10 Strange Things About The Universe Space The universe can be a very strange place. While groundbreaking ideas such as quantum theory, relativity and even the Earth going around the Sun might be commonly accepted now, science still continues to show that the universe contains things you might find it difficult to believe, and even more difficult to get your head around. Theoretically, the lowest temperature that can be achieved is absolute zero, exactly ? One of the properties of a negative-energy vacuum is that light actually travels faster in it than it does in a normal vacuum, something that may one day allow people to travel faster than the speed of light in a kind of negative-energy vacuum bubble. One prediction of Einstein’s theory of general relativity is that when a large object moves, it drags the space-time around it, causing nearby objects to be pulled along as well. Relativity of Simultaneity Since this extra dimension is so small, only tiny objects, such as particles, can move along it. Antimatter Retrocausality
free university lectures - computer science, mathematics, physic Whether your goal is to earn a promotion, graduate at the top of your class, or just accelerate your life, lectures can help get you there. Our archives of lectures cover a huge range of topics and have all been handpicked and carefully designed by experienced instructors throughout the world who are dedicated to helping you take the next step toward meeting your career goals. Lifelong learns can turn their free time turn into self-improvement time. The online lectures on this list are more than lecture notes or a slideshow on a topic -- they were designed for audiences like you, with carefully sequenced themes and topics taught by veteran educators, and often with additional resources for your own independent study. The lectures are available to anybody, completely free of charge. Lecture courses are a valid and vital learning tool, and may be one of the best methods of learning available.
Einstein for Everyone Einstein for Everyone Nullarbor Press 2007revisions 2008, 2010, 2011, 2012, 2013 Copyright 2007, 2008, 2010, 2011, 2012, 2013 John D. All Rights Reserved John D. An advanced sequel is planned in this series:Einstein for Almost Everyone 2 4 6 8 9 7 5 3 1 ePrinted in the United States of America no trees were harmed web*bookTM This book is a continuing work in progress. January 1, 2015. Preface For over a decade I have taught an introductory, undergraduate class, "Einstein for Everyone," at the University of Pittsburgh to anyone interested enough to walk through door. With each new offering of the course, I had the chance to find out what content worked and which of my ever so clever pedagogical inventions were failures. At the same time, my lecture notes have evolved. Its content reflects the fact that my interest lies in history and philosophy of science and that I teach in a Department of History and Philosophy of Science. This text owes a lot to many. i i i
Electromagnetic waves At this point in the course we'll move into optics. This might seem like a separate topic from electricity and magnetism, but optics is really a sub-topic of electricity and magnetism. This is because optics deals with the behavior of light, and light is one example of an electromagnetic wave. Light and other electromagnetic waves Light is not the only example of an electromagnetic wave. speed of light in vacuum: c = 3.00 x 108 m/s As we'll go into later in the course when we get to relativity, c is the ultimate speed limit in the universe. There is a wonderful connection between c, the speed of light in a vacuum, and the constants that appeared in the electricity and magnetism equations, the permittivity of free space and the permeability of free space. This clearly shows the link between optics, electricity, and magnetism. Creating an electromagnetic wave We've already learned how moving charges (currents) produce magnetic fields. Focus on these two facts: Energy in an electromagnetic wave
Special Relativity Special Relativity These pages are ok as far as they go, but they are missing the planned highlight, to show you what things actually look like when you travel at near the speed of light. I hope to have the opportunity to develop these pages further as time permits. Here is my opinionated Guide to Special Relativistic Flight Simulator Sites. Meanwhile, these pages comprise an animated introduction to the elements of Special Relativity. And don't miss Prasenjit Saha's Interactive Lorentz Transformations. © 1998, 1999 Andrew Hamilton. Forward to The Postulates of Special Relativity Hey, get me back to Falling into a Black Hole Unless otherwise stated, clicking on images gives you enlarged versions thereof, which may be easier to view in a classroom environment. Special Relativity: Index Andrew Hamilton's Homepage Other Relativity and Black Hole links
Erasing history? Temporal cloaks adjust light's throttle to hide an event in time Researchers from Cornell University in Ithaca, N.Y., have demonstrated for the first time that it's possible to cloak a singular event in time, creating what has been described as a "history editor." In a feat of Einstein-inspired physics, Moti Fridman and his colleagues sent a beam of light traveling down an optical fiber and through a pair of so-called "time lenses." Between these two lenses, the researchers were able to briefly create a small bubble, or gap, in the flow of light. During that fleetingly brief moment, lasting only the tiniest fraction of a second, the gap functioned like a temporal hole, concealing the fact that a brief burst of light ever occurred. The team is presenting their findings at the Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2011 ( taking place in San Jose, Calif. next week. To test the performance of their temporal cloak, the researchers created pulses of light directly between the two lenses.
