scholarly journals Probing quantum gravity effects with quantum mechanical oscillators

2020 ◽  
Vol 74 (9) ◽  
Author(s):  
Michele Bonaldi ◽  
Antonio Borrielli ◽  
Avishek Chowdhury ◽  
Gianni Di Giuseppe ◽  
Wenlin Li ◽  
...  

Abstract Phenomenological models aiming to join gravity and quantum mechanics often predict effects that are potentially measurable in refined low-energy experiments. For instance, modified commutation relations between position and momentum, that account for a minimal scale length, yield a dynamics that can be codified in additional Hamiltonian terms. When applied to the paradigmatic case of a mechanical oscillator, such terms, at the lowest order in the deformation parameter, introduce a weak intrinsic nonlinearity and, consequently, deviations from the classical trajectory. This point of view has stimulated several experimental proposals and realizations, leading to meaningful upper limits to the deformation parameter. All such experiments are based on classical mechanical oscillators, i.e., excited from a thermal state. We remark indeed that decoherence, that plays a major role in distinguishing the classical from the quantum behavior of (macroscopic) systems, is not usually included in phenomenological quantum gravity models. However, it would not be surprising if peculiar features that are predicted by considering the joined roles of gravity and quantum physics should manifest themselves just on purely quantum objects. On the basis of this consideration, we propose experiments aiming to observe possible quantum gravity effects on macroscopic mechanical oscillators that are preliminary prepared in a high purity state, and we report on the status of their realization. Graphical abstract

2000 ◽  
Vol 09 (06) ◽  
pp. 669-686 ◽  
Author(s):  
MARÍA E. ANGULO ◽  
GUILLERMO A. MENA MARUGÁN

Linearly polarized cylindrical waves in four-dimensional vacuum gravity are mathematically equivalent to rotationally symmetric gravity coupled to a Maxwell (or Klein–Gordon) field in three dimensions. The quantization of this latter system was performed by Ashtekar and Pierri in a recent work. Employing that quantization, we obtain here a complete quantum theory which describes the four-dimensional geometry of the Einstein–Rosen waves. In particular, we construct regularized operators to represent the metric. It is shown that the results achieved by Ashtekar about the existence of important quantum gravity effects in the Einstein–Maxwell system at large distances from the symmetry axis continue to be valid from a four-dimensional point of view. The only significant difference is that, in order to admit an approximate classical description in the asymptotic region, states that are coherent in the Maxwell field need not contain a large number of photons anymore. We also analyze the metric fluctuations on the symmetry axis and argue that they are generally relevant for all of the coherent states.


2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Shovon Biswas ◽  
Mir Mehedi Faruk

Planck scale inspired theories which are also often accompanied with maximum energy and/or momentum scale predict deformed dispersion relations compared to ordinary special relativity and quantum mechanics. In this paper, we resort to the methods of statistical mechanics in order to determine the effects of a deformed dispersion relation along with an upper bound in the partition function that maximum energy and/or momentum scale can have on the thermodynamics of photon gas. We also analyzed two distinct quantum gravity models in this paper.


2020 ◽  
Vol 74 (11) ◽  
Author(s):  
Michele Bonaldi ◽  
Antonio Borrielli ◽  
Avishek Chowdhury ◽  
Gianni Di Giuseppe ◽  
Wenlin Li ◽  
...  

Author(s):  
Salah Hassan Mohammed ◽  
Mahaa Ahmed Al-Mawla

The Study is based on the state as one of the main pillars in international politics. In additions, it tackles its position in the international order from the major schools perspectives in international relations, Especially, these schools differ in the status and priorities of the state according to its priorities, also, each scholar has a different point of view. The research is dedicated to providing a future vision of the state's position in the international order in which based on the vision of the major schools in international relations.


2019 ◽  
Author(s):  
POHSUN WANG

Basic shape is one of the most important components of the learning design process. Using Western design thinking to understand shape, color and composition layout and attempting to reinterpret the application of traditional calligraphy from a design point of view—whether it is the expression of form or the meaning of content—are both important aspects of design thinking. The writing patterns of traditional calligraphy and the design creation of modern experiments may have different biases. If the artistic value of "the brush and ink of the time" is compared to the science and technology of innovation as the main appeal, the expressiveness of the traditional writing mode is obviously difficult to achieve. Using science and technology as an option for design creation is a difficult way to proceed; however, technology, ideas and thinking can still be in sync with the cultural issues of an entire era. This is also the test of the times to which contemporary creations are subjected. There are infinite possibilities for development, and it is worthwhile to explore these possibilities together with artistic aspirants. On the other hand, if we follow the well-beaten path of the status quo, the creativity of traditional calligraphic art will wither, it will deviate from the larger environment of the era in which it operates, and it will inevitably be neglected and pushed out by other art categories. The design and creation process uses the traditional calligraphy characters and drums as the theme, assisted by digital tools in the creation, and finally transforms the traditional calligraphy visual form into an expression of the art of science and technology.


