I found the discussion about searching for alien life forms or communications that may manifest in a way that we do not yet recognize intriguing. As Professor Goodman put it, "we have zero examples of what we're actually looking for." We have come a long way from looking for green people with antennas, and it seems that we become more open minded every day about what extraterrestrial life could look like. I am curious about how the way that scientists have imagined extraterrestrial life has changed over time. Could you provide some historical background on why we focus on alien electromagnetic signals primarily? What new trains of thought are driving the shift to diversify our ways of searching for and concept of aliens?