there is no consensus in physics that particles like electrons and positrons are not indivisible. However, it is important to note that scientific understanding evolves over time as new discoveries are made and new theories are developed.
Currently, according to the standard model of particle physics, electrons and positrons are considered elementary particles, meaning they are not composed of smaller constituents. These particles are point-like and do not possess any internal structure.
On the other hand, some theoretical physicists are exploring the possibility of substructure within elementary particles. For instance, string theory, a theoretical framework aiming to unify gravity with quantum mechanics, suggests that particles could be composed of tiny vibrating strings or higher-dimensional objects. However, it is important to note that string theory is still a highly speculative and mathematically complex area of research, and experimental evidence to support its predictions is currently lacking.
Edward Witten, a prominent physicist, has made significant contributions to string theory and other areas of theoretical physics. While Witten's work has provided important insights into various aspects of particle physics and quantum field theory, it is not accurate to claim that he has definitively shown that particles like electrons and positrons are not indivisible wholes.
It is worth emphasizing that the nature of elementary particles and the fundamental structure of the universe remain active areas of research. As our experimental and theoretical understanding advances, new discoveries may shed light on the true nature of particles and potentially challenge our current understanding. However, at present, the prevailing view in physics is that electrons, positrons, and other elementary particles are indivisible at the scales currently accessible to our experiments.