Relative Locations

2018 ◽  
Author(s):  
Andrew Bacon
Keyword(s):  
Space Time ◽  
Pivotal Role ◽  
Abstract Objects ◽  
Time Points ◽  
The Cost ◽  
Physical Laws

The fact that physical laws often admit certain kinds of space-time symmetries is often thought to be problematic for substantivalism—the view that space-time is as real as the objects it contains. The most prominent alternative, relationism, avoids these problems but at the cost of giving abstract objects (rather than space-time points) a pivotal role in the fundamental metaphysics. This incurs related problems concerning the relation of the physical to the mathematical. This paper presents a version of substantivalism that respects Leibnizian theses about space-time symmetries, and argues that it is superior to both relationism and the more orthodox form of substantivalism.

scholarly journals S-money: virtual tokens for a relativistic economy

2019 ◽  
Vol 475 (2225) ◽  
pp. 20190170 ◽  
Author(s):  
Adrian Kent
Keyword(s):  
Data Storage ◽  
Relevant Information ◽  
Space Time ◽  
User Privacy ◽  
Standard Quantum ◽  
Bit Commitment ◽  
Time Points ◽  
Security Questions ◽  
Time Point

We propose definitions and implementations of ‘S-money’—virtual tokens designed for high-value fast transactions on networks with relativistic or other trusted signalling constraints, defined by inputs that in general are made at many network points, some or all of which may be space-like separated. We argue that one significant way of characterizing types of money in space–time is via the ‘summoning’ tasks they can solve: that is, how flexibly the money can be propagated to a desired space–time point in response to relevant information received at various space–time points. We show that S-money is more flexible than standard quantum or classical money in the sense that it can solve deterministic summoning tasks that they cannot. It requires the issuer and user to have networks of agents with classical data storage and communication, but no long-term quantum state storage, and is feasible with current technology. User privacy can be incorporated by secure bit commitment and zero-knowledge proof protocols. The level of privacy feasible in given scenarios depends on efficiency and composable security questions that remain to be systematically addressed.

Cross-view action matching using a novel projective invariant on non-coplanar space-time points

2015 ◽  
Vol 75 (19) ◽  
pp. 11661-11682 ◽  
Author(s):  
Qi Jia ◽  
Xin Fan ◽  
Zhongxuan Luo ◽  
Haojie Li ◽  
Kang Huyan ◽  
...  
Keyword(s):  
Space Time ◽  
Time Points ◽  
Projective Invariant

Not Observed Ontology

2020 ◽  
pp. 37-43
Author(s):  
Oleg V. Avchenko ◽  
Keyword(s):  
Physical Space ◽  
Space Time ◽  
Ordinary Space ◽  
Quantum Objects ◽  
Biological Laws ◽  
Experimental Works ◽  
Small Change ◽  
Physical Laws ◽  
The Universe ◽  
Real Area

Two narratives – natural science and religious, intersect in the area of ​​unobserv­able ontology – an immaterial, transcendental, but real area that paradoxically exists outside and inside ordinary physical space-time. It is assumed that mathe­matical constructs, physical laws, physical constants, quantum objects, and even biological laws can be associated with this area. It is argued that physical laws are not invented by man, but are discovered, since they contain physical con­stants measured in special experimental works. Universal constants were not invented for reasons of convenience – physics accepts them as an inevitable con­sequence of the coincidence of the results of all special measurements. Observa­tional data are presented that indicate an extremely small change in fundamental constants or even their constancy over the entire time of the existence of the Uni­verse, although this interesting problem cannot be considered finally solved. The ontology of quantum objects is considered within the framework of Seval­nikov's polyiontic paradigm, according to which two modes are distinguished – potential and actual. The potential existence of quantum objects is described by the Schrödinger wave function, and the actual one appears during the transition from the spectrum of possible states to the only observable one. It is emphasized that potential being does not belong to the classical space, but is in an unobserv­able ontology. The observed state, on the contrary, is already in ordinary space – time and can be recorded by the device. This determines the existence of a spe­cial transcendental layer of reality, along with the material, which may indicate a certain duality in the structure of the Universe. Then it should be assumed that our Universe is not a universal, but a multiverse – a set of different worlds onto­logically having a different nature. In addition, the polyiontic paradigm leads to the idea that, at the quantum level, matter can be derived from information hid­den in an unobservable ontology.

scholarly journals Aligned Space Time Block Codes for the 2-User X Channel with Secrecy Constraints

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Manar Mohaisen
Keyword(s):  
A Priori ◽  
Block Codes ◽  
Space Time ◽  
Diversity Gain ◽  
A Priori Knowledge ◽  
Time Block ◽  
Orthogonal Matrices ◽  
Space Time Block Codes ◽  
The Cost

Interference alignment (IA) is a technique used to reduce the dimension of the interference, where consequently the multiplexing rate is increased. In the 2-user X channel, combining IA with space-time block codes increases the diversity gain. These gains are achieved with the cost of leaked information at unintended receivers, where this leaked information can be used to decode other receiver’s signals. In this paper, we consider each of the two two-antenna receivers as an eavesdropper with 1 or 2 additional eavesdropping antennas. As such, we suggest receiver structures to answer the question: “Is the leaked information sufficient to properly decode the unintended signals?” besides quantifying the leaked information in terms of secrecy sum rates (SSR). Interestingly, we show that the SSR is negative, indicating that the quality of the eavesdropped signals is superior to that of the intended signals. To assure confidentiality, we propose an interleaved multiple rotation-based transformation scheme that neutralizes any a priori knowledge about the structure of the eavesdropped information and rotates the transmitted symbols using orthogonal matrices, preserving both the power and the distance between symbols.

