Ernst Mach of experimental physics concentrated on the interference, diffraction, polarization and refraction of light in different media under external influences. From there followed important explorations in the field of supersonic fluid mechanics. Mach and physicist-photographer Peter Salcher presented their paper on this subject in 1887; it correctly describes the sound effects observed during the supersonic motion of a projectile. They deduced and experimentally confirmed the existence of a shock wave of conical shape, with the projectile at the apex. The ratio of the speed of a fluid to the local speed of sound "v"/"v" is now called the Mach number. It
Mach Song to 100,00 copies, distributed through their vast community networks within and without their areas of physical presence. In the aftermath of Hurricane Katrina (2005), Mach Song monthly printed 50,000 additional copies for six months for distribution to hurricane victims. They similarly increased the circulation of Mach Song monthly after Hurricane Ike (2008). Mach Song Mach Song (, literally "Life Stream") is a national monthly bilingual Vietnamese–English newspaper published in Houston, Texas. The paper has a readership of approximately 75,000 in 15 cities across the United States and is published by "Boat People SOS"—a national Vietnamese American 501(c)(3) nonprofit organization. Working