What strategies and electromagnetic frequencies are thought to be the most logical for long-range communication across the unive
rse with other intelligent beings? A. explosion of nuclear devices at specific intervals and in specific patterns across Earth when we are closest to a nearby star B. night-by-night photography of nearby stars at hydrogen Balmer wavelengths C. continuous radio and microwave listening and transmitting at frequencies at which the natural radio sky noise background is low D. X-ray surveys of space at appropriate times (e.g., when Earth is closest to nearby stars in its orbit), in view of the penetrability of space at these wavelengths
The answer is C. The widely used technique for finding extraterrestrial life is use of SETI (search for extraterrestrial intelligence) dishes that listen for radio waves from outer space. NASA has also been sending radio waves to outer space with messages that could purportedly be decoded by alien intelligent life.
