What are Binaural Beats? Tones produced specifically for the purpose of altering your brainwave frequencies. The posts in the link also contains an exclusive free binaural beats sample of a pure alpha wave.
Super Massive Black Holes by PHD Comics. Sagittarius A*, the super massive black hole at the center of the Milky Way, has a mass million times the mass of our sun, and a diameter equal to the distance between the sun and Mercury.