text: kept alive by the new generations of social centres, anarchists and environmentalists who view the idea as an intriguing way to raise awareness about consumer culture and to promote the reuse of commodities. peer - to - peer ( p2p ) is not restricted to technology, but covers every social process with a peer - to - peer dynamic, whether these peers are humans or computers. peer - to - peer as a term originated from the popular concept of p2p distributed application architecture that partitions tasks or workloads between peers. this application structure was popularized by file sharing systems like napster, the first of its kind in the late 1990s. the concept has inspired new structures and philosophies in many areas of human interaction. p2p human dynamic affords a critical look at current authoritarian and centralized social structures. peer - to - peer is also a political and social program for those who believe that in many cases, peer - to - peer modes are a preferable option. p2p is a specific form of relational dynamic, based on the assumed equipotency of its participants, organized through the free cooperation of equals in view of the performance of a common task, for the creation of a common good, with forms of decision - making and autonomy that are widely distributed throughout the network. there are three fundamental aspects of social p2p processes : - peer production - the collaborative production of use value is open to participation and use to the widest possible number ( as defined by yochai benkler, in his essay coase ' s penguin ) ; 127 - peer governance - production or project is governed by the community of producers themselves, not by market allocation or corporate hierarchy ; - peer property - the use - value of property is freely accessible on a universal basis ; peer services and products are distributed through new modes of property, which are not exclusive, though recognize individual authorship ( i. e. the gnu general public license or the creative commons licenses ). peer production does not produce commodities for exchange value, and does not use the price mechanism or corporate hierarchy to determine the allocation of resources. it must therefore be distinguished from both the capitalist market ( though it can be linked and embedded in the broader market ) and from production through state and corporate planning ; as a mode of governance it differs from traditional linear hierarchies ; and as a mode of property it differs from both traditional private property and state - based collective public property ; it is rather the common property of its producers and users and the whole of humankind. unlike

source_dataset: HuggingFaceFW/fineweb-edu


text: by ben dean, ph. d. definition : what is wisdom? the strength of wisdom refers to the ability to take stock of life in large terms, in ways that make sense to oneself and others [ ii ] wisdom is the product of knowledge and experience, but it is more than the accumulation of information. it is the coordination of this information and its deliberate use to improve well - being. in a social context, wisdom allows the individual to listen to others, to evaluate what they say, and then offer them good ( sage ) advice. famous paragons of wisdom include the major religious leaders of history - - leaders such as jesus, lao - tzu, the buddha, the prophet. famous statesmen and stateswomen throughout history such as winston churchill, and eleanor roosevelt are also exemplars of the strength of wisdom. who studies wisdom? since the time of aristotle, wisdom has been contemplated by philosophers, theologians, and most anyone concerned with the good life and how to live it. ( for a good review of the history of wisdom, see assmann, 1994. ) in recent psychological history, two major research groups stand out as major contributors to the scientific study of wisdom : paul baltes and his colleagues at the max planck institue for human development in berlin and robert sternberg and colleagues at yale university. there is much overlap between the way the two groups conceptualize wisdom and their research findings are often complementary. yet it is interesting to note the unique theoretical slant that drives the research of each group : - baltes and colleagues define wisdom as expertise in the conduct and meaning of life. according to their theory, a wise person is someone who knows what is most important in life and how to get it. he or she knows what constitutes the meaningful life and how to plan for and manage such a life ( baltes & staudinger, 2000 ). - sternberg ' s most recent definition of wisdom stems from his " balance theory of wisdom. " according to this theory, people are wise to the extent that they use their intelligence to seek a common good. they do so by balancing their own interests with those of other people and those of larger entities ( e. g., family, community, country ). wise people can adapt to new environments, change their environments, or select new environments to achieve an outcome that includes but goes beyond their personal self - interest ( sternberg, 1998 ) interesting research findings about wisdom wisdom is a positive predictor of successful aging. in fact, wisdom is more robustly


