”I re-experience once again the stimulating atmosphere of each of the ISQMs: There were theoretical discussions in diverse frontier areas of physics as well as descriptions of beautiful new (or planned) experiments and technologies. From each of the Symposia I always came away with the exciting feeling of how wonderful physics is and how lucky it is to be a physicist in this era.”Chen Ning YangThis volume is selected from the First through Fourth International Symposia on Foundations of Quantum Mechanics. The International Symposia on Foundations of Quantum Mechanics in the Light of New Technology (ISQMs) provide a unique interdisciplinary forum where distinguished theorists and experimentalists of diverse fields of research gather to discuss basic problems in quantum mechanics in the light of new technology. This volume collects 51 papers selected from over 200 papers by many distinguished scientists. It includes articles by C N Yang, J A Wheeler, Y Nambu, L Esaki and M P A Fisher, to name just a few, and contains topics ranging from quantum measurements to quantum cosmology.