who ) cites malaria as one of the most serious risks to international travelers. this potentially fatal disease, transmitted through mosquito bites, occurs in more than 100 countries — many of which are popular destinations, such as mexico, the caribbean, india, egypt, and south africa. also of concern are vaccine - preventable hepatitis a and b, both of which can cause liver damage. travel health clinics can provide you with information about the year - round health risks that exist in your destination and alert you about new outbreaks that may arise prior to your time of travel. they will also provide you with the recommended immunizations and antibiotics to safeguard against tropical and other illnesses. of main concern are the following : - hepatitis a or b — mexico, central and south america, africa, the middle east, asia, the caribbean, eastern and southern europe - malaria — asia, africa, the middle east, the south pacific, mexico, eastern europe, central america, and the caribbean - traveler ’ s diarrhea — latin america, africa, asia, and the middle east - yellow fever — africa and south america - cholera — southeast asia - typhoid — asia, africa, soviet union - japanese encephalitis — southeast asia while some countries only recommend that visitors get vaccinated before arriving, others require vaccination as a condition of entry, and will inspect health records to verify that the necessary vaccinations have been taken. in these countries, anyone who has not been vaccinated may be quarantined until they have been, or denied entry altogether. a travel health clinic can determine the vaccination requirements for your destination, administer inoculations and provide you with the necessary documentation, such as an international certificate of vaccination as well as other travel health records, which can be updated before each trip. travel clinic services your destination, length of stay, itinerary, and previous medical history are important factors to consider when seeking travel health advice. the staffs at most travel health clinics consist of physicians and nurse practitioners with specialized degrees in infectious diseases or tropical medicine. they are qualified to develop a travel care plan customized to your individual health needs ; administer vaccines and booster shots for polio or measles, mumps, and rubella ; and write prescriptions for antibiotics and other medications. it is important to make an appointment 4 - 6 weeks in advance of your trip. this will give you enough time to begin a malaria vaccine regimen if you need to, and for vaccinations to


prescriptions for antibiotics and other medications. it is important to make an appointment 4 - 6 weeks in advance of your trip. this will give you enough time to begin a malaria vaccine regimen if you need to, and for vaccinations to boost your immune system before your trip. in general, services provided by most travel health clinics include : - cdc and who information about health risks and recommendations in your area of travel - united states state department travel advisories ; consulate information - pre - travel counseling based on destination, length of stay, and medical history, including how to care for chronic conditions while traveling - an individualized plan of prevention and treatment, including recommendations for food and water safety, and recommendations for avoiding insect - borne diseases - vaccinations for influenza ; hepatitis a and b ; yellow fever ; typhoid ; polio ; tetanus / diphtheria ; japanese encephalitis ; measles, mumps, and rubella ; and rabies - vaccination certificates required by some countries before entry - antibiotics or over - the - counter medications for diarrhea or prescriptions for malaria prevention - permanent medical records listing any present illness as well as medical needs - a list of recommended doctors or clinics abroad - information about traveler ’ s medical insurance, which provides affordable coverage for medical emergencies ( also check with your current provider ) - tests to determine whether any illnesses were acquired abroad - treatment of any illnesses acquired abroad another essential aspect of travel clinic services is post - travel care. this is particularly important for those with chronic conditions and anyone experiencing persistent health problems upon their return, including the following : - fever ( seek immediate attention if you have traveled to an area where malaria is prevalent ) - urinary tract or genital infections - skin disorders many hospitals and medical centers provide travel health services. the following site can provide you with a list of travel health clinics in your area : http : / / http : / / wwwnc. cdc. gov / travel /. centers for disease control and prevention united states state department world health organization aurora health care travelers clinic. staying healthy abroad starts with healthy advice at home. available at : http : / / www. aurorahealthcare. org / services / travelclinic / index. asp. accessed july 2005. centers for disease control and prevention. pre - and post - travel general health recommendations. health information for international travel, 2005 - 2006. available at : http : / / www. 2ncid. cdc. gov / travel /


accessed july 2005. centers for disease control and prevention. pre - and post - travel general health recommendations. health information for international travel, 2005 - 2006. available at : http : / / www. 2ncid. cdc. gov / travel / yb / utls / ybget. asp? section = recs & obj = food - drink - risks. htm. accessed july 2005. centers for disease control and prevention. malaria and travelers. available at : www. cdc. gov / malaria / travel / index. htm. accessed july 2005. centers for disease control and prevention. vaccination certificate requirements for direct travel from the united states to other countries. available at : www. cdc. gov / travel / vaccinations / cert - requirements2. htm. accessed july 2005. internal medicine doctors for adults. health care topics : travel immunization. available at : www. doctorsforadults. com / topics / dfa _ travel. htm. accessed july 2005. mayoclinic. com. global travel : advance planning can prevent illness. available at : http : / / www. mayoclinic. com / invoke. cfm : id = hq00760. accessed july 2005. medical college of wisconsin. health risks of travel range from unusual to mundane. available at : http : / / healthlink. mcw. edu / article / 1031002363. html. accessed july 2005. medicalnewsservice. com. american society of travel agents urge healthy travel for consumers. available at : http : / / www. medicalnewsservice. com / fullstory. cfm? storyid = 3029 & fback = yes. accessed july 2005. medical university of south carolina. travel clinic. available at : http : / / www. muschealth. com / medical _ services / specialty _ listing / travelclinic /. accessed july 2005. see a doctor before you travel. centers for disease control and prevention website. available at : http : / / wwwnc. cdc. gov / travel / page / see - doctor. htm. created july 31, 2008. updated january 13, 2011. accessed august 8, 2011. tulane university. clinic keeps travelers fit. available at : http : / / www2. tulane. edu / article _ news _ details. cfm? articleid = 5752. accessed july 2005. umass memorial


august 8, 2011. tulane university. clinic keeps travelers fit. available at : http : / / www2. tulane. edu / article _ news _ details. cfm? articleid = 5752. accessed july 2005. umass memorial medical center. traveler ’ s health services. available at : http : / / www. umassmemorial. org / ummhc / hospitals / med _ center / services / travelers / index. cfm. accessed july 2005. university of connecticut health center. the international traveler ’ s medical service. available at : http : / / health / uchc. edu / clinicalservices / travel /. accessed july 2005. university of maryland medical center. travel medicine. guide for the adventurous traveler. available at : http : / / www. umm. edu / travel / guide. htm. accessedaccessed july 2005. university of texas health services. travel medicine. available at : http : / / www. uth. tmc. edu / uths / travel. html. accessed july 2005. united states state department. medical information for americans traveling abroad. available at : http : / / travel. state. gov / travel / tips / health / health _ 1185. html. accessed july 2005. vanderbilt international travel clinic. health services you ’ ll receive after you return. available at : http : / / www. vanderbilttravelclinic. com / services / after. html. accessed july 2005. vanderbilt international travel clinic. health services you ’ ll receive before you travel. available at : http : / / www. vanderbiltclinic. com / services / before. html. accessed july 2005. last reviewed august 2011 by brian randall, md please be aware that this information is provided to supplement the care provided by your physician. it is neither intended nor implied to be a substitute for professional medical advice. call your healthcare provider immediately if you think you may have a medical emergency. always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


i have been enjoying reading all the posts on this thread.... thank you for sharing your work. i have one question. if as you say : " all the letters of the hebrew alphabet are contained in the letter bet ", why is it that the modern form of its shape is different from its ancient form? i would think that the original forms of the hebrew letters would be where design would be found if it were there. we know that the meanings of the letters did not change, but their shapes did... your welcome rose! for starters let me just say this : there is no linguist in the world that can confidently tell anyone where language or written writing originally came from. they cannot truly tell you that so and so writing came before so and so writing. all they can do is surmise. now, i will tell you from lengthy study that all written writing compiled from every known alphabet ( even chinese ) can all be linked to the hebrew block style of writing that first appeared when moses came down from mount sinai with the 10 commandments. we can see similarity in these letters even to cuneiform which is said to be the oldest. so what i estimate happened was that adam and eve originally spoke this language, and the 7th generation from them which was enoch ( who was recorded in his book as well as the book of jubilees and additionally the dead sea scrolls ) who was the first scribe of written writing which was shown to him by g - dis appointed angel ' uriel '. enoch calls these ' ketav einayim ' ( eye writings ). now through the centuries these letters became mottled and distorted ( but we can still see the similarities ). then the letters were revised again ( in their proper forms ) when moses came down from mount sinai. in my book i have a whole chapter called ' language similarities ' in which i reveal how all the alphabetical letters that are found in every single alphabet ever found in the world are still nonetheless the same hebrew letters. hebrew was the original primordial language! - always has, and always will be.