text: logging in or signing up welding asguest26654 download post to : url : related presentations : share add to flag embed email send to blogs and networks add to channel uploaded from authorpoint lite insert youtube videos in powerpont slides with as desktop copy embed code : embed : flash ipad copy does not support media & animations wordpress embed customize embed url : copy thumbnail : copy the presentation is successfully added in your favorites. views : 2283 category : news & reports.. license : some rights reserved like it ( 2 ) dislike it ( 0 ) added : september 23, 2009 this presentation is public favorites : 1 presentation description no description available. comments posting comment... premium member presentation transcript welding : welding is a materials joining process which produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material. welding is used for making permanent joints. it is used in the manufacture of automobile bodies, aircraft frames, railway wagons, machine frames, structural works, tanks, furniture, boilers, general repair work and ship building. welding types : types plastic welding or pressure welding the piece of metal to be joined are heated to a plastic state and forced together by external pressure ( ex ) resistance welding fusion welding or non - pressure welding the material at the joint is heated to a molten state and allowed to solidify ( ex ) gas welding, arc welding classification of welding processes : : classification of welding processes : ( i ). arc welding carbon arc metal arc metal inert gas tungsten inert gas plasma arc submerged arc electro - slag ( ii ). gas welding oxy - acetylene air - acetylene oxy - hydrogen ( iii ). resistance welding butt spot seam projection percussion ( iv ) thermit welding ( v ) solid state welding friction ultrasonic diffusion explosive ( vi ) newer welding electron - beam laser ( vii ) related process oxy - acetylene cutting arc cutting hard facing brazing soldering arc welding : arc welding equipments : a welding generator ( d. c. ) or transformer ( a. c. ) two cables - one for work and one for electrode electrode holder electrode protective shield gloves wire brush chipping hammer goggles arc welding equipments : arc welding equipments metal arc welding : metal arc welding arc welding : arc welding uses an electric arc to coalesce metals arc welding is the most common method of welding metals electricity


text: " producer " when applied to finite agents or causes. the " creation " of the world is in reality a theophania, or showing forth of the essence of god in the things created. just as he reveals himself to the mind and the soul in higher intellectual and spiritual truth, so he reveals himself to the senses in the created world around us. creation is, therefore, a process of unfolding of the divine nature, and if we retain the word creator in the sense of " one who makes things out of nothing ", we must understand that god " makes " the world out of his own essence, which, because of its incomprehensibility, may be said to be " nothing ". ( 2 ) nature in the second sense, " nature which creates and is created ", is the world of primordial causes, or ideas, which the father " created " in the son, and which in turn " create ", that is determine the generic and specific natures of concrete visible things. these, says eriugena, were called " prototypes ", theia thelemata, and " ideas ", by the greeks. their function is that of exemplar and efficient causes. for since they are, though created, identical with god, and since their locus is the word of god, the second person of the blessed trinity, they are operative causes and not merely static types. they are coeternal with the word of god. from this, however, it is not necessary to infer, as some critics have done, that according to eriugena the primordial causes are identical with the word. as examples of primordial causes eriugena enumerates goodness, wisdom, intuition ( insight ), understanding, virtue, greatness, power, etc. these are united in god, partly separate or scattered in the word, and fully separate or scattered in the world of phenomena. for there is underlying all eriugena ' s doctrine of the origin of things the image to which he often referred, namely, that of a circle, the radii of which are united at the centre. the centre is god, the radii at a point near the centre are the primordial causes, the radii at the circumference are phenomena. ( 3 ) these phenomena are " nature " in the third sense, " which is created and does not create ". the stream of reality, setting out from the centre, god, passing through


