PhysicsPub Date : 2023-10-13DOI: 10.1103/physics.16.177
Rachel Berkowitz
{"title":"How Rotation Drives Magnetic Levitation","authors":"Rachel Berkowitz","doi":"10.1103/physics.16.177","DOIUrl":"https://doi.org/10.1103/physics.16.177","url":null,"abstract":"Spin and lift. A spherical magnet is attached to an upright drill with its magnetization axis in a horizontal orientation. When the drill is turned on, a second spherical magnet is drawn up and levitates just below the first magnet. The close-up image shows how the floater magnet orients its magnetization axis in a nearly perpendicular configuration with that of the rotor magnet.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135919558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-12DOI: 10.3390/physics5040065
Noah Graham
{"title":"Electromagnetic Casimir–Polder Interaction for a Conducting Cone","authors":"Noah Graham","doi":"10.3390/physics5040065","DOIUrl":"https://doi.org/10.3390/physics5040065","url":null,"abstract":"Using the formulation of the electromagnetic Green’s function of a perfectly conducting cone in terms of analytically continued angular momentum, we compute the Casimir–Polder interaction energy of a cone with a polarizable particle. We introduce this formalism by first reviewing the analogous approach for a perfectly conducting wedge, and then demonstrate the calculation through numerical evaluation of the resulting integrals.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-12DOI: 10.1103/physics.16.176
Katherine Wright
{"title":"Linking a Respiratory Drop’s Size to Its Origin","authors":"Katherine Wright","doi":"10.1103/physics.16.176","DOIUrl":"https://doi.org/10.1103/physics.16.176","url":null,"abstract":"A parameterization scheme that links a drop’s size to its origin in the respiratory tract could help clinicians identify the most effective mitigation strategies for halting the spread of an infectious disease.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-11DOI: 10.1103/physics.16.172
Berihu Teklu
{"title":"Matching a Measurement to a Quantum State","authors":"Berihu Teklu","doi":"10.1103/physics.16.172","DOIUrl":"https://doi.org/10.1103/physics.16.172","url":null,"abstract":"A quantum sensor is a device that can leverage quantum behaviors, such as quantum entanglement, coherence, and superposition, to enhance the measurement capabilities of a classical detector [1–5]. For example, the LIGO gravitational-wave detector employs entangled states of light to improve the distance-measurement capabilities of its interferometer arms, allowing the detection of distance changes 10,000 times smaller than the width of a proton.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136252957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-11DOI: 10.1103/physics.16.s143
Charles Day
{"title":"Detection of the Orbital Hall Effect","authors":"Charles Day","doi":"10.1103/physics.16.s143","DOIUrl":"https://doi.org/10.1103/physics.16.s143","url":null,"abstract":"I n the spin Hall effect, an applied electric field drives a current of electron spin in a direction transverse to the field. In a transitionmetal, theorists predict that an orbital angular momentum (OAM) current can also flow. Now two groups have independently observed this so-called orbital Hall effect (OHE) [1, 2]. These observations supplement onemade by a third group earlier this year [3]. Together these demonstrations constitute a step toward the development of “orbitronic” devices based on an electron’s orbital degree of freedom.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136253790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-10DOI: 10.1103/physics.16.s136
Rachel Berkowitz
{"title":"Far-Field Flow Forces Attraction","authors":"Rachel Berkowitz","doi":"10.1103/physics.16.s136","DOIUrl":"https://doi.org/10.1103/physics.16.s136","url":null,"abstract":"L ong-range attraction between distant objects can arise from gravitational or electrostatic forces. For objects suspended in active fluids—those containing a large number of tiny motile particles—efforts to understand how these forces drive effective interactions focus on direct collisions between the objects and the active agents. Now Luhui Ning and Yi Peng of the Chinese Academy of Sciences and their colleagues show that indirect effects can also play an important role in generating long-range attraction [1]. By examining the effective interactions between two plates immersed in a bacterial suspension, they show that hydrodynamic forces generated by swimming bacteria have a strong influence on the plates’ behaviors. The results open a new pathway toward developing active fluids to manipulate interactions between passive objects, a common objective in biomedicine andmaterials science.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136359355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-09DOI: 10.1103/physics.16.169
