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Galaxy’s Gamma Glow Illuminates Cosmic-Ray Origins 星系的伽马光照亮了宇宙射线的起源
Physics Pub Date : 2023-10-09 DOI: 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}
引用次数: 0
On Possible Minimal Length Deformation of Metric Tensor, Levi-Civita Connection, and the Riemann Curvature Tensor 论度量张量的可能最小长度变形、列维-西维塔连接和黎曼曲率张量
Physics Pub Date : 2023-10-09 DOI: 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}
引用次数: 0
Chemistry Nobel Prize: Quantum Rules Provide Controllable Colors 诺贝尔化学奖:量子规则提供可控颜色
Physics Pub Date : 2023-10-06 DOI: 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}
引用次数: 0
New Way for a Black Hole to be a Messy Eater 黑洞成为“混乱食客”的新方法
Physics Pub Date : 2023-10-05 DOI: 10.1103/physics.16.173
Charles Day
{"title":"New Way for a Black Hole to be a Messy Eater","authors":"Charles Day","doi":"10.1103/physics.16.173","DOIUrl":"https://doi.org/10.1103/physics.16.173","url":null,"abstract":"F ive to ten percent of the black holes in galaxies sit at the center of an accretion disk, where blobs of plasma slowly lose angular momentum and spiral inward to feed the black hole. In a simulation, Nicholas Kaaz of Northwestern University, Illinois, and his collaborators now find that for a rapidly spinning black hole surrounded by a thin, tilted disk this “eating” process is quicker andmessier than previously thought [1].","PeriodicalId":20136,"journal":{"name":"Physics","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135547594","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}
引用次数: 0
Unexpected Noise in Next-Generation Mirror Material 新一代镜面材料中的意外噪音
Physics Pub Date : 2023-10-03 DOI: 10.1103/physics.16.170
Michael Schirber
{"title":"Unexpected Noise in Next-Generation Mirror Material","authors":"Michael Schirber","doi":"10.1103/physics.16.170","DOIUrl":"https://doi.org/10.1103/physics.16.170","url":null,"abstract":"N ext-generation gravitational-wave detectors need to be less noisy if they are going to help solve lingering mysteries about black holes and neutron stars. One avenue for reducing noise is to improve the quality of the reflective materials used to determine gravitational-wave-induced length changes in such detectors. Now tests of gallium arsenide, a promising alternative mirror substance, reveal an unexpected amount of noise in the light-reflection properties of thin films made from thematerial [1]. The experiments were performed at cryogenic temperatures, which are being considered for some—but not all—future gravitational-wave detectors. Further testing is needed to assess the potential impact of this new noise on mirror design choices.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135789084","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}
引用次数: 0
Nobel Prize : Flashes of Light Catch Electrons in the Act 诺贝尔奖:闪光捕捉电子的行为
Physics Pub Date : 2023-10-03 DOI: 10.1103/physics.16.171
Michael Schirber
{"title":"<i>Nobel Prize</i> <i>:</i> Flashes of Light Catch Electrons in the Act","authors":"Michael Schirber","doi":"10.1103/physics.16.171","DOIUrl":"https://doi.org/10.1103/physics.16.171","url":null,"abstract":"short","PeriodicalId":20136,"journal":{"name":"Physics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135789083","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}
引用次数: 0
Perfect Cones Are as Weak as They Seem 完美的锥体和它们看起来一样脆弱
Physics Pub Date : 2023-10-03 DOI: 10.1103/physics.16.s137
Marric Stephens
{"title":"Perfect Cones Are as Weak as They Seem","authors":"Marric Stephens","doi":"10.1103/physics.16.s137","DOIUrl":"https://doi.org/10.1103/physics.16.s137","url":null,"abstract":"P hysicists simplify problems to make calculations easier, but doing so risks neglecting important physical properties, as illustrated by the fabled spherical cow in a vacuum, for example. For decades, oversimplification was thought to explain why thin-walled cones crumple under smaller loads than predicted by theory. Researchers suspected that the descrepancy might result from imperfections in real cones that are absent from theoretically ideal cones. Now Daniel Duffy of the University of Cambridge and his colleagues show that the biggest problem is not that models lack those microscopic details, but that the models assume the wrong boundary conditions [1]. Their result could have implications for the emerging field of soft robotics.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135789082","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}
引用次数: 0
Golden Ticket to Stockholm 前往斯德哥尔摩的金票
Physics Pub Date : 2023-10-02 DOI: 10.1103/physics.16.168
Michael Schirber
{"title":"Golden Ticket to Stockholm","authors":"Michael Schirber","doi":"10.1103/physics.16.168","DOIUrl":"https://doi.org/10.1103/physics.16.168","url":null,"abstract":"F ew would ever admit it, but some scientists dream of getting a call on an early October morning from a Scandinavian area code. Winning a Nobel Prize is never a guarantee even for highly lauded scientists, but certain huge discoveries beg for recognition. The first detection of gravitational waves in 2015 is a perfect example. The Nobel Committee didn’t wait long to honor this breakthrough with its 2017 prize in physics.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"2015 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135902447","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}
引用次数: 0
How AI and ML Will Affect Physics AI和ML将如何影响物理
Physics Pub Date : 2023-10-02 DOI: 10.1103/physics.16.166
Sankar Das Sarma
{"title":"How AI and ML Will Affect Physics","authors":"Sankar Das Sarma","doi":"10.1103/physics.16.166","DOIUrl":"https://doi.org/10.1103/physics.16.166","url":null,"abstract":"T he advent of ChatGPT, Bard, and other large language models (LLM) has naturally excited everybody, including the entire physics community. There are many evolving questions for physicists about LLMs in particular and artificial intelligence (AI) in general. What do these stupendous developments in large-data technology mean for physics? How can they be incorporated in physics? What will be the role of machine learning (ML) itself in the process of physics discovery?","PeriodicalId":20136,"journal":{"name":"Physics","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135902441","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}
引用次数: 1
Turbulent Jets Doubly Detrimental to Fluid-Based Batteries 湍流射流对液体电池倍加有害
Physics Pub Date : 2023-10-02 DOI: 10.1103/physics.16.s141
Katherine Wright
{"title":"Turbulent Jets Doubly Detrimental to Fluid-Based Batteries","authors":"Katherine Wright","doi":"10.1103/physics.16.s141","DOIUrl":"https://doi.org/10.1103/physics.16.s141","url":null,"abstract":"C onverting waste heat from renewable-energy technologies into electricity could reduce the need for fossil-fuel power stations—but only if that energy can be stored efficiently, for example, in a thermal battery. Researchers have partially solved this problem by designing batteries with vacuum insulation panels that reduce thermal leakage to the environment. But the useful energy available to the system can diminish even if environmental heat loss is reduced to zero. Now Christian Cierpka of the Technical University of Ilmenau, Germany, and colleagues have explored one such energy drain: mixing of hot and cold regions within a fluid-based energy-storage device [1]. The results could aid in the design of more-efficient thermal-energy-storage systems, potentially making such facilities useful as backups for intermittent renewable-energy sources.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135902750","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}
引用次数: 0
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