The most important development in physics that I can imagine in the next 50 years would be the discovery of a final theory that dictates all properties of particles and fields. That may be too much to hope for. A major step in this direction would be the discovery of particles like gauginos or squarks that are required by supersymmetry. Alas, we don’t know what the masses of these particles would be, and they may be beyond the reach of any particle accelerator.
On the other hand, we can confidently predict breakthroughs in cosmology. We will know whether the density…
