scholarly journals Resolution of the Age-Old Dilemma about a Magnitude of the Momentum of Light in Matter

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
V. P. Torchigin ◽  
A. V. Torchigin

There are two competitive opinions about a magnitude of the momentum of light in matter. The Balazs thought experiment gives unambiguous theoretical evidence based only on laws of mechanics that the momentum of light in matter is smaller by n times than that of the same light in free space where n is the refractive index of the matter. On the other hand, there is other theoretical evidence confirmed by experimental investigation that the momentum of light in matter is greater by n times than that in free space. This ancient dilemma cannot be resolved till now. We show that the momentum density flux of light in matter is greater by n times than that in free space. In the same time we present an alternative interpretation of the Balazs thought experiment where two optical pressures arising in the regions of the matter where leading and trailing edges of the pulse are propagating are taken into account. This enables us to match contradictory results of mentioned experiments. Since the contradiction is overcome, the dilemma disappears.

PIERS Online ◽  
2010 ◽  
Vol 6 (5) ◽  
pp. 400-405 ◽  
Author(s):  
Mitsuji Matsumoto ◽  
Kamugisha Kazaura ◽  
Kazuhiko Wakamori ◽  
Takeshi Higashino ◽  
Katsutoshi Tsukamoto ◽  
...  

Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Umar Farooque ◽  
Rakesh Ranjan

AbstractIn order to select the heterogeneous multicore fiber (MCF) configuration with ultra-low crosstalk and low peak bending radius, comparative crosstalk analysis have been done for the three possible core configurations, namely, Configuration 1 - different refractive index (R.I.) and different radius, Configuration 2 - different R.I., and Configuration 3 - different radius. Using the coupled mode equation and the simplified expressions of mode coupling coefficient (MCC) for different configurations of heterogeneous cores, the crosstalk performance of all the heterogeneous MCF configurations along with the homogeneous MCF have been investigated analytically with respect to core pitch (D) and fiber bending radius (${R}_{b}$). Further, these expressions of MCC have been extended to obtain the simplified expressions of MCC for the estimation of crosstalk levels in respective trench-assisted (TA) heterogeneous MCF configurations. It is observed from the analysis that in Configuration 1, crosstalk level is lowest and the rate of decrease in the crosstalk with respect to the core pitch is highest compared to the other configurations of heterogeneous MCF. The values of crosstalk obtained analytically have been validated by comparing it with the values obtained from finite element method (FEM) based numerical simulation results. Further, we have investigated the impact of a fixed percent change (5%) in the core parameters (radius and/or R.I.) of one of the core of a homogeneous MCF, to realize the different heterogeneous MCF configurations, on the variations in crosstalk levels, difference in the mode effective refractive index of the core 1 and core 2 ($\Delta {n}_{eff}={n}_{eff1}-{n}_{eff2}$), and the peak bending radius (${R}_{pk}$). For the same percent variations (5%) in the core parameters (radius and/or R.I.) of different configurations of cores (Config. 1-Config. 3), Config. 1 MCF has highest variation in $\Delta {n}_{eff}$ value compared to other configurations of MCF. Further, this highest variation in $\Delta {n}_{eff}$ value of Config. 1 MCF results in smallest peak bending radius. The smaller value of peak bending radius allows MCF to bend into smaller radius. Therefore, Configuration 1 is the potential choice for the design of MCF with smaller peak bending radius and ultra-low crosstalk level compared to the other configurations of SI-heterogeneous MCF.


2018 ◽  
Vol 64 (No. 7) ◽  
pp. 296-302 ◽  
Author(s):  
Dini Morteza ◽  
Nikooy Mehrdad ◽  
Naskovets Michael Trofimovich ◽  
Ghomi Alireza

In this research, the results of an experimental survey on the measurement of vertical stresses are presented. Four treatments were used in this study such as combination of geotextile vertical and horizontal structure with dimensions of 5 × 5 and 10 × 10 cm, horizontal geotextile and the treatment without geotextile. Five sensors were installed in different hole locations and the lead of the truck traffic was transmitted by cables to data logging and recording devices to measure the pressure from vehicle traffic on the simulated pavement layer. Mean comparison of the treatments showed that the geotextile with vertical and horizontal structure and dimensions of 5 × 5 cm exerted the lowest pressure on the lower layers compared with the other treatments and there was a significant difference between the value of this treatment and the other treatments and that this treatment could significantly reduce the pressure of truck traffic on the forest road.


Religions ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 389
Author(s):  
James Robert Brown

Religious notions have long played a role in epistemology. Theological thought experiments, in particular, have been effective in a wide range of situations in the sciences. Some of these are merely picturesque, others have been heuristically important, and still others, as I will argue, have played a role that could be called essential. I will illustrate the difference between heuristic and essential with two examples. One of these stems from the Newton–Leibniz debate over the nature of space and time; the other is a thought experiment of my own constructed with the aim of making a case for a more liberal view of evidence in mathematics.


1982 ◽  
Vol 60 (5) ◽  
pp. 679-686 ◽  
Author(s):  
R. Fletcher

This paper provides a brief survey of the experimental and theoretical situation regarding the galvano- and thermomagnetic properties of potassium viewed within the context of the behaviour of other metals. Most of the data are consistent with various sample imperfections as being the major source of the anomalies that are found. However, the precise nature of the imperfections and the mechanism by which the imperfections produce the anomalies are not yet known. It is argued that the recently discovered detailed structure in the high field induced torque of K should be subjected to intensive experimental investigation before drawing any conclusions with regards to the possible presence of a charge density wave; the other magnetotransport properties offer little evidence either for or against such a possibility.


