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. They were later maintained and enlarged by Michael Weiss and Philip Gibbs. Others who have written for the FAQ are credited at the top of the items they submitted, while many more who have made smaller contributions have been thanked privately. 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
10,000 Suns -Most Dense Star Cluster in Milky Way Located With a mass of more than 10 000 suns packed into a volume with a diameter of a mere three light-years, the massive young star cluster in the nebula NGC 3603 is one of the most compact stellar clusters in the Milky Way and a natural lab to test theories for their formation, revealing whether the stars were in the process of drifting apart, or about to settle down. The cluster, formally known as the NGC 3603 Young Cluster, is about 20 000 light-years from the Sun which makes these measurements extraordinarily difficult. It is necessary to compare images that were made years or even decades apart. The telescope and camera used must give very sharp images and be extremely stable over long periods. A team of astronomers from the Max-Planck Institute for Astronomy in Heidelberg and the University of Cologne led by Wolfgang Brandner realized that the Hubble Space Telescope was the best for the job. Stars are born when a gigantic cloud of gas and dust collapses.
State of the Nation If possible, the first images in each set will be true-color, as you would see them with your own eyes. Most images will either be true-color or monochrome (black and white), unless stated otherwise. Many images can be vastly enlarged by clicking on them and choosing a larger size from the Flickr page. Downloading them may allow even larger sizes. It appears there's a limit to the size of diaries, so this first part of the tour ends about 3/4 of the way through the Saturn system (which is quite extensive). I. You might be tempted to think Mercury is very similar to the Moon, but compare and contrast them, and think about what the differences might mean. II. Through UV and orange filters: From the Soviet Venera 13 lander: From Venera 14: This is a perspective mosaic of Venera images put together by Don P. III. Can you spot Earth in this Voyager 2 image taken beyond Pluto? Luna IV. There are only two NEOs that have clear, interesting, photographic images at the moment. 25143 Itokawa 433 Eros V. Io
2012 March 12 - The Scale of the Universe Interactive Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2012 March 12 The Scale of the Universe - Interactive Flash Animation Credit & Copyright: Cary & Michael Huang Explanation: What does the universe look like on small scales? Tomorrow's picture: dust before galaxies Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)NASA Official: Phillip Newman Specific rights apply.NASA Web Privacy Policy and Important NoticesA service of:ASD at NASA / GSFC& Michigan Tech.
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
2010 August 21 - Perseid Storm Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2010 August 21 Explanation: Storms on the distant horizon and comet dust raining through the heavens above are combined in this alluring nightscape. The scene was recorded in the early hours of August 13 from the Keota Star Party site on the Pawnee National Grasslands of northeastern Colorado, USA. Looking east across the prairie, the composite of 8 consecutive exposures each 30 seconds long captures the flash of lightning and a bright Perseid meteor.
Your Age on Other Worlds Want to melt those years away? Travel to an outer planet! <div class="js-required"><hr> This Page requires a Javascript capable browser <hr></div> Fill in your birthdate below in the space indicated. (Note you must enter the year as a 4-digit number!) The Days (And Years) Of Our Lives Looking at the numbers above, you'll immediately notice that you are different ages on the different planets. The earth is in motion. The top-like rotation of the earth on its axis is how we define the day. The revolution of the earth around the sun is how we define the year. We all learn in grade school that the planets move at differing rates around the sun. Why the huge differences in periods? Johannes Kepler Tycho Brahe Kepler briefly worked with the great Danish observational astronomer, Tycho Brahe. Here you see a planet in a very elliptical orbit. Kepler's third law is the one that interests us the most. Let's just solve for the period by taking the square root of both sides: Isaac Newton
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). [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). [39] Bekenstein, J. (1971). [40-41] Lehninger, A. (1971).
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! 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)