text: properties of the elements properties of an element are sometimes classed as either chemical or physical. chemical properties are usually observed in the course of a chemical reaction, while physical properties are observed by examining a sample of the pure element. the chemical properties of an element are due to the distribution of electrons around the atom ' s nucleus, particularly the outer, or valence, electrons ; it is these electrons that are involved in chemical reactions. a chemical reaction does not affect the atomic nucleus ; the atomic number therefore remains unchanged in a chemical reaction. some properties of an element can be observed only in a collection of atoms or molecules of the element. these properties include color, density, melting point, boiling point, and thermal and electrical conductivity. while some of these properties are due chiefly to the electronic structure of the element, others are more closely related to properties of the nucleus, e. g., mass number. the elements are sometimes grouped according to their properties. one major classification of the elements is as metals, nonmetals, and metalloids. elements with very similar chemical properties are often referred to as families ; some families of elements include the halogens, the inert gases, and the alkali metals. in the periodic table the elements are arranged in order of increasing atomic weight in such a way that the elements in any column have similar properties. sections in this article : the columbia electronic encyclopedia, 6th ed. copyright © 2012, columbia university press. all rights reserved.


text: methane ( methˈan ) [ key ], ch4, colorless, odorless, gaseous saturated hydrocarbon ; the simplest alkane. it is less dense than air, melts at - 184°c, and boils at - 161. 4°c. it is combustible and can form explosive mixtures with air. methane occurs naturally as the principal component of natural gas ; it is formed by the decomposition of plant and animal matter. when this decomposition occurs underwater in swamps and marshes, marsh gas is released. the firedamp of coal mines is chiefly methane. in the atmosphere methane is a greenhouse gas, helping to trap infrared radiation and warm the earth ( see also global warming ). methane, in the form of icelike methane hydrate ( composed of methane and frozen water ), also is stored in seabed sediments at ocean depths where sufficiently low temperatures and high pressures prevail. methane can be prepared in the laboratory by heating sodium acetate with sodium hydroxide, by the reaction of aluminum carbide with water, by the direct combination of carbon and hydrogen, or by the destructive distillation of coal or wood. as natural gas, methane is widely used for fuel. it is also used for carbonizing steel. it is unaffected by many common chemical reagents but reacts violently with chlorine or fluorine in the presence of light and is therefore important as a starting material for the synthesis of solvents, e. g., methylene chloride, chloroform, and carbon tetrachloride, and of some of the freon refrigerants. the columbia electronic encyclopedia, 6th ed. copyright © 2012, columbia university press. all rights reserved. more on methane from fact monster : see more encyclopedia articles on : organic chemistry


text: borg inject nanoprobes, not nanites. : ) ” but what is the difference? | cryogenics ( 11 : 32am est sun jan 26 2003 ) it ' s only a matter of time before nanoscopic electronic devices become a reality. the only thing that could stop such invention is a complete breakdown of our society. though that ' s a real possibility but i will forgo the argument in favor of the positive outlook we will at least continue on into 2200 with our current system intact. the theory of nanoscopic electronic devices has moved out of the “ if ' category and into the “ when ” category. the medical possibilities of reengineering our atomic structure our endless. but the most profound application has yet to be mentioned here. cryogenics. the freezing process slows down molecular decay and for all intents and purposes, halts cell degradation. there is a few percentile worth of cell damage that occurs during deep freezing. nanoscopic electronic devices could reverse this damage. one could easily remain in cryogenic stasis until the technology catches up to the level necessary for reanimation. since it is now only a matter of when nonoscopic electronic devises are able to manipulate the subatomic universe, suddenly cryogenics has a whole new importance. - by kameron


