String Theory as a field of study was not solely dependent on Ed Witten's contributions, including his proposal of M-Theory. While Witten's work has been influential and has significantly advanced our understanding of string theory, it is important to recognize that string theory has a broader foundation and a history of contributions from various physicists.
String theory emerged as a theoretical framework in the late 1960s and early 1970s as an attempt to reconcile quantum mechanics with gravity. Several physicists, such as Gabriele Veneziano, Leonard Susskind, Holger Bech Nielsen, and Yoichiro Nambu, made important early contributions to the development of string theory.
Over the years, numerous researchers have contributed to the advancement of string theory, exploring its mathematical structures, developing new techniques, and uncovering various aspects of its physical implications. This collective effort has built a foundation for string theory, with numerous insights and discoveries made by physicists other than Ed Witten.
Ed Witten's work, particularly his proposal of M-Theory in the mid-1990s, has indeed been highly influential and has opened up new avenues of research within string theory. M-Theory provides a unified description that encompasses different versions of string theory and incorporates additional dimensions and objects called branes. This proposal has led to new insights and connections within the field.
However, it is important to note that the development of string theory is a collective endeavor involving contributions from a diverse community of physicists. While Witten's contributions have been significant, it would be inaccurate to claim that string theory would be dead without him. String theory as a field of research is a product of the collective efforts of many physicists, each building upon the work of others and pushing the boundaries of our understanding.