Neutron star Neutron stars contain 500,000 times the mass of the Earth in a sphere with a diameter no larger than that of Brooklyn, United States A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Neutron stars are the densest and tiniest stars known to exist in the universe; although having only the diameter of about 10 km (6 mi), they may have a mass of several times that of the Sun. Neutron stars probably appear white to the naked eye. Neutron stars are the end points of stars whose inert core's mass after nuclear burning is greater than the Chandrasekhar limit for white dwarfs, but whose mass is not great enough to overcome the neutron degeneracy pressure to become black holes. The discovery of pulsars in 1967 suggested that neutron stars exist. Neutron star collision Formation[edit] Properties[edit] Gravitational light deflection at a neutron star. Given current values Structure[edit]
What Is a Black Hole? An artist's drawing a black hole named Cygnus X-1. It formed when a large star caved in. This black hole pulls matter from blue star beside it. A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. Because no light can get out, people can't see black holes. How Big Are Black Holes? Another kind of black hole is called "stellar." An artist's drawing shows the current view of the Milky Way galaxy. The largest black holes are called "supermassive." How Do Black Holes Form? Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. Scientists think supermassive black holes were made at the same time as the galaxy they are in. This image of the center of the Milky Way galaxy was taken by the Chandra X-ray Observatory. Image Credit: NASA/CXC/MIT/F.K. If Black Holes Are "Black," How Do Scientists Know They Are There? Image Credit:
Neutron Stars - Introduction Neutron stars are compact objects that are created in the cores of massive stars during supernova explosions. The core of the star collapses, and crushes together every proton with a corresponding electron turning each electron-proton pair into a neutron. The neutrons, however, can often stop the collapse and remain as a neutron star. Neutron stars are fascinating objects because they are the most dense objects known. Like their less massive counterparts, white dwarfs, the heavier a neutron star gets the smaller it gets. Neutron stars can be observed occasionally, as with Puppis A above, as an extremely small and hot star within a supernova remnant.
Black hole A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping.[1] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole.[2] Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[3][4] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. History General relativity
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
Milky Way (chocolate bar) The Milky Way bar was created in 1923 by Frank C. Mars and originally manufactured in Minneapolis, Minnesota. The name and taste were taken from a famed malted milk drink (milkshake) of the day – not the Earth’s galaxy, as many contend.[1][2] On March 10, 1925, the Milky Way trademark was registered in the U.S., claiming a first-use date of 1922.[3] In 1924, the Milky Way bar was introduced nationally and sold USD800,000 that year. The chocolate for the chocolate coating was supplied by Hershey's.[4] In 1935 the slogan was "The sweet you can eat between meals In 2010, the Milky Way Simply Caramel bar went on sale. In 2012, Milky Way Caramel Apple Minis went on sale as a limited time offering for the Halloween season. The American Milky Way bar contains 260 Calories in each 58 gram bar, while the smaller Milky Way Midnight contains 220 Calories in each 50 gram bar and the Milky Way Simply Caramel bar contains 250 calories in each 54 gram bar.[9] List of chocolate bar brands
Creating your first iOS app If you already have Xcode, you can skip this step. If you want to develop apps for iOS, you need the SDK, which is provided with Xcode. Xcode only runs on Mac OS X (yes, Apple is doing that on purpose), so if you are running a windows (or linux, or pretty much any non-Mac OS X) operating system, you have a couple options: 1. Get a mac, by far the easiest, but it can be rather expensive. 2. 3. Now that's settled, onto the IDE. Milky Way Stars and gases at a wide range of distances from the Galactic center orbit at approximately 220 kilometers per second. The constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much of the mass of the Milky Way does not emit or absorb electromagnetic radiation. This mass has been given the name “dark matter”.[22] The rotational period is about 240 million years at the position of the Sun.[9] The Galaxy as a whole is moving at a velocity of approximately 600 km per second with respect to extragalactic frames of reference. The oldest known star in the Galaxy is at least 13.6 billion years old and thus must have formed shortly after the Big Bang.[6] Surrounded by several smaller satellite galaxies, the Milky Way is part of the Local Group of galaxies, which forms a subcomponent of the Virgo Supercluster. Appearance[edit] The Milky Way has a relatively low surface brightness. Size and mass[edit] Schematic illustration showing the galaxy in profile
String theory String theory was first studied in the late 1960s[3] as a theory of the strong nuclear force before being abandoned in favor of the theory of quantum chromodynamics. Subsequently, it was realized that the very properties that made string theory unsuitable as a theory of nuclear physics made it a promising candidate for a quantum theory of gravity. Five consistent versions of string theory were developed until it was realized in the mid-1990s that they were different limits of a conjectured single 11-dimensional theory now known as M-theory.[4] Many theoretical physicists, including Stephen Hawking, Edward Witten and Juan Maldacena, believe that string theory is a step towards the correct fundamental description of nature: it accommodates a consistent combination of quantum field theory and general relativity, agrees with insights in quantum gravity (such as the holographic principle and black hole thermodynamics) and has passed many non-trivial checks of its internal consistency.
HSF > Living In Space > SPACE WEAR Astronauts wear various types of clothing for all aspects of a mission to space. Whether preparing for launch, working inside the space shuttle or the space station, working outside in space, or landing back on Earth, astronauts wear the proper garments for both comfort and protection. Space Station Clothing International Space Station crewmembers choose the shirts, shorts and pants they will wear in space months before they are scheduled to launch. Space station crews can choose from either Russian or U.S. clothing supplies. Because it's expensive to take supplies into space and there's no washing machine aboard the space station -- in order to save water -- station crews don't change clothes as often as people do on Earth. On average, station crewmembers get one pair of shorts and a T-shirt for every three days of exercising. When a piece of clothing has been worn as many times as possible, it's placed in a bag for disposal. Space Shuttle Clothing Launch and Landing
iPadiPhone Course By Sarah Jane Keller Steve Fyffe Paul Hegarty teaches students how to program applications for iPads and iPhones in a free online course that's the most popular download on Stanford's iTunes U site, with more than 10 million views. Students may covet seats in Stanford's popular iPhone and iPad application development course, but you don't need to be in the classroom to take the course. Anyone with app dreams can follow along online. Stanford has just released the iOS 5 incarnation of iPhone Application Development on iTunes U, where the public can download course lectures and slides for free. When Stanford's first iPhone apps course appeared online in 2009, it made iTunes history by rocketing to a million downloads in just seven weeks. Alberto Martín is an engineer and independent iOS developer in Salamanca, Spain. He has created applications, now for sale in Apple's App Store, that organize your photos and make navigating while driving less distracting. L.A. Media Contact 126 Stumble