text: the science of mind, by ernest shurtleff holmes, at sacred - texts. com lesson two : metaphysical meaning of words used in individual chart no. ii - b spirit. - - that part of man which enables him to be self - conscious. that which he really is. we do not see the spirit of man any more than we see the spirit of god. we see what man does ; but we do not see the doer. christ, logos. - - the word of god manifest in and through man. in a liberal sense the christ means the entire manifestation of god and is, therefore, the second person of the trinity. christ is a universal idea, and each one " puts on the christ " 34 to the degree that he surrenders a limited sense of life to the divine realization. sonship. - - we are all sons of god and all partake of the divine nature. microcosm. - - the individual world as distinguished from the universal. emmanuel. - god - with - us. - - means that christ is in every one. personality. - - the external evidence of individualized being. individuality. - - each one is a separate identity in mind and no two are alike. each is an individualized center of god - consciousness. our personality is the use that we make of our divine individuality. conscious - state. - - the conscious - state is the self - knowing mind of man. it is the only thing that distinguishes him from brute creation. without a conscious - state of mind man would not be at all ; or, at least, he would not know that he is. the conscious mind should be carefully guarded, as it is the real man. mental. - - means that man is mentally conscious. spiritual. - - means that man is a spiritual being. reason : inductive and deductive. - - the conscious mind of man can reason both inductively and deductively. it can reason from the whole to a part or from a part to the whole. will. - - means conscious ability to determine. choice. - - ability to differentiate and choose. volition. - - power to act independently. intellect. - - mental quality of analysis. purpose. - - determination with incentive. decision. - - ability to choose. soul. - - the subjective side of life. man ' s place in the one subjective mind of the universe ; his identity in mind. man ' s soul life reenacts the soul life of the universe with


text: individual has ever said, thought, seen, heard, felt, read or been told ; and, indeed, everything that has ever happened to him. it also contains race memory, and may, or may not, contain much of what we call cosmic purposes. cosmic purposes mean the ideas of god. the soul of man, being in constant contact with the soul of the universe, might contact tremendous powers if it would turn to the one. conflict. - - in the study of psycho - analysis, which means the analysis of the soul, we learn that the subjective side of thought, being the seat of memory, often retains thoughts and suppressed emotions which more or less tear or bind. this is what is meant by inner conflict. inherited tendencies. - - the subjective, being the seat of memory, contains the race characteristics and tendencies. we do not inherit diseases, but we do inherit tendencies. this is the way that family and race traits are handed down. race - suggestion. - - the tendency to reproduce what the race has thought and experienced. prenatal conditions. - - the tendency to inherit family traits. images of thought. - - the soul, or subjective mind, contains all of our thoughts as mental images or pictures. auto - suggestion. - - the soul receives the suggestions of the individual. reason deductive only. - - that which is subjective can reason deductively only. body. - - the definite outline of flesh, containing all of the ideas which go to make the complete physical instrument. effect. - - that which follows cause. the body is always an effect. affairs. - - that which happens to the external man. conditions. - - external things, the result of thought. click to enlarge lesson two : metaphysical chart no. ii - b. this chart shows how man reenacts the whole and is subject to the law of his own being. if the meaning of this chart is carefully studied it will be made plain that man thinks consciously and that his conscious thought becomes the law of his life. the upper section stands for the self - conscious man ; the middle section stands for the subconscious man ; and the lowest section stands for the man as he appears in the flesh and in the conditions of his life. health. - - result of correct thinking. disease. - - result of wrong thinking. destiny. - - result of what man thinks. riches. - - result of a consciousness of supply. poverty. - - result of limited thought. business. - - also result of thought. vo