2021 ◽  
Vol 16 (5) ◽  
pp. 838-843
Author(s):  
Yan Zhang ◽  
Minru Hao ◽  
Min Shao ◽  
Yunzhe Zhang

We theoretically analyze the linear momentum density and orbital angular momentum (OAM) propagation characteristics of Gaussian vortex beams in free space, and perform detailed numerical simulation analysis of the linear momentum density and OAM propagation characteristics. Further, we study the variation of the propagation characteristics with different topological charges. In addition, we also analyzed the position of momentum in the transverse profile, where the momentum density of the spot will be broadened with propagation distance. This study can provide guidance for using vortex beams in optical communication and manipulation.


2021 ◽  
Vol 27 (1) ◽  
pp. 124-144
Author(s):  
Thomas Studer

Standard epistemic modal logic is unable to adequately deal with the FrauchigerRenner paradox in quantum physics. We introduce a novel justification logic CTJ, in which the paradox can be formalized without leading to an inconsistency. Still CTJ is strong enough to model traditional epistemic reasoning. Our logic tolerates two different pieces of evidence such that one piece justifies a proposition and the other piece justifies the negation of that proposition. However, our logic disallows one piece of evidence to justify both a proposition and its negation. We present syntax and semantics for CTJ and discuss its basic properties. Then we give an example of epistemic reasoning in CTJ that illustrates how the different principles of CTJ interact. We continue with the formalization of the Frauchiger–Renner thought experiment and discuss it in detail. Further, we add a trust axiom to CTJ and again discuss epistemic reasoning and the paradox in this extended setting.


2021 ◽  
Author(s):  
◽  
Samuele Tonello

<p>This thesis in divided in two main parts. First, I develop the claim that current democracies are unable to properly defend what I deem the pivotal feature to evaluate the quality of a political system - namely the people’s liberty - due to what I call a twofold democratic dilemma. On the one hand, common citizens are affected by biases that compromise their ability to successfully maintain forms of self-government. On the other hand, even representative forms of democracy that limit to a certain degree the people’s power are threatened by an oligarchic power. That is, oligarchs are using their wealth power to sway governments towards pursuing oligarchic interests rather than common ones, thus hindering the people’s liberty. For this reason, I argue that we ought to rely on Pettit’s view of liberty as non-domination to resolve the democratic dilemma. The thesis conceives these two threats as two forms of domination that must be avoided and focuses on adding a supplementary editorial and contestatory dimension of democracy to the classical participatory one. Republicanism could offer a solution to both sides of the dilemma. On the one hand, citizens’ political task would be more compatible with the people’s biases, since citizens would limit their participation to control that government’s policies do not entail oligarchic domination. On the other hand, framing liberty as a battle between dominating masters and dominated slaves, republicanism could offer the many the institutional means to counteract elites’ political domination. In this way, I conclude the first part of the thesis, but this opens the gates to the main question of the thesis, namely to how we should structure this contestatory democracy. The problem is that whereas republican scholars agree on the importance of setting freedom as non-domination at the basis of our political systems, there is no such agreement on the best way to institutionally enhance the republican ideal. I analyse this debate, maintaining that while Pettitt’s ideal is the view to pursue, we should reject his editorial solution because small committees of experts are likely to increase oligarchic domination rather than to protect the people’s liberty. Rejecting Pettit’s model does not yet imply refusing any editorial model, since I argue that critical scholars mistakenly identify the editorial component of democracy with Pettit’s answer only. In this way, they neglect alternative solutions to Pettit’s, such as Bellamy’s and McCormick’s. Having explained that Bellamy’s solution does not resolve the democratic dilemma, since this scholar rejects editorial bodies, I argue that McCormick’s “Machiavellian Democracy” framed on a divided conception of the populace offers instead the solution I am looking for. Institutionally recognizing the social differences among the populace, we could create modern bodies similar to the Roman “Tribune of the Plebs” to offer the weaker part of the population a class-specific institution to use as defence from oligarchic domination. The problem is how to implement a modern “Tribune of the plebs” making sure that these bodies are effective but popular in character at the same time. I thus explain how modern editorial tribunates could work in practice, drawing from McCormick’s “thought experiment”. I agree with most of McCormick’s ideas – lottery selection, wealth threshold exclusion, large size tribunates, etc. - but I suggest that we must review some of his suggestions with features more concerned with improving the people’s knowledge – specialization, education selection, etc. Hence, I conclude the thesis describing my thought experiment of a system of Specialized Ministerial Tribunates. In this way, I argue that we could better resolve the democratic dilemma. On the one hand, tribunates’ editorship would be more specific and would not require members of the tribunate to analyse the operation of governments on a too broad spectrum, thus reducing the problems of the people’s biases. On the other hand, tribunates’ operation could be primarily connected to detecting oligarchic features in the policies enacted by single ministries, thus challenging more precisely any oligarchic influence over governments. In sum, I argue that an editorial dimension could produce significant improvements to the people’s liberty. Thanks to a modern “Tribune of the plebs”, citizens could participate more meaningfully in politics, while taming more efficiently the influence oligarchs have on how modern societies are politically directed.</p>


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