Ever since radio was invented, we have been emitting a variety of electromagnetic waves as a means of communication. These waves travel through space and will continue travelling forever at the speed of light. So some of the early waves have travelled about one hundred light years.
Astronomers have been looking at electromagnetic waves received from space to study other stars and possible signs of extraterrestrial activity. There might be someone out there studying our activities through our electromagnetic waves.
Nightscapes of cities are small-scale analogues of what we see in the sky at night. Energy-concentrated sports stadiums or street lights parallel clusters and constellations of stars. Constantly moving car headlights are like shooting stars. Yet there seems to be enormous distance between us and space because no one replies.
Broadcasting studios are also energy-concentrated spaces (especially those which are focused on 'discussion'). Our human energy is transmitted by electromagnetic waves, which are broadcast to other parts of the world as well as to space. The studio sets resemble science fiction spacecraft control rooms. In fact they are real spacecraft control rooms in a way, because they emit electromagnetic waves into space while trying to reach a larger audience.
The fact that the Earth abounds in elements heavier than hydrogen and helium suggests that our solar system has condensed out of interstellar material that contained the remnants of such explosions (supernovas). Thus all the elements around us - including those in our bodies - were manufactured in the interior of stars that no longer exist. As one scientist put it: " In truth, we are the children of the Universe." (D Halliday, R Rensnick, J Walker "Fourth edition Fundamentals of Physics")
Shigeru Takato, 2003.