JOURNAL OF ADVANCES IN PHYSICS scientific, open access, scholarly, peer-reviewed, fully referred international journal with DOI, ISSN ICV and IF en-US <p>Authors retain the copyright of their manuscripts, and all Open Access articles are distributed under the terms of the&nbsp;<a href="">Creative Commons Attribution License</a>, which permits unrestricted use, distribution, and reproduction in any medium, provided that the original work is properly cited.</p> <p>The use of general descriptive names, trade names, trademarks, and so forth in this publication, even if not specifically identified, does not imply that these names are not protected by the relevant laws and regulations. The submitting author is responsible for securing any permissions needed for the reuse of copyrighted materials included in the manuscript.</p> <p>While the advice and information in this journal are believed to be true and accurate on the date of its going to press, neither the authors, the editors, nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.</p> (Chief Editor) (Editorial Support Team) Thu, 01 Feb 2018 05:02:41 +0000 OJS 60 The Nature of Time - A 21st Century View <p>21st Century View – Abstract</p> <p>• In 1905 it was generally believed that the universe had always existed. The exact age of Earth was not known. Life on Earth did not start until many years after Earth came into existence.<br>• During the 20th century our understanding of the universe was greatly expanded. The assumptions used in this article follow.<br>o Two mathematical equations, and three experiments are used to develop the ideas presented in this article. <br>o The Universe came into existence about 13.8 billion years ago, Earth came into existence about 4.5 billion years ago, observers probably appeared less than a billion years ago, so time existed without observers for about 3.5 billion years.<br>o This article consists of the application of logic to the above assumptions.<br>• Physical time vs observed time.<br>o The time that existed before observers appeared is termed ‘physical time’. After observers appeared, physical time continued to exist and ‘observed time’ came into being.<br>• The characteristics of physical time are:<br>o Absolute time<br>o Physical events<br>o Physical ‘now’<br>o Physical frame of reference<br>• Physical time dilation<br>o Objects that move through space experience time dilation; but they do not observe it.<br>o The Lorentz Transformation describes the computation of time dilation but does not describe physically how it occurs.<br>o The Time Distance Diagram illustrates physically what occurs when a particle experiences time.<br>o The diagram is based on the proposed concept that when a particle experiences time it either moves a tick through time or a Planck time through space; it cannot do both. <br>o Which it does is based on its speed expressed as the probability v/c derived from the Lorentz transformation. <br>• Absolute time<br>o Photons — and the resulting time — came into existence with the big bang. Photons have been moving through space continuously since the big bang — one Planck length, one Planck time (or tick) at a time.<br>o The movement of photons thru spacetime constitutes absolute time. <br>• Physical Events<br>o Without events, nothing happens.<br>o Every event has a frame of reference.<br>• Physical ‘Now’<br>o ‘Now’ can occur in both physical time and observed time.<br>o A physical event always results in a physical ‘now’.<br>• Physical Frame of Reference<br>o Every event must have a frame of reference.<br>o The frame of reference for a physical event has components that cannot be observed, so the frame of reference must be universal.<br>• The characteristics of observed time are:<br>o Observed events.<br>o Observed ‘now’.<br>o Observed frame of reference.<br>• Observed Event<br>o To an observer, his/her observation of an event is unique and is not necessarily the same as the actual event itself or the observation of another observer.<br>• Observed Now<br>o If an event is observed, each observer has his/her own observed ‘now’ which occurs in observer’s frame of reference.<br>o The ‘now’ experienced by observers is not the same ‘now’ as physical ‘now’ or the ‘now’ experienced by another observer.<br>• Observed Frame of Reference<br>o Each observer has her/his own frame of reference and his/her own personal clock. <br>• Time Dilation<br>o The current definition of time dilation is no longer relevant. Time dilation must have existed in the period before observers appeared on earth, so time dilation must be an aspect of physical time, not of observed time. <br>• Lorentz Transformation<br>o The Lorentz transformation factor ‘γ’ is computed by dividing ‘v2’ which is a vector by ‘c2’ which is scalar. Both terms should be scalar.</p> Sydney Baldwin Self ##submission.copyrightStatement## Thu, 01 Feb 2018 05:02:11 +0000 Old Inconsistency In Electromagnetism And A Way To Eliminate It <p>Classical electromagnetic theory uses axial pseudo-vectors to describe magnetic interactions. It is impossible to explain adequately magnetic interaction at the micro level (elements of conductors and the magnetic interactions of charges) by axial vectors. As a result, the correct form of interactions in classical electrodynamics is only an integral one. The differential formulas for magnetic interactions violate the third Newton’s law.</p> <p>In the paper, we use polar vectors (real physical vectors) to describe magnetic interactions. On this way, we show that the real physical magnetic field, in contrast to the solenoidal field of the axial vector magnetic induction <strong><em>B</em></strong>, has two components: a potential field with nonvanishing divergence and a solenoidal field with vanishing divergence. These two fields act separately and independently and have different models of interactions.</p> <p>Doing so, we can write differential form &nbsp;for the Ampere’s law obtaining correct formula for the magnetic interactions and adequate interpretation of the Biot-Savart law.</p> Valerij Disan Petushchak ##submission.copyrightStatement## Thu, 01 Feb 2018 05:15:05 +0000 Evaluation of using radiographic films in measurements of penumbra width for radiotherapy applications and stereotactic radiosurgery <p><em></em></p> <p>The accuracy of treatment field size in is a success key in cancer radiotherapy. As Increase in dose may lead to overdose side effects, and decrease in dose lead to subtherapeutic effect which increased incidence of tumor recurrence or incomplete recovery of patient. Many physical parameters should be measured very accurately in order to predict the dose distribution as physical penumbra of radiation fields. Ionization chamber is considered as slandered tools for measuring penumbra.</p> <p>Mega voltage x-ray energy penumbra is measured using ionization chamber due to its high accuracy in measuring absolute dose. This technique can produce the gold standard for penumbra measurements; however, it is a very time consuming and demanding process.</p> <p>Aim of this work is to evaluate the using radiographic films in penumbra width measurements for radiotherapy applications and stereotactic radiosurgery by comparing results obtained by standard ionization chambers to radiographic films as new tool for penumbral width measurements.</p> <p>Comparison between penumbra region measured by ionization chamber and o-xmat v Kodak radiographic films were carried out under the same physical and dosimeteric conditions.</p> <p>Penumbra width differences were found to be less than 1 mm for 6 mev, 15 mev photon beam and 6 mv, 15 mv electron beam used in radiotherapy. Measured differences were considered very small and has no effect on penumbra width measurements however o-xmat v Kodak films provide fast .easy and economic method for penumbra measurement used in radiotherapy dosimetery.&nbsp;</p> ehab A Hegazy ##submission.copyrightStatement## Thu, 01 Feb 2018 05:23:05 +0000