The absorption spectrum of K2-18b’s atmosphere taken with the JWST’s instruments. The detections of methane and carbon dioxide—and the nondetection of ammonia—suggest the presence of an ocean underneath a hydrogen-rich atmosphere, according to planetary models. There’s also a hint of DMS, which on Earth is tied to biological activity.
{"title":"The Skinny on Detecting Life with the JWST","authors":"Katherine Wright","doi":"10.1103/physics.16.178","DOIUrl":"https://doi.org/10.1103/physics.16.178","url":null,"abstract":"The absorption spectrum of K2-18b’s atmosphere taken with the JWST’s instruments. The detections of methane and carbon dioxide—and the nondetection of ammonia—suggest the presence of an ocean underneath a hydrogen-rich atmosphere, according to planetary models. There’s also a hint of DMS, which on Earth is tied to biological activity.","PeriodicalId":20136,"journal":{"name":"Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135919557","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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
Fady Tarek Farouk, Abdel Nasser Tawfik, Fawzy Salah Tarabia, Muhammad Maher
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.
{"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":null,"pages":null},"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}
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