Kazumasa Kawata
{"title":"Galaxy’s Gamma Glow Illuminates Cosmic-Ray Origins","authors":"Kazumasa Kawata","doi":"10.1103/physics.16.169","DOIUrl":"https://doi.org/10.1103/physics.16.169","url":null,"abstract":"Interstellar magnetic fields perturb the trajectories of cosmic rays, making it difficult to identify their sources. A new survey of gamma radiation produced when cosmic rays interact with the interstellar medium should help in this identification.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135149214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-09DOI: 10.3390/physics5040064
Fady Tarek Farouk, Abdel Nasser Tawfik, Fawzy Salah Tarabia, Muhammad Maher
{"title":"On Possible Minimal Length Deformation of Metric Tensor, Levi-Civita Connection, and the Riemann Curvature Tensor","authors":"Fady Tarek Farouk, Abdel Nasser Tawfik, Fawzy Salah Tarabia, Muhammad Maher","doi":"10.3390/physics5040064","DOIUrl":"https://doi.org/10.3390/physics5040064","url":null,"abstract":"The minimal length conjecture is merged with a generalized quantum uncertainty formula, where we identify the minimal uncertainty in a particle’s position as the minimal measurable length scale. Thus, we obtain a quantum-induced deformation parameter that directly depends on the chosen minimal length scale. This quantum-induced deformation is conjectured to require the generalization of Riemannian spacetime geometry underlying the classical theory of general relativity to an eight-dimensional spacetime fiber bundle, which dictates the deformation of the line element, metric tensor, Levi-Civita connection, Riemann curvature tensor, etc. We calculate the deformation thus produced in the Levi-Civita connection and find it to explicitly and exclusively depend on the product of the minimum measurable length and the particle’s spacelike four-acceleration vector, L2x¨2. We find that the deformed Levi-Civita connection preserves all properties of its undeformed counterpart, such as torsion freedom and metric compatibility. Accordingly, we have constructed a deformed version of the Riemann curvature tensor whose expression can be factorized in all its terms with different functions of L2x¨2. We also show that the classical four-manifold status of being Riemannian is preserved when the quantum-induced deformation is negligible. We study the dependence of a parallel-transported tangent vector on the spacelike four-acceleration. We illustrate the impact of the minimal-length-induced quantum deformation on the classical geometrical objects of the general theory of relativity using the unit radius two-sphere example. We conclude that the minimal length deformation implies a correction to the spacetime curvature and its contractions, which is manifest in the additional curvature terms of the corrected Riemann tensor. Accordingly, quantum-induced effects endow an additional spacetime curvature and geometrical structure.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135093205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PhysicsPub Date : 2023-10-06DOI: 10.1103/physics.16.174
Philip Ball
{"title":"<i>Chemistry Nobel Prize:</i> Quantum Rules Provide Controllable Colors","authors":"Philip Ball","doi":"10.1103/physics.16.174","DOIUrl":"https://doi.org/10.1103/physics.16.174","url":null,"abstract":"T he 2023 Nobel Prize in Chemistry has been awarded to Alexei Ekimov of Nanocrystals Technology in New York, Louis Brus of Columbia University, and Moungi Bawendi of the Massachusetts Institute of Technology for their work on the development of nanoscale particles known as quantum dots: specks of matter so small that quantum effects make their size rather than their chemical composition the key determinant of their electronic and optical behavior. The award has left somemischievously asking if it is for chemistry or for physics. In fact, it’s a bit of both: quantum physics is needed to understand the properties of quantum dots, while ingenious chemistry is needed to make them.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134945401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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