Ernst Mach
Austrian physicist and philosopher of science. After teaching at Graz and Prague, he was invited to the University of Vienna in 1895, and remained there until 1901. Although his denial of atomism brought him a disreputation sometimes, his acute criticisms of Newtonian mechanics, and of space and time are valuable. His histocal studies on mechanics and thermodynamics are also important.
Although many philosophers, in particular those with the Marxist bent, criticizes severely his instrumentalistic view of science as "idealism", it will revive again and again; it seems that "realistic philosophy" is far more uncritical and metaphysical than Mach's "idealism".
For Mach's Principle, click here.