Physics Homework Help, Physics Help, Physics Tutors 4192741 When you turn on a torch, does the light instantly reach the speed of light? Or does it accelerate up to that speed very quickly? The short answer is that light coming out of your torch instantly reaches the speed of light. Light can only ever travel at the speed of light — 300,000,000 metres per second in a vacuum, and a bit slower in air because it bumps into molecules. So why is light only allowed to travel at that one speed? "There are two ways to answer that question" says David Jamieson, professor of physics at the University of Melbourne. Thankfully he has a better way — with an analogy to waves in string. "Imagine you've got a tight string and you pluck it and a wave goes shooting down the string. But there's a big difference between light waves and these waves. The physicist James Clerk Maxwell worked out that all light is made of oscillating electric and magnetic fields, coupled together and reinforcing one another. Two constants make another constant
Special Relativity and Electrodynamics (Spring, 2012) 1 The Lorentz transformation In the first lecture of the course Professor Susskind introduces the original principle of relativity - also known as Galilean Invariance - and discusses inertial reference frames and simultaneity. He then derives the Lorentz transformation of... [more] 2 Adding velocities Professor Susskind starts with a brief review of the Lorentz transformation, and moves on to derive the relativistic velocity addition formula. He then discusses invariant intervals, proper-time and distance, and light cones. Note: this is only a 1...
Backreaction The Feynman Lectures on Physics Home | Practical Physics This website is for teachers of physics in schools and colleges. It is a collection of experiments that demonstrate a wide range of physical concepts and processes. Some of the experiments can be used as starting-points for investigations or for enhancement activities. Physics is a practical science. Good quality, appropriate physics experiments and investigations are the key to enhanced learning, and clarification and consolidation of theory. We have published a new set of resources to support the teaching of practical science for Key Stages 3-5.
stars.chromeexperiments General Relativity (Fall, 2012) 1 The equivalence principle and tensor analysis The principle of equivalence of gravity and acceleration, or gravitational and inertial mass is the fundamental basis of general relativity. This was Einstein's key insight. Professor Susskind begins the first lecture of the course with Einstein'...
Not Even Wrong I’ve just replaced the old version of my draft “spacetime is right-handed” paper (discussed here) with a new, hopefully improved version. If it is improved, thanks are due to a couple people who sent helpful comments on the older version, sometimes making clear that I wasn’t getting across at all the main idea. To further clarify what I’m claiming, here I’ll try and write out an informal explanation of what I see as the relevant fundamental issues about four-dimensional geometry, which appear even for $\mathbf R^4$, before one starts thinking about manifolds. Spinors, twistors and complex spacetime In complex spacetime $\mathbf C^4$ the story of spinors and twistors is quite simple and straightforward. While spinors are the irreducible objects for understanding complex four-dimensional rotations, twistors are the irreducible objects for understanding complex four-dimensional conformal transformations. Real forms In this case the conjugation acts in a subtle manner. Some philosophy
edX - Paradigms of computer programming Skip to this view's content Please enter your e-mail address below, and we will e-mail instructions for setting a new password. Help For questions on course lectures, homework, tools, or materials for this course, post in the course discussion forum. Have general questions about edX? Have a question about something specific? Report a problem Make a suggestion Ask a question Please note: The edX support team is English speaking. Thank you for your inquiry or feedback. Course Updates & News Course Handouts PhysicsCentral: Learn How Your World Works untitled Cosmology (Winter, 2013) 1 The expanding (Newtonian) universe Professor Susskind introduces the topic of modern Cosmology, which started with the discovery of cosmic microwave background radiation in 1964. However, this lecture focuses on the classical or Newtonian view of the universe. Beginning with the... [more] 2 Matter and radiation dominated universes After reviewing the basic equation for an expanding universe, Professor Susskind solves the equation explicitly for a zero energy universe, and then extends the derivation to universes with non-zero energy. These universes can take two forms:... [more] 3 Geometries of space: flat, spherical, hyperbolic Professor Susskind presents three possible geometries of homogeneous space: flat (infinite), spherical (positively curved and finite), hyperbolic (negatively curved and infinite).