Author(s):  
Ирина Викторовна Евстафьева

В статье исследуются вопросы попечительства в отношении несовершеннолетних, отбывающих наказание в виде лишения свободы. Проблема, поднимаемая автором настоящей статьи, многогранна, касается различных аспектов отбывания наказания несовершеннолетними в воспитательных колониях и требует комплексного исследования, способного ответить на определенно значимый вопрос: является ли колония законным представителем находящихся в ней несовершеннолетних со всеми вытекающими из статуса законных представителей последствиями. При этом необходимо обращать внимание на специфику правового статуса лиц, отбывающих наказание в воспитательных колониях, которые, во-первых, являются несовершеннолетними, то есть не обладают дееспособностью в полном объеме и нуждаются в особой заботе, защите и представительстве, а во-вторых, осуждены за совершение тяжкого или особо тяжкого преступления, влекущего изоляцию от общества и определенные ограничения и лишения. Отечественное законодательство достаточно детально регламентирует особенности режима отбывания наказания в виде лишения свободы несовершеннолетними, не определяя при этом статуса воспитательных колоний, кем они являются: воспитателями, попечителями или исключительно учреждениями исполнения наказаний. Между тем правильное понимание значения и роли воспитательной колонии в жизни находящихся в ней несовершеннолетних преступников, по мнению автора, поможет избежать ряда проблем, объективно складывающихся в учреждениях подобного рода. С этой точки зрения предлагаемая тема представляет интерес не только для ученых-теоретиков, но и для практиков - сотрудников соответствующих учреждений. Особо следует подчеркнуть, что исследований по данной тематике в специальной литературе нет. Отдельные исследования, встречающиеся в современной литературе, касаются исключительно общего гражданско-правового статуса несовершеннолетних осужденных. Однако это обстоятельство может свидетельствовать только о новизне данной темы, но никак не об отсутствии самой проблемы. The article analyzes the issues of the status of educational colonies as guardians of minors serving a sentence of imprisonment. In fact, the problem raised by the author of this article is multifaceted, concerns various aspects of the serving of punishment by minors in educational colonies and requires a comprehensive study that can answer, it seems, a definitely significant question: whether the colony is the legal representative of the minors in it with all the consequences arising from the status of legal representatives in the form of duties and responsibilities. At the same time, it seems, it is necessary to pay attention to the specifics of the legal status of citizens serving sentences in educational colonies, who, firstly, are minors, i.e. do not have full legal capacity and need special care, protection and representation, and, secondly, are convicted of committing a serious or particularly serious crime, entailing isolation from society and certain restrictions and deprivation. Domestic legislation regulates in sufficient detail the peculiarities of the regime of serving sentences in the form of deprivation of liberty by minors, without determining the status of educational colonies. Who are they: educators, Trustees or only institutions of execution of punishments. Meanwhile, the correct understanding of the importance and role of the educational colony in the life of juvenile offenders in it, according to the author, will help to avoid a number of problems that objectively develop in institutions of this kind. From this point of view, the proposed topic is of interest not only for theoretical scientists, but for practitioners-employees of relevant institutions. It should be emphasized that there are no studies on this subject in the special literature. However, this circumstance can testify only about novelty of the given subject, but in any way about absence of the problem. It seems that the relevance and importance of a problem is not always measured by the number of studies devoted to it. Sometimes these its traits are manifest only under particularly careful consideration.


Author(s):  
Christopher McCarroll

This chapter sets out some key issues related to a philosophical analysis of point of view in memory. It does so by looking at examples of psychological, philosophical, and literary accounts of the phenomenon, as well as examples of the author’s own observer perspective memories. The chapter provides an overview of some of the empirical evidence related to visual perspective in memory. Despite these consistent empirical findings, however, a number of doubts and misconceptions about remembering from-the-outside still linger, especially concerning the status of observer perspectives in memory. This chapter outlines some of the skepticism to the possibility of remembering from-the-outside and points to a possible diagnosis of why such skepticism arises. This chapter points to a way of thinking about memory—to be developed through the course of the book—which eases the worries about remembering from-the-outside.


Author(s):  
Jennifer Knust

The pericope adulterae (John 7:53–8:11) is often interpreted as an inherently feminist story, one that validates women’s humanity in the face of a patriarchal order determined to reduce sexual sinners and women more generally to the status of object. Reading this story within a framework of queer narratology, however, leads to a different point of view, one that challenges the consequences of seeking rescue from a god and a text that are both quite willing to forge male homosocial bonds at a woman’s expense. As the history of this story also shows, texts and their meanings remain unsettled and therefore open to further unpredictable and contingent elaboration. Pondering my own feminist commitments, I attempt to imagine a world and a story where a woman is a person and Jesus is in need of rescue. Perhaps such a world is possible. Or perhaps it is not.


Author(s):  
Chris Lorenz

This introductory chapter assesses the role of theory in history and traces the developments in the discipline of history. Theoretical reflection about the ‘true nature’ of history fulfils three interrelated practical functions. First, theory legitimizes a specific historical practice—a specific way of ‘doing history’—as the best one from an epistemological and a methodological point of view. Second, theory sketches a specific programme of doing history. Third, theoretical reflections demarcate a specific way of ‘doing history’ from other ways of ‘doing history’, which are excluded or degraded. The chapter then considers three phases of theoretical changes from analytical to narrative philosophy of history, and then on to ‘history from below’ and the ‘presence’ of history, ultimately leading to the current return of fundamental ontological and normative questions concerning the status of history and history-writing.


2015 ◽  
Vol 22 (04) ◽  
pp. 1550021 ◽  
Author(s):  
Fabio Benatti ◽  
Laure Gouba

When dealing with the classical limit of two quantum mechanical oscillators on a noncommutative configuration space, the limits corresponding to the removal of configuration-space noncommutativity and position-momentum noncommutativity do not commute. We address this behaviour from the point of view of the phase-space localisation properties of the Wigner functions of coherent states under the two limits.


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