Nov 14, 2020 05:39 AM
https://www.quantamagazine.org/what-is-a...-20201112/
INTRO: Given that everything in the universe reduces to particles, a question presents itself: What are particles? The easy answer quickly shows itself to be unsatisfying. Namely, electrons, photons, quarks and other “fundamental” particles supposedly lack substructure or physical extent. “We basically think of a particle as a pointlike object,” said Mary Gaillard, a particle theorist at the University of California, Berkeley who predicted the masses of two types of quarks in the 1970s. And yet particles have distinct traits, such as charge and mass. How can a dimensionless point bear weight?
“We say they are ‘fundamental,’” said Xiao-Gang Wen, a theoretical physicist at the Massachusetts Institute of Technology. “But that’s just a [way to say] to students, ‘Don’t ask! I don’t know the answer. It’s fundamental; don’t ask anymore.’”
With any other object, the object’s properties depend on its physical makeup — ultimately, its constituent particles. But those particles’ properties derive not from constituents of their own but from mathematical patterns. As points of contact between mathematics and reality, particles straddle both worlds with an uncertain footing.
When I recently asked a dozen particle physicists what a particle is, they gave remarkably diverse descriptions. They emphasized that their answers don’t conflict so much as capture different facets of the truth. They also described two major research thrusts in fundamental physics today that are pursuing a more satisfying, all-encompassing picture of particles.
“‘What is a particle?’ indeed is a very interesting question,” said Wen. “Nowadays there is progress in this direction. I should not say there’s a unified point of view, but there’s several different points of view, and all look interesting.” (MORE)
COVERED: A Particle Is a ‘Collapsed Wave Function’ ..... A Particle Is a ‘Quantum Excitation of a Field ..... A Particle Is an ‘Irreducible Representation of a Group’ ..... ‘Particles Have So Many Layers ..... Particles ‘Might Be Vibrating Strings’ ..... A Particle Is a ‘Deformation of the Qubit Ocean’ ..... ‘Particles Are What We Measure in Detectors’
INTRO: Given that everything in the universe reduces to particles, a question presents itself: What are particles? The easy answer quickly shows itself to be unsatisfying. Namely, electrons, photons, quarks and other “fundamental” particles supposedly lack substructure or physical extent. “We basically think of a particle as a pointlike object,” said Mary Gaillard, a particle theorist at the University of California, Berkeley who predicted the masses of two types of quarks in the 1970s. And yet particles have distinct traits, such as charge and mass. How can a dimensionless point bear weight?
“We say they are ‘fundamental,’” said Xiao-Gang Wen, a theoretical physicist at the Massachusetts Institute of Technology. “But that’s just a [way to say] to students, ‘Don’t ask! I don’t know the answer. It’s fundamental; don’t ask anymore.’”
With any other object, the object’s properties depend on its physical makeup — ultimately, its constituent particles. But those particles’ properties derive not from constituents of their own but from mathematical patterns. As points of contact between mathematics and reality, particles straddle both worlds with an uncertain footing.
When I recently asked a dozen particle physicists what a particle is, they gave remarkably diverse descriptions. They emphasized that their answers don’t conflict so much as capture different facets of the truth. They also described two major research thrusts in fundamental physics today that are pursuing a more satisfying, all-encompassing picture of particles.
“‘What is a particle?’ indeed is a very interesting question,” said Wen. “Nowadays there is progress in this direction. I should not say there’s a unified point of view, but there’s several different points of view, and all look interesting.” (MORE)
COVERED: A Particle Is a ‘Collapsed Wave Function’ ..... A Particle Is a ‘Quantum Excitation of a Field ..... A Particle Is an ‘Irreducible Representation of a Group’ ..... ‘Particles Have So Many Layers ..... Particles ‘Might Be Vibrating Strings’ ..... A Particle Is a ‘Deformation of the Qubit Ocean’ ..... ‘Particles Are What We Measure in Detectors’
