Quantum entanglement

Leonard Susskind describes how apparent conflicts in physics led him to work on quark confinement, string theory, and the holographic principle. He explains how the holographic principle connects black hole information to the universe’s boundary, and discusses the proposed relationship between quantum entanglement and Einstein-Rosen bridges. He surveys open problems including quantum gravity, dark energy, and quantum complexity, while distinguishing scientific curiosity from speculation without explanatory or predictive value. He also reflects on Richard Feynman’s approach to philosophy and on why teaching physics to the public helps him clarify his own ideas.

John Preskill traces quantum computing from Feynman’s proposal to simulate nature with quantum systems through quantum error correction and today’s hardware approaches. He explains entanglement, interference, and Grover’s search algorithm, emphasizing that quantum computers do not simply perform many readable calculations at once. He discusses likely applications in materials and chemistry, the risks to current public-key cryptography, and quantum communication and sensing. He also describes open challenges in scaling hardware, the uncertain prospects of competing technologies, and how quantum information may inform basic physics and education.