1.
Cosmic microwave background radiation
–
The cosmic microwave background is the electromagnetic radiation left over from the time of recombination in Big Bang cosmology. In older literature, the CMB is also known as cosmic microwave background radiation or relic radiation. The CMB is a cosmic radiation that is fundamental to observational cosmology because it is the oldest light in the universe. With a traditional optical telescope, the space between stars and galaxies is completely dark, however, a sufficiently sensitive radio telescope shows a faint background glow, almost isotropic, that is not associated with any star, galaxy, or other object. This glow is strongest in the region of the radio spectrum. The discovery of CMB is landmark evidence of the Big Bang origin of the universe, when the universe was young, before the formation of stars and planets, it was denser, much hotter, and filled with a uniform glow from a white-hot fog of hydrogen plasma. As the universe expanded, both the plasma and the radiation filling it grew cooler, when the universe cooled enough, protons and electrons combined to form neutral hydrogen atoms. These atoms could no longer absorb the radiation, and so the universe became transparent instead of being an opaque fog. This is the source of the alternative term relic radiation, precise measurements of the CMB are critical to cosmology, since any proposed model of the universe must explain this radiation. The CMB has a black body spectrum at a temperature of 2. 72548±0.00057 K. The spectral radiance dEν/dν peaks at 160.23 GHz, in the range of frequencies. In particular, the radiance at different angles of observation in the sky contains small anisotropies, or irregularities. This is an active field of study, with scientists seeking both better data and better interpretations of the initial conditions of expansion. Although many different processes might produce the form of a black body spectrum. As a result, most cosmologists consider the Big Bang model of the universe to be the best explanation for the CMB. The high degree of uniformity throughout the universe and its faint but measured anisotropy lend strong support for the Big Bang model in general. Moreover, the fluctuations are coherent on angular scales that are larger than the apparent cosmological horizon at recombination, either such coherence is acausally fine-tuned, or cosmic inflation occurred. The cosmic microwave radiation is an emission of uniform, black body thermal energy coming from all parts of the sky
Cosmic microwave background radiation
–
The
Holmdel Horn Antenna on which Penzias and Wilson discovered the cosmic microwave background.
Cosmic microwave background radiation
–
This artist's impression shows how light from the early universe is deflected by the gravitational lensing effect of massive cosmic structures forming B-modes as it travels across the universe. (Credit: ESA)
Cosmic microwave background radiation
–
Comparison of
CMB results from
COBE,
WMAP and
Planck – March 21, 2013.
2.
Jet Propulsion Laboratory
–
The Jet Propulsion Laboratory is a federally funded research and development center and NASA field center in La Cañada Flintridge, California and Pasadena, California, United States. The JPL is managed by the nearby California Institute of Technology for NASA, the laboratorys primary function is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASAs Deep Space Network and they are also responsible for managing the JPL Small-Body Database, and provides physical data and lists of publications for all known small Solar System bodies. The JPLs Space Flight Operations Facility and Twenty-Five-Foot Space Simulator are designated National Historic Landmarks, JPL traces its beginnings to 1936 in the Guggenheim Aeronautical Laboratory at the California Institute of Technology when the first set of rocket experiments were carried out in the Arroyo Seco. Malinas thesis advisor was engineer/aerodynamicist Theodore von Kármán, who arranged for U. S. Army financial support for this GALCIT Rocket Project in 1939. In 1941, Malina, Parsons, Forman, Martin Summerfield, in 1943, von Kármán, Malina, Parsons, and Forman established the Aerojet Corporation to manufacture JATO motors. The project took on the name Jet Propulsion Laboratory in November 1943, during JPLs Army years, the laboratory developed two deployed weapon systems, the MGM-5 Corporal and MGM-29 Sergeant intermediate range ballistic missiles. These missiles were the first US ballistic missiles developed at JPL and it also developed a number of other weapons system prototypes, such as the Loki anti-aircraft missile system, and the forerunner of the Aerobee sounding rocket. At various times, it carried out testing at the White Sands Proving Ground, Edwards Air Force Base. A lunar lander was developed in 1938-39 which influenced design of the Apollo Lunar Module in the 1960s. The team lost that proposal to Project Vanguard, and instead embarked on a project to demonstrate ablative re-entry technology using a Jupiter-C rocket. They carried out three successful flights in 1956 and 1957. Using a spare Juno I, the two organizations then launched the United States first satellite, Explorer 1, on February 1,1958, JPL was transferred to NASA in December 1958, becoming the agencys primary planetary spacecraft center. JPL engineers designed and operated Ranger and Surveyor missions to the Moon that prepared the way for Apollo, JPL also led the way in interplanetary exploration with the Mariner missions to Venus, Mars, and Mercury. In 1998, JPL opened the Near-Earth Object Program Office for NASA, as of 2013, it has found 95% of asteroids that are a kilometer or more in diameter that cross Earths orbit. JPL was early to employ women mathematicians, in the 1940s and 1950s, using mechanical calculators, women in an all-female computations group performed trajectory calculations. In 1961, JPL hired Dana Ulery as their first woman engineer to work alongside male engineers as part of the Ranger and Mariner mission tracking teams, when founded, JPLs site was a rocky flood-plain just outside the city limits of Pasadena. Almost all of the 177 acres of the U. S, the city of La Cañada Flintridge, California was incorporated in 1976, well after JPL attained international recognition with a Pasadena address
Jet Propulsion Laboratory
–
Aerial view of JPL in Pasadena, California
Jet Propulsion Laboratory
–
The control room at JPL
Jet Propulsion Laboratory
–
MSL mockup compared with the
Mars Exploration Rover and
Sojourner rover by the Jet Propulsion Laboratory on May 12, 2008
Jet Propulsion Laboratory
–
Research rockets on display at JPL.
3.
Electromagnetic radiation
–
In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating through space carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-, classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vacuum. The oscillations of the two fields are perpendicular to other and perpendicular to the direction of energy and wave propagation. The wavefront of electromagnetic waves emitted from a point source is a sphere, the position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength. Electromagnetic waves are produced whenever charged particles are accelerated, and these waves can interact with other charged particles. EM waves carry energy, momentum and angular momentum away from their source particle, quanta of EM waves are called photons, whose rest mass is zero, but whose energy, or equivalent total mass, is not zero so they are still affected by gravity. Thus, EMR is sometimes referred to as the far field, in this language, the near field refers to EM fields near the charges and current that directly produced them, specifically, electromagnetic induction and electrostatic induction phenomena. In the quantum theory of electromagnetism, EMR consists of photons, quantum effects provide additional sources of EMR, such as the transition of electrons to lower energy levels in an atom and black-body radiation. The energy of a photon is quantized and is greater for photons of higher frequency. This relationship is given by Plancks equation E = hν, where E is the energy per photon, ν is the frequency of the photon, a single gamma ray photon, for example, might carry ~100,000 times the energy of a single photon of visible light. The effects of EMR upon chemical compounds and biological organisms depend both upon the power and its frequency. EMR of visible or lower frequencies is called non-ionizing radiation, because its photons do not individually have enough energy to ionize atoms or molecules, the effects of these radiations on chemical systems and living tissue are caused primarily by heating effects from the combined energy transfer of many photons. In contrast, high ultraviolet, X-rays and gamma rays are called ionizing radiation since individual photons of high frequency have enough energy to ionize molecules or break chemical bonds. These radiations have the ability to cause chemical reactions and damage living cells beyond that resulting from simple heating, Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the speed of light. Maxwell’s equations were confirmed by Heinrich Hertz through experiments with radio waves, according to Maxwells equations, a spatially varying electric field is always associated with a magnetic field that changes over time. Likewise, a varying magnetic field is associated with specific changes over time in the electric field. In an electromagnetic wave, the changes in the field are always accompanied by a wave in the magnetic field in one direction
Electromagnetic radiation
4.
Electrical resistance
–
The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor. The inverse quantity is electrical conductance, and is the ease with which a current passes. Electrical resistance shares some parallels with the notion of mechanical friction. The SI unit of resistance is the ohm, while electrical conductance is measured in siemens. An object of uniform cross section has a proportional to its resistivity and length. All materials show some resistance, except for superconductors, which have a resistance of zero and this proportionality is called Ohms law, and materials that satisfy it are called ohmic materials. In other cases, such as a diode or battery, V and I are not directly proportional. The ratio V/I is sometimes useful, and is referred to as a chordal resistance or static resistance, since it corresponds to the inverse slope of a chord between the origin and an I–V curve. In other situations, the derivative d V d I may be most useful, in the hydraulic analogy, current flowing through a wire is like water flowing through a pipe, and the voltage drop across the wire is like the pressure drop that pushes water through the pipe. Conductance is proportional to how much flow occurs for a given pressure, the voltage drop, not the voltage itself, provides the driving force pushing current through a resistor. In hydraulics, it is similar, The pressure difference between two sides of a pipe, not the pressure itself, determines the flow through it, for example, there may be a large water pressure above the pipe, which tries to push water down through the pipe. But there may be a large water pressure below the pipe. If these pressures are equal, no water flows, in the same way, a long, thin copper wire has higher resistance than a short, thick copper wire. A pipe filled with hair restricts the flow of more than a clean pipe of the same shape. The difference between copper, steel, and rubber is related to their structure and electron configuration. In addition to geometry and material, there are other factors that influence resistance and conductance, such as temperature. Substances in which electricity can flow are called conductors, a piece of conducting material of a particular resistance meant for use in a circuit is called a resistor. Conductors are made of high-conductivity materials such as metals, in particular copper, Resistors, on the other hand, are made of a wide variety of materials depending on factors such as the desired resistance, amount of energy that it needs to dissipate, precision, and costs
Electrical resistance
–
A 6.5 MΩ
resistor, as identified by its
electronic color code (blue–green–black-yellow). An
ohmmeter could be used to verify this value.