text: strategy should therefore be capable of producing a climate timescale ( decades to centuries and longer ) tsi record with useful traceability for assessing climate response to tsi variation. • a redundant, overlapping tsi measurement strategy using existing ‘ ambient temperature ’ instrumentation can provide the long term traceability required by a tsi database for climate change on climate time scales. the state of the art measurement uncertainty for flight observations on an ‘ absolute scale ’ in the international system of units ( si ) has not been demonstrated to be significantly less than 1000 parts per million ( ppm ). the results of tsi monitoring experiments are reported on their ' native scales ' as defined in si by the ‘ self - calibration ’ features of their sensor technologies. systematic uncertainties in the metrology used to relate their observations to si caused the ± 0. 25 % spread of results during the first decade of monitoring. the tighter clustering of results after 1990 is attributable to dissemination of more accurate sensor metrology among the various experiments and national standards labs. a new approach to calibrating tsi sensors has been developed by several laboratories including absolute cryogenic infrared radiometry at the at the national institute of standards and technology ( nist ) lbir facility and the tsi radiometer facility ( trf ) at the laboratory for atmospheric and space physics ( lasp ) of the university of colorado. high powered lasers are calibrated in si units using self - calibrating cryogenic irradiance detectors, similar in design to the self - calibrating ambient temperature sensors employed by satellite tsi monitors, but operated at lhe temperature. self - calibrating irradiance sensors are thermal detectors that compare the heating effects of solar irradiance and electrical heating on a cavity detector. the uncertainty of their ability to define irradiance in si units is temperature dependent. when cooled to lhe temperatures self - calibrating irradiance sensors can define irradiance at the 1 tsi level with uncertainties approaching a few hundred ppm. the calibrated lasers are used as transfer standards to irradiate ambient temperature satellite tsi sensors and compare their basic ' self - calibrated ' si scales to that defined by the lhe cryogenic detector ' s. the effects of scattering and diffraction on sensor calibrations can also be determined by varying the beam size of the laser. the si uncertainty of trf calibrations can be on the order of 500 parts per million ( ppm ) or less, with the


text: “ semantics ” refers to the meaning behind words, sentences, or phrases. this is its general meaning. in technology, even the word “ semantics ” has more meanings. semantics, and semantic models, refer to how data is organized within a database to make it more useful for users. so, in technology, semantics have the meaning of “ makes sense to the user. ” from a purely programming point of view, the semantics might not seem important. databases are just warehouses of knowledge. you input information and simply must make the right queries to get the information returned. however, from a user ’ s point of view, this is complicated, difficult, and time - consuming. in the first place, different users might be interested in different results, and different fields might be interested in results that others have no use for. imagine the different uses that an accounting firm and a police station might have for databases. name and address are important for both, but finances, history, location, or fingerprint information will have a different significance. that is where semantic models come into play. there are many different types of models that database administrators will be interested in, however, they all have some similarities. first, there are usually queried and reporting tools. they behave like any query, however they are tailored to return specific information that specific users are interested in. they will obviously be particular to each type of user and each type of company. another part of a semantic model is the “ data cube. ” this is a way of grouping data in hierarchies so that users can scroll easily to find as general or specific an idea as possible. to put it simply, semantic models allow the user to query the information available in a way that is natural to them, which will allow the user to process and understand the wide variety of information that is available in a typical database. obviously, designing a semantic model to best suit your users is going to vary from field to field and even from user to user. understanding the idea behind semantic models, what they are, and a few key concepts to start out with will get you well on your way to implementing them in your own database. reference : pinal dave ( http : / / blog. sqlauthority. com )


text: the element sulfur [ click for isotope data ] atomic number : 16 atomic weight : 32. 065 melting point : 388. 36 k ( 115. 21°c or 239. 38°f ) boiling point : 717. 75 k ( 444. 60°c or 832. 28°f ) density : 2. 067 grams per cubic centimeter phase at room temperature : solid element classification : non - metal period number : 3 group number : 16 group name : chalcogen what ' s in a name? from the sanskrit word sulvere and the latin word sulphurium. say what? sulfur is pronounced as sul - fer. history and uses : sulfur, the tenth most abundant element in the universe, has been known since ancient times. sometime around 1777, antoine lavoisier convinced the rest of the scientific community that sulfur was an element. sulfur is a component of many common minerals, such as galena ( pbs ), gypsum ( caso4 · 2 ( h2o ), pyrite ( fes2 ), sphalerite ( zns or fes ), cinnabar ( hgs ), stibnite ( sb2s3 ), epsomite ( mgso4 · 7 ( h2o ) ), celestite ( srso4 ) and barite ( baso4 ). nearly 25 % of the sulfur produced today is recovered from petroleum refining operations and as a byproduct of extracting other materials from sulfur containing ores. the majority of the sulfur produced today is obtained from underground deposits, usually found in conjunction with salt deposits, with a process known as the frasch process. sulfur is a pale yellow, odorless and brittle material. it displays three allotropic forms : orthorhombic, monoclinic and amorphous. the orthorhombic form is the most stable form of sulfur. monoclinic sulfur exists between the temperatures of 96°c and 119°c and reverts back to the orthorhombic form when cooled. amorphous sulfur is formed when molten sulfur is quickly cooled. amorphous sulfur is soft and elastic and eventually reverts back to the orthorhombic form. most of the sulfur that is produced is used in the manufacture of sulfuric acid ( h2so4 ). large amounts of sulfuric acid, nearly 40 million tons, are used each year to make fertilizers, lead - acid batteries