quantum time waits for no quantum theory, also quantum mechanics, in physics, a theory based on using the concept of the quantum unit to describe the dynamic properties of subatomic particles and the interactions of matter and radiation. the foundation was laid by the german physicist max planck, who postulated in 1900 that energy can be emitted or absorbed by matter only in small, discrete units called quanta. fundamental to the development of quantum mechanics was the uncertainty principle, formulated by the german physicist werner heisenberg in 1927, which states that the position and momentum of a subatomic particle cannot be specified simultaneously. spectral lines of atomic hydrogen : when an electron makes a transition from one energy level to another, the electron emits a photon with a particular energy. these photons are then observed as emission lines using a spectroscope. the lyman series involves transitions to the lowest or ground state energy level. to the second energy level are called the balmer series. these transitions involve frequencies in the visible part of the spectrum. in this frequency range each transition is characterized by a in the 18th and 19th centuries, newtonian, or classical, mechanics appeared to provide a wholly accurate description of the motions of bodies — for example, planetary motion. in the late 19th and early 20th centuries, however, experimental findings raised doubts about the completeness of newtonian theory. among the newer observations were the lines that appear in the spectra of light emitted by heated gases, or gases in which electric discharges take place. model of the atom developed in the early 20th century by the english physicist ernest rutherford, in which negatively charged electrons circle a positive nucleus in orbits prescribed by newton ’ s laws of motion, scientists had also expected that the electrons would emit light over a broad frequency range, rather than in the narrow frequency ranges that form the lines in a spectrum. another puzzle for physicists was the coexistence of two theories of light : the corpuscular theory, which explains light as a stream of particles, and the wave theory, which views light as electromagnetic waves. a third problem was the absence of a molecular basis for in his book elementary principles in statistical mechanics ( 1902 ), the american mathematical physicist j. willard gibbs conceded the impossibility of framing a theory of molecular action that reconciled thermodynamics, radiation, and electrical phenomena as they were then understood. at the turn of the century, physicists did not yet clearly recognize that these and other difficulties in physics were in any way related. the first development that led to the solution of these difficulties


, radiation, and electrical phenomena as they were then understood. at the turn of the century, physicists did not yet clearly recognize that these and other difficulties in physics were in any way related. the first development that led to the solution of these difficulties was planck ’ s introduction of the concept of the quantum, as a result of physicists ’ studies of blackbody radiation during the closing years of the 19th century. ( the term blackbody refers to an ideal body or surface that absorbs all radiant energy without any reflection. ) a body at a moderately high temperature — a " red heat " — gives off most of its radiation in the low frequency ( red and infrared ) regions ; a body at a higher temperature — " white heat " — gives off comparatively more radiation in higher frequencies ( yellow, green, or blue ). during the 1890s physicists conducted detailed quantitative studies of these phenomena and expressed their results in a series of curves or graphs. the classical, or prequantum, theory predicted an altogether different set of curves from those actually observed. what planck did was to devise a mathematical formula that described the curves exactly ; he then deduced a physical hypothesis that could explain the formula. his hypothesis was that energy is radiated only in quanta of energy hu, where u is the frequency and h is the quantum action, now known as the next important developments in quantum mechanics were the work of german - born american physicist and nobel laureate albert einstein. he used planck ’ s concept of the quantum to explain certain properties of the photoelectric effect — an experimentally observed phenomenon in which electrons are emitted from metal surfaces when radiation falls on these surfaces. according to classical theory, the energy, as measured by the voltage of the emitted electrons, should be proportional to the intensity of the radiation. the energy of the electrons, however, was found to be independent of the intensity of radiation — which determined only the number of electrons emitted — and to depend solely on the frequency of the radiation. the higher the frequency of the incident radiation, the greater is the electron energy ; below a certain critical frequency no electrons are emitted. these facts were explained by einstein by assuming that a single quantum of radiant energy ejects a single electron from the metal. of the quantum is proportional to the frequency, and so the energy of the electron depends on the frequency. in 1911 rutherford established the existence of the atomic nucleus. he assumed, on the basis of experimental evidence obtained from the scattering of alpha particles by the nuclei of gold atoms, that every atom consists of a


the energy of the electron depends on the frequency. in 1911 rutherford established the existence of the atomic nucleus. he assumed, on the basis of experimental evidence obtained from the scattering of alpha particles by the nuclei of gold atoms, that every atom consists of a dense, positively charged nucleus, surrounded by negatively charged electrons revolving around the nucleus as planets revolve around the sun. electromagnetic theory developed by the british physicist james clerk maxwell unequivocally predicted that an electron revolving around a nucleus will continuously radiate electromagnetic energy until it has lost all its energy, and eventually will fall into the nucleus. thus, according to classical theory, an atom, as described by rutherford, is unstable. this difficulty led the danish physicist niels bohr, in 1913, to postulate that in an atom the classical theory does not hold, and that electrons move in fixed orbits. every change in orbit by the electron corresponds to the absorption or emission of a quantum of radiation. the application of bohr ’ s theory to atoms with more than one electron proved difficult. the mathematical equations for the next simplest atom, the helium atom, were solved during the 1910s and 1920s, but the results were not entirely in accordance with for more complex atoms, only approximate solutions of the equations are possible, and these are only partly concordant the french physicist louis victor de broglie suggested in 1924 that because electromagnetic waves show particle characteristics, particles should, in some cases, also exhibit wave properties. this prediction was verified experimentally within a few years by the american physicists clinton joseph davisson and lester halbert germer and the british physicist george paget thomson. that a beam of electrons scattered by a crystal produces a diffraction pattern characteristic of a wave ( see diffraction ). the wave concept of a particle led the austrian physicist erwin schrodinger to develop a so - called wave equation to describe the wave properties of a particle and, more specifically, the wave behavior of the electron in the hydrogen atom. although this differential equation was continuous and gave solutions for all points in space, the permissible solutions of the equation were restricted by certain conditions expressed by mathematical equations called eigenfunctions ( german eigen, " own " ). the schrodinger wave equation thus had only certain discrete solutions ; these solutions were mathematical expressions in which quantum numbers appeared as parameters. ( quantum numbers are integers developed in particle physics to give the magnitudes of certain characteristic quantities of particles or systems. ) schrodinger equation was solved for the hydrogen atom and


; these solutions were mathematical expressions in which quantum numbers appeared as parameters. ( quantum numbers are integers developed in particle physics to give the magnitudes of certain characteristic quantities of particles or systems. ) schrodinger equation was solved for the hydrogen atom and gave conclusions in substantial agreement with earlier quantum theory. moreover, it was solvable for the helium atom, which earlier theory had failed to explain adequately, and here also it was in agreement with experimental evidence. the solutions of the schrodinger equation also indicated that no two electrons could have the same four quantum numbers — that is, be in the same energy state. rule, which had already been established empirically by austro - american physicist and nobel laureate wolfgang pauli in 1925, is called the exclusion principle. what is matter in the 20th century, physicists discovered that matter behaved as both a wave and a particle. austrian physicist and nobel prize winner erwin schrodinger discussed this apparent paradox in a lecture in geneva, switzerland, in 1952. a condensed and translated version of his lecture appeared in scientific american the following what is matter? the wave - particle dualism afflicting modern physics is best resolved in favor of waves, believes the author, but there is no clear picture of matter on which physicists can agree fifty years ago science seemed on the road to a clear - cut answer to the ancient question which is the title of this article. it looked as if matter would be reduced at last to its ultimate building blocks — to certain submicroscopic but nevertheless tangible and measurable particles. but it proved to be less simple than that. today a physicist no longer can distinguish significantly between matter and something else. we no longer contrast matter with forces or fields of force as different entities ; we know now that these concepts must be merged. it is true that we speak of " empty " space ( i. e., space free of matter ), but space is never really empty, because even in the remotest voids of the universe there is always starlight — and that is matter. besides, space is filled with gravitational fields, and according to einstein gravity and inertia cannot very well be separated. thus the subject of this article is in fact the total picture of space - time reality as envisaged by physics. we have to admit that our conception of material reality today is more wavering and uncertain than it has been for a long time. we know a great many interesting details, learn new ones every week. but to construct a clear, easily comprehensible


have to admit that our conception of material reality today is more wavering and uncertain than it has been for a long time. we know a great many interesting details, learn new ones every week. but to construct a clear, easily comprehensible picture on which all physicists would agree — that is simply impossible. physics stands at a grave crisis of ideas. in the face of this crisis, many maintain that no objective picture of reality is possible. however, the optimists among us ( of whom i consider myself one ) look upon this view as a philosophical extravagance born of despair. we hope that the present fluctuations of thinking are only indications of an upheaval of old beliefs which in the end will lead to something better than the mess of formulas which today surrounds our subject. since the picture of matter that i am supposed to draw does not yet exist, since only fragments of it are visible, some parts of this narrative may be inconsistent with others. like cervantes ’ tale of sancho panza, who loses his donkey in one chapter but a few chapters later, thanks to the forgetfulness of the author, is riding the dear little animal again, our story has contradictions. we must start with the well - established concept that matter is composed of corpuscles or atoms, whose existence has been quite " tangibly " demonstrated by many beautiful experiments, and with max planck ’ s discovery that energy also comes in indivisible units, called quanta, which are supposed to be transferred abruptly from one carrier to another. but then sancho panza ’ s donkey will return. for i shall have to ask you to believe neither in corpuscles as permanent individuals nor in the suddenness of the transfer of an energy quantum. discreteness is present, but not in the traditional sense of discrete single particles, let alone in the sense of abrupt processes. discreteness arises merely as a structure from the laws governing the phenomena. these laws are by no means fully understood ; a probably correct analogue from the physics of palpable bodies is the way various partial tones of a bell derive from its shape and from the laws of elasticity to which, of themselves, nothing discontinuous adheres. the idea that matter is made up of ultimate particles was advanced as early as the fifth century b. c. by leucippus and democritus, who called these particles atoms. the corpuscular theory of matter was lifted to physical reality in the theory of gases developed during the 19th century by james clerk maxwell


