11. Also, from 1953, Heisenberg's theoretical work concentrated on the unified field theory of elementary particles. 12. Unified field theory is about expanding relativity into the field of electromagnetism, not quantum mechanics.13. Earlier attempts based on classical physics are described in the article on classical unified field theories . 14. There is no accepted unified field theory , and thus it remains an open line of research. 15. Glass laughs, referring to Einstein's failed effort to forge the original unified field theory of physics. 16. Research in this direction ultimately proved fruitless; the desired classical unified field theory was not found. 17. We still don't have a unified field theory . 18. This article describes unified field theory as it is currently understood in connection with quantum theory. 19. Von Weizs�cker also did not want to burden Heim with the development of a unified field theory . 20. Albert Einstein, who, in his search for a Unified Field Theory , did not accept wave-particle duality, wrote: