Proceedings of 1st Electronic Conference on Universe最新文献

Gravitomagnetic resonance and gravitational waves 重力磁共振和引力波

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-26 DOI: 10.1142/9789811269776_0335

M. Ruggiero, A. Ortolan

{"title":"Gravitomagnetic resonance and gravitational waves","authors":"M. Ruggiero, A. Ortolan","doi":"10.1142/9789811269776_0335","DOIUrl":"https://doi.org/10.1142/9789811269776_0335","url":null,"abstract":"Gravitational waves are usually described in terms of a transverse and traceless (TT) tensor, which allows to introduce the so-called TT coordinates. However, another possible approach is based on the use of a Fermi coordinates system, defined in the vicinity of the world-line of an observer arbitrarily moving in spacetime. In particular, Fermi coordinates have a direct operational meaning, since they are the coordinates an observer would use to perform space and time measurements; indeed, using these coordinates the metric tensor contains (up to the required approximation level) only quantities that are invariant under coordinate transformations internal to the reference frame. Using this approach it is simple to emphasise that what an observer measures depends both on the background field where he is moving and, also, on his kind of motion. This is quite similar to what happens when we study classical mechanics in non inertial frames: inertial forces appear, depending on the peculiar motion of the frame with respect to an inertial one. We show that using Fermi coordinates the effects of a plane gravitational wave can be described by gravitoelectromagnetic fields: in other words, the wave field is equivalent to the action of a gravitoelectric and a gravitomagnetic field, that are transverse to the propagation direction and orthogonal to each other. In particular, the gravito-magnetic field acts on spinning particles and we show that, due to the action of the gravitational wave field a gravitomagnetic resonance may appear. We give both a classical and a quantum description of this phenomenon and suggest that it can be used as the basis for a new type of gravitational wave detectors.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130685160","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

Dynamics of disk and elliptical galaxies in Refracted Gravity 圆盘和椭圆星系在折射重力下的动力学

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09292

V. Cesare

{"title":"Dynamics of disk and elliptical galaxies in Refracted Gravity","authors":"V. Cesare","doi":"10.3390/ecu2021-09292","DOIUrl":"https://doi.org/10.3390/ecu2021-09292","url":null,"abstract":"I investigate the dynamics of galaxies in refracted gravity (RG), a novel theory of modified gravity which does not resort to dark matter (DM). The DM presence is mimicked by a gravitational permittivity, a monotonic increasing function of the local mass density that depends on three, in principle, universal parameters. RG reproduces the kinematic profiles of 30 disk galaxies in the DiskMass Survey (DMS), with mass-to-light ratios in agreement with stellar population synthesis models, disk-scale heights consistent with edge-on galaxies observations, and the RG parameters from the individual galaxies in agreement with one another, suggesting their universality. RG models the radial acceleration relation of the DMS galaxies with the correct asymptotic limits but with residuals correlating with some galaxies properties and with a too large intrinsic scatter, in contrast with observations, which requires further investigation. RG also describes the velocity dispersions of stars and of blue and red globular clusters in three elliptical E0 galaxies from the SLUGGS survey with sensible mass-to-light ratios and anisotropy parameters and with the three RG parameters consistent with one another. These parameters are also in agreement with the mean RG parameters estimated from the individual DMS galaxies.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"100 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120818945","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

Gravitational Collapse in 4D-Einstein Gauss-Bonnet Gravity 4d -爱因斯坦-高斯-邦纳引力中的引力坍缩

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09279

Omia Masood, H. H. Shah, H. Shah, A. Issakhov, S. Z. Abbas

{"title":"Gravitational Collapse in 4D-Einstein Gauss-Bonnet Gravity","authors":"Omia Masood, H. H. Shah, H. Shah, A. Issakhov, S. Z. Abbas","doi":"10.3390/ecu2021-09279","DOIUrl":"https://doi.org/10.3390/ecu2021-09279","url":null,"abstract":"We investigate the gravitational collapse of a gravitational bounded object constituted of dust cloud and dark energy. We considered the the effects of homogenous and isotropic fluid on newly suggested 4D limit for Einstein-Gauss-Bonnet gravity(EGB) (For detail about EGB gravity, arXiv:1905.03601v3). For this purpose, we consider the gravitational collapse of gravitational object made of dust cloud ρDM in the background of dark energy, p = wρ with (w < −1/3). We illustrate that the procedure is qualitatively equivalent to the scenario of theory of Einstein for the collapse of the gravitational object composed of homogeneous dust. Further, we consider the collapse for dark energy by considering the equation of state p = wρ to find that black hole also may form in EGB case, which predict that end state of gravitational collapse in EGB case is consistent with results carried out in pure Einstein’s gravity theory. \u0000We have discussed two separate case, first, gravitational collapse of dust cloud in the context of EGB, in the second case, gravitational collapse of dark energy in EGB background. It is found that, gravitational collapse leads to formation of black hole in both cases. It is also worth mentioning that, end state of gravitational collapse in EGB context is same as in pure Einstein's gravity. Here, in this study dark matter refer to dust cloud, a matter with zero pressure.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128003962","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

Modified Commutators vs Modified Operators in a Quantum Gravity minimal length scale 量子引力最小长度尺度下的修正换向子与修正算子

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.1063/5.0033527

Joey Contreras, Douglas Singleton, Michael Bishop, Jaeyeong Lee

{"title":"Modified Commutators vs Modified Operators in a Quantum Gravity minimal length scale","authors":"Joey Contreras, Douglas Singleton, Michael Bishop, Jaeyeong Lee","doi":"10.1063/5.0033527","DOIUrl":"https://doi.org/10.1063/5.0033527","url":null,"abstract":": Generic theories of quantum gravity often postulate that at some high energy/momentum scale there will be a ﬁxed, minimal length. Such a minimal length can be phenomenologically investigated by modifying the standard Heisenberg Uncertainty relationship. This is generally done in practice by modifying the commutator between position and momentum operators, which in turn means modifying these operators. However, modiﬁcations such that the uncertainty relation changes lead to conﬂicts with observational data (gamma ray bursts). This arises in the form of a predicted minimal length energy scale that is above the Planck energy rather than below it. As a result there seems to be an implication that there is no minimal length scale in these generic theories. Meanwhile, modifying the operators such that the standard uncertainty relation retains the same form, leads to no such conﬂict with observational data. We show that it is this modiﬁcation of the position and momentum operators that is the key determining factor in the existence (or not) of a minimal length scale. By focusing primarily on the role of these operators we also show that one can avoid the constraints from the observations of short gamma ray bursts, which in certain cases seem to push the minimal length scale above the Planck scale.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133054102","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: 2

Atoms, molecules, photons and phonons in primary science 初级科学中的原子，分子，光子和声子

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09318

David Wood

{"title":"Atoms, molecules, photons and phonons in primary science","authors":"David Wood","doi":"10.3390/ecu2021-09318","DOIUrl":"https://doi.org/10.3390/ecu2021-09318","url":null,"abstract":"Traditional science education wisdom suggests that abstract concepts are beyond the majority of primary-school aged students. This includes introducing atoms and molecules. \u0000 The Einstein-First curriculum introduces atoms and molecules into Year 3 via songs, role plays and simple atomic models made from plasticine (modelling clay) and balls with embedded magnets. They use these models and analogies to relate what they see at a macroscopic level to the miniscule structures of atoms and molecules, and the electrical forces that hold them together. At this early stage, we concentrate particularly on students becoming familiar with the language of modern science: atoms, molecules and photons. \u0000 The challenge is to introduce an atomic model that is faithful to the quantum and probabilistic nature of atoms and yet avoids both the misconceptions of planetary type orbitals which dominate almost all introductory chemistry. Instead we show easily accessible images from the internet of the beautiful complexity of electron orbitals. We present atoms as a miniscule nucleus of protons and neutrons surrounded by an electron cloud in which the electrons are ‘in there somewhere’. \u0000 This presentation will concisely outline our spiral learning approach in which students in Years 3 to 6 will revisit and develop concepts throughout four years of primary education. They will leave primary school with clear concepts of photons and phonons, changes of state (Year 3), physical properties of materials (Year 4), states of matter (Year 5) and simple reversible and irreversible changes to materials.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123281238","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

Particle physics for primary schools—enthusing children to modern science 小学粒子物理学——让孩子们对现代科学充满热情

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09321

C. Lazzeroni

{"title":"Particle physics for primary schools—enthusing children to modern science","authors":"C. Lazzeroni","doi":"10.3390/ecu2021-09321","DOIUrl":"https://doi.org/10.3390/ecu2021-09321","url":null,"abstract":"A particle physics workshop for UK primary schools has been designed and trialed in 2016-2017 as a collaboration between the University of Birmingham and the Odgen Trust. The workshop allows young children (ages 8–11) to learn the world of fundamental particles, use creative design to make particle models, and learn creatively about how particles interact. The initial resources were reviewed and improved, based on the feedback received from school teachers and communicators. The final workshop has been delivered in many primary schools in UK in 2017-2020, receiving very positive evaluation and clear evidence of impact. A set of primary school teachers have been trained to deliver the workshop. Resources specifically created for teachers and educators have been made available on the University website. Despite particle physics is often classified as a subject too difficult and abstract for primary schools, the workshop uses familiar concepts to children that make particle physics accessible and enjoyable. The workshop explores the ability of young children to be imaginative and creative and exploits it to teach them the fundamentals of particle physics in a fun way. Most importantly, the workshop is effective in enthusing children to modern science and gives a wider understanding of how science works. The resources have been used in the Playing with Protons events for teachers at CERN, and have been translated in Greek and Italian.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124360698","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: 2

Differentially rotating relativistic stars with post-merger-like rotational profiles 具有类似合并后旋转轮廓的差分旋转的相对论性恒星

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09312

P. Iosif, N. Stergioulas

引用次数: 0

Teaching Einsteinian gravity in Italian primary school 在意大利小学教授爱因斯坦引力

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09319

Sara Mattiello, M. Ruggiero, M. Leone

引用次数: 0

Lattice gravity and cosmology 点阵引力和宇宙学

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09302

J. Bilski

{"title":"Lattice gravity and cosmology","authors":"J. Bilski","doi":"10.3390/ecu2021-09302","DOIUrl":"https://doi.org/10.3390/ecu2021-09302","url":null,"abstract":"The background-independent quantum gravity is the necessary framework to construct generally relativistic quantum field theory. By assuming the ADM decomposition of spacetime, it is possible to define the metric-independent Fock space for this formulation. This space, known as spin network, is invariant under the SU(2) symmetry and the spatial diffeomorphisms transformations. It is the Fock space for the model called loop quantum gravity in which the canonical operators are the quantized holonomies of the Ashtekar connection and the fluxes of densitized dreibein. I will present an improved construction of the lattice gravity and its gauge-fixed cosmological reduction based on the same lattice variables. \u0000The approach is based on the geometric expansion of holonomies into power series up to the quadratic order terms in the regularization parameter. As a result, a more accurate procedure is obtained in which the symmetry of holonomies assigned to links is directly reflected in the related distribution of connections. The application of the procedure to the Hamiltonian constraint regularization provides its lattice analog, the domain of which has a natural structure of elementary cells sum. In consequence, the related scalar constraint operator, which spectrum is independent of intertwiners, can be defined. \u0000The cosmological phase space reduction of lattice gravity requires rigorous application of gauge-fixing conditions that reduce the SU(2) symmetry and the spatial diffeomorphisms invariance. The internal symmetry is fixed to the Abelian case and the diffeomorphisms invariance is simultaneously reduced to spatial translations. The obtained Hamiltonian constraint is finite (without any cut-off introduction) and exact (without the holonomy expansion around short links). Furthermore, it has the expected form of the sum over elementary cuboidal cells. Finally, the simple structure of its homogeneities and anisotropies should allow to describe the quantum cosmological evolution of the Universe in terms of transition amplitudes, instead of using perturbative approximations.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114704260","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

Integrating Einsteinian physics in the year 7 Australian Science Curriculum: What are the challenges in design and implementation? 将爱因斯坦物理学融入澳大利亚七年级科学课程:设计和实施的挑战是什么?

Proceedings of 1st Electronic Conference on Universe Pub Date : 2021-02-22 DOI: 10.3390/ecu2021-09326

S. Boublil

{"title":"Integrating Einsteinian physics in the year 7 Australian Science Curriculum: What are the challenges in design and implementation?","authors":"S. Boublil","doi":"10.3390/ecu2021-09326","DOIUrl":"https://doi.org/10.3390/ecu2021-09326","url":null,"abstract":"Integrating Einsteinian physics into school curricula has become a challenge for researchers. This process involves choosingappropriate disciplinary knowledge to be accommodated in the curriculum and researching ways to illustrate how teachers can use this knowledgein their classrooms. The Einstein-first project research is centered on building a new curriculum on Einsteinian physics (space, time, geometry,gravity) in Western Australia and on teacher’s ability to embrace this modern paradigm and enhance their scientific and didactical knowledge.My research is designed to trial a learning progression of Einsteinian concepts within an overall curriculum structure for year 7. Manyconcepts related to Einstein’s theory of gravity will be included in association to the existing year 7 curriculum in Australia. I willidentify the primary challenges in design and implementation, which helps organize appropriate teacher professional learning to understandand teach Einsteinian physics concepts. A series of 14 physics lessons were developed for the Year 7 Science curriculum in Western Australia.The first three lessons introduce concepts of measurement, straight lines, Geometry, space (curved), time, nature of spacetime. The conceptof velocity, terminal velocity, acceleration, inertia and mass are then developed. Students then learn about Einstein’s conception of gravitythrough the analysis of free-falling bodies and thought experiments. They use the spacetime simulator to investigate topics of generalrelativity, the attractional force between masses and orbits in our Solar System. The learning progression ends with introducing black holesand gravitational waves.","PeriodicalId":252710,"journal":{"name":"Proceedings of 1st Electronic Conference on Universe","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132394559","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