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General relativity

General relativity
General relativity, or the general theory of relativity, is the geometric theory of gravitation published by Albert Einstein in 1916[1] and the current description of gravitation in modern physics. General relativity generalizes special relativity and Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of partial differential equations. Some predictions of general relativity differ significantly from those of classical physics, especially concerning the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light. Einstein's theory has important astrophysical implications. History[edit] Albert Einstein developed the theories of special and general relativity. Related:  physics

Physics World reveals its top 10 breakthroughs for 2011 The two physics stories that dominated the news in 2011 were questions rather than solid scientific results, namely "Do neutrinos travel faster than light?" and "Has the Higgs boson been found?". However, there have also been some fantastic bona fide research discoveries over the last 12 months, which made it difficult to decide on the Physics World 2011 Breakthrough of the Year. But after much debate among the Physics World editorial team, this year's honour goes to Aephraim Steinberg and colleagues from the University of Toronto in Canada for their experimental work on the fundamentals of quantum mechanics. Using an emerging technique called "weak measurement", the team is the first to track the average paths of single photons passing through a Young's double-slit experiment – something that Steinberg says physicists had been "brainwashed" into thinking is impossible. We have also awarded nine runners-up (see below). 1st place: Shifting the morals of quantum measurement

Quantum Diaries (Thoughts on work and life from particle physicists from around the world.) Gravitational lens A light source passes behind a gravitational lens (point mass placed in the center of the image). The aqua circle is the light source as it would be seen if there was no lens, white spots are the multiple images (or Einstein ring) of the source. A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity.[1][2] (Classical physics also predicts the bending of light, but only half that predicted by general relativity.[3]) Although Einstein made unpublished calculations on the subject in 1912,[4] Orest Khvolson (1924)[5] and Frantisek Link (1936)[citation needed] are generally credited with being the first to discuss the effect in print. Description[edit] 1. 2. 3. History[edit] Notes

Gravitational microlensing Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects ranging from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit lots of light (stars) or large objects that block background light (clouds of gas and dust). These objects make up only a tiny fraction of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light. When a distant star or quasar gets sufficiently aligned with a massive compact foreground object, the bending of light due to its gravitational field, as discussed by Einstein in 1915, leads to two distorted unresolved images resulting in an observable magnification. Since microlensing observations do not rely on radiation received from the lens object, this effect therefore allows astronomers to study massive objects no matter how faint. How it works[edit] History[edit] . . . . .

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 ?273.15°C, where the motion of all particles stops completely. However, you can never actually cool something to this temperature because, in quantum mechanics, every particle has a minimum energy, called “zero-point energy,” which you cannot get below. 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. Relativity of Simultaneity Antimatter Retrocausality

Usenet Physics FAQ Version Date: March 2013 This list of answers to frequently asked questions in physics was created by Scott Chase in 1992. Its purpose was to provide good answers to questions that had been discussed often in the sci.physics and related Internet news groups. The articles in this FAQ are based on those discussions and on information from good reference sources. Most of the entries that you'll find here were written in the days when the Internet was brand new. So because of their age, the FAQ entries that you'll find here have a great deal of academic credibility—but they are not always perfect and complete. This document is copyright. General Physics Particle and Nuclear Physics Quantum Physics Relativity and Cosmology Speed of Light Special Relativity General Relativity and Cosmology Black Holes Reference Topics There are many other places where you may find answers to your question. This FAQ is currently available from these web sites: Australia:

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. 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

IoHT :: 110+ Variations of the Second Law of Thermodynamics Questions about these second law variations? Know of other second law definitions? Copyright © Institute of Human Thermodynamics and IoHT Publishing Ltd. All Rights Reserved [1] Hippocrates (c. 440 BC). NEED SOURCE [email me if you have it] [2] Lavoisier, A. (1789). [3-4] Carnot, S. (1824). [5-8] Clausius, R. (1850). [9] Kelvin, L. (1852). [10] Kelvin, L. (1852). [11] Kelvin, L. (1852). [12] Kelvin, L. (1852). [13] Kelvin, L. (1852). the Philosophical Magazine, October, 1852; also Mathematical and Physical Papers, vol. i, art. 59. [14] Clausius, R. (1865). [15] Kelvin & Planck. (1879). [16-17] Planck. [18] Caratheodory, C. (1908). [19-21] Fermi, E. (1936). [22-23] Bridgman, P. (1941). [24] Keenan, J. (1941). [25-26] Klotz. [27] Fritz, A. (1959). [28] King, A. (1962). [29-30] Lee, J. & Sears, F. (1963). [31-32] Bazarov, I. (1964). [33] Bent, H. (1965). [34] Hatsopoulos, G. & Keenan, J. (1965). [35-37] Kern, R. & Weisbrod, A. (1967). [38] Battino, R. & Wood, S. (1968). [58] Ebbing (1990). 1.

Dimensions Home A film for a wide audience! Nine chapters, two hours of maths, that take you gradually up to the fourth dimension. Mathematical vertigo guaranteed! Background information on every chapter: see "Details". Click on the image on the left to watch the trailer ! Free download and you can watch the films online! The film can also be ordered as a DVD. This film is being distributed under a Creative Commons license. Now with even more languages for the commentary and subtitles: Commentary in Arabic, English, French, German, Italian, Japanese, Spanish and Russian. Film produced by: Jos Leys (Graphics and animations) Étienne Ghys (Scenario and mathematics) Aurélien Alvarez (Realisation and post-production)

Articles on "Electricity" Why three prongs?Why do wall outlets have three holes? "Grounding" and safety. Right Angle CircuitryDo Lenz' Law and the Right Hand rule still work... after you've been turned INSIDE OUT by that greasy black Fog? "Static Electric" misconceptionsA list of things which gave me a warped view of Electrostatics. Speed of "Electricity"? Triboelectric Series If a cat gets trapped in a clothes dryer full of nylon pantyhose, which way do the electrons flow? Where does EM energy flow in a circuit? How Scientists Define the word "Electricity" Quotes from J.C. Barriers to Understanding ElectricityTwenty misconceptions which prevented me from understanding simple electrical science as a student. "Static" Electricity is really just high voltage.Scuff on the rug, then measure your body voltage. Electricity mistakes and 'nitpicking' also How SHOULD we teach Electricity? "Static" sparks Doorknob sparks and zapping yourself on the car door... and people who suffer from an "electric shock" disease.

HPS 0410 Einstein for Everyone Title page, Preface and Table of Contents for Einstein for Everyone Introduction: the Questions Special Relativity Special Relativity: the Principles Special Relativity: Clocks and Rods Special Relativity: Adding Velocities Special Relativity: the Relativity of Simultaneity Is Special Relativity Paradoxical? E=mc2 Origins of Special Relativity Einstein's Pathway to Special Relativity Spacetime Spacetime Spacetime and the Relativity of Simultaneity Spacetime, Tachyons, Twins and Clocks What is a four dimensional space like? Philosophical Significance of the Special Theory of Relativity. Skeptical Morals. Morals About Theory and Evidence. Morals About Time. Non-Euclidean Geometry Euclidean Geometry: The First Great Science Euclid's Fifth Postulate Non-Euclidean Geometry: A Sample Construction Non-Euclidean Geometry and Curved Spaces Spaces of Constant Curvature Spaces of Variable Curvature General Relativity General Relativity Gravity Near a Massive Body Einstein's Pathway to General Relativity Relativistic Cosmology

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