as the fifth century b. c. by leucippus and democritus, who called these particles atoms. the corpuscular theory of matter was lifted to physical reality in the theory of gases developed during the 19th century by james clerk maxwell and ludwig boltzmann. the concept of atoms and molecules in violent motion, colliding and rebounding again and again, led to full comprehension of all the properties of gases : their elastic and thermal properties, their viscosity, heat conductivity and diffusion. at the same time it led to a firm foundation of the mechanical theory of heat, namely, that heat is the motion of these ultimate particles, which becomes increasingly violent with rising temperature. within one tremendously fertile decade at the turn of the century came the discoveries of x - rays, of electrons, of the emission of streams of particles and other forms of energy from the atomic nucleus by radioactive decay, of the electric charges on the various particles. the masses of these particles, and of the atoms themselves, were later measured very precisely, and from this was discovered the mass defect of the atomic nucleus as a whole. mass of a nucleus is less than the sum of the masses of its component particles ; the lost mass becomes the binding energy holding the nucleus firmly together. this is called the packing effect. the nuclear forces of course are not electrical forces — those are repellent — but are much stronger and act only within very short distances, about 10 - 13 centimeter. here i am already caught in a contradiction. didn ’ t i say at the beginning that we no longer assume the existence of force fields apart from matter? i could easily talk myself out of it by saying : well, the force field of a particle is simply considered a part of it. but that is not the fact. the established view today is rather that everything is at the same time both particle and field. everything has the continuous structure with which we are familiar in fields, as well as the discrete structure with which we are equally familiar in particles. this concept is supported by innumerable experimental facts and is accepted in general, though opinions differ on details, as we shall see. in the particular case of the field of nuclear forces, the particle structure is more or less known. most likely the continuous force field is represented by the so - called pi mesons. on the other hand, the protons and neutrons, which we think of as discrete particles, indisputably also have a continuous wave structure, as is shown by the interference patterns


field is represented by the so - called pi mesons. on the other hand, the protons and neutrons, which we think of as discrete particles, indisputably also have a continuous wave structure, as is shown by the interference patterns they form when diffracted by a crystal. the difficulty of combining these two so very different character traits in one mental picture is the main stumbling - block that causes our conception of matter to be so uncertain. neither the particle concept nor the wave concept is hypothetical. the tracks in a photographic emulsion or in a wilson cloud chamber leave no doubt of the behavior of particles as discrete units. the artificial production of nuclear particles is being attempted right now with terrific expenditure, defrayed in the main by the various state ministries of defense. it is true that one cannot kill anybody with one such racing particle, or else we should all be dead by now. but their study promises, indirectly, a hastened realization of the plan for the annihilation of mankind which is so close to all our you can easily observe particles yourself by looking at a luminous numeral of your wrist watch in the dark with a magnifying glass. the luminosity surges and undulates, just as a lake sometimes twinkles in the sun. the light consists of sparklets, each produced by a so - called alpha particle ( helium nucleus ) expelled by a radioactive atom which in this process is transformed into a different atom. a specific device for detecting and recording single particles is the geiger - muller counter. in this short resume i cannot possibly exhaust the many ways in which we can observe single particles. now to the continuous field or wave character of matter. wave structure is studied mainly by means of diffraction and interference — phenomena which occur when wave trains cross each other. for the analysis and measurement of light waves the principal device is the ruled grating, which consists of a great many fine, parallel, equidistant lines, closely engraved on a specular metallic light impinging from one direction is scattered by them and collected in different directions depending on its wavelength. but even the finest ruled gratings we can produce are too coarse to scatter the very much shorter waves associated with matter. the fine lattices of crystals, however, which max von laue first used as gratings to analyze the very short x - rays, will do the same for " matter waves. " directed at the surface of a crystal, high - velocity streams of particles manifest their wave nature. with crystal


max von laue first used as gratings to analyze the very short x - rays, will do the same for " matter waves. " directed at the surface of a crystal, high - velocity streams of particles manifest their wave nature. with crystal gratings physicists have diffracted and measured the wavelengths of electrons, neutrons and protons. what does planck ’ s quantum theory have to do with all this? planck told us in 1900 that he could comprehend the radiation from red - hot iron, or from an incandescent star such as the sun, only if this radiation was produced in discrete portions and transferred in such discrete quantities from one carrier to another ( e. g., from atom to this was extremely startling, because up to that time energy had been a highly abstract concept. five years later einstein told us that energy has mass and mass is energy ; in other words, that they are one and the same. now the scales begin to fall from our eyes : our dear old atoms, corpuscles, particles are planck ’ s energy quanta. the carriers of those quanta are themselves quanta. one gets dizzy. something quite fundamental must lie at the bottom of this, but it is not surprising that the secret is not yet understood. after all, the scales did not fall suddenly. it took 20 or 30 years. and perhaps they still have not fallen completely. the next step was not quite so far reaching, but important enough. by an ingenious and appropriate generalization of planck ’ s hypothesis niels bohr taught us to understand the line spectra of atoms and molecules and how atoms were composed of heavy, positively charged nuclei with light, negatively charged electrons revolving each small system — atom or molecule — can harbor only definite discrete energy quantities, corresponding to its nature or its constitution. in transition from a higher to a lower " energy level " it emits the excess energy as a radiation quantum of definite wavelength, inversely proportional to the quantum given off. this means that a quantum of given magnitude manifests itself in a periodic process of definite frequency which is directly proportional to the quantum ; the frequency equals the energy quantum divided by the famous planck ’ s constant, h. according to einstein a particle has the energy mc2, m being the mass of the particle and c the velocity of light. in 1925 louis de broglie drew the inference, which rather suggests itself, that a particle might have associated with it a wave process of frequency mc2 divided by h. the particle for which he postulated


particle and c the velocity of light. in 1925 louis de broglie drew the inference, which rather suggests itself, that a particle might have associated with it a wave process of frequency mc2 divided by h. the particle for which he postulated such a wave was the electron. within two years the " electron waves " required by his theory were demonstrated by the famous electron diffraction experiment of c. j. davisson and l. h. germer. this was the starting point for the cognition that everything — anything at all — is simultaneously particle and wave field. thus de broglie ’ s dissertation initiated our uncertainty about the nature of matter. both the particle picture and the wave picture have truth value, and we cannot give up either one or the other. but we do not know how to that the two pictures are connected is known in full generality with great precision and down to amazing details. but concerning the unification to a single, concrete, palpable picture opinions are so strongly divided that a great many deem it altogether impossible. i shall briefly sketch the connection. but do not expect that a uniform, concrete picture will emerge before you ; and do not blame the lack of success either on my ineptness in exposition or your own denseness — nobody has yet succeeded. one distinguishes two things in a wave. first of all, a wave has a front, and a succession of wave fronts forms a system of surfaces like the layers of an onion. you are familiar with the two - dimensional analogue of the beautiful wave circles that form on the smooth surface of a pond when a stone is thrown in. the second characteristic of a wave, less intuitive, is the path along which it travels — a system of imagined lines perpendicular to the wave fronts. these lines are known as the wave " normals " or " rays. " we can make the provisional assertion that these rays correspond to the trajectories of particles. indeed, if you cut a small piece out of a wave, approximately 10 or 20 wavelengths along the direction of propagation and about as much across, such a " wave packet " would actually move along a ray with exactly the same velocity and change of velocity as we might expect from a particle of this particular kind at this particular place, taking into account any force fields acting on the particle. here i falter. for what i must say now, though correct, almost contradicts this provisional assertion. although the behavior of the wave packet gives us a more or less intuitive picture of a particle,


any force fields acting on the particle. here i falter. for what i must say now, though correct, almost contradicts this provisional assertion. although the behavior of the wave packet gives us a more or less intuitive picture of a particle, which can be worked out in detail ( e. g., the momentum of a particle increases as the wavelength decreases ; the two are inversely proportional ), yet for many reasons we cannot take this intuitive picture quite seriously. for one thing, it is, after all, somewhat vague, the more so the greater the wavelength. for another, quite often we are dealing not with a small packet but with an extended wave. for still another, we must also deal with the important special case of very small " packelets " which form a kind of " standing wave " which can have no wave fronts or wave normals. one interpretation of wave phenomena which is extensively supported by experiments is this : at each position of a uniformly propagating wave train there is a twofold structural connection of interactions, which may be distinguished as " longitudinal " and " transversal. " the transversal structure is that of the wave fronts and manifests itself in diffraction and interference experiments ; the longitudinal structure is that of the wave normals and manifests itself in the observation of single particles. however, these concepts of longitudinal and transversal structures are not sharply defined and absolute, since the concepts of wave front and wave normal are not, the interpretation breaks down completely in the special case of the standing waves mentioned above. here the whole wave phenomenon is reduced to a small region of the dimensions of a single or very few wavelengths. you can produce standing water waves of a similar nature in a small basin if you dabble with your finger rather uniformly in its center, or else just give it a little push so that the water surface undulates. in this situation we are not dealing with uniform wave propagation ; what catches the interest are the normal frequencies of these standing waves. the water waves in the basin are an analogue of a wave phenomenon associated with electrons, which occurs in a region just about the size of the atom. the normal frequencies of the wave group washing around the atomic nucleus are universally found to be exactly equal to bohr ’ s atomic " energy levels " divided by planck ’ s constant h. thus the ingenious yet somewhat artificial assumptions of bohr ’ s model of the atom, as well as of the older quantum theory in general, are superseded by the far more natural idea of