text: occam ' s razor ( or ockham ' s razor ) is the philosophical principle which states : entities should not be multiplied beyond necessity. in layman ' s terms this means " out of several equally good explanations, pick the simplest one. " in this definition, the word " simplest " means " the explanation that contains the fewest assumptions. " similarly, " equally good " refers to the ability of the explanation to account for the observation and not to the veracity of the explanation. assume a child contracts a nasty disease which leaves her in terrible pain. she is taken to the doctor and is given medicine. meanwhile, the parents pray to god for her safe recovery. a few days later she is perfectly healthy again and the parents, in their happiness, proclaim " god saved our child! " a better explanation for the child ' s recovery, however, would be that the medicine the doctors gave her did its job. when one compares the two explanations ( " god did it " and " the medicine worked " ) it is clear that the second requires fewer assumptions. god isn ' t required for the medicine to have worked in the second explanation, therefore it is the one that should be chosen. extending the razor consider any observation which requires a causal explanation ; a rainbow, for example. we can devise numerous explanations for this phenomenon : - yahweh creates them as a reminder of his promise to never again flood the entire earth - light dispersion due to refraction as it passes through water droplets - sky pixies sprinkle colored dust in the sky - leprechauns create them to mark pots of gold each of these explanations answers the question and they all also prompt additional questions, but only the second answer explains the phenomena in terms which we adequately understand. the additional questions raised by the second explanation ( dispersion, refraction, visible spectrum, etc. ) are simpler concepts supported by consistent, reliable definitions. further the way light is defracted is well understood by scientists and supported by experimental evidence. ( incidentally even if yahweh used scientific defraction to remind us of his promise this leaves unanswered why light was not defracted before the flood and how all the other problems with the story of noah ' s ark can be answered. ) each of the other explanations could be considered equivalent non - answers. the causal subjects are complex constructs which prompt many additional, unanswered questions about the nature of those subjects and how they managed to create the rainbow


text: ark can be answered. ) each of the other explanations could be considered equivalent non - answers. the causal subjects are complex constructs which prompt many additional, unanswered questions about the nature of those subjects and how they managed to create the rainbow. the fact that these explanations are non - answers can be made more clear by substituting the subjects into different answer : - yahweh creates them to mark pots of gold - leprechauns sprinkle colored dust in the sky - sky pixies create them as a reminder of their promise to never again flood the entire earth to understand why occam ’ s razor is a strong - atheistic argument, we must first understand what occam ’ s razor implies, and what its consequences are. occam ’ s razor is a method to choose between hypotheses which explain the same facts. we can express it simply as : the hypothesis we must choose is the simplest. more rigorously, we can express it as such : • posit two hypotheses a and b, both explaining the same set of facts s. • the set of explanatory entities and processes of hypothesis a is called ea. • the set of explanatory entities and processes of hypothesis b is called eb. • the intersection of a and b ’ s explanatory entities and processes is called i. • if neither ea - i nor eb - i equals zero, the hypothesis with the smallest number of superfluous entities and processes is probably the valid one. we do not have a sufficiently large s, or good enough hypotheses, to choose in all confidence. ( insufficient context ) • if ea - i or eb - i equals zero, then the corresponding hypothesis is the valid one. ( sufficient context ) to understand this better, we might want to look at an example of each outcome. suppose that we are in ancient greece, and are ignorant of natural law altogether. we are asked to compare : s. the apparent variety and adaptation of lifeforms on earth. a. creation from one or many divine agents. b. gradual adaptation from generation to generation due to natural processes. from this, we deduce : ea. one or many divine agents, and their act of creation. eb. unknown processes acting on successive material forms. i. empty set. in this case, what is the cardinality of ea - i and eb - i? at first glance, we should say that eb -


text: nobel prize in physics but in 1890 his first priority was to work on an habilitation thesis : - wien wrote to heinrich hertz in 1890 to ask his opinion of research he had undertaken into the question of the localisation of energy. he told hertz that, like poynting and lodge, he wanted to endow energy with properties analogous to those of matter. his guiding idea was that the individual parts of energy have a traceable motion ; his teacher helmholtz did not like the idea, and wien now tried it out on hertz. heinrich hertz was, like helmholtz, not particularly enthusiastic about wien ' s ideas but his work on the localisation of energy led to his habilitation in berlin in 1892. however, returning to 1890, wien reported on the current state of the theory of energy to the physics section of the german association. details of his report are given in. wien ' s 1890 report is at this link. in his habilitation dissertation of 1892 : - wien linked, very generally, j h poynting ' s ' energy flux ' of electric currents with the concept of the entropy of radiation. further, by analogy with the continuous change of position of matter in motion, he also established the motion of the energy of electrodynamic radiation, pursuing the question raised by hertz of whether this energy can be localised at all during movement. the localisation of energy was not the only topic that wien worked on in his first years at the physikalisch - technische reichsanstalt. he conducted an unsuccessful series of experiments, using platinum foil, trying to establish a new unit of light : - in this dual concern with theory and experiment lay the seed of wien ' s development into the rare physicist who possesses equally good knowledge of both areas. in 1893 wien stated his displacement law of blackbody radiation spectra at different temperatures. his method is described in : - it was [ wien ' s ] idea to use as a good approximation for the ideal blackbody an oven with a small hole. any radiation that enters the small hole is scattered and reflected from the inner walls of the oven so often that nearly all incoming radiation is absorbed and the chance of some of it finding its way out of the hole again can be made exceedingly small. the radiation coming out of this hole is then very close to the equilibrium blackbody electromagnetic radiation corresponding to the oven temperature. next wien derived a distribution law of radiation which he published in june 1896. max planck, who was a colleague


text: exceedingly small. the radiation coming out of this hole is then very close to the equilibrium blackbody electromagnetic radiation corresponding to the oven temperature. next wien derived a distribution law of radiation which he published in june 1896. max planck, who was a colleague of wien ' s when he was carrying out this work, later, in 1900, based quantum theory on the fact that wien ' s law, while valid at high frequencies, broke down completely at low frequencies. planck suggested a more complicated version of wien ' s law in 1900. wien received the 1911 nobel prize for his work on heat radiation. in his nobel lecture he explained his ' thought experiment ' approach which has proved so fruitful in physics research : - using known physical laws it was possible to derive a general law of radiation theory which has, under the name of the displacement law, been acclaimed by fellow workers. in applying thermodynamics to the theory of radiation, we make use of the ideal processes which have been found so fruitful elsewhere. these are mental experiments whose realization is frequently impracticable and which nevertheless lead to reliable results. such deliberations can only be undertaken if all the processes on which, governed by laws, the mental experiments are based, are known, so that the effect of any change can be stated accurately and completely. further, to be allowed to idealize, we must neglect all non - essential secondary phenomena, while considering only everything indissolubly connected with the processes under examination. in the application of mechanical heat theory, this method has proved to be extremely fruitful. in 1892 wien had been promoted to a lecturer in berlin and he was happy working at the physikalisch - technische reichsanstalt but in 1894 helmholtz died and friedrich kohlrausch was appointed to succeed him. kohlrausch had very definite ideas about how he should run the physikalisch - technische reichsanstalt, drawing up very specific and rigid research plans. this certainly did not fit in with wien ' s approach determined by his extremely independent nature. when, therefore, he received an offer in 1896 of a professorship at the rhenish - westphalian technical university of aachen ( rwth aachen ) he was delighted to accept the position. in aachen, wien met luise mehler ; they married in 1898 and had two sons, waltraut and karl, and two daughters, gerda and hildegard. wien had been appointed to fill the chair previously held by philipp eduard anton


text: scale to the announcement earlier this month by a different european physics group on a subatomic level — with the finding of the higgs boson particle that explains mass in the universe. " what a wonderful triumph of the mathematical approach to describing nature. the precision is breathtaking, " brian greene, a columbia university physicist, said in an email thursday. " the satellite is measuring temperature variations in space — which arose from processes that took place almost 14 billion years ago — to 1 part in a million. amazing. " the big bang theory says the universe was smaller than an atom in the beginning when, in a split second, it exploded, cooled and expanded faster than the speed of light — an idea that scientists call inflation. it ' s based in part on albert einstein ' s theory of general relativity — from about 90 years ago. " the universe is described amazingly well by a simple model, " said charles lawrence, the lead planck scientist for nasa, which took part in the research. " what is new is how well the model fits both the old data and the new data from planck. " the $ 900 million planck space telescope, launched in 2009, is named for the german physicist max planck, the originator of quantum physics. it has spent 15 1 / 2 months mapping the sky, examining so - called light fossils and sound echoes from the big bang by looking at background radiation. when the light first burst out, it was blinding, but it is now fractions of a degree above absolute zero, lawrence said. the space telescope is expected to keep transmitting data until late this year, when it runs out of cooling fluid. planck ' s examination of the big bang ' s afterglow set the universe ' s age at about 13. 8 billion years. scientists often round up to 14 billion years anyway, and caltech ' s carroll said an additional 100 million years is nothing — like adding a month to the age of a 13 - year - old. but 100 million years is important, countered planck scientist martin white : " 100 million years here and there really start to add up. " the new results also mean there ' s slightly less dark energy in the universe than scientists figured. instead of 71. 4 percent of the universe being that mysterious force, it ' s 68. 3 percent. this dark energy is smoothly spread throughout the universe and gives the " push " to its expansion, carroll said. the results also slightly boosted the amount of dark matter in the universe — up to 26. 8 percent — and more normal matter,


text: science & technology - posted by anna blackaby - warwick on monday, october 1, 2012 10 : 33 - 1 comment electron ring images confirm landau levels u. warwick ( uk ) — physicists have directly imaged landau levels for the first time since nobel prize - winner lev landau conceived of them in 1930. landau levels are quantum levels that determine electron behavior in a strong magnetic field. using scanning tunneling spectroscopy — a spatially resolved probe that interacts directly with the electrons — scientists at institutions including the university of warwick and tohoku university have revealed the internal ring - like structure of these landau levels at the surface of a semiconductor. in the image, electrons form concentric rings, which increase in number according to their energy level. ( credit : u. warwick ) straight from the source the experimental challenge in the work was to have sufficient spatial resolution in order to overcome the intrinsic disorder in the material which usually only allows the observation of smeared out “ drift ” states. the images clearly show that landau was right when he predicted that, in a clean system, the electrons would take on the form of concentric rings, the number of which increase according to their energy level. this simple counting behavior forms the basis of the so - called quantum hall effect. while originally of mostly fundamental interest, more recently the effect has been used to define the standard for what we mean by electrical resistance and could soon be employed to define the kilogram as well. “ this is an exciting step for us, ” says professor rudolf roemer of the department of physics. “ we are really seeing for the first time individual quantum mechanical wave functions of electrons in real materials. “ on the face of it this might seem far removed from everyday life. however the question of what defines a kilogram is currently being debated, with the spacing between the rings of these landau levels acting as a kind of marker for a universal weight. “ so next time you measure out your sugar to bake a cake, you might unknowingly be making use of these quantum rings. ” the research was published in the journal physical review letters. source : university of warwick