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9,500 | A photon that enters the interferometer from the left will then be acted upon with a beam splitter formula_33, a phase shifter formula_28, and another beam splitter formula_33, and so end up in the state | https://en.wikipedia.org/wiki?curid=25202 |
9,501 | One can therefore use the Mach–Zehnder interferometer to estimate the phase shift by estimating these probabilities. | https://en.wikipedia.org/wiki?curid=25202 |
9,502 | It is interesting to consider what would happen if the photon were definitely in either the "lower" or "upper" paths between the beam splitters. This can be accomplished by blocking one of the paths, or equivalently by removing the first beam splitter (and feeding the photon from the left or the bottom, as desired). In both cases there will be no interference between the paths anymore, and the probabilities are given by formula_129, independently of the phase formula_122. From this we can conclude that the photon does not take one path or another after the first beam splitter, but rather that it is in a genuine quantum superposition of the two paths. | https://en.wikipedia.org/wiki?curid=25202 |
9,503 | Quantum mechanics has had enormous success in explaining many of the features of our universe, with regards to small-scale and discrete quantities and interactions which cannot be explained by classical methods. Quantum mechanics is often the only theory that can reveal the individual behaviors of the subatomic particles that make up all forms of matter (electrons, protons, neutrons, photons, and others). Solid-state physics and materials science are dependent upon quantum mechanics. | https://en.wikipedia.org/wiki?curid=25202 |
9,504 | In many aspects modern technology operates at a scale where quantum effects are significant. Important applications of quantum theory include quantum chemistry, quantum optics, quantum computing, superconducting magnets, light-emitting diodes, the optical amplifier and the laser, the transistor and semiconductors such as the microprocessor, medical and research imaging such as magnetic resonance imaging and electron microscopy. Explanations for many biological and physical phenomena are rooted in the nature of the chemical bond, most notably the macro-molecule DNA. | https://en.wikipedia.org/wiki?curid=25202 |
9,505 | The rules of quantum mechanics assert that the state space of a system is a Hilbert space and that observables of the system are Hermitian operators acting on vectors in that space – although they do not tell us which Hilbert space or which operators. These can be chosen appropriately in order to obtain a quantitative description of a quantum system, a necessary step in making physical predictions. An important guide for making these choices is the correspondence principle, a heuristic which states that the predictions of quantum mechanics reduce to those of classical mechanics in the regime of large quantum numbers. One can also start from an established classical model of a particular system, and then try to guess the underlying quantum model that would give rise to the classical model in the correspondence limit. This approach is known as quantization. | https://en.wikipedia.org/wiki?curid=25202 |
9,506 | When quantum mechanics was originally formulated, it was applied to models whose correspondence limit was non-relativistic classical mechanics. For instance, the well-known model of the quantum harmonic oscillator uses an explicitly non-relativistic expression for the kinetic energy of the oscillator, and is thus a quantum version of the classical harmonic oscillator. | https://en.wikipedia.org/wiki?curid=25202 |
9,507 | Complications arise with chaotic systems, which do not have good quantum numbers, and quantum chaos studies the relationship between classical and quantum descriptions in these systems. | https://en.wikipedia.org/wiki?curid=25202 |
9,508 | Quantum decoherence is a mechanism through which quantum systems lose coherence, and thus become incapable of displaying many typically quantum effects: quantum superpositions become simply probabilistic mixtures, and quantum entanglement becomes simply classical correlations. Quantum coherence is not typically evident at macroscopic scales, except maybe at temperatures approaching absolute zero at which quantum behavior may manifest macroscopically. | https://en.wikipedia.org/wiki?curid=25202 |
9,509 | Many macroscopic properties of a classical system are a direct consequence of the quantum behavior of its parts. For example, the stability of bulk matter (consisting of atoms and molecules which would quickly collapse under electric forces alone), the rigidity of solids, and the mechanical, thermal, chemical, optical and magnetic properties of matter are all results of the interaction of electric charges under the rules of quantum mechanics. | https://en.wikipedia.org/wiki?curid=25202 |
9,510 | Early attempts to merge quantum mechanics with special relativity involved the replacement of the Schrödinger equation with a covariant equation such as the Klein–Gordon equation or the Dirac equation. While these theories were successful in explaining many experimental results, they had certain unsatisfactory qualities stemming from their neglect of the relativistic creation and annihilation of particles. A fully relativistic quantum theory required the development of quantum field theory, which applies quantization to a field (rather than a fixed set of particles). The first complete quantum field theory, quantum electrodynamics, provides a fully quantum description of the electromagnetic interaction. Quantum electrodynamics is, along with general relativity, one of the most accurate physical theories ever devised. | https://en.wikipedia.org/wiki?curid=25202 |
9,511 | The full apparatus of quantum field theory is often unnecessary for describing electrodynamic systems. A simpler approach, one that has been used since the inception of quantum mechanics, is to treat charged particles as quantum mechanical objects being acted on by a classical electromagnetic field. For example, the elementary quantum model of the hydrogen atom describes the electric field of the hydrogen atom using a classical formula_131 Coulomb potential. This "semi-classical" approach fails if quantum fluctuations in the electromagnetic field play an important role, such as in the emission of photons by charged particles. | https://en.wikipedia.org/wiki?curid=25202 |