Electrical resistance
–
Electromagnetism
Electrical resistance
–
Running current through a material with high resistance creates heat, in a phenomenon called
Joule heating. In this picture, a
cartridge heater, warmed by Joule heating, is
glowing red hot.
5.
Samuel Pierpont Langley
–
Samuel Pierpont Langley was an American astronomer, physicist, inventor of the bolometer and pioneer of aviation. He was born in Roxbury, Boston on 22 August 1834, Langley was the founder of the Smithsonian Astrophysical Observatory. In 1888 Langley was elected a member of the American Antiquarian Society, by then, the department was in disarray – equipment was broken, there was no library and the building needed repairs. Through the friendship and aid of William Thaw, a Pittsburgh industrial leader, Langley was able to improve the observatory equipment, one of the new instruments was a small transit telescope used to observe the position of the stars as they cross the celestial meridian. He raised money for the department in large part by distributing standard time to cities, up until then, correct time had only occasionally been sent from American observatories for public use. Clocks were manually wound in those days and time tended to be imprecise, exact time had not been especially necessary. It was enough to know that at noon the sun was directly above the head, all that until railroad tracks were installed. As railroads became operational, that unpredictability of time became dangerous, trains ran by a published schedule, but the scheduling was chaotic. If the watches of an engineer and a switch operator differed by even a minute or two, it could mean disaster, two trains could be on the same track at the same time and crash. Using astronomical observations obtained from the new telescope, Langley devised a time standard – including time zones – that became known as the Allegheny Time System. Initially he broadcast time signals to Allegheny city business and the Pennsylvania Railroad, eventually, twice a day, the Allegheny time signals broadcast the correct time via 4713 miles of telegraph lines to all railroads in the US and Canada. Langley used the money from the railroads to finance the observatory, from about 1868, revenues from the Allegheny Time continued to fund the observatory until the US Naval Observatory provided the signals for free in 1883. Once funding was secure, Langley devoted his time at the Observatory initially in researching the sun and he used his draftsman skills to produce hundreds of drawings of solar phenomena, many of which were the first the world had seen. His 1873 remarkably detailed illustration of a sun spot, observed while using the observatorys 13-inch Fitz-Clark refractor became a classic and it is featured on page 21 of his book, The New Astronomy, but was also widely reprinted – in the Americas as well as throughout Europe. In 1886, Langley received the inaugural Henry Draper Medal from the National Academy of Sciences for his contributions to solar physics, in 1898, Langley received the Prix Jules Janssen, the highest award of the Société astronomique de France. Langley attempted to make a working piloted heavier-than-air aircraft and his models flew, but his two attempts at piloted flight were not successful. Langley began experimenting with rubber-band powered models and gliders in 1887 and he built a rotating arm and made larger flying models powered by miniature steam engines. It flew on trial over two hundred yards, and drowned itself in the waters of the Potomac, which was cause of great mirth, Langley took it coolly enough and said to me that, though he would never live till then, I should see the aeroplane established
Samuel Pierpont Langley
–
Samuel Pierpont Langley
Samuel Pierpont Langley
–
Langley, right, with protégé Charles Manly
Samuel Pierpont Langley
–
Langley
Aerodrome No. 6 at
Posvar Hall,
University of Pittsburgh
Samuel Pierpont Langley
–
First failure of the manned Aerodrome,
Potomac River, Oct. 7, 1903
6.
Heat capacity
–
Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to an object to the resulting temperature change. The unit of capacity is joule per kelvin J K. Specific heat is the amount of heat needed to raise the temperature of one kilogram of mass by 1 kelvin, Heat capacity is an extensive property of matter, meaning it is proportional to the size of the system. The molar heat capacity is the capacity per unit amount of a pure substance. In some engineering contexts, the heat capacity is used. Other contributions can come from magnetic and electronic degrees of freedom in solids, for quantum mechanical reasons, at any given temperature, some of these degrees of freedom may be unavailable, or only partially available, to store thermal energy. In such cases, the capacity is a fraction of the maximum. As the temperature approaches zero, the heat capacity of a system approaches zero. Quantum theory can be used to predict the heat capacity of simple systems. In a previous theory of common in the early modern period, heat was thought to be a measurement of an invisible fluid. Bodies were capable of holding an amount of this fluid, hence the term heat capacity, named. Heat is no longer considered a fluid, but rather a transfer of disordered energy, nevertheless, at least in English, the term heat capacity survives. In some other languages, the thermal capacity is preferred. In the International System of Units, heat capacity has the unit joules per kelvin, if the temperature change is sufficiently small the heat capacity may be assumed to be constant, C = Q Δ T. Heat capacity is a property, meaning it depends on the extent or size of the physical system studied. A sample containing twice the amount of substance as another sample requires the transfer of twice the amount of heat to achieve the change in temperature. For many purposes it is convenient to report heat capacity as an intensive property. In practice, this is most often an expression of the property in relation to a unit of mass, in science and engineering, International standards now recommend that specific heat capacity always refer to division by mass
Heat capacity
Heat capacity
–
Molecules undergo many characteristic internal vibrations. Potential energy stored in these internal degrees of freedom contributes to a sample’s energy content, but not to its temperature. More internal degrees of freedom tend to increase a substance's specific heat capacity, so long as temperatures are high enough to overcome quantum effects.
7.
Thermal conductivity
–
In physics, thermal conductivity is the property of a material to conduct heat. It is evaluated primarily in terms of Fouriers Law for heat conduction, heat transfer occurs at a lower rate across materials of low thermal conductivity than across materials of high thermal conductivity. Correspondingly, materials of high thermal conductivity are used in heat sink applications. The thermal conductivity of a material may depend on temperature, the reciprocal of thermal conductivity is called thermal resistivity. Thermal conductivity is actually a tensor, which means it is possible to have different values in different directions, in SI units, thermal conductivity is measured in watts per meter-kelvin. The dimension of thermal conductivity is M1L1T−3Θ−1 and these variables are mass, length, time, and temperature. In Imperial units, thermal conductivity is measured in BTU/, other units which are closely related to the thermal conductivity are in common use in the construction and textile industries. The construction industry makes use of such as the R-value. Although related to the conductivity of a material used in an insulation product, R-. Likewise the textile industry has several units including the tog and the clo which express thermal resistance of a material in a way analogous to the R-values used in the construction industry, there are a number of ways to measure thermal conductivity. Each of these is suitable for a range of materials, depending on the thermal properties. There is a distinction between steady-state and transient techniques, in general, steady-state techniques are useful when the temperature of the material does not change with time. This makes the signal analysis straightforward, the disadvantage is that a well-engineered experimental setup is usually needed. The Divided Bar is the most common used for consolidated rock solids. Thermal conductivity is important in science, research, electronics, building insulation and related fields. Several materials are shown in the list of thermal conductivities and these should be considered approximate due to the uncertainties related to material definitions. High energy generation rates within electronics or turbines require the use of materials with high thermal conductivity such as copper, aluminium, the reciprocal of thermal conductivity is thermal resistivity, usually expressed in kelvin-meters per watt. For a given thickness of a material, that particular constructions thermal resistance, unfortunately, there are differing definitions for these terms
Thermal conductivity
–
Ceramic coatings with low thermal conductivities are used on exhaust systems to prevent heat from reaching sensitive components
Thermal conductivity
–
Gas atoms moving randomly through a surface.
8.
Thermometer
–
A thermometer is a device that measures temperature or a temperature gradient. A thermometer has two important elements, a sensor in which some physical change occurs with temperature. Thermometers are widely used in industry to control and regulate processes, in the study of weather, in medicine, there are various principles by which different thermometers operate. They include the expansion of solids or liquids with temperature. Radiation-type thermometers measure the energy emitted by an object, allowing measurement of temperature without contact. Most metals are good conductors of heat and they are solids at room temperature, Mercury is the only one in liquid state at room temperature, and has high coefficient of expansion. Hence, the slightest change in temperature is notable when its used in a thermometer and this is the reason behind mercury and alcohol being used in thermometer. Some of the principles of the thermometer were known to Greek philosophers of two years ago. The modern thermometer gradually evolved from the thermoscope with the addition of a scale in the early 17th century, while an individual thermometer is able to measure degrees of hotness, the readings on two thermometers cannot be compared unless they conform to an agreed scale. Today there is a thermodynamic temperature scale. Internationally agreed temperature scales are designed to approximate this closely, based on fixed points, the most recent official temperature scale is the International Temperature Scale of 1990. It extends from 0.65 K to approximately 1,358 K, various authors have credited the invention of the thermometer to Hero of Alexandria. The thermometer was not an invention, however, but a development. The expansion and contraction of the air caused the position of the interface to move along the tube. Such a mechanism was used to show the hotness and coldness of the air with a tube in which the water level is controlled by the expansion and contraction of the gas. These devices were developed by several European scientists in the 16th and 17th centuries, as a result, devices were shown to produce this effect reliably, and the term thermoscope was adopted because it reflected the changes in sensible heat. The difference between a thermoscope and a thermometer is that the latter has a scale, though Galileo is often said to be the inventor of the thermometer, what he produced were thermoscopes. The first clear diagram of a thermoscope was published in 1617 by Giuseppe Biancani and this was a vertical tube, closed by a bulb of air at the top, with the lower end opening into a vessel of water
Thermometer
–
Mercury thermometer for measurement of room temperature.