energy levels " divided by planck ’ s constant h. thus the ingenious yet somewhat artificial assumptions of bohr ’ s model of the atom, as well as of the older quantum theory in general, are superseded by the far more natural idea of de broglie ’ s wave phenomenon. phenomenon forms the " body " proper of the atom. it takes the place of the individual pointlike electrons which in bohr ’ s model are supposed to swarm around the nucleus. such pointlike single particles are completely out of the question within the atom, and if one still thinks of the nucleus itself in this way one does so quite consciously for reasons of expediency. what seems to me particularly important about the discovery that " energy levels " are virtually nothing but the frequencies of normal modes of vibration is that now one can do without the assumption of sudden transitions, or quantum jumps, since two or more normal modes may very well be excited simultaneously. the discreteness of the normal frequencies fully suffices — so i believe — to support the considerations from which planck started and many similar and just as important ones — i mean, in short, to support all of quantum the theory of quantum jumps is becoming more and more unacceptable, at least to me personally, as the years go on. its abandonment has, however, far - reaching consequences. it means that one must give up entirely the idea of the exchange of energy in well - defined quanta and replace it with the concept of resonance between vibrational frequencies. yet we have seen that because of the identity of mass and energy, we must consider the particles themselves as planck ’ s energy quanta. this is at first frightening. for the substituted theory implies that we can no longer consider the individual particle as a well - defined permanent entity. that it is, in fact, no such thing can be reasoned in other ways. for one thing, there is werner heisenberg ’ s famous uncertainty principle, according to which a particle cannot simultaneously have a well - defined position and a sharply defined velocity. this uncertainty implies that we cannot be sure that the same particle could ever be observed twice. another conclusive reason for not attributing identifiable sameness to individual particles is that we must obliterate their individualities whenever we consider two or more interacting particles of the same kind, e. g., the two electrons of a helium atom. two situations which are distinguished only by the interchange of the two electrons must be counted as one and the same ; if they are counted as two equal situations,


particles of the same kind, e. g., the two electrons of a helium atom. two situations which are distinguished only by the interchange of the two electrons must be counted as one and the same ; if they are counted as two equal situations, nonsense obtains. this circumstance holds for any kind of particle in arbitrary numbers without exception. most theoreticians will probably accept the foregoing reasoning and admit that the individual particle is not a well - defined permanent entity of detectable identity or sameness. nevertheless this inadmissible concept of the individual particle continues to play a large role in their ideas and discussions. even deeper rooted is the belief in " quantum jumps, " which is now surrounded with a highly abstruse terminology whose common - sense meaning is often difficult for instance, an important word in the standing vocabulary of quantum theory is " probability, " referring to transition from one level to another. but, after all, one can speak of the probability of an event only assuming that, occasionally, it actually occurs. if it does occur, the transition must indeed be sudden, since intermediate stages are disclaimed. moreover, if it takes time, it might conceivably be interrupted halfway by an unforeseen disturbance. this possibility leaves one completely at sea. the wave v. corpuscle dilemma is supposed to be resolved by asserting that the wave field merely serves for the computation of the probability of finding a particle of given properties at a given position if one looks for it there. but once one deprives the waves of reality and assigns them only a kind of informative role, it becomes very difficult to understand the phenomena of interference and diffraction on the basis of the combined action of discrete single particles. it certainly seems easier to explain particle tracks in terms of waves than to explain the wave phenomenon in terms of corpuscles. " real existence " is, to be sure, an expression which has been virtually chased to death by many philosophical hounds. its simple, naive meaning has almost become lost to us. therefore i want to recall something else. i spoke of a corpuscle ’ s not being an individual. properly speaking, one never observes the same particle a second time — very much as heraclitus says of the river. you cannot mark an electron, you cannot paint it red. indeed, you must not even think of it as marked ; if you do, your " counting " will be false and you will get wrong results at every step — for the structure of line spectra, in thermod


you cannot paint it red. indeed, you must not even think of it as marked ; if you do, your " counting " will be false and you will get wrong results at every step — for the structure of line spectra, in thermodynamics and elsewhere. a wave, on the other hand, can easily be imprinted with an individual structure by which it can be recognized beyond doubt. think of the beacon fires that guide ships at sea. the light shines according to a definite code ; for example : three seconds light, five seconds dark, one second light, another pause of five seconds, and again light for three seconds — the skipper knows that is san sebastian. or you talk by wireless telephone with a friend across the atlantic ; as soon as he says, " hello there, edward meier speaking, " you know that his voice has imprinted on the radio wave a structure which can be distinguished from any other. but one does not have to go that far. if your wife calls, " francis! " from the garden, it is exactly the same thing, except that the structure is printed on sound waves and the trip is shorter ( though it takes somewhat longer than the journey of radio waves across the atlantic ). all our verbal communication is based on imprinted individual wave structures. and, according to the same principle, what a wealth of details is transmitted to us in rapid succession by the movie or the television picture! this characteristic, the individuality of the wave phenomenon, has already been found to a remarkable extent in the very much finer waves of particles. one example must suffice. a limited volume of gas, say helium, can be thought of either as a collection of many helium atoms or as a superposition of elementary wave trains of matter waves. both views lead to the same theoretical results as to the behavior of the gas upon heating, compression, and so on. when you attempt to apply certain somewhat involved enumerations to the gas, you must carry them out in different ways according to the mental picture with which you approach it. if you treat the gas as consisting of particles, then no individuality must be ascribed to them, as i said. if, however, you concentrate on the matter wave trains instead of on the particles, every one of the wave trains has a well - defined structure which is different from that of any other. it is true that there are many pairs of waves which are so similar to each other that they could change roles without any noticeable effect on the gas. but if


the wave trains has a well - defined structure which is different from that of any other. it is true that there are many pairs of waves which are so similar to each other that they could change roles without any noticeable effect on the gas. but if you should count the very many similar states formed in this way as merely a single one, the result would be quite wrong. in spite of everything we cannot completely banish the concepts of quantum jump and individual corpuscle from the vocabulary of physics. we still require them to describe many details of the structure of matter. how can one ever determine the weight of a carbon nucleus and of a hydrogen nucleus, each to the precision of several decimals, and detect that the former is somewhat lighter than the 12 hydrogen nuclei combined in it, without accepting for the time being the view that these particles are something quite concrete and real? this view is so much more convenient than the roundabout consideration of wave trains that we cannot do without it, just as the chemist does not discard his valence - bond formulas, although he fully realizes that they represent a drastic simplification of a rather involved wave - mechanical situation. if you finally ask me : " well, what are these corpuscles, really? " i ought to confess honestly that i am almost as little prepared to answer that as to tell where sancho panza ’ s second donkey came from. at the most, it may be permissible to say that one can think of particles as more or less temporary entities within the wave field whose form and general behavior are nevertheless so clearly and sharply determined by the laws of waves that many processes take place as if these temporary entities were substantial permanent beings. the mass and the charge of particles, defined with such precision, must then be counted among the structural elements determined by the wave laws. the conservation of charge and mass in the large must be considered as a statistical effect, based on the " law of large numbers. " simultaneously with the development of wave mechanics, heisenberg evolved a different mathematical analysis known as matrix mechanics. according to heisenberg ’ s theory, which was developed in collaboration with the german physicists max born and ernst pascual jordan, the formula was not a differential equation but a matrix : an array consisting of an infinite number of rows, each row consisting of an infinite number of quantities. matrix mechanics introduced infinite matrices to represent the position and momentum of an electron inside an atom. also, different matrices exist, one for each observable physical property associated with the motion of an electron,


each row consisting of an infinite number of quantities. matrix mechanics introduced infinite matrices to represent the position and momentum of an electron inside an atom. also, different matrices exist, one for each observable physical property associated with the motion of an electron, such as energy, position, momentum, and angular momentum. these matrices, like schrodinger ’ s differential equations, could be solved ; in other words, they could be manipulated to produce predictions as to the frequencies of the lines in the hydrogen spectrum and other observable quantities. like wave mechanics, matrix mechanics was in agreement with the earlier quantum theory for processes in which the earlier quantum theory agreed with experiment ; it was also useful in explaining phenomena that earlier quantum theory could not explain. schrodinger subsequently succeeded in showing that wave mechanics and matrix mechanics are different mathematical versions of the same theory, now called quantum mechanics. even for the simple hydrogen atom, which consists of two particles, both mathematical interpretations are extremely complex. the next simplest atom, helium, has three particles, and even in the relatively simple mathematics of classical dynamics, the three - body problem ( that of describing the mutual interactions of three separate bodies ) is not the energy levels can be calculated accurately, however, even if not exactly. in applying quantum - mechanics mathematics to relatively complex situations, a physicist can use one of a number of mathematical formulations. the choice depends on the convenience of the formulation for obtaining suitable although quantum mechanics describes the atom purely in terms of mathematical interpretations of observed phenomena, a rough verbal description can be given of what the atom is now thought to be like. surrounding the nucleus is a series of stationary waves ; these waves have crests at certain points, each complete standing wave representing an orbit. the absolute square of the amplitude of the wave at any point is a measure of the probability that an electron will be found at that point at any given time. thus, an electron can no longer be said to be at any precise point at any given time. the impossibility of pinpointing an electron at any precise time was analyzed by heisenberg, who in 1927 formulated the uncertainty principle. this principle states the impossibility of simultaneously specifying the precise position and momentum of any particle. in other words, the more accurately a particle ’ s momentum is measured and known, the less accuracy there can be in the measurement and knowledge of its position. this principle is also fundamental to the understanding of quantum mechanics as it is generally accepted today : the wave and particle character of electromagnetic radiation can be understood


