All articles tagged with #quantum mechanics
A new biography by Philip Ball argues that Niels Bohr was the more radical and influential figure of 20th-century physics compared to Albert Einstein. The book details Bohr’s development of the Copenhagen Interpretation, which posits that observation determines quantum states, and traces his role in the atomic age despite his opposition to nuclear weapons.
Researchers at South China Normal University have experimentally confirmed the two foundational postulates of Richard Feynman’s path-integral formulation of quantum mechanics for the first time. By tracking single photons through an optical grid, the team validated that particles take all possible paths and that these paths contribute equally in magnitude but differ by phase. Published in Science Advances, the results achieve high fidelity, resolving a decades-old gap in direct experimental verification of this core quantum framework.
Physicists at the LHC report strong evidence (4.7 sigma) that a Higgs-boson decay into two Z bosons yields entangled spins, with Z bosons acting as qutrits. The analysis uses the rare Higgs→ZZ→4 leptons channel to infer the spins and show entanglement, including the involvement of a virtual Z due to energy constraints. While not hitting the 5-sigma discovery threshold, the result published in Physical Review Letters provides the strongest evidence to date for entanglement between Z bosons produced in Higgs decays.
A team led by Ron Folman built the Quantum Galileo Interferometer (QGI) to place a single atom in a superposition of two trajectories—one undergoing free fall and the other held stationary—and then recombine them to measure gravity’s effect on a quantum wave. The observed phase aligns with the equivalence principle within about 2.5%, demonstrating gravity can act on a quantum system in superposition and outlining future tests with heavier objects (like nanodiamonds) to probe whether gravity is truly quantum or induces wavefunction collapse.
Researchers analyzing collapse models (Diósi–Penrose and Continuous Spontaneous Localization) find that if such models reflect reality, time itself would have a tiny intrinsic uncertainty, implying a fundamental limit on clock precision far beyond current detection; the effect doesn’t affect everyday timekeeping but could provide a testbed for connecting quantum mechanics and gravity and guiding future experiments in quantum gravity.
Steve Fuller argues that breakthroughs in neuroscience, quantum mechanics, and AI show we don’t merely hold different perspectives on one shared reality; we actually inhabit multiple, incommensurable realities that only appear to converge in decisive moments, challenging traditional realism and prompting a rethink of knowledge.
German physicists have demonstrated a fully working quantum-mechanics formulation that uses only real numbers and can predict the same experimental outcomes as the standard complex-number framework, suggesting imaginary numbers aren’t fundamental to quantum mechanics but are still a convenient mathematical language. While the real-number approach matches all predictions, researchers note complex numbers remain useful in describing quantum systems, and this work revisits debates sparked by a 2021 Nature study on the necessity of complex numbers in quantum theory.
Quantum physics uses Hilbert space, an abstract arena where a system’s state is a vector whose direction encodes the probabilities of future outcomes; before observation, a particle can inhabit a superposition across many possibilities, and upon measurement the vector snaps to a definite axis with probabilities set by its alignment. Von Neumann unified Heisenberg’s and Schrödinger’s formulations via two axioms (completeness and an inner product), and the space’s dimensionality—2 for a qubit, higher for more complex systems, or infinite for a freely moving particle—determines what can be described. Debates linger on whether Hilbert space reflects reality or is a practical mathematical framework, with broader tools like von Neumann algebras expanding the language for quantum information and spacetime questions.
New observations of magnetar 1E 1547-5408 with IXPE and other telescopes show X-ray polarization about three times higher than standard models and aligned with the star’s magnetic field, providing strong evidence for vacuum birefringence — the idea that empty space behaves like a prism under ultra-strong magnetic fields and a prediction dating back to Heisenberg and Euler nearly 90 years ago; the findings test fundamental physics and future missions like GoSOX may help confirm the effect and illuminate the fabric of reality.
Jim Choyke, a 100-year-old emeritus professor in Pitt's physics and astronomy department, spent decades studying silicon carbide—the semiconductor material underpinning AI, quantum computing, and advanced batteries. He moved to Pittsburgh in 1952 for a Westinghouse role, joined Pitt in 1974, and says he never believed in retirement because he loves physics. His work and mentorship helped advance the field and inspire a generation of scientists, and he continues to work and teach from his Pitt office.
An interview with Guido Tonelli ties humanity’s long obsession with time to a journey from myth (Chronos) to modern science, explaining how relativity rewrites time for fast-moving particles and gravity, how time’s arrow emerges for macroscopic systems but can blur or reverse in microscopic realms, and how the Heisenberg principle lets physicists measure particle lifetimes (including the Higgs boson). Tonelli argues time remains fundamental but not necessarily ultimate, with future theories potentially reimagining or even abandoning it as a basic concept, a vision explored in his book Time: The Dream of Killing Chronos.
A plain‑language primer on quantum ideas: at tiny scales particles can be in superpositions and only take a definite state when measured, while entangled particles remain linked across distances. These quirks enable qubits that can encode many possibilities in parallel, potentially solving problems in drug design, materials science and cryptography far faster than classical computers. Real-world quantum tech is still fragile and not a substitute for everyday tasks; nonetheless, progress raises both exciting capabilities and security/ethical questions as encryption faces new risks and quantum‑safe networks develop.
Albert Einstein, celebrated for relativity and groundbreaking insights, also had notable missteps—most famously a mistaken belief that gravitational waves might not exist due to a mathematical hiccup later corrected with peer input, and early skepticism about black holes and quantum entanglement. The process of identifying and fixing these errors, rather than undermining his genius, helped push physics forward and underscored how even the brightest minds progress through errors and rigorous critique.
Physicists built a working version of quantum mechanics using only real numbers, recreating all predictions of the standard theory by replacing the usual complex-number tensor product with a real-number rule and a bookkeeping flag system. The approach shows complex numbers aren’t fundamental to quantum mechanics, though the work currently covers finite systems and does not alter experimental predictions.
A Science perspective shows how quantum mechanics evolved from a puzzling 20th‑century idea to the foundation of lasers, microchips, secure communications, and emerging quantum computers, driven by coherence and entanglement; the piece highlights quantum heat engines that may exceed classical limits and notes expanding applications in biology, gravity, and turbulence, with open questions about quantizing gravity and the future impact of quantum technologies.