Thermometer
–
An infrared thermometer is a kind of
pyrometer (
bolometer).
Thermometer
–
Digital thermometer.
Thermometer
–
Various thermometers from the 19th century.
9.
Semiconductor
–
Semiconductors are crystalline or amorphous solids with distinct electrical characteristics. They are of high electrical resistance — higher than typical resistance materials and their resistance decreases as their temperature increases, which is behavior opposite to that of a metal. The behavior of charge carriers which include electrons, ions and electron holes at these junctions is the basis of diodes, transistors and all modern electronics. Semiconductor devices can display a range of properties such as passing current more easily in one direction than the other, showing variable resistance. The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of carriers in a crystal lattice. Doping greatly increases the number of carriers within the crystal. When a doped semiconductor contains mostly free holes it is called p-type, the semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p- and n-type dopants. A single semiconductor crystal can have many p- and n-type regions, although some pure elements and many compounds display semiconductor properties, silicon, germanium, and compounds of gallium are the most widely used in electronic devices. Elements near the so-called metalloid staircase, where the metalloids are located on the table, are usually used as semiconductors. Some of the properties of materials were observed throughout the mid 19th. The first practical application of semiconductors in electronics was the 1904 development of the Cats-whisker detector, developments in quantum physics in turn allowed the development of the transistor in 1947 and the integrated circuit in 1958. There are several developed techniques that allow semiconducting materials to behave like conducting materials and these modifications have two outcomes, n-type and p-type. These refer to the excess or shortage of electrons, respectively, an unbalanced number of electrons would cause a current to flow through the material. Heterojunctions Heterojunctions occur when two differently doped semiconducting materials are joined together, for example, a configuration could consist of p-doped and n-doped germanium. This results in an exchange of electrons and holes between the differently doped semiconducting materials, the n-doped germanium would have an excess of electrons, and the p-doped germanium would have an excess of holes. The transfer occurs until equilibrium is reached by a process called recombination, a product of this process is charged ions, which result in an electric field. Excited Electrons A difference in electric potential on a material would cause it to leave thermal equilibrium. This introduces electrons and holes to the system, which interact via a process called ambipolar diffusion, whenever thermal equilibrium is disturbed in a semiconducting material, the amount of holes and electrons changes
Semiconductor
–
Silicon crystals are the most common semiconducting materials used in
microelectronics and
photovoltaics.
10.
Superconductor
–
It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8,1911, in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a mechanical phenomenon. It is characterized by the Meissner effect, the ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be simply as the idealization of perfect conductivity in classical physics. The electrical resistance of a metallic conductor decreases gradually as temperature is lowered, in ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature, an electric current flowing through a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have a temperature above 90 K. Such a high temperature is theoretically impossible for a conventional superconductor. There are many criteria by which superconductors are classified, by theory of operation, It is conventional if it can be explained by the BCS theory or its derivatives, or unconventional, otherwise. By material, Superconductor material classes include chemical elements, alloys, ceramics, on the other hand, there is a class of properties that are independent of the underlying material. For instance, all superconductors have exactly zero resistivity to low applied currents when there is no magnetic field present or if the field does not exceed a critical value. The resistance of the sample is given by Ohms law as R = V / I, if the voltage is zero, this means that the resistance is zero. Superconductors are also able to maintain a current with no applied voltage whatsoever, experiments have demonstrated that currents in superconducting coils can persist for years without any measurable degradation. Experimental evidence points to a current lifetime of at least 100,000 years, theoretical estimates for the lifetime of a persistent current can exceed the estimated lifetime of the universe, depending on the wire geometry and the temperature. In a normal conductor, an electric current may be visualized as a fluid of electrons moving across an ionic lattice. As a result, the energy carried by the current is constantly being dissipated and this is the phenomenon of electrical resistance and Joule heating. The situation is different in a superconductor, in a conventional superconductor, the electronic fluid cannot be resolved into individual electrons
Superconductor
–
A
magnet levitating above a
high-temperature superconductor, cooled with
liquid nitrogen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (
Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet.
Superconductor
–
A high-temperature superconductor levitating above a magnet
Superconductor
–
Electric cables for accelerators at
CERN. Both the massive and slim cables are rated for 12,500
A. Top: conventional cables for
LEP; bottom: superconductor-based cables for the
LHC
Superconductor
–
Heike Kamerlingh Onnes (right), the discoverer of superconductivity.
Paul Ehrenfest,
Hendrik Lorentz,
Niels Bohr stand to his left.
11.
Photon
–
A photon is an elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force. The photon has zero rest mass and is moving at the speed of light. Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a photon may be refracted by a lens and exhibit wave interference with itself. The quanta in a light wave cannot be spatially localized, some defined physical parameters of a photon are listed. The modern concept of the photon was developed gradually by Albert Einstein in the early 20th century to explain experimental observations that did not fit the classical model of light. The benefit of the model was that it accounted for the frequency dependence of lights energy. The photon model accounted for observations, including the properties of black-body radiation. In that model, light was described by Maxwells equations, in 1926 the optical physicist Frithiof Wolfers and the chemist Gilbert N. Lewis coined the name photon for these particles. After Arthur H. Compton won the Nobel Prize in 1927 for his studies, most scientists accepted that light quanta have an independent existence. In the Standard Model of particle physics, photons and other particles are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of particles, such as charge, mass and it has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers, in 1900, the German physicist Max Planck was studying black-body radiation and suggested that the energy carried by electromagnetic waves could only be released in packets of energy. In his 1901 article in Annalen der Physik he called these packets energy elements, the word quanta was used before 1900 to mean particles or amounts of different quantities, including electricity. In 1905, Albert Einstein suggested that waves could only exist as discrete wave-packets. He called such a wave-packet the light quantum, the name photon derives from the Greek word for light, φῶς. Arthur Compton used photon in 1928, referring to Gilbert N. Lewis, the name was suggested initially as a unit related to the illumination of the eye and the resulting sensation of light and was used later in a physiological context. Although Wolferss and Lewiss theories were contradicted by many experiments and never accepted, in physics, a photon is usually denoted by the symbol γ
Photon
–
Large Hadron Collider tunnel at
CERN
12.
Radiation
–
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles, Ionizing radiation carries more than 10 eV, which is enough to ionize atoms and molecules, and break chemical bonds. This is an important distinction due to the difference in harmfulness to living organisms. A common source of ionizing radiation is radioactive materials that emit α, β, or γ radiation, consisting of helium nuclei, electrons or positrons, gamma rays, X-rays and the higher energy range of ultraviolet light constitute the ionizing part of the electromagnetic spectrum. The lower-energy, longer-wavelength part of the spectrum including visible light, infrared light, microwaves and this type of radiation only damages cells if the intensity is high enough to cause excessive heating. Ultraviolet radiation has some features of both ionizing and non-ionizing radiation and these properties derive from ultraviolets power to alter chemical bonds, even without having quite enough energy to ionize atoms. The word radiation arises from the phenomenon of waves radiating from a source and this aspect leads to a system of measurements and physical units that are applicable to all types of radiation. This law does not apply close to a source of radiation or for focused beams. Radiation with sufficiently high energy can ionize atoms, that is to say it can knock electrons off atoms, ionization occurs when an electron is stripped from an electron shell of the atom, which leaves the atom with a net positive charge. Because living cells and, more importantly, the DNA in those cells can be damaged by this ionization, thus ionizing radiation is somewhat artificially separated from particle radiation and electromagnetic radiation, simply due to its great potential for biological damage. While an individual cell is made of trillions of atoms, only a fraction of those will be ionized at low to moderate radiation powers. If the source of the radiation is a radioactive material or a nuclear process such as fission or fusion. Particle radiation is subatomic particles accelerated to relativistic speeds by nuclear reactions, because of their momenta they are quite capable of knocking out electrons and ionizing materials, but since most have an electrical charge, they dont have the penetrating power of ionizing radiation. The exception is neutron particles, see below, there are several different kinds of these particles, but the majority are alpha particles, beta particles, neutrons, and protons. Roughly speaking, photons and particles with energies above about 10 electron volts are ionizing, particle radiation from radioactive material or cosmic rays almost invariably carries enough energy to be ionizing. The radiation is invisible and not directly detectable by human senses, as a result, in some cases, it may lead to secondary emission of visible light upon its interaction with matter, as in the case of Cherenkov radiation and radio-luminescence. Ionizing radiation has many uses in medicine, research and construction. Ultraviolet, of wavelengths from 10 nm to 125 nm, ionizes air molecules, causing it to be absorbed by air
Radiation
–
Illustration of the relative abilities of three different types of
ionizing radiation to penetrate solid matter. Typical alpha particles (α) are stopped by a sheet of paper, while beta particles (β) are stopped by an aluminium plate. Gamma radiation (γ) is damped when it penetrates lead. Note caveats in the text about this simplified diagram.
13.
Dark matter
–
Dark matter is an unidentified type of matter distinct from dark energy, baryonic matter, and neutrinos whose existence would explain a number of otherwise puzzling astronomical observations. The name refers to the fact that it does not emit or interact with radiation, such as light. The standard model of cosmology indicates that the total mass–energy of the universe contains 4. 9% ordinary matter,26. 8% dark matter and 68. 3% dark energy. Thus, dark matter constitutes 84. 5% of total mass, the most widely accepted hypothesis on the form for dark matter is that it is composed of weakly interacting massive particles that interact only through gravity and the weak force. All these lines of evidence suggest that galaxies, galaxy clusters, and the universe as a whole contain far more matter than that which is observable via electromagnetic signals. Many experiments to detect proposed dark matter particles through non-gravitational means are under way, however, no dark matter particle has been conclusively identified. ”In 1906 Henri Poincaré in the “The Milky Way and Theory of Gases” used dark matter, ” or “matière obscure” in French in discussing Kelvins work. The first to suggest the existence of matter was Dutch astronomer Jacobus Kapteyn in 1922. Fellow Dutchman and radio astronomy pioneer Jan Oort also hypothesized the existence of matter in 1932. In 1933, Swiss astrophysicist Fritz Zwicky, who studied galactic clusters while working at the California Institute of Technology, Zwicky applied the virial theorem to the Coma galaxy cluster and obtained evidence of unseen mass that he called dunkle Materie dark matter. Zwicky estimated its mass based on the motions of galaxies near its edge and compared that to an estimate based on its brightness and he estimated that the cluster had about 400 times more mass than was visually observable. The gravity effect of the galaxies was far too small for such fast orbits. Based on these conclusions, Zwicky inferred that some unseen matter provided the mass and this was the first formal inference about the existence of dark matter. However, Zwicky did correctly infer that the bulk of the matter was dark, the first robust indications that the mass to light ratio was anything other than unity came from measurements of galaxy rotation curves. In 1939, Horace W. Babcock reported the rotation curve for the Andromeda nebula and he attributed it to either light absorption within the galaxy or modified dynamics in the outer portions of the spiral and not to missing matter. Vera Rubin and Kent Ford in the 1960s–1970s provided further strong evidence, Rubin worked with a new spectrograph to measure the velocity curve of edge-on spiral galaxies with greater accuracy. This result was confirmed in 1978, an influential paper presented Rubins results in 1980. According to consensus among cosmologists, dark matter is composed primarily of a not yet characterized type of subatomic particle, the search for this particle, by a variety of means, is one of the major efforts in particle physics. In cosmology, the CMB is explained as relic radiation which has travelled freely since the era of recombination, the CMB’s anisotropies are explained as the result of small primordial density fluctuations, and subsequent acoustic oscillations in the photon-baryon plasma whose restoring force is gravity
Dark matter
–
Dark matter is invisible. Based on the effect of
gravitational lensing, a ring of dark matter has been inferred in this image of a galaxy cluster (
CL0024+17) and has been represented in blue.
Dark matter
–
Simulated
Large Hadron Collider CMS particle detector data depicting a
Higgs boson produced by colliding protons decaying into hadron jets and electrons
Dark matter
–
Estimated distribution of matter and energy in the universe, today (top) and when the
CMB was released (bottom)
Dark matter
–
Observations have provided hints that the dark matter around one of the central four merging galaxies is not moving with the galaxy itself.
14.
Platinum
–
Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious and its name is derived from the Spanish term platina, translated into little silver. Platinum is a member of the group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes and it is one of the rarer elements in Earths crust with an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some deposits, mostly in South Africa. Because of its scarcity in Earths crust, only a few hundred tonnes are produced annually, Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the sands of various rivers. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Being a heavy metal, it leads to health issues upon exposure to its salts, compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer. Pure platinum is a lustrous, ductile, and malleable, silver-white metal, Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold. The metal has excellent resistance to corrosion, is stable at temperatures and has stable electrical properties. Platinum reacts with oxygen slowly at high temperatures. It reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride and it is also attacked by chlorine, bromine, iodine, and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia to form chloroplatinic acid and its physical characteristics and chemical stability make it useful for industrial applications. Its resistance to wear and tarnish is well suited to use in fine jewelry, the most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are common, and are often stabilized by metal bonding in bimetallic species. As is expected, tetracoordinate platinum compounds tend to adopt 16-electron square planar geometries, Platinum has six naturally occurring isotopes, 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt
Platinum
–
Platinum, 78 Pt
Platinum
–
Platinum being dissolved in hot
aqua regia
Platinum
–
A native platinum nugget,
Kondyor mine,
Khabarovsk Krai
Platinum
–
Antonio de Ulloa is credited with the discovery of platinum.
15.
Lampblack
–
Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of carbon that has a high surface-area-to-volume ratio. It is dissimilar to soot in its much higher surface-area-to-volume ratio, however, carbon black is widely used as a model compound for diesel soot for diesel oxidation experiments. Carbon black is used as a reinforcing filler in tires. In plastics, paints, and inks carbon black is used as a color pigment, the current International Agency for Research on Cancer evaluation is that, Carbon black is possibly carcinogenic to humans. Short-term exposure to concentrations of carbon black dust may produce discomfort to the upper respiratory tract. Total production was around 8,100,000 metric tons in 2006, the most common use of carbon black is as a pigment and reinforcing phase in automobile tires. Carbon black also helps conduct heat away from the tread and belt area of the tire, reducing thermal damage, the high tinting strength and stability of carbon black has also provided use in coloring of resins and films. About 20% of world production goes into belts, hoses, the balance is mainly used as a pigment in inks, coatings and plastics. For example, it is added to polypropylene because it absorbs ultraviolet radiation, Carbon black from vegetable origin is used as a food coloring, in Europe known as additive E153. It is approved for use as additive 153 in Australia and New Zealand but has been banned in the US, Carbon black has been used in various applications for electronics. As a good conductor of electricity, carbon black is used as a mixed in plastics, elastomer, films, adhesives. Application of carbon black as an agent has provided uses as an additive for fuel caps. Additionally, the color pigment carbon black has been used in food. It is used in multi-layer UHT milk bottles in the US, parts of Europe and Asia, and South Africa, the Canadian Government’s assessment in 2011 concluded that carbon black should continue to be used in products – including food packaging for consumers – in Canada. The highest volume use of black is as a reinforcing filler in rubber products. It is used often in the Aerospace industry in elastomers for aircraft vibration control components such as engine mounts, practically all rubber products where tensile and abrasion wear properties are crucial use carbon black, so they are black in color. Traditionally silica fillers had worse abrasion wear properties, but the technology has improved to a point where they can match carbon black abrasion performance
Lampblack
–
A small mound of carbon black.
16.
Wheatstone bridge
–
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of a bridge is its ability to provide extremely accurate measurements. Its operation is similar to the original potentiometer, the Wheatstone bridge was invented by Samuel Hunter Christie in 1833 and improved and popularized by Sir Charles Wheatstone in 1843. One of the Wheatstone bridges initial uses was for the purpose of soils analysis, in the figure, R x is the unknown resistance to be measured, R1, R2, and R3 are resistors of known resistance and the resistance of R2 is adjustable. If the bridge is unbalanced, the direction of the current indicates whether R2 is too high or too low, R2 is varied until there is no current through the galvanometer, which then reads zero. Detecting zero current with a galvanometer can be done to extremely high accuracy, therefore, if R1, R2, and R3 are known to high precision, then R x can be measured to high precision. Very small changes in R x disrupt the balance and are readily detected and this setup is frequently used in strain gauge and resistance thermometer measurements, as it is usually faster to read a voltage level off a meter than to adjust a resistance to zero the voltage. The equation for this is, V G = V s where VG is the voltage of node D relative to node B, the Wheatstone bridge illustrates the concept of a difference measurement, which can be extremely accurate. Variations on the Wheatstone bridge can be used to measure capacitance, inductance, impedance and other quantities, such as the amount of gases in a sample. The Kelvin bridge was adapted from the Wheatstone bridge for measuring very low resistances. The concept was extended to alternating current measurements by James Clerk Maxwell in 1865, the Wheatstone bridge is the fundamental bridge, but there are other modifications that can be made to measure various kinds of resistances when the fundamental Wheatstone bridge is not suitable. Some of the modifications are, Carey Foster bridge, for measuring small resistances Kelvin bridge, for measuring small four-terminal resistances Maxwell bridge, Wheatstone Bridge – Interactive Tutorial National High Magnetic Field Laboratory Test Set I-49
Wheatstone bridge
–
Wheatstone bridge
circuit diagram.