scholarly journals Self-Supervised Video Representation Learning with Space-Time Cubic Puzzles

2019 ◽  
Vol 33 ◽  
pp. 8545-8552 ◽  
Author(s):  
Dahun Kim ◽  
Donghyeon Cho ◽  
In So Kweon
Keyword(s):  
Action Recognition ◽  
Large Scale ◽  
State Of The Art ◽  
Representation Learning ◽  
Space Time ◽  
Temporal Relation ◽  
Still Images ◽  
Video Frames ◽  
Spatio Temporal ◽  
The Cost

Self-supervised tasks such as colorization, inpainting and zigsaw puzzle have been utilized for visual representation learning for still images, when the number of labeled images is limited or absent at all. Recently, this worthwhile stream of study extends to video domain where the cost of human labeling is even more expensive. However, the most of existing methods are still based on 2D CNN architectures that can not directly capture spatio-temporal information for video applications. In this paper, we introduce a new self-supervised task called as Space-Time Cubic Puzzles to train 3D CNNs using large scale video dataset. This task requires a network to arrange permuted 3D spatio-temporal crops. By completing Space-Time Cubic Puzzles, the network learns both spatial appearance and temporal relation of video frames, which is our final goal. In experiments, we demonstrate that our learned 3D representation is well transferred to action recognition tasks, and outperforms state-of-the-art 2D CNN-based competitors on UCF101 and HMDB51 datasets.

scholarly journals Lorentz-invariant quantum fields in the space-time tangent bundle

2003 ◽  
Vol 2003 (24) ◽  
pp. 1529-1546 ◽  
Author(s):  
Howard E. Brandt
Keyword(s):  
Tangent Bundle ◽  
Planck Scale ◽  
Beltrami Operator ◽  
Space Time ◽  
Quantum Field ◽  
Time Points ◽  
High Energies ◽  
Maximal Acceleration ◽  
Particle Spectra ◽  
Invariant Quantum

A maximal-acceleration invariant quantum field is defined on the space-time tangent bundle with vanishing eigenvalue when acted on by the Laplace-Beltrami operator of the bundle, and the case is addressed in which the space-time is Minkowskian, and the field is Lorentz invariant. In this case, the field is shown to be automatically regularized at the Planck scale, and particle spectra are cut off at extremely high energies. The microcausality is addressed by calculating the appropriate field commutators; and it is shown that provided the adjoint field is consistently generalized, the necessary commutators are vanishing and the field is microcausal, but that there are Planck-scale modifications of the boundary of the causal domain that are significant for extremely large relative four-velocities between the separated space-time points. For vanishing relative four-velocity, the causal domain is canonical. The geometry of the causal domain indicates that near the Planck scale, causal connectivity may occur between spacelike separated points, and also at larger scales for extremely large relative four-velocities.

scholarly journals Seasonal Differences in the Cost and Engagement of Facebook Advertisements for a Physical Activity Smartphone App

2021 ◽  
pp. 089011712199730
Author(s):  
Celine Northcott ◽  
Rachel Curtis ◽  
Svetlana Bogomolova ◽  
Timothy Olds ◽  
Corneel Vandelanotte ◽  
...  
Keyword(s):  
Physical Activity ◽  
Target Population ◽  
Cross Sectional Study ◽  
Smartphone App ◽  
Chi Square ◽  
Cross Sectional ◽  
Time Points ◽  
Time Of Year ◽  
The Cost ◽  
First Time

Purpose: To evaluate the performance of Facebook advertisements for a physical activity smartphone app at different times of the year. Design: A repeated cross-sectional study examined the cost and engagement levels of advertisements during 3 time points: Post-Easter April-May 2019, Pre-Summer October 2019, and New Year January 2020 . Setting: Advertisements were delivered on Facebook. Subjects: The target population was Australian females aged 25-60 years. Measures: Cost was evaluated in terms of reach per dollar. Engagement was evaluated in terms of click-through and app downloads per reach. Analysis: ANOVA and Chi-square were used to assess differences in reach per dollar, click-through, and app downloads per reach between time points. Results: Reach per dollar was highest in Post-Easter, but declined in Pre-Summer and New Year (reach/$ 34.8 vs 31.5 vs 27.5; p = .004). Click-through was highest in New Year followed by Post-Easter, then Pre-Summer (click-through 3.2% vs 1.9% vs 1.2%; p < .001). New Year and Post-Easter advertisements achieved higher app downloads per reach than Pre-Summer (downloads 0.9% vs 0.7% vs 0.3%; p < .001). Conclusion: Facebook advertisements were cheaper in the first time-point, and appear to be getting more expensive (i.e. declining reach/$). Advertisements in the New Year achieved the highest click-through and app downloads per reach, suggesting a useful time of year to promote physical activity products.

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