All communication is limited to c. Any novel forms which are not limited to c are beyond our ken so we lack even the ability to look. At this point, scientists

All communication is limited to c. Any novel forms which are not limited to c are beyond our ken so we lack even the ability to look. At this point, scientists are looking for someone who would want to talk to us. (We are very unlikely to intercept anything not intended for us.) Anyone who wanted to talk to a fledgeling civilization is probably smart enough to know to use radio waves.