On the Electrodynamics of Moving Bodies By A. Einstein June 30, 1905 It is known that Maxwell's electrodynamics—as usually understood at the present time—when applied to moving bodies, leads to asymmetries which do not appear to be inherent in the phenomena. Take, for example, the reciprocal electrodynamic action of a magnet and a conductor. The observable phenomenon here depends only on the relative motion of the conductor and the magnet, whereas the customary view draws a sharp distinction between the two cases in which either the one or the other of these bodies is in motion. Examples of this sort, together with the unsuccessful attempts to discover any motion of the earth relatively to the “light medium,” suggest that the phenomena of electrodynamics as well as of mechanics possess no properties corresponding to the idea of absolute rest. § 1. If we wish to describe the motion of a material point, we give the values of its co-ordinates as functions of the time. from A towards B, let it at the “B time” § 2. (a) (b) . where or
Eddy current brake An eddy current brake of a German ICE 3 in action. An eddy current brake, like a conventional friction brake, is responsible for slowing an object, such as a train or a roller coaster. However, unlike electro-mechanical brakes, which apply mechanical pressure on two separate objects, eddy current brakes slow an object by creating eddy currents through electromagnetic induction which create resistance, and in turn either heat or electricity. Construction and operation Circular eddy current brake Principle of the linear eddy current brake Japanese Shinkansen trains had employed circular eddy current brake system on trailer cars since 100 Series Shinkansen. Linear eddy current brake The principle of the linear eddy current brake has been described by the French physicist Foucault, hence in French the eddy current brake is called the "frein à courants de Foucault". The braking energy of the vehicle is converted in eddy current losses which lead to a warming of the rail. K.D.
Physics Flash Animations We have been increasingly using Flash animations for illustrating Physics content. This page provides access to those animations which may be of general interest. The animations will appear in a separate window. The animations are sorted by category, and the file size of each animation is included in the listing. In addition, I have prepared a small tutorial in using Flash to do Physics animations. LInks to versions of these animations in other languages, other links, and license information appear towards the bottom of this page. The Animations There are 99 animations listed below. Other Languages and Links These animations have been translated into Catalan, Spanish and Basque: En aquest enllaç podeu trobar la versió al català de les animacions Flash de Física. Many animations have been translated into Greek by Vangelis Koltsakis. Most animations have been translated into Hungarian by Sandor Nagy, Eötvös Loránd University.
Russell's Paradox First published Fri Dec 8, 1995; substantive revision Tue Dec 3, 2013 Russell's paradox is the most famous of the logical or set-theoretical paradoxes. Also known as the Russell-Zermelo paradox, the paradox arises within naïve set theory by considering the set of all sets that are not members of themselves. Such a set appears to be a member of itself if and only if it is not a member of itself. Hence the paradox. Some sets, such as the set of all teacups, are not members of themselves. Although also noticed by Ernst Zermelo, the contradiction was not thought to be important until it was discovered independently by Bertrand Russell in the spring of 1901. 1. Is R a member of itself? As Russell tells us, it was after he applied the same kind of reasoning he found in Cantor's diagonal argument to a “supposed class of all imaginable objects” that he was led to the contradiction: 2. Russell wrote to Frege with news of his paradox on June 16, 1902. 3. As Whitehead and Russell explain, 4.
Light and Matter: open-source physics textbooks Extras Who's Using the Books Adoptions of Light and Matter Colleges and Universities High Schools Parker School, Kamuela, HI (Matt Hamilton) Little Axe High School, Norman, Oklahoma (Michael Dean) Orion International Academy, Pasadena, CA (John Gaines's Introduction to Physics) Ballinger High School, Ballinger, TX (Mr. Adoptions of Mechanics University of British Columbia (Profs. Pine Tree High School, Longview, Texas (Blake Sansom's AP Physics C) Ballinger High School, Ballinger, TX (Mr. Adoptions of Simple Nature Regis College (Prof. Adoptions of Special Relativity University of Peradeniya (Prof. Adoptions of Conceptual Physics University of Cincinnati, Blue Ash (Prof. Adoptions of Discover Physics Ohlone College (Otis Walton's Physics 108) Harmony Academies St. Adoptions of Fundamentals of Calculus Bellingham Technical College (Anita Peng's Math 148) Within each section above, schools are listed in reverse chronological order of adoption. Alignment with California Standards