17.
Galvanometer
–
A galvanometer is an electromechanical instrument for detecting and measuring electric current. The most common use of galvanometers was as analog measuring instruments, called ammeters, a galvanometer works as an actuator, by producing a rotary deflection, in response to electric current flowing through a coil in a constant magnetic field. Galvanometers developed from the observation that the needle of a compass is deflected near a wire that has electric current flowing through it. They were the first instruments used to detect and measure small amounts of electric currents, the name comes from the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk. Sensitive galvanometers have been essential for the development of science and technology in many fields, today the main type of galvanometer mechanism, still in use, is the moving coil, DArsonval/Weston type. Modern galvanometers, of the DArsonval/Weston type, are constructed with a small pivoting coil of wire in the field of a permanent magnet, the coil is attached to a thin pointer that traverses a calibrated scale. A tiny torsion spring pulls the coil and pointer to the zero position, when a direct current flows through the coil, the coil generates a magnetic field. This field acts against the permanent magnet, the coil twists, pushing against the spring, and moves the pointer. The hand points at a scale indicating the electric current, careful design of the pole pieces ensures that the magnetic field is uniform, so that the angular deflection of the pointer is proportional to the current. A useful meter generally contains provision for damping the mechanical resonance of the coil and pointer. The basic sensitivity of a meter might be, for instance,100 microamperes full scale, such meters are often calibrated to read some other quantity that can be converted to a current of that magnitude. The use of current dividers, often called shunts, allows a meter to be calibrated to measure larger currents, a meter can be calibrated as a DC voltmeter if the resistance of the coil is known by calculating the voltage required to generate a full scale current. A meter can be configured to read other voltages by putting it in a voltage divider circuit and this is generally done by placing a resistor in series with the meter coil. A meter can be used to resistance by placing it in series with a known voltage. In a preparatory step, the circuit is completed and the resistor adjusted to produce full scale deflection. When an unknown resistor is placed in series in the circuit the current will be less than full scale and an appropriately calibrated scale can display the value of the previously unknown resistor. Because the pointer of the meter is usually a distance above the scale of the meter. To counter this, some include a mirror along the markings of the principal scale
Galvanometer
–
D'Arsonval/Weston galvanometer movement (ca. 1900). Part of the magnet's left
pole piece is broken out to show the coil.
Galvanometer
–
An early D'Arsonval galvanometer showing magnet and rotating coil
Galvanometer
–
Tangent galvanometer made by J. H. Bunnell Co. around 1890.
Galvanometer
–
Top view of a tangent galvanometer made about 1950. The indicator needle of the compass is perpendicular to the shorter, black magnetic needle.
18.
Fraunhofer line
–
In physics and optics, the Fraunhofer lines are a set of spectral lines named after the German physicist Joseph von Fraunhofer. The lines were observed as dark features in the optical spectrum of the Sun. In 1802, the English chemist William Hyde Wollaston was the first person to note the appearance of a number of features in the solar spectrum. In 1814, Fraunhofer independently rediscovered the lines and began a systematic study, in all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters. Modern observations of sunlight can detect thousands of lines. About 45 years later Kirchhoff and Bunsen noticed that several Fraunhofer lines coincide with characteristic emission lines identified in the spectra of heated elements and it was correctly deduced that dark lines in the solar spectrum are caused by absorption by chemical elements in the solar atmosphere. Some of the features were identified as telluric lines originating from absorption by oxygen molecules in the Earths atmosphere. The Fraunhofer lines are typical spectral absorption lines, absorption lines are dark lines, narrow regions of decreased intensity, that are the result of photons being absorbed as light passes from the source to the detector. In the Sun, Fraunhofer lines are a result of gas in the photosphere, the photosphere gas is colder than the inner regions and absorbs light emitted from those regions. The D1 and D2 lines form the sodium doublet, the centre wavelength of which is given the designation letter D. This historical designation for this line has stuck and is given to all the transitions between the state and the first excited state of the other alkali atoms as well. The D1 and D2 lines correspond to the splitting of the excited states. This may be confusing because the state for this transition is the P-state of the alkali. Similarly, there is ambiguity with reference to the e-line, since it can refer to the lines of both iron and mercury. In order to resolve ambiguities that arise in usage, ambiguous Fraunhofer line designations are preceded by the element with which they are associated, because of their well defined wavelengths, Fraunhofer lines are often used to characterize the refractive index and dispersion properties of optical materials. Abbe number, measure of glass dispersion defined using Fraunhofer lines Timeline of solar astronomy Spectrum analysis Myles W. Jackson, Joseph von Fraunhofer and the Craft of Precision Optics
Fraunhofer line
–
Solar spectrum with Fraunhofer lines as it appears visually.
19.
Infrared
–
It extends from the nominal red edge of the visible spectrum at 700 nanometers, to 1000000 nm. Most of the radiation emitted by objects near room temperature is infrared. Like all EMR, IR carries radiant energy, and behaves both like a wave and like its quantum particle, the photon, slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has an effect on Earths climate. Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements and it excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared range, Infrared radiation is used in industrial, scientific, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected, Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatuses. Thermal-infrared imaging is used extensively for military and civilian purposes, military applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10 μm, Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers to 1 mm. This range of wavelengths corresponds to a range of approximately 430 THz down to 300 GHz. Below infrared is the portion of the electromagnetic spectrum. Sunlight, at a temperature of 5,780 kelvins, is composed of near thermal-spectrum radiation that is slightly more than half infrared. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level, of this energy,527 watts is infrared radiation,445 watts is visible light, and 32 watts is ultraviolet radiation. Nearly all the radiation in sunlight is near infrared, shorter than 4 micrometers. On the surface of Earth, at far lower temperatures than the surface of the Sun, almost all thermal radiation consists of infrared in mid-infrared region, much longer than in sunlight. Of these natural thermal radiation processes only lightning and natural fires are hot enough to produce much visible energy, thermal infrared radiation also has a maximum emission wavelength, which is inversely proportional to the absolute temperature of object, in accordance with Wiens displacement law. Therefore, the band is often subdivided into smaller sections. Due to the nature of the blackbody radiation curves, typical hot objects, such as exhaust pipes, the three regions are used for observation of different temperature ranges, and hence different environments in space
Infrared
–
This infrared space telescope image has (false color) blue, green and red corresponding to 3.4, 4.6, and 12
µm wavelengths, respectively.
Infrared
–
A
false color image of two people taken in long-wavelength infrared (body-temperature thermal) light.
Infrared
–
Materials with higher
emissivity appear to be hotter. In this thermal image, the ceramic cylinder appears to be hotter than its cubic container (made of silicon carbide), while in fact they have the same temperature.
Infrared
–
Active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the
human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.
20.
Nikola Tesla
–
He immigrated to the United States in 1884, where he would become a naturalized citizen. He worked for a time at the Edison Machine Works in New York City before he struck out on his own. With the help of partners to finance and market his ideas, attempting to develop inventions he could patent and market, Tesla conducted a range of experiments with mechanical oscillators/generators, electrical discharge tubes, and early X-ray imaging. He also built a boat, one of the first ever exhibited. Tesla became well known as an inventor and would demonstrate his achievements to celebrities and wealthy patrons at his lab, in 1893, he made pronouncements on the possibility of wireless communication with his devices. After Wardenclyffe, Tesla went on to try and develop a series of inventions in the 1910s and 1920s with varying degrees of success, having spent most of his money, he lived in a series of New York hotels, leaving behind unpaid bills. The nature of his work and the pronouncements he made to the press later in life earned him the reputation of an archetypal mad scientist in American popular culture. Tesla died in New York City in January 1943 and his work fell into relative obscurity following his death, but in 1960, the General Conference on Weights and Measures named the SI unit of magnetic flux density the tesla in his honor. There has been a resurgence in popular interest in Tesla since the 1990s, Tesla was born on 10 July 1856 into a Serb family in the village of Smiljan, Austrian Empire. His father, Milutin Tesla, was an Orthodox priest, Teslas mother, Đuka Tesla, whose father was also an Orthodox priest, had a talent for making home craft tools and mechanical appliances and the ability to memorize Serbian epic poems. Đuka had never received a formal education, Tesla credited his eidetic memory and creative abilities to his mothers genetics and influence. Teslas progenitors were from western Serbia, near Montenegro, Tesla was the fourth of five children. He had a brother, Dane, and three sisters, Milka, Angelina and Marica. Dane was killed in an accident when Tesla was aged five. In 1861 Tesla attended primary school in Smiljan, where he studied German, arithmetic, in 1862 the Tesla family moved to Gospić, Austrian Empire, where Teslas father worked as parish priest. Nikola completed primary school, followed by middle school, in 1870 Tesla moved to Karlovac to attend school at the Higher Real Gymnasium. The classes were held in German, as it was a school within the Austro-Hungarian Military Frontier, Tesla would later write that he became interested in demonstrations of electricity by his physics professor. Tesla noted that these demonstrations of this mysterious phenomena made him want to more of this wonderful force
Nikola Tesla
–
Tesla, aged 34, 1890, photo by
Napoleon Sarony
Nikola Tesla
–
Rebuilt, Tesla's house (parish hall) in
Smiljan,
Croatia, where he was born, and the rebuilt church, where his father served. During the
Yugoslav Wars, several of the buildings were severely damaged by fire. They were restored and reopened in 2006.
Nikola Tesla
–
Nikola Tesla's father Milutin,
Orthodox priest in the village of
Smiljan
Nikola Tesla
–
Tesla aged 23, c. 1879
21.
Wavelength
–
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the waves shape repeats, and thus the inverse of the spatial frequency. Wavelength is commonly designated by the Greek letter lambda, the concept can also be applied to periodic waves of non-sinusoidal shape. The term wavelength is also applied to modulated waves. Wavelength depends on the medium that a wave travels through, examples of wave-like phenomena are sound waves, light, water waves and periodic electrical signals in a conductor. A sound wave is a variation in air pressure, while in light and other electromagnetic radiation the strength of the electric, water waves are variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary, wavelength is a measure of the distance between repetitions of a shape feature such as peaks, valleys, or zero-crossings, not a measure of how far any given particle moves. For example, in waves over deep water a particle near the waters surface moves in a circle of the same diameter as the wave height. The range of wavelengths or frequencies for wave phenomena is called a spectrum, the name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum. In linear media, any pattern can be described in terms of the independent propagation of sinusoidal components. The wavelength λ of a sinusoidal waveform traveling at constant speed v is given by λ = v f, in a dispersive medium, the phase speed itself depends upon the frequency of the wave, making the relationship between wavelength and frequency nonlinear. In the case of electromagnetic radiation—such as light—in free space, the speed is the speed of light. Thus the wavelength of a 100 MHz electromagnetic wave is about, the wavelength of visible light ranges from deep red, roughly 700 nm, to violet, roughly 400 nm. For sound waves in air, the speed of sound is 343 m/s, the wavelengths of sound frequencies audible to the human ear are thus between approximately 17 m and 17 mm, respectively. Note that the wavelengths in audible sound are much longer than those in visible light, a standing wave is an undulatory motion that stays in one place. A sinusoidal standing wave includes stationary points of no motion, called nodes, the upper figure shows three standing waves in a box. The walls of the box are considered to require the wave to have nodes at the walls of the box determining which wavelengths are allowed, the stationary wave can be viewed as the sum of two traveling sinusoidal waves of oppositely directed velocities. Consequently, wavelength, period, and wave velocity are related just as for a traveling wave, for example, the speed of light can be determined from observation of standing waves in a metal box containing an ideal vacuum. In that case, the k, the magnitude of k, is still in the same relationship with wavelength as shown above
Wavelength
–
Wavelength is decreased in a medium with slower propagation.
Wavelength
–
Wavelength of a
sine wave, λ, can be measured between any two points with the same
phase, such as between crests, or troughs, or corresponding
zero crossings as shown.
Wavelength
–
Various local wavelengths on a crest-to-crest basis in an ocean wave approaching shore
Wavelength
–
A wave on a line of atoms can be interpreted according to a variety of wavelengths.
22.
Submillimeter astronomy
–
Submillimetre astronomy or submillimeter astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a few hundred micrometres and a millimetre and it is still common in submillimetre astronomy to quote wavelengths in microns, the old name for micrometre. Using submillimetre observations, astronomers examine molecular clouds and dark cloud cores with a goal of clarifying the process of formation from earliest collapse to stellar birth. Submillimetre observations of dark clouds can be used to determine chemical abundances. In addition, submillimetre observations give information on the mechanisms for the formation and evolution of galaxies, the most significant limitation to the detection of astronomical emission at submillimetre wavelengths with ground based observatories is atmospheric emission, noise and attenuation. Like the infrared, the atmosphere is dominated by numerous water vapour absorption bands. The ideal submillimetre observing site is dry, cool, has stable weather conditions and is away from population centres. There are only a handful of sites identified, they include Mauna Kea, the Llano de Chajnantor Observatory on the Atacama Plateau, the South Pole. Comparisons show that all four sites are excellent for submillimetre astronomy, there has been some recent interest in high-altitude Arctic sites, particularly Summit Station in Greenland where the PWV measure is always better than at Mauna Kea. The Submillimeter Array is another interferometer, located at Mauna Kea, the largest existing submillimetre telescope, the James Clerk Maxwell Telescope, is also located on Mauna Kea. With high-altitude balloons and aircraft, one can get even more of the atmosphere. The BLAST experiment and SOFIA are two examples, respectively, although SOFIA can also handle near infrared observations, space-based observations at the submillimetre wavelengths remove the ground-based limitations of atmospheric absorption. The Submillimeter Wave Astronomy Satellite was launched into low Earth orbit on December 5,1998 as one of NASAs Small Explorer Program missions, the mission of the spacecraft is to make targeted observations of giant molecular clouds and dark cloud cores. The focus of SWAS is five spectral lines, water, isotopic water, isotopic carbon monoxide, molecular oxygen, the SWAS satellite was repurposed in June,2005 to provide support for the NASA Deep Impact mission. SWAS provided water production data on the comet until the end of August 2005, the European Space Agency launched a space-based mission known as the Herschel Space Observatory in 2009. Herschel deploys the largest mirror ever launched into space and studies radiation in the far infrared, rather than an Earth orbit, Herschel entered into a Lissajous orbit around L2, the second Lagrangian point of the Earth-Sun system. L2 is located approximately 1.5 million km from Earth, herschels mission focuses primarily on the origins of galaxies and galactic formation
Submillimeter astronomy
–
The
Caltech Submillimeter Observatory at
Mauna Kea Observatory was commissioned in 1988, and has a 10.4 m(34 ft) dish
Submillimeter astronomy
–
Panoramic view of the Chajnantor plateau, spanning about 180 degrees from north (on the left) to south (on the right) shows the antennas of the
Atacama Large Millimeter Array.
23.
Terahertz radiation
–
Photon energy in THz regime is less than band-gap of nonmetallic materials and thus THz beam can traverse through such materials. The transmitted THz beam is used for material characterization, layer inspection, terahertz radiation falls in between infrared radiation and microwave radiation in the electromagnetic spectrum, and it shares some properties with each of these. Like infrared and microwave radiation, terahertz radiation travels in a line of sight and is non-ionizing, like microwave radiation, terahertz radiation can penetrate a wide variety of non-conducting materials. Terahertz radiation can pass through clothing, paper, cardboard, wood, masonry, plastic, the penetration depth is typically less than that of microwave radiation. Terahertz radiation has limited penetration through fog and clouds and cannot penetrate liquid water or metal, THz is not ionizing yet can penetrate some distance through body tissue, so it is of interest as a replacement for medical X-rays. Due to its wavelength, images made using THz are low resolution. However, at distances of ~10 meters the band may still allow many useful applications in imaging and construction of high bandwidth wireless networking systems, terahertz radiation is emitted as part of the black-body radiation from anything with temperatures greater than about 10 kelvin. The opacity of the Earths atmosphere to submillimeter radiation restricts these observatories to very high altitude sites, and electronic oscillators based on resonant tunneling diodes have been shown to operate up to 700 GHz. There have also been solid-state sources of millimeter and submillimeter waves for many years, AB Millimeter in Paris, for instance, produces a system that covers the entire range from 8 GHz to 1000 GHz with solid state sources and detectors. Nowadays, most time-domain work is done via ultrafast lasers, in mid-2007, scientists at the U. S. The group was led by Ulrich Welp of Argonnes Materials Science Division, the device uses high-temperature superconducting crystals, grown at the University of Tsukuba in Japan. This alternating current induces an electromagnetic field, even a small voltage can induce frequencies in the terahertz range, according to Welp. In 2008, engineers at Harvard University achieved room temperature emission of several hundred nanowatts of coherent terahertz radiation using a semiconductor source, THz radiation was generated by nonlinear mixing of two modes in a mid-infrared quantum cascade laser. Previous sources had required cryogenic cooling, which limited their use in everyday applications. In 2009, it was discovered that the act of unpeeling adhesive tape generates non-polarized terahertz radiation, with a peak at 2 THz. In 2011, Japanese electronic parts maker Rohm and a team at Osaka University produced a chip capable of transmitting 1.5 Gbit/s using terahertz radiation. Such an antenna would broadcast in the frequency range. Unlike X-rays, terahertz radiation is not ionizing radiation and its low photon energies in general do not damage tissues, some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content and reflect back
Terahertz radiation
–
Terahertz waves lie at the far end of the infrared band, just before the start of the microwave band.
24.