momentum is measured and known, the less accuracy there can be in the measurement and knowledge of its position. this principle is also fundamental to the understanding of quantum mechanics as it is generally accepted today : the wave and particle character of electromagnetic radiation can be understood as two complementary properties of radiation. another way of expressing the uncertainty principle is that the wavelength of a quantum mechanical principle is inversely proportional to its momentum. as atoms are cooled they slow down and their corresponding wavelength grows larger. at a low enough temperature this wavelength is predicted to exceed the spacing between particles, causing atoms to overlap, becoming indistinguishable, and melding into a single quantum state. in 1995 a team of colorado scientists, led by national institutes of standards and technology physicist eric cornell and university of colorado physicist carl weiman, cooled rubidium atoms to a temperature so low that the particles entered this merged state, known as a bose - einstein condensate. the condensate essentially behaves like one atom even though it is made up of thousands. - physicists condense supercooled atoms, forming new state of matter a team of colorado physicists has cooled atoms of gas to a temperature so low that the particles entered a merged state, known as a " bose - einstein condensate. " this phenomenon was first predicted about 70 years ago by the theories of german - born american physicist albert einstein and indian physicist satyendra nath bose. the condensed particles are considered a new state of matter, different from the common states of matter — gas, liquid, and solid — and from plasma, a high temperature, ionized form of matter that is found in the sun and other stars. physicists have great expectations for the application of this discovery. because the condensate essentially behaves like one atom even though it is made up of thousands, investigators should be able to measure interactions at the atomic and subatomic level that were previously extremely difficult, if not impossible, to study the condensate was detected june 5 by a colorado team led by national institutes of standards and technology physicist eric cornell and university of colorado physicist carl wieman. their discovery was reported in the journal science on july 14. cornell and wieman formed their condensate from rubidium gas. several groups of physicists, including the teams in texas and colorado and a group at the massachusetts institute of technology, have been working to form pure condensate in recent years. the goal of the investigations has been to create a pure chunk of condensate out of atoms in


including the teams in texas and colorado and a group at the massachusetts institute of technology, have been working to form pure condensate in recent years. the goal of the investigations has been to create a pure chunk of condensate out of atoms in an inert medium, such as a diffuse, nonreactive gas. the effort began when methods of cooling and trapping became refined enough that it seemed possible to reach the required conditions of temperature and density. the colorado team used two techniques : first laser cooling and then evaporative cooling. the laser technique used laser light whose frequency was carefully tuned to interact with the rubidium atoms and gently reduce their speeds. a number of lasers were aimed at the gas to slow the motion of the atoms in different directions. the colorado physicists then switched to evaporative cooling. in this method, the gas is " trapped " by a magnetic field that dwindles to zero at its center. atoms that are moving wander out of the field, while the coldest atoms cluster at the center. because a few very cold atoms could still escape at the zero field point of the trap, the physicists perfected their system by adding a second slowly circling magnetic field so that the zero point moved, not giving the atoms the chance to escape through it. physicists will now begin to explore the properties of the condensate and see what other materials they can use to form it. one unusual characteristic of the condensate is that it is composed of atoms that have lost their individual identities. this is analogous to laser light, which is composed of light particles, or photons, that similarly have become indistinguishable and all behave in exactly the same manner. the laser has found a myriad of uses both in practical applications and in theoretical research, and the bose - einstein condensate may turn out to be just as important. some scientists speculate that if a condensate can be readily produced and sustained, it could be used to miniaturize and speed up computer components to a scale and quickness not possible before. the prediction that a merged form of matter will emerge at extremely low temperatures is based on a number of aspects of the quantum theory. this theory governs the interaction of particles on a subatomic scale. the basic principle of quantum theory is that particles can only exist in certain discrete energy states. the exact " quantum state " of a particle takes into consideration such factors as the position of the particle and its " spin, " which can only have certain discrete values.


principle of quantum theory is that particles can only exist in certain discrete energy states. the exact " quantum state " of a particle takes into consideration such factors as the position of the particle and its " spin, " which can only have certain discrete values. a particle ’ s spin categorizes it as either a boson or a fermion. those two groups of particles behave according to different sets of statistical rules. bosons have spins that are a constant number multiplied by an integer ( e. g., 0, 1, 2, 3 ). fermions have spins that are that same constant multiplied by an odd half - integer ( 1 / 2, 3 / 2, 5 / 2, etc. ). examples of fermions are the protons and neutrons that make up an atom ’ s nucleus, and composite particles, such as nuclei and atoms, are classified as bosons or fermions based on the sum of the spins of their constituent particles. for instance, an isotope of helium called helium - 4 turns out to be a bose particle. helium - 4 is made up of six fermi particles : two electrons orbiting a nucleus made up of two protons and two neutrons. adding up six odd half - integers will yield a whole integer, making helium - 4 a boson. the atoms of rubidium used in the colorado experiment are bose particles as well. only bose atoms may form a condensate, but they do so only at a sufficiently low temperature and high density. at their lab in colorado, cornell and wieman cooled a rubidium gas down to a temperature as close to absolute zero, the temperature at which particles stop moving, as they could get. the slower the particles, the lower their momentum. in essence, the cooling brought the momentum of the gas particles closer and closer to precisely zero, as the temperature decreased to within a few billionths of a degree kelvin. ( kelvin degrees are on the scale of degrees celsius, but zero kelvin is absolute zero, while zero celsius is the freezing point of water. ) as the temperature, and thus the momentum, of the gas particles dropped to an infinitesimal amount, the possible locations of the atom at any given moment increased proportionally. the goal of the experiment was to keep the gas atoms packed together closely enough that during this process — as their momentum got lower and lower, and their wavelengths got larger and larger — their waves would begin to overlap. this interplay of position and movement in three dimensions with the


was to keep the gas atoms packed together closely enough that during this process — as their momentum got lower and lower, and their wavelengths got larger and larger — their waves would begin to overlap. this interplay of position and movement in three dimensions with the relative distances between particles is known as the phase - space density and is the key factor in forming a condensate. in essence, the momentum of the atoms would become so precisely pinpointed ( near zero ) that their position would become less and less certain and there would be a relatively large amount of space that would define each atom ’ s position. as the atoms slowed to almost a stop, their positions became so fuzzy that each atom came to occupy the same position as every other atom, losing their individual identity. this odd phenomenon is a bose - einstein as their experimental conditions neared the realm of bose - einstein condensation, cornell and wieman noticed an abrupt rise in the peak density of their sample, a type of discontinuity that strongly indicates a phase transition. the colorado physicists estimated that after progressive evaporative cooling of the rubidium, they were left with a nugget of about 2, 000 atoms of pure condensate. and wieman then released the atoms from the " trap " in which they had been cooling and sent a pulse of laser light at the condensate, basically blowing it apart. they recorded an image of the expanding cloud of atoms. prior to the light pulse, when the density dropped after the atoms were released, the physicists believed the temperature of the condensate fell to an amazing frigidity of 20 nanokelvins ( 20 billionths of one degree above absolute zero ). the image showed a larger, expanding sphere of particles with a smaller, more concentrated elliptical - looking center. cornell and wieman observed that when a gas is constrained and then released ( in an extreme example, as in a bomb ), thermodynamics specifies that it will expand outward equally in all directions regardless of the shape in which it had been contained. this occurs because the particles in that gas, even if the gas was very cold, were moving in all different directions with various energies when the gas was this rule of uniform expansion does not hold for a bose - einstein condensate. because the particles were all acting in exactly the same manner at the time of the light pulse, their expansion should give some indication of the shape of the space they had previously inhabited. the uneven, elliptical - looking clump of atoms in the


discussion. in the 1930s the application of quantum mechanics and special relativity to the theory of the electron ( see quantum electrodynamics ) allowed the british physicist paul dirac to formulate an equation that referred to the existence of the spin of the electron. it further led to the prediction of the existence of the positron, which was experimentally verified by the american physicist carl david anderson. the application of quantum mechanics to the subject of electromagnetic radiation led to explanations of many phenomena, such as bremsstrahlung ( german, " braking radiation, " the radiation emitted by electrons slowed down in matter ) and pair production ( the formation of a positron and an electron when electromagnetic energy interacts with matter ). it also led to a grave problem, however, called the divergence difficulty : certain parameters, such as the so - called bare mass and bare charge of electrons, appear to be infinite in dirac ’ s equations. ( the terms bare mass and bare charge refer to hypothetical electrons that do not interact with any matter or radiation ; in reality, electrons interact with their own electric this difficulty was partly resolved in 1947 - 49 in a program called renormalization, developed by the japanese physicist shin ’ ichiro tomonaga, the american physicists julian s. schwinger and richard feynman, and the british physicist freeman dyson. in this program, the bare mass and charge of the electron are chosen to be infinite in such a way that other infinite physical quantities are canceled out in the equations. renormalization greatly increased the accuracy with which the structure of atoms could be calculated from first principles. theoretical physicist c. llewellyn smith discusses the discoveries that scientists have made to date about the electron and other elementary particles — subatomic particles that scientists believe cannot be split into smaller units of matter. scientists have discovered what smith refers to as sibling and cousin particles to the electron, but much about the nature of these particles is still one way scientists learn about these particles is to accelerate them to high energies, smash them together, and then study what happens when they collide. by observing the behavior of these particles, scientists hope to learn more about the fundamental structures of the universe. electrons : the first hundred years the discovery of the electron was announced by j. j. thomson just over 100 years ago, on april 30, 1897. in the intervening years we have come to understand the mechanics that describe the behavior of electrons — and indeed of all matter on a small scale — which is called quantum mechanics.