9,512 | Quantum field theories for the strong nuclear force and the weak nuclear force have also been developed. The quantum field theory of the strong nuclear force is called quantum chromodynamics, and describes the interactions of subnuclear particles such as quarks and gluons. The weak nuclear force and the electromagnetic force were unified, in their quantized forms, into a single quantum field theory (known as electroweak theory), by the physicists Abdus Salam, Sheldon Glashow and Steven Weinberg. | https://en.wikipedia.org/wiki?curid=25202 |
9,513 | Even though the predictions of both quantum theory and general relativity have been supported by rigorous and repeated empirical evidence, their abstract formalisms contradict each other and they have proven extremely difficult to incorporate into one consistent, cohesive model. Gravity is negligible in many areas of particle physics, so that unification between general relativity and quantum mechanics is not an urgent issue in those particular applications. However, the lack of a correct theory of quantum gravity is an important issue in physical cosmology and the search by physicists for an elegant "Theory of Everything" (TOE). Consequently, resolving the inconsistencies between both theories has been a major goal of 20th- and 21st-century physics. This TOE would combine not only the models of subatomic physics but also derive the four fundamental forces of nature from a single force or phenomenon. | https://en.wikipedia.org/wiki?curid=25202 |
9,514 | One proposal for doing so is string theory, which posits that the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries gravitational force. | https://en.wikipedia.org/wiki?curid=25202 |
9,515 | Another popular theory is loop quantum gravity (LQG), which describes quantum properties of gravity and is thus a theory of quantum spacetime. LQG is an attempt to merge and adapt standard quantum mechanics and standard general relativity. This theory describes space as an extremely fine fabric "woven" of finite loops called spin networks. The evolution of a spin network over time is called a spin foam. The characteristic length scale of a spin foam is the Planck length, approximately 1.616×10 m, and so lengths shorter than the Planck length are not physically meaningful in LQG. | https://en.wikipedia.org/wiki?curid=25202 |
9,516 | Since its inception, the many counter-intuitive aspects and results of quantum mechanics have provoked strong philosophical debates and many interpretations. The arguments centre on the probabilistic nature of quantum mechanics, the difficulties with wavefunction collapse and the related measurement problem, and quantum nonlocality. Perhaps the only consensus that exists about these issues is that there is no consensus. Richard Feynman once said, "I think I can safely say that nobody understands quantum mechanics." According to Steven Weinberg, "There is now in my opinion no entirely satisfactory interpretation of quantum mechanics." | https://en.wikipedia.org/wiki?curid=25202 |
9,517 | The views of Niels Bohr, Werner Heisenberg and other physicists are often grouped together as the "Copenhagen interpretation". According to these views, the probabilistic nature of quantum mechanics is not a "temporary" feature which will eventually be replaced by a deterministic theory, but is instead a "final" renunciation of the classical idea of "causality". Bohr in particular emphasized that any well-defined application of the quantum mechanical formalism must always make reference to the experimental arrangement, due to the complementary nature of evidence obtained under different experimental situations. Copenhagen-type interpretations remain popular in the 21st century. | https://en.wikipedia.org/wiki?curid=25202 |
9,518 | Albert Einstein, himself one of the founders of quantum theory, was troubled by its apparent failure to respect some cherished metaphysical principles, such as determinism and locality. Einstein's long-running exchanges with Bohr about the meaning and status of quantum mechanics are now known as the Bohr–Einstein debates. Einstein believed that underlying quantum mechanics must be a theory that explicitly forbids action at a distance. He argued that quantum mechanics was incomplete, a theory that was valid but not fundamental, analogous to how thermodynamics is valid, but the fundamental theory behind it is statistical mechanics. In 1935, Einstein and his collaborators Boris Podolsky and Nathan Rosen published an argument that the principle of locality implies the incompleteness of quantum mechanics, a thought experiment later termed the Einstein–Podolsky–Rosen paradox. In 1964, John Bell showed that EPR's principle of locality, together with determinism, was actually incompatible with quantum mechanics: they implied constraints on the correlations produced by distance systems, now known as Bell inequalities, that can be violated by entangled particles. Since then several experiments have been performed to obtain these correlations, with the result that they do in fact violate Bell inequalities, and thus falsify the conjunction of locality with determinism. | https://en.wikipedia.org/wiki?curid=25202 |
9,519 | Bohmian mechanics shows that it is possible to reformulate quantum mechanics to make it deterministic, at the price of making it explicitly nonlocal. It attributes not only a wave function to a physical system, but in addition a real position, that evolves deterministically under a nonlocal guiding equation. The evolution of a physical system is given at all times by the Schrödinger equation together with the guiding equation; there is never a collapse of the wave function. This solves the measurement problem. | https://en.wikipedia.org/wiki?curid=25202 |
9,520 | Everett's many-worlds interpretation, formulated in 1956, holds that "all" the possibilities described by quantum theory "simultaneously" occur in a multiverse composed of mostly independent parallel universes. This is a consequence of removing the axiom of the collapse of the wave packet. All possible states of the measured system and the measuring apparatus, together with the observer, are present in a real physical quantum superposition. While the multiverse is deterministic, we perceive non-deterministic behavior governed by probabilities, because we don't observe the multiverse as a whole, but only one parallel universe at a time. Exactly how this is supposed to work has been the subject of much debate. Several attempts have been made to make sense of this and derive the Born rule, with no consensus on whether they have been successful. | https://en.wikipedia.org/wiki?curid=25202 |
9,521 | Relational quantum mechanics appeared in the late 1990s as a modern derivative of Copenhagen-type ideas, and QBism was developed some years later. | https://en.wikipedia.org/wiki?curid=25202 |
9,522 | Quantum mechanics was developed in the early decades of the 20th century, driven by the need to explain phenomena that, in some cases, had been observed in