Rutherford, Ernest (Baron Rutherford of Nelson) (1871–1937),
British physicist. Rutherford is ranked with Isaac Newton and Michael Faraday for his fundamental contributions to physics and his lasting influence on scientific thought. He developed the basis for nuclear physics by investigating radioactivity, discovering the alpha particle, and developing the concept of the nuclear atom. In 1902 with Frederick Soddy he developed the theory of radioactive decay. A year later he demonstrated that alpha particles can be deflected by electric and magnetic fields, the direction of the deflection proving that the rays are particles of positive charge. In 1904 he identified the alpha particle as a helium atom. He produced in 1919 the first nuclear reaction by bombarding atoms of nitrogen with alpha particles, thus demonstrating that the atom is not the ultimate building block of the physical universe. His research opened up the whole new field of nuclear energy. In 1908 he was awarded the Nobel Prize for Chemistry.