Will Alien life be friendly towards humans??!!, Remember the Alien.?Xenomorph.!!??

[John Edgar Slow Horses]

To serve humanity.

 

[ReinyDays]

Our atmosphere is transparent to radio waves ... and fairly low energy to produce ... bats use the exact same system except using sound waves ...

For the record ... EM radiation, in general, was discovered by James Maxwell ... Hertz demonstrated these, but Maxwell proved they exist ... and really, William Herschel was the first to report these "caloric rays" in the 18th Century ...

"To Herschel’s surprise, he observed that the temperatures on the thermometers located beyond the red light were even higher than the temperatures within the red part of the spectrum. This observation was pivotal. It demonstrated that there was a form of radiation, invisible to the human eye, that could carry heat. He was not looking for it; it was an unforeseen, serendipitous discovery borne from careful observation." -- {Cite}

Radar is a basic technology that any advanced civilization would have ... like nuclear power ... these steps have to be taken, or no way the they achieve interstellar travel ...