Why we haven't heard from aliens yet
What's the story
A new study by the SETI Institute has found that stormy space weather may be masking signals from extraterrestrial life. The research suggests that stellar activities like solar storms and plasma turbulence can broaden narrow radio signals from distant stars. This makes them harder to detect with traditional narrowband searches, potentially explaining some of the silence in technosignature searches for non-human life.
Signal distortion
What does the study say?
The study, co-authored by SETI astronomer Vishal Gajjar and research assistant Grayce C Brown, was published in the Astrophysical Journal. It highlights an "overlooked complication" in the search for extraterrestrial life: even if an alien transmitter sends a perfectly narrow signal, it might not stay that way as it leaves its home system. Plasma density fluctuations and coronal mass ejections can distort radio waves near their source, "smearing" the signal's frequency and reducing its peak strength.
Search strategy
Rethinking the search
The SETI team made their discovery by calibrating the effects of stellar activity using radio transmissions from spacecraft in our solar system. This was then extrapolated to the environments of faraway stars. Brown said these findings mean space listeners may have to rethink their long-established search mechanics for alien lifeforms, including conducting future observation surveys at higher frequencies.
Communication challenges
Designing better searches for extraterrestrial life
The study's findings suggest that aliens could be out there and might be trying to communicate with us. However, unpredictable space weather has garbled their messages, making them undetectable. Brown said that by quantifying how the stellar activity can reshape narrowband signals, we can make searches that are better matched to what actually arrives at Earth.