, scientists must consider how they move in relation to Earth. This gives rise to the Doppler Effect – a change in frequency or wavelength of a wave, such as sound or light, in relation to an observer’s motion relative to the source of the wave.

In SETI astronomy, the Doppler Effect leads to a shift in signal frequency, known as the “drift rate,” due to the relative motion between the transmitting exoplanet and Earth. A lower drift rate signifies more stable alien signals, a crucial factor for distinguishing potential alien transmissions from natural interference.

Previous research led by Sofia Sheikh from the SETI Institute proposed a threshold of 200 nanoHertz (nHz) as a benchmark, indicating the maximum drift rate that exoplanetary systems could exhibit. This threshold served as a guiding principle for prioritizing alien signals that were more likely to be stable and potentially of interest.

However, the new study, which analyzed data from over 5,300 known exoplanets from the NASA Exoplanet Archive, revealed that in 99 percent of cases, the drift rate caused by these exoplanets was only 53 nHz. For stars without known orbiting planets, the drift rate was just 0.44 nHz. These findings suggest that the previous 200 nHz threshold underestimated the potential stability of alien signals from extraterrestrial civilizations.

This lower drift rate threshold allows SETI researchers to focus on more stable alien signals, which are easier and faster to analyze. “These results imply that, in many cases, the drift rate will be so low that we can prioritize other parameters, such as covering more frequencies or analyzing datasets faster, without worrying that we will miss true signals,” Sheikh explained.

The newly established limits, which include the majority of drift rates generated by stable radio signals from exoplanets, are poised to revolutionize future searches for alien signals. It promises to dramatically reduce the time and computing resources required for SETI campaigns, including the one planned by Breakthrough Listen using the MeerKAT telescope.

The potential outcome is a search for alien signals that could become nearly a thousand times faster and more cost-effective, as stated in the research paper. This discovery marks a remarkable turning point in the quest to detect extraterrestrial life. The increased precision in distinguishing signals from noise allows for a more efficient allocation of resources in the search for that elusive needle in the cosmic haystack.