If you live in suburbia, then within a few hundred yards of your own home, there will most probably be a towering display of mankind's ability to harness natural energy. On a dark and damp winter's day, the power lines suspended between the beneficent arms of electricity pylons, fizz and crackle in the cold rain. It is a sound derived from a cascade of energy flows which starts with nuclear fusion in the Sun, proceeds via photosynthesis to the creation of metabolic fuels in plant-life, is geologically transformed into hydrocarbon deposits, which are combusted to produce steam, thus impelling turbines to rotate, creating the electric power flows, of which a small fraction is dissipated as sound energy close to your home.
The photograph above is an image of the centre of our galaxy, obtained by the UK's new infrared telescope, Vista. The centre of the galaxy is obscured at visible wavelengths by interstellar dust, Iain Nicolson reporting that "along the line of sight to the galactic centre, of each 10 billion photons that should be arriving from the galactic nucleus, only about one actually does so," (Unfolding our Universe, p198). An infrared telescope, however, is able to peer through this dust, and it's well worth clicking to expand the image, for there are a million stars in this field of view.
"Whereas a sphere 5 light-years in diameter centred on the Sun would contain only four stars (the three components of the Alpha Centauri system and the Sun itself), a similar sized sphere close to the centre of the nuclear bulge [at the centre of our galaxy] would contain about ten million stars...To an observer on a planet located deep within the nuclear bulge, the sky would be aglow with millions of stars...several hundred of which would be brighter than the full Moon," (ibid., p203).
All the stars in Vista's image represent the starting points for cascading energy flows, some of which may be powering the evolution of alien biospheres and civilisations, and ultimately enabling alien observers to hear the fizz and crackle from alien power lines held aloft by beneficent alien pylons.