The Second Law and Energy (second law event) 10/05/2007 1:00 PM Broad InstituteSteven Chu, Secretary of EnergyDescription: This Nobel Prize"winning scientist admits to staying up late the night before his talk to bone up on thermodynamics. He puts his research to good use, discussing the history and application of the laws of thermodynamics, which have served as "the scientific foundation of how we harness energy, and the basis of the industrial revolution, the wealth of nations." Taking Watt's 1765 steam engine, Stephen Chu illustrates basic principles of thermodynamics -- that energy is conserved, that you can do work from heat, especially when you maximize the difference in temperature in the system and minimize heat dissipation from friction. The game hasn't changed all that much in the past few centuries. Another potentially rich energy source, Chu says, involves converting sun light into fuel the way plants do in photosynthesis. credit MIT World -- special events and lectures license MIT TechTV
General relativity General relativity, or the general theory of relativity, is the geometric theory of gravitation published by Albert Einstein in 1916 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 Albert Einstein developed the theories of special and general relativity.
Free Physics Video and Audio Courses These are the free physics video and audio courses. They are ordered based on their difficulty, starting with easiest first and ending with the most difficult. Also if you love physics, check out my friend's video websites dedicated to three famous physicists: And here are the physics video lectures: Descriptive introduction to physics: No prior physics is required. Classical Mechanics: In addition to the basic concepts of Newtonian Mechanics, Fluid Mechanics, and Kinetic Gas Theory, a variety of interesting topics are covered in this course: Binary Stars, Neutron Stars, Black Holes, Resonance Phenomena, Musical Instruments, Stellar Collapse, Supernovae, Astronomical observations from very high flying balloons (lecture #35), and you will be allowed a peek into the intriguing Quantum World. Introductory Physics Introduction to forces, kinetics, equilibria, fluids, waves, and heat. Electricity and Magnetism: Vibrations and Waves: Symmetry, Structure, and Tensor Properties of Materials
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. We have also awarded nine runners-up (see below). 1st place: Shifting the morals of quantum measurement Steinberg's work stood out because it challenges the widely held notion that quantum mechanics forbids us any knowledge of the paths taken by individual photons as they travel through two closely spaced slits to create an interference pattern. How to ask a 'forbidden question'
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. (Classical physics also predicts the bending of light, but only half that predicted by general relativity.) Although Einstein made unpublished calculations on the subject in 1912, Orest Khvolson (1924) and Frantisek Link (1936) are generally credited with being the first to discuss the effect in print. Description 1. 2. 3. History 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. 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. Microlensing by an isolated object was first detected in 1989. How it works Observing microlensing .
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. 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 This is similar to arranging tiles evenly on a floor.
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. 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: England: Germany: India: Netherlands:
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. Some of the fun stuff: 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