Astronomy
–
Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets, while the phenomena include supernovae explosions, gamma ray bursts, more generally, all astronomical phenomena that originate outside Earths atmosphere are within the purview of astronomy. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole, Astronomy is the oldest of the natural sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, during the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the results and observations being used to confirm theoretical results. Astronomy is one of the few sciences where amateurs can play an active role, especially in the discovery. Amateur astronomers have made and contributed to many important astronomical discoveries, Astronomy means law of the stars. Astronomy should not be confused with astrology, the system which claims that human affairs are correlated with the positions of celestial objects. Although the two share a common origin, they are now entirely distinct. Generally, either the term astronomy or astrophysics may be used to refer to this subject, however, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics. Few fields, such as astrometry, are purely astronomy rather than also astrophysics, some titles of the leading scientific journals in this field includeThe Astronomical Journal, The Astrophysical Journal and Astronomy and Astrophysics. In early times, astronomy only comprised the observation and predictions of the motions of objects visible to the naked eye, in some locations, early cultures assembled massive artifacts that possibly had some astronomical purpose. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye, most of early astronomy actually consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon, the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the model of the Universe, or the Ptolemaic system. The Babylonians discovered that lunar eclipses recurred in a cycle known as a saros
Astronomy
–
A
star -forming region in the
Large Magellanic Cloud, an
irregular galaxy.
Astronomy
–
A giant
Hubble mosaic of the
Crab Nebula, a
supernova remnant
Astronomy
–
19th century
Sydney Observatory,
Australia (1873)
Astronomy
–
19th century
Quito Astronomical Observatory is located 12 minutes south of the
Equator in
Quito,
Ecuador.
25.
Absolute zero
–
Absolute zero is the lower limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reaches its minimum value, taken as 0. The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition, in the quantum-mechanical description, matter at absolute zero is in its ground state, the point of lowest internal energy. And a system at absolute zero still possesses quantum mechanical zero-point energy, the kinetic energy of the ground state cannot be removed. Scientists and technologists routinely achieve temperatures close to zero, where matter exhibits quantum effects such as superconductivity and superfluidity. At temperatures near 0 K, nearly all molecular motion ceases and ΔS =0 for any adiabatic process, in such a circumstance, pure substances can form perfect crystals as T →0. Max Plancks strong form of the law of thermodynamics states the entropy of a perfect crystal vanishes at absolute zero. The Nernst postulate identifies the isotherm T =0 as coincident with the adiabat S =0, although other isotherms, as no two adiabats intersect, no other adiabat can intersect the T =0 isotherm. Consequently no adiabatic process initiated at nonzero temperature can lead to zero temperature, a perfect crystal is one in which the internal lattice structure extends uninterrupted in all directions. The perfect order can be represented by translational symmetry along three axes, every lattice element of the structure is in its proper place, whether it is a single atom or a molecular grouping. For substances that exist in two crystalline forms, such as diamond and graphite for carbon, there is a kind of chemical degeneracy. The question remains whether both can have zero entropy at T =0 even though each is perfectly ordered, using the Debye model, the specific heat and entropy of a pure crystal are proportional to T3, while the enthalpy and chemical potential are proportional to T4. These quantities drop toward their T =0 limiting values and approach with zero slopes, for the specific heats at least, the limiting value itself is definitely zero, as borne out by experiments to below 10 K. Even the less detailed Einstein model shows this curious drop in specific heats, in fact, all specific heats vanish at absolute zero, not just those of crystals. Likewise for the coefficient of thermal expansion, maxwells relations show that various other quantities also vanish. Since the relation between changes in Gibbs free energy, the enthalpy and the entropy is Δ G = Δ H − T Δ S thus, as T decreases, ΔG and ΔH approach each other. Experimentally, it is found that all spontaneous processes result in a decrease in G as they proceed toward equilibrium, if ΔS and/or T are small, the condition ΔG <0 may imply that ΔH <0, which would indicate an exothermic reaction. However, this is not required, endothermic reactions can proceed spontaneously if the TΔS term is large enough, moreover, the slopes of the derivatives of ΔG and ΔH converge and are equal to zero at T =0. e. An actual process is the most exothermic one, one model that estimates the properties of an electron gas at absolute zero in metals is the Fermi gas
Absolute zero
–
Robert Boyle pioneered the idea of an absolute zero.
Absolute zero
–
Velocity-distribution data of a gas of
rubidium atoms at a temperature within a few billionths of a degree above absolute zero. Left: just before the appearance of a Bose–Einstein condensate. Center: just after the appearance of the condensate. Right: after further evaporation, leaving a sample of nearly pure condensate.
Absolute zero
–
The rapid expansion of gases leaving the
Boomerang Nebula causes the lowest observed temperature outside a laboratory: 1 K
26.
Kelvin
–
The kelvin is a unit of measure for temperature based upon an absolute scale. It is one of the seven units in the International System of Units and is assigned the unit symbol K. The kelvin is defined as the fraction 1⁄273.16 of the temperature of the triple point of water. In other words, it is defined such that the point of water is exactly 273.16 K. The Kelvin scale is named after the Belfast-born, Glasgow University engineer and physicist William Lord Kelvin, unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or typeset as a degree. The kelvin is the unit of temperature measurement in the physical sciences, but is often used in conjunction with the Celsius degree. The definition implies that absolute zero is equivalent to −273.15 °C, Kelvin calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time. This absolute scale is known today as the Kelvin thermodynamic temperature scale, when spelled out or spoken, the unit is pluralised using the same grammatical rules as for other SI units such as the volt or ohm. When reference is made to the Kelvin scale, the word kelvin—which is normally a noun—functions adjectivally to modify the noun scale and is capitalized, as with most other SI unit symbols there is a space between the numeric value and the kelvin symbol. Before the 13th CGPM in 1967–1968, the unit kelvin was called a degree and it was distinguished from the other scales with either the adjective suffix Kelvin or with absolute and its symbol was °K. The latter term, which was the official name from 1948 until 1954, was ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the form was degrees absolute. The 13th CGPM changed the name to simply kelvin. Its measured value was 0.01028 °C with an uncertainty of 60 µK, the use of SI prefixed forms of the degree Celsius to express a temperature interval has not been widely adopted. In 2005 the CIPM embarked on a program to redefine the kelvin using a more experimentally rigorous methodology, the current definition as of 2016 is unsatisfactory for temperatures below 20 K and above 1300 K. In particular, the committee proposed redefining the kelvin such that Boltzmanns constant takes the exact value 1. 3806505×10−23 J/K, from a scientific point of view, this will link temperature to the rest of SI and result in a stable definition that is independent of any particular substance. From a practical point of view, the redefinition will pass unnoticed, the kelvin is often used in the measure of the colour temperature of light sources. Colour temperature is based upon the principle that a black body radiator emits light whose colour depends on the temperature of the radiator, black bodies with temperatures below about 4000 K appear reddish, whereas those above about 7500 K appear bluish
Kelvin
–
Lord Kelvin, the namesake of the unit
Kelvin
–
A thermometer calibrated in degrees Celsius (left) and kelvins (right).
27.
Herschel Space Observatory
–
The Herschel Space Observatory was a space observatory built and operated by the European Space Agency. It was active from 2009 to 2013, and was the largest infrared telescope ever launched, carrying a single 3. 5-metre mirror and instruments sensitive to the far infrared and submillimetre wavebands. Herschel was the fourth and final mission in the Horizon 2000 programme, following SOHO/Cluster II, XMM-Newton. The observatory was carried into orbit in May 2009, reaching the second Lagrangian point of the Earth–Sun system,1,500,000 kilometres from Earth, about two months later. Herschel is named after Sir William Herschel, the discoverer of the spectrum and planet Uranus. The observatory was capable of seeing the coldest and dustiest objects in space, for example, cool cocoons where stars form, the observatory sifted through star-forming clouds—the slow cookers of star ingredients—to trace the path by which potentially life-forming molecules, such as water, form. The telescopes lifespan was governed by the amount of coolant available for its instruments, when that coolant ran out, at the time of its launch, operations were estimated to last 3.5 years. It continued to operate until 29 April 201315,20 UTC, in 1982 the Far Infrared and Sub-millimetre Telescope was proposed to ESA. The ESA long-term policy-plan Horizon 2000, produced in 1984, called for a High Throughput Heterodyne Spectroscopy mission as one of its cornerstone missions, in 1986, FIRST was adopted as this cornerstone mission. It was selected for implementation in 1993, following a study in 1992–1993. The mission concept was redesigned from Earth-orbit to the Lagrangian point L2, in 2000, FIRST was renamed Herschel. After being put out to tender in 2000, industrial activities began in 2001, as of 2010, the Herschel mission is estimated to cost 1,100 million €. This figure includes spacecraft and payload, launch and mission expenses, during the mission, Herschel made over 35,000 scientific observations and amass more than 25,000 hours worth of science data from about 600 different observing programs. The mission involved the first space observatory to cover the far infrared. At 3.5 metres wide, Herschel carried the largest optical telescope ever deployed in space and it was made not from glass but from sintered silicon carbide. The light reflected by the mirror was focused onto three instruments, whose detectors were kept at temperatures below 2 K, the instruments were cooled with over 2,300 litres of liquid helium, boiling away in a near vacuum at a temperature of approximately 1.4 K. The supply of helium on board the spacecraft was a limit to the operational lifetime of the space observatory. Herschel carried three detectors, PACS An imaging camera and low-resolution spectrometer covering wavelengths from 55 to 210 micrometres, the spectrometer had a spectral resolution between R=1000 and R=5000 and was able to detect signals as weak as −63 dB
Herschel Space Observatory
–
Artist's impression of the Herschel spacecraft
Herschel Space Observatory
–
A model of the SPIRE instrument.
Herschel Space Observatory
–
Herschel in a clean room
Herschel Space Observatory
–
A mosaic of infrared images (orange) taken by Herschel and X-ray images (blue) taken by the
XMM-Newton telescope of the Andromeda galaxy
28.
James Clerk Maxwell Telescope
–
The James Clerk Maxwell Telescope is a submillimetre-wavelength telescope at Mauna Kea Observatory in Hawaii. The telescope is near the summit of Mauna Kea at 13,425 feet and its primary mirror is 15 metres across, it is the largest single-dish telescope that operates in submillimetre wavelengths of the electromagnetic spectrum. Scientists use it to study the Solar System, interstellar dust and gas, the JCMT started operations in 1987, and was funded until February 2015 by a partnership between the United Kingdom and Canada, and the Netherlands. It was operated by the Joint Astronomy Centre and was named in honour of mathematical physicist James Clerk Maxwell, in March 2015 the operation of the JCMT was taken over by the East Asian Observatory. The JCMT has the second-largest telescope mirror on Mauna Kea, the telescope was combined with the Caltech Submillimeter Observatory next to it, to form the first submillimetre interferometer. This success was important in pushing ahead the construction of the later Submillimeter Array, in the late 1960s, the Astronomy Committee of the UKs Science Research Council considered the importance of astronomical observations at submillimetre and millimetre wavelengths. The project, then called the National New Technology Telescope, was to be an 80/20 per cent collaboration with the Netherlands Organisation for the Advancement of Science. Site tests were made at Mauna Kea in Hawaii, the Pinaleno Mountains in Arizona, and a site in Chile, the NNTT was to be larger and with more instruments than competing telescopes such as the CSO and SMT. The final specifications called for the worlds largest telescope optimised for submillimetre wavelengths and it was to be a parabolic 15-metre antenna composed of 276 individually adjustable panels with a surface accuracy of better than 50 µm. It would be an altitude-azimuth mounted Cassegrain telescope with a mirror to direct the incoming radiation onto a number of different receivers. The antenna and mountings were to be protected from the elements by a carousel with a transparent membrane stretched across the carousel aperture. Building work started in 1983 and went well apart from a delay caused by the hijacking of the ship carrying the telescope across the Pacific by modern-day pirates. The telescope saw first light in 1987, the name for the final facility was changed to the James Clerk Maxwell Telescope. The telescope itself was operated by the Joint Astronomy Centre, from Hilo, from 1987 until March 2013 this the telescope was funded by a partnership of the United Kingdom, Canada, and the Netherlands ). In 2013 the Netherlands withdrew, and until 2015 the shares became UK75 percent, the JCMT has two kinds of instruments—broadband continuum receivers and heterodyne detection spectral line receivers. Continuum emission is a tracer of star formation in galaxies and gives astronomers clues to the presence, distance. Within our own galaxy dust emission is associated with stellar nurseries, spectral-line observations can be used to identify particular molecules in molecular clouds, study their distribution and chemistry and determine gas velocity gradients across astronomical objects. The older continuum single pixel UKT14 bolometer receiver was replaced around 1995 by the Submillimetre Common-User Bolometer Array and this instrument operated simultaneously at wavelengths of 450 and 850 micron, and was sensitive to the thermal emission from interstellar dust
James Clerk Maxwell Telescope
–
Scale model of JCMT
James Clerk Maxwell Telescope
–
The JCMT sub-mm telescope in the centre
James Clerk Maxwell Telescope
–
The primary mirror seen from behind, showing the construction from many panels
James Clerk Maxwell Telescope
–
The Submillimetre Common-User Bolometer Array
29.
Stratospheric Observatory for Infrared Astronomy
–
The Stratospheric Observatory for Infrared Astronomy is an 80/20 joint project of NASA and the German Aerospace Center to construct and maintain an airborne observatory. NASA awarded the contract for the development of the aircraft, operation of the observatory, the DSI manages the German parts of the project which are primarily science and telescope related. SOFIAs telescope saw first light on May 26,2010, SOFIA is the successor to the Kuiper Airborne Observatory. This telescope is designed for infrared astronomy observations in the stratosphere at altitudes of about 12 kilometres, SOFIAs flight capability allows it to rise above almost all of the water vapor in the Earths atmosphere, which blocks some infrared wavelengths from reaching the ground. At the aircrafts cruising altitude, 85% of the infrared range will be available. The aircraft can travel to almost any point on the Earths surface. Once ready for use, observing flights were expected to be three or four nights a week. SOFIA uses a 2.5 m reflector telescope, which has an oversized,2.7 m diameter primary mirror, the optical system uses a Cassegrain reflector design with a parabolic primary mirror and a remotely configurable hyperbolic secondary. In order to fit the telescope into the fuselage, the primary is shaped to an f-number as low as 1.3, a flat, tertiary, dichroic mirror is used to deflect the infrared part of the beam to the Nasmyth focus where it can be analyzed. An optical mirror located behind the mirror is used for a camera guidance system. 3–1.1 μm. The main instruments are the FLITECAM, an infrared camera covering 1–5 μm, FORCAST, covering the mid-infrared range of 5–40 μm, and HAWC. The other four instruments include an optical photometer and infrared spectrometers with various spectral ranges, sOFIA’s telescope is by far the largest ever to be placed in an aircraft. For each mission one interchangeable science instrument will be attached to the telescope, two groups of general purpose instruments are available. In addition an investigator can also design and build a special purpose instrument, the open cavity housing the telescope will be exposed to high-speed turbulent winds. In addition, the vibrations and motions of the aircraft introduce observing difficulties, the telescope was designed to be very lightweight, with a honeycomb shape milled into the back of the mirror and polymer composite material used for the telescope assembly. The mount includes a system of bearings in pressurized oil to isolate the instrument from vibration, tracking is achieved through a system of gyroscopes, high speed cameras, and magnetic torque motors to compensate for motion, including vibrations from airflow and the aircraft engines. The telescope cabin must be cooled prior to aircraft takeoff to ensure the telescope matches the temperature to prevent thermally induced shape changes. Prior to landing the compartment is flooded with gas to prevent condensation of moisture on the chilled optics
Stratospheric Observatory for Infrared Astronomy
–
SOFIA with the telescope door open in flight.
Stratospheric Observatory for Infrared Astronomy
–
The NASA logo reflected in SOFIAs 2.5-meter primary mirror.
Stratospheric Observatory for Infrared Astronomy
–
SOFIA
Stratospheric Observatory for Infrared Astronomy
–
The SOFIA aircraft pictured during a test flight in 1998. Still mostly in
United Airlines livery, a black square has been painted on the aft fuselage to indicate the location of the door that will be opened in flight to allow the telescope access to the sky.
30.
Particle physics
–
Particle physics is the branch of physics that studies the nature of the particles that constitute matter and radiation. By our current understanding, these particles are excitations of the quantum fields that also govern their interactions. The currently dominant theory explaining these fundamental particles and fields, along with their dynamics, is called the Standard Model, in more technical terms, they are described by quantum state vectors in a Hilbert space, which is also treated in quantum field theory. All particles and their interactions observed to date can be described almost entirely by a field theory called the Standard Model. The Standard Model, as formulated, has 61 elementary particles. Those elementary particles can combine to form composite particles, accounting for the hundreds of species of particles that have been discovered since the 1960s. The Standard Model has been found to agree with almost all the tests conducted to date. However, most particle physicists believe that it is a description of nature. In recent years, measurements of mass have provided the first experimental deviations from the Standard Model. The idea that all matter is composed of elementary particles dates from at least the 6th century BC, in the 19th century, John Dalton, through his work on stoichiometry, concluded that each element of nature was composed of a single, unique type of particle. Throughout the 1950s and 1960s, a variety of particles were found in collisions of particles from increasingly high-energy beams. It was referred to informally as the particle zoo, the current state of the classification of all elementary particles is explained by the Standard Model. It describes the strong, weak, and electromagnetic fundamental interactions, the species of gauge bosons are the gluons, W−, W+ and Z bosons, and the photons. The Standard Model also contains 24 fundamental particles, which are the constituents of all matter, finally, the Standard Model also predicted the existence of a type of boson known as the Higgs boson. Early in the morning on 4 July 2012, physicists with the Large Hadron Collider at CERN announced they had found a new particle that behaves similarly to what is expected from the Higgs boson, the worlds major particle physics laboratories are, Brookhaven National Laboratory. Its main facility is the Relativistic Heavy Ion Collider, which collides heavy ions such as gold ions and it is the worlds first heavy ion collider, and the worlds only polarized proton collider. Its main projects are now the electron-positron colliders VEPP-2000, operated since 2006 and its main project is now the Large Hadron Collider, which had its first beam circulation on 10 September 2008, and is now the worlds most energetic collider of protons. It also became the most energetic collider of heavy ions after it began colliding lead ions and its main facility is the Hadron Elektron Ring Anlage, which collides electrons and positrons with protons
Particle physics
–
Large Hadron Collider tunnel at
CERN