. j. thomson just over 100 years ago, on april 30, 1897. in the intervening years we have come to understand the mechanics that describe the behavior of electrons — and indeed of all matter on a small scale — which is called quantum mechanics. by exploiting this knowledge, we have learned to manipulate electrons and make devices of a tremendous practical and economic importance, such as transistors and lasers. meanwhile, what have we learned of the nature of the electron itself? from the start, electrons were found to behave as elementary particles, and this is still the case today. we know that if the electron has any structure, it is on a scale of less than 1018 m, i. e. less than 1 billionth of 1 billionth of a meter. however, a major complication has emerged. we have discovered that the electron has a sibling and cousins that are apparently equally fundamental. the sibling is an electrically neutral particle, called the neutrino, which is much lighter than the electron. the cousins are two electrically charged particles, called the mu and the which also have neutral siblings. the mu and the tau seem to be identical copies of the electron, except that they are respectively 200 and 3, 500 times heavier. their role in the scheme of things and the origin of their different masses remain mysteries — just the sort of mysteries that particle physicists, who study the constituents of matter and the forces that control their behavior, wish to resolve. we therefore know of six seemingly fundamental particles, the electron, the mu, the tau and their neutral siblings, which — like the electron — do not feel the nuclear force, and incidentally are known generically as leptons. what about the constituents of atomic nuclei, which of course do feel the nuclear force? at first sight, nuclei are made of protons and neutrons, but these particles turned out not to be elementary. it was found that when protons and neutrons are smashed together, new particles are created. we now know that all these particles are made of more elementary entities, called quarks. in a collision, pairs of quarks and their antiparticles, called antiquarks, can be created : part of the energy ( e ) of the incoming particles is turned into mass ( m ) of these new particles, thanks to the famous equivalence e = mc2. the quarks in the projectiles and the created quark - antiquark pairs can then rearrange themselves to make various different sorts of new particles. today


) of these new particles, thanks to the famous equivalence e = mc2. the quarks in the projectiles and the created quark - antiquark pairs can then rearrange themselves to make various different sorts of new particles. today, six types of quarks are known which, like the leptons ( the electron and its relations ) have simple properties, and could be elementary. in the past 30 years a recipe that describes the behavior of these particles has been developed. it is called the " standard model " of particle physics. however, we lack a real understanding of the nature of these particles, and the logic behind the standard model. what is wrong with the standard model? first, it does not consistently combine einstein ’ s theory of the properties of space ( called general relativity ) with a quantum mechanical description of the properties of matter. it is therefore second, it contains too many apparently arbitrary futures — it is too baroque, too byzantine — to be complete. it does not explain the role of the mu and the tau, or answer the question whether the fact that the numbers of leptons and quarks are the same — six each — is a coincidence, or an indication of a deep connection between these different types of particles. on paper, we can construct theories that give better answers and explanations, and in which there are such connections, but we do not know which, if any, of these theories is correct. third, it has a missing, untested, element. this is not some minor detail, but a central element, namely a mechanism to generate the observed masses of the known particles, and hence also the different ranges of the known forces ( long range for gravity and electromagnetism, as users of magnetic compasses know, but very short range for the nuclear and the so - called weak forces, although in every other respect these forces appear very similar ). on paper, a possible mechanism is known, called the higgs mechanism, after the british physicist peter higgs who invented it. but there are alternative mechanisms, and in any case the higgs mechanism is a generic idea. we not only need to know if nature uses it, but if so, how it is realized in detail. luckily the prospects of developing a deeper understanding are good. the way forward is to perform experiments that can distinguish the different possibilities. we know that the answer to the mystery of the origin of mass, and the different ranges of forces, and certain other very important questions, must lie in an energy


are good. the way forward is to perform experiments that can distinguish the different possibilities. we know that the answer to the mystery of the origin of mass, and the different ranges of forces, and certain other very important questions, must lie in an energy range that will be explored in experiments at the large hadron collider, a new accelerator now under construction at cern [ also known as the european laboratory for particle physics ] near geneva. the fundamental tools on which experimental particle physics depends are large accelerators, like the large hadron collider, which accelerate particles to very high energies and smash them together. by studying what happens in the collisions of these particles, which are typically electrons or protons ( the nuclei of hydrogen atoms ), we can learn about their natures. the conditions that are created in these collisions of particles existed just after the birth of the universe, when it was extremely hot and dense. knowledge derived from experiments in particle physics is therefore essential input for those who wish to understand the structure of the universe as a whole, and how it evolved from an initial fireball into its present the large hadron collider will therefore not only open up a large new window on the nature of matter, when it comes into operation in 2005, but also advance our understanding of the structure of the universe. however, although it will undoubtedly resolve some major questions and greatly improve our knowledge of nature, it would be very surprising if it established a " final theory. " the only candidate theory currently known which appears to have the potential to resolve all the problems mentioned above — the reason for the existence of the mu and tau, reconciliation of general relativity with quantum mechanics, etc. — describes the electron and its relatives and the quarks, not as pointlike objects, but as different vibrating modes of tiny strings. however, these strings are so small ( 10 - 35 m ) that they will never be observed if this is so, the electron and the other known particles will continue forever to appear to be fundamental pointlike objects, even if the — currently very speculative — " string theory " scores enough successes to convince us that this is not the case! future prospects : quantum mechanics underlies current attempts to account for the strong nuclear force and to develop a unified theory for all the fundamental interactions nevertheless, doubts exist about the completeness of quantum theory. the divergence difficulty, for example, is only partly resolved. just as newtonian mechanics was eventually amended by quantum mechanics and relativity, many scientists — and einstein was among them — are convinced


nevertheless, doubts exist about the completeness of quantum theory. the divergence difficulty, for example, is only partly resolved. just as newtonian mechanics was eventually amended by quantum mechanics and relativity, many scientists — and einstein was among them — are convinced that quantum theory will also undergo profound changes in the future. great theoretical difficulties exist, for example, between quantum mechanics and chaos theory, which began to develop rapidly in the 1980s. ongoing efforts are being made by theorists such as the british physicist stephen hawking, to develop a system that encompasses both relativity and quantum mechanics. breakthroughs occurred in the area of quantum computing in the late 1990s. quantum computers under development use components of a chloroform molecule ( a combination of chlorine and hydrogen atoms ) and a variation of a medical procedure called magnetic resonance imaging ( mri ) to compute at a molecular level. scientists used a branch of physics called quantum mechanics, which describes the activity of subatomic particles ( particles that make up atoms ), as the basis for quantum computing. quantum computers may one day be thousands to millions of times faster than current computers, because they take advantage of the laws that govern the behavior of subatomic particles. these laws allow quantum computers to examine all possible answers to a query at one time. future uses of quantum computers could include code breaking and large database queries. quantum time waits for no cosmos the intriguing notion that time might run backwards when the universe collapses has run into difficulties. raymond laflamme, of the los alamos national laboratory in new mexico, has carried out a new calculation which suggests that the universe cannot start out uniform, go through a cycle of expansion and collapse, and end up in a uniform state. it could start out disordered, expand, and then collapse back into disorder. but, since the cobe data show that our universe was born in a smooth and uniform state, this symmetric possibility cannot be applied to the real universe. physicists have long puzzled over the fact that two distinct " arrows of time " both point in the same direction. in the everyday world, things wear out - - cups fall from tables and break, but broken cups never re - assemble themselves spontaneously. in the expanding universe at large, the future is the direction of time in which galaxies are further apart. many years ago, thomas gold suggested that these two arrows might be linked. that would mean that if and when the expansion of the universe were to reverse, then the everyday arrow of time would also reverse, with broken cups re - assem


apart. many years ago, thomas gold suggested that these two arrows might be linked. that would mean that if and when the expansion of the universe were to reverse, then the everyday arrow of time would also reverse, with broken cups re - assembling themselves. more recently, these ideas have been extended into quantum physics. there, the arrow of time is linked to the so - called " collapse of the wave function ", which happens, for example, when an electron wave moving through a tv tube collapses into a point particle on the screen of the tv. some researchers have tried to make the quantum description of reality symmetric in time, by including both the original state of the system ( the tv tube before the electron passes through ) and the final state ( the tv tube after the electron has passed through ) in one mathematical description. murray gell - mann and james hartle recently extended this idea to the whole universe. they argued that if, as many cosmologists believe likely, the universe was born in a big bang, will expand out for a finite time and then recollapse into a big crunch, the time - neutral quantum theory could describe time running backwards in the contracting half of its life. unfortunately, laflamme has now shown that this will not work. he has proved that if there are only small inhomogeneities present in the big bang, then they must get larger throughout the lifetime of the universe, in both the expanding and the contracting phases. " a low entropy universe at the big bang cannot come back to low entropy at the big crunch " ( classical and quantum gravity, vol 10 p l79 ). he has found time - asymmetric solutions to the equations - - but only if both big bang and big crunch are highly disordered, with the universe more ordered in the middle of its life. observations of the cosmic microwave background radiation show that the universe emerged from the big bang in a very smooth and uniform state. this rules out the time - symmetric solutions. is that even if the present expansion of the universe does reverse, time will not run backwards and broken cups will not start re -


glucose is a type of sugar. it comes from food, and is also created in the liver. glucose travels through the body in the blood. it moves from the blood to cells with the help of a hormone called insulin. once glucose is in those cells, it can be used for energy. diabetes is a condition that makes it difficult for the body to use glucose. this causes a buildup of glucose in the blood. it also means the body is not getting enough energy. type 2 diabetes is one type of diabetes. it is the most common type. medication, lifestyle changes, and monitoring can help control blood glucose levels. type 2 diabetes is often caused by a combination of factors. one factor is that your body begins to make less insulin. a second factor is that your body becomes resistant to insulin. this means there is insulin in your body, but your body cannot use it effectively. insulin resistance is often related to excess body fat. the doctor will ask about your symptoms and medical history. you will also be asked about your family history. a physical exam will be done. diagnosis is based on the results of blood testing. american diabetes association ( ada ) recommends diagnosis be made if you have one of the following : symptoms of diabetes and a random blood test with a blood sugar level greater than or equal to 200 mg / dl ( 11. 1 mmol / l ) - fasting blood sugar test — done after you have not eaten for eight or more hours — showing blood sugar levels greater than or equal to 126 mg / dl ( 7 mmol / l ) on two different days - glucose tolerance test — measuring blood sugar two hours after you eat glucose — showing glucose levels greater than or equal to 200 mg / dl ( 11. 1 mmol / l ) - hba1c level of 6. 5 % or higher — indicates poor blood sugar control over the past 2 - 4 months mg / dl = milligrams per deciliter of blood ; mmol / l = millimole per liter of blood treatment aims to : - maintain blood sugar at levels as close to normal as possible - prevent or delay complications - control other conditions that you may have, like high blood pressure and high cholesterol food and drinks have a direct effect on your blood glucose level. eating healthy meals can help you control your blood glucose. it will also help your overall health. some basic tips include : if you are overweight, weight loss will help your body use insulin better. talk to your doctor about a healthy weight goal. you and


meals can help you control your blood glucose. it will also help your overall health. some basic tips include : if you are overweight, weight loss will help your body use insulin better. talk to your doctor about a healthy weight goal. you and your doctor or dietitian can make a safe meal plan for you. these options may help you lose weight : physical activity can : - make the body more sensitive to insulin - help you reach and maintain a healthy weight - lower the levels of fat in your blood exercise is any activity that increases your heart rate. resistance training helps build muscle strength. both types of exercise help to improve long - term glucose control. regular exercise can also help reduce your risk of heart disease. talk to your doctor about an activity plan. ask about any precautions you may need to take. certain medicines will help to manage blood glucose levels. medication taken by mouth may include : - metformin — to reduce the amount of glucose made by the body and to make the body more sensitive to insulin medications that encourage the pancreas to make more insulin such as sulfonylureas ( glyburide, tolazamide ), dipeptidyl peptidase - 4 inhibitors ( saxagliptin, insulin sensitizers such as pioglitazone — to help the body use insulin better starch blockers such as miglitol — to decrease the amount of glucose absorbed into the blood some medicine needs to be given through injections, such as : incretin - mimetics such as stimulate the pancreas to produce insulin and decrease appetite ( can assist with weight loss ) amylin analogs such as replace a protein of the pancreas that is low in people with type 2 diabetes insulin may be needed if : - the body does not make enough of its own insulin. - blood glucose levels cannot be controlled with lifestyle changes and medicine. insulin is given through injections. blood glucose testing you can check the level of glucose in your blood with a blood glucose meter. checking your blood glucose levels during the day can help you stay on track. it will also help your doctor determine if your treatment is working. keeping track of blood sugar levels is especially important if you take insulin. regular testing may not be needed if your diabetes is under control and you don ' t take insulin. talk with your doctor before stopping blood sugar monitoring. may also be done at your doctor ' s office. this is a measure of blood glucose control over a long period of time. doctors advise


" we believe this is the first time bacterial horizontal gene transfer has been observed in eukaryotes at such scale, " says senior author igor grigoriev of doe jgi. " this study gets us closer to explaining the dramatic diversity across the genera of diatoms, morphologically, behaviorally, but we still haven ' t yet explained all the differences conferred by the genes contributed by the other taxa. " from plants, the diatom inherited photosynthesis, and from animals the production of urea. bowler speculates that the diatom uses urea to store nitrogen, not to eliminate it like animals do, because nitrogen is a precious nutrient in the ocean. what ' s more, the tiny alga draws the best of both worldsit can convert fat into sugar, as well as sugar into fatextremely useful in times of nutrient shortage. the team documented more than 300 genes sourced from bacteria and found in both types of diatoms, pointing to their ancient origin and suggesting novel mechanisms of managing nutrientsfor example utilization of organic carbon and nitrogenand detecting cues from their environment. diatoms, encapsulated by elaborate lacework - like shells made of glass, are only about one - third of a strand of hair in diameter. " the diatom genomes will help us to understand how they can make these structures at ambient temperatures and pressures, something that humans are not able to do. if we can learn how they do it, we could open up all kinds of new nanotechnologies, like for building miniature silicon chips or for biomedical applications, " says bowler. diatoms reside in fresh or salt water and can be divided into two camps, centrics and pennates. the centric thalassiosira resemble a round " camembert " cheese box ( only much smaller ) and pennates like phaeodactylum look more like a cross between a boomerang and a narrow three - cornered hathence the species name, tricornutum. not only is their shape and habitat dive | contact : david gilbert | doe / joint genome institute


the amount of nitrogen entering the gulf each spring has increased about 300 percent since the 1960s, mainly due to increased agricultural runoff, scavia said. " yes, the floodwaters really matter, but the fact that there ' s so much more nitrogen in the system now than there was back in the ' 60s is the real issue, " he said. scavia ' s computer model suggests that if today ' s floods contained the level of nitrogen from the last comparable flood, in 1973, the predicted dead zone would be 5, 800 square miles rather than 8, 500. " the growth of these dead zones is an ecological time bomb, " scavia said. " without determined local, regional and national efforts to control them, we are putting major fisheries at risk. " the gulf of mexico / mississippi river watershed nutrient task force has set the goal of reducing the size of the dead zone to about 1, 900 square miles. in 2009, the dockside value of commercial fisheries in the gulf was $ 629 million. nearly 3 million recreational fishers further contributed more than $ 1 billion to the gulf economy, taking 22 million fishing trips. the gulf hypoxia research team is supported by noaa ' s center for sponsored coastal ocean research and includes scientists from the university of michigan, louisiana state university and the louisiana universities marine consortium. noaa has funded investigations and forecast development for the dead zone in the gulf of mexico since 1990. " while there is some uncertainty regarding the size, position and timing of this year ' s hypoxic zone in the gulf, the forecast models are in overall agreement that hypoxia will be larger than we have typically seen in recent years, " said noaa administrator jane lubchenco. the actual size of the 2011 gulf hypoxic zone will be announced | contact : jim erickson | university of michigan


the americas iba directory the conservation of rare birdlife has been the focus of birdlife international for many years. in 1995 they began a project by the name of iba, or important bird area program, to pinpoint areas across the globe that are home to endangered species, identifying the various species and protecting those areas to assist in conserving vital birdlife. at present, more than ten thousand of these areas have been identified, and conservation and environmental initiatives have been implemented. now a new program has been established, namely the americas iba directory. hundreds of bird species will benefit from the americas iba directory, as it will be a guideline for both conservationists and for authorities. the directory covers 57 different countries and has 2 345 of the most significant areas listed that need to be protected at all costs. authorities will be able to refer to the directory to find out which of their areas are vital to the survival of birdlife, which bird species are located in that area and the biodiversity of the area, to enable them to take the right steps in protecting the natural habitat and the birds. some areas that have been listed are significant in the migratory patterns of certain species, while others are crucial nesting sites for numerous endangered birds. due to a number of these areas being inhabited by local communities, also relying on the natural resources such as water, authorities can assist these communities with sustainable development that will not only benefit the communities but the birdlife as well. hundreds of organizations have provided support and assistance in the compiling of the americas iba directory. president of bird studies canada, george finney, explained : “ from breeding grounds in canada, to wintering sites in the south, and all points in between, it is imperative that we understand what is happening to bird populations and the forces that drive change. bird studies canada is proud to work closely with our international partners on this issue, so that better management decisions and conservation actions can be taken. ” a large number of agencies will be working together as iba caretakers, tracking migratory patterns and data in regard to bird populations, to note changes being made by the birds, and keeping the iba directory as up to date and accurate as possible.


