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.
Deep Time - Interactive Infographic La relativité - 1,2,3,4, dimensions La théorie de la Relativité Concepts fondamentaux Corpus théorique (I) Avant de poursuivre cette initiation à la relativité, il est indispensable d'introduire quelques rudiments de mathématiques afin de fourbir votre esprit avec la meilleure arme intellectuelle qui soit pour comprendre la suite du récit. Il faut en effet à présent définir quelques notions fondamentales, quitte à devoir faire usage d’un peu de symbolique mathématique. Mais n'ayez pas d'inquiétudes, le sujet retiendra votre attention. J’ai tout imaginé pour vous éviter cette partie “dure” du sujet , en tous cas sa partie nettement moins littéraire, c’est-à-dire les définitions du cadre relativiste; mais à mesure que je relisais ce passage tout en le rédigeant, je me suis finalement rendu compte que s’il y avait une chose sur laquelle il fallait bien insister quand on apprend une nouvelle matière, c’était par définition les notions de bases. 1,2, 3, 4 dimensions A lire : Flatland, E.Abbott, 1884 (PDF) Vecteur, champ et tenseur
Nothingness: Why nothing matters Read more: “The nature of nothingness“ SHAKESPEARE had it right, even in ways he couldn’t have imagined. For centuries, scientists have indeed been making much ado about nothing – and with good reason. Nothing, or rather what we’ve long taken to be nothing, may be the key to understanding everything from why particles have mass to the expansion of the universe. As explored in this special issue of New Scientist (see “The nature of nothingness“), nothing is a rich and subtle subject whose biography is far from finished. “Nothing is a rich and subtle subject whose biography is far from finished” The modern story of nothing began with a thought experiment dreamed up by Isaac Newton. With that answer, Newton made something out of nothing. The discovery of quantum mechanics took the story of nothing further still. This year’s Nobel prize in physics recognises the power of nothing on cosmic scales. Profile
The Worlds of David Darling How Quantum Suicide Works A man sits down before a gun, which is pointed at his head. This is no ordinary gun; it's rigged to a machine that measures the spin of a quantum particle. Each time the trigger is pulled, the spin of the quantum particle -- or quark -- is measured. Depending on the measurement, the gun will either fire, or it won't. Nervously, the man takes a breath and pulls the trigger. Go back in time to the beginning of the experiment. But, wait. This thought experiment is called quantum suicide.
Hubble's Panoramic View Several million stars are vying for attention in this NASA/ESA Hubble Space Telescope image of a raucous stellar breeding ground in 30 Doradus, located in the heart of the Tarantula nebula. 30 Doradus is the brightest star-forming region in our galactic neighbourhood and home to the most massive stars ever seen. The nebula resides 170 000 light-years away in the Large Magellanic Cloud, a small, satellite galaxy of our Milky Way. No known star-forming region in our galaxy is as large or as prolific as 30 Doradus. The image comprises one of the largest mosaics ever assembled from Hubble photos and consists of observations taken by Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys, combined with observations from the European Southern Observatory’s MPG/ESO 2.2-metre telescope that trace the location of glowing hydrogen and oxygen. The image is being released to celebrate Hubble’s 22nd anniversary. The colours come from the glowing hot gas that dominates regions of the image. Notes
Space.com Buy This Infographic as a Full-Size Poster Astronomers have discovered more than 700 alien planets beyond the solar system, and the count is rising all the time. Some are large and hot, and others are smaller and cooler, but scientists are still on the lookout for an Earth twin. They just got closer, with the announcement Dec. 5 of a planet found by NASA's Kepler space telescope to lie in the habitable zone around its star where liquid water, and perhaps life, could exist. You can purchase a 20"x60" poster of this SPACE.com infographic on high-quality 14G Photo Paper from the SPACE.com store here: Buy Poster Embed: Paste the code below into your site. <a href=" alt="Astronomers searching for another Earth are getting closer, thanks to recent discoveries by the Kepler space telescope. " src="
Your Sky by John Walker Welcome to Your Sky, the interactive planetarium of the Web. You can produce maps in the forms described below for any time and date, viewpoint, and observing location. If you enter the orbital elements of an asteroid or comet, Your Sky will compute its current position and plot it on the map. Each map is accompanied by an ephemeris for the Sun, Moon, planets, and any tracked asteroid or comet. A control panel permits customisation of which objects are plotted, limiting magnitudes, colour scheme, image size, and other parameters; each control is linked to its description in the help file. Your Sky provides three ways to view the sky with links, where appropriate, among the various presentations. Sky Map The sky map shows the entire sky as viewed from a given location at a specified time and date. Horizon Views Horizon Views, showing the stars above the horizon as seen from a specified observing site at a given date and time. The Virtual Telescope Your Sky help Related Software
SIMBAD Astronomical Database What is SIMBAD, and what is it not ? % The purpose of Simbad is to provide information on astronomical objects of interest which have been studied in scientific articles. Simbad is a dynamic database, updated every working day. It provides the bibliography, as well as available basic information such as the nature of the object, its coordinates, magnitudes, proper motions and parallax, velocity/redshift, size, spectral or morphological type, and the multitude of names (identifiers) given in the literature. Simbad is a meta-compilation built from what is published in the literature, and from our expertise on cross-identifications. Simbad is not a catalogue, and should not be used as a catalogue.
leaves something to be desired Spinning black hole: Scientists measure supermassive black hole rotating at nearly the speed of light. Image credit: NASA/JPL-Caltech Black holes are the Universe’s ultimate garbage disposals: Stuff falls in, and never gets back out. It can’t. To get out, you’d have to travel faster than the speed of light, which (as far as we know) is impossible. Black holes grow by consuming matter, and in the centers of galaxies they can grow to huge size. In the gorgeous barred spiral galaxy NGC 1365 (shown below), there’s one lurking in the core that has about two million times as much mass as our Sun. This takes some explaining. Black holes are confusing, but the bottom line is that they are such highly-concentrated massive objects that their escape velocity is faster than light—I wrote a somewhat more lengthier explanation on the old blog here and here if you want more details. Mass is the critical one, because the more mass a black hole has, the bigger it gets and the stronger its gravity is as well. But there’s more. Image credit: ESO/P.