first ever direct measurement of the earth ’ s rotation geodesists are pinpointing the orientation of the earth ’ s axis using the world ’ s most stable ring laser a group with researchers at the technical university of munich ( tum ) and the federal agency for cartography and geodesy ( bkg ) are the first to plot changes in the earth ’ s axis through laboratory measurements. to do this, they constructed the world ’ s most stable ring laser in an underground lab and used it to determine changes in the earth ’ s rotation. previously, scientists were only able to track shifts in the polar axis indirectly by monitoring fixed objects in space. capturing the tilt of the earth ’ s axis and its rotational velocity is crucial for precise positional information on earth – and thus for the accurate functioning of modern navigation systems, for instance. the scientists ’ work has been recognized an exceptional research spotlight by the american physical society. the earth wobbles. like a spinning top touched in mid - spin, its rotational axis fluctuates in relation to space. this is partly caused by gravitation from the sun and the moon. at the same time, the earth ’ s rotational axis constantly changes relative to the earth ’ s surface. on the one hand, this is caused by variation in atmospheric pressure, ocean loading and wind. these elements combine in an effect known as the chandler wobble to create polar motion. named after the scientist who discovered it, this phenomenon has a period of around 435 days. on the other hand, an event known as the “ annual wobble ” causes the rotational axis to move over a period of a year. this is due to the earth ’ s elliptical orbit around the sun. these two effects cause the earth ’ s axis to migrate irregularly along a circular path with a radius of up to six meters. capturing these movements is crucial to create a reliable coordinate system that can feed navigation systems or project trajectory paths in space travel. “ locating a point to the exact centimeter for global positioning is an extremely dynamic process – after all, at our latitude, we are moving at around 350 meters to the east per second, ” explains prof. karl ulrich schreiber, meanwhile as station director of the geodetic observatory wettzell where the ring laser is settled. karl ulrich schreiber had directed the project in tum ’ s research section satellite geodesy. the geodetic observatory wettzell is run together by tum and bkg. the researchers have succeeded in corrobor


special thanks to our guest blogger, chris myers, u. s. space and rocket center®, huntsville, al for this post bringing the cosmos to space camp®! at the u. s. space and rocket center® and space camp, we are constantly looking for fun and innovative ways to teach our museum guests and trainees about space history and the science and math concepts that surround it. naturally, we were excited to participate in the harvard - smithsonian center for astrophysics series of instructional webinars in order to get some fresh ideas and content. the creativity started to flow as we reviewed the background material, but the amount and quality of the lesson plans and information presented to us by mary dussault and erin braswell was impressive. by the end of the first hour of the webinar, we had solid ideas and lesson plans that could be implemented in every program from summer day camp for 5 - year - olds to advanced space academy® for high - school seniors. and they meet both state and national curriculum guidelines! in this case, our target subject was astronomy. for our younger trainees, we adapted the activities that dealt with colors and filters into a hands - on component for our astronomy briefing “ tenacious telescopes. ” we use pvc pipe, colored felt and theater lighting gel in the primary colors to teach the trainees about how real telescopes like the hubble space telescope use filters to look for specific information, and how scientists can put these single - color images together to make a full - color picture. in addition to making it look more like a real telescope, mounting the color filter inside a pvc pipe telescope has the added bonus of keeping our filters fingerprint and wrinkle free. for our advanced academy ( junior high to high school ) trainees, we added an image processing component into our existing astronomy curriculum which is made up of four components. at the beginning of the week, the trainees participate in a lecture called “ exploring the night sky ” where they learn the basics of astronomy and focus on finding and naming the constellations and deep space objects. our second astronomy block is the “ micro observatory lab, ” where our trainees use the mobs software to compile full - color images of deep space objects. our third astronomy block is a “ night telescope ” activity, where the trainees use real telescopes to find the same objects in the sky of which they compiled images the day before. and for our final astronomy block, our advanced academy trainees learn the stories behind selected constellations in our infl


songwriting for beginners : ‘ just enough ’ music theoryby jeff oxenford • category : how to write songs, songwriting articles ( this is an article in the series “ songwriting for beginners ”. we are filing the series under the songwriting basics category. ) question : how do you stop a guitarist from playing? answer : put music in front of him. that ’ s me. i can ’ t read music and i doubt i ever will. however, over the last three years, i ’ ve learned just enough about music theory to be dangerous. what i ’ ve found is that by understanding some basic concepts, i ’ ve been able to find that next chord i was always searching for. the first step in understanding is that most songs are played in a single key and that the chords in the come from that key. the formula ( i. e. what order ) you use for the chords is what make up the song. for example, blues often uses the 1, 4, and 5 chords. if you ’ re playing blues in e, the chords are e, a, b ( or b7 ). the blues progression in the key of c, uses c, f, and g. if you can understand the table below, you ’ ve got the majority of theory you need. | 1 ( root ) | | 2 | | 3 | | 4 | | 5 | | 6 | | 7 | | 8 ( root ) | | major | | minor | | minor | | major | | major or dominant | | minor | | diminished | | major | here ’ s how to understand this table : guitar frets are in half ( h ) step intervals. in other words, moving up one fret is moving up a half ( h ) step. moving up 2 frets is a whole ( w ) step. notes and intervals on a guitar, the open string and the 12th fret on the same string are the same note ( just different octave ). if you look at the a string, the notes are : | a note | | a | | a # or bb | | b | | c | | c # or db | | d | | d # oreb | | e | | f | | f # orgb | | g | | g # orab | | a | to go from a to b is a whole ( w ) step. to go from a to a # ( or bb ) is a half ( h ) step. also, note that for b to c


| g # orab | | a | to go from a to b is a whole ( w ) step. to go from a to a # ( or bb ) is a half ( h ) step. also, note that for b to c and e to f, there is only a half step. there is no b # ( cb ) or e # ( fb ). the major scale has the following intervals, w w h w w w h. ( do, rae, me fae, so la, te, do ) applying this formula, the notes in the a major scale are : a, b, c #, d, e, f #, g #, a. as seen on the guitar the a scale looks like : practice tip – on any string of the guitar, apply the formula w, w, h, w, w, w, h. in other words pick the string : open, 2, 4, 5, 7, 9, 11, 12. you ’ ve just played a major scale. numbers for the notes we describe the notes in a scale by their numbers ( 1 – 8 ). when your playing in the key of a, a is the 1 note, b is 2 – you get the idea. chords in the major scale to find chords that will work in the key of a, take the root notes from the scale and use the a chord type a from the table below : | major | | minor | | minor | | major | | major or dom | | minor | | diminished | | major | the 1, 4 and 5 chord are major chords ( a, d, e ). the 2, 3 and 6 chords are minor ( bm, etc. ) the 7th chord is diminished below is a listing of the chords in the major scale for all keys. a use the table by following a row : practice tip : take one row and play the chords in order. it should like the major scale. then try the 1, 4 and 5 chords. move to another row and try the 1, 4, 5. it should sound pretty familiar. how do you use this in songwriting? most songs in folk, rock and blues primarily use combinations of the 1, 4, 5 chords. the 6 and 3 are used often and sometimes the 2. the 7 chord ( diminished ) isn ’ t used as often, but it does have a very distinctive sound. * ( other books use roman numerals, so be ready to see i, iv, v )


excerpt of how to read and why by harold bloom ( page 2 of 5 ) printer friendly excerpt i turn to reading as a solitary praxis, rather than as an educational enterprise. the way we read now, when we are alone with ourselves, retains considerable continuity with the past, however it is performed in the academies. my ideal reader ( and lifelong hero ) is dr. samuel johnson, who knew and expressed both the power and the limitation of incessant reading. like every other activity of the mind, it must satisfy johnson ' s prime concern, which is with " what comes near to ourself, what we can put to use. " sir francis bacon, who provided some of the ideas that johnson put to use, famously gave the advice : " read not to contradict and confute, nor to believe and take for granted, nor to find talk and discourse, but to weigh and consider. " i add to bacon and johnson a third sage of reading, emerson, fierce enemy of history and of all historicisms, who remarked that the best books " impress us with the conviction, that one nature wrote and the same reads. " let me fuse bacon, johnson, and emerson into a formula of how to read : find what comes near to you that can be put to the use of weighing and considering, and that addresses you as though you share the one nature, free of time ' s tyranny. pragmatically that means, first find shakespeare, and let him find you. if king lear is fully to find you, then weigh and consider the nature it shares with you ; its closeness to yourself. i do not intend this as an idealism, but as a pragmatism. putting the tragedy to use as a complaint against patriarchy is to forsake your own prime interests, particularly as a young woman, which sounds rather more ironical than it is. shakespeare, more than sophocles, is the inescapable authority upon intergenerational conflict, and more than anyone else, upon the differences between women and men. be open to a full reading of king lear, and you will understand better the origins of what you judge to be patriarchy. ultimately we read - - as bacon, johnson, and emerson agree - - in order to strengthen the self, and to learn its authentic interests. we experience such augmentations as pleasure, which may be why aesthetic values have always been deprecated by social moralists, from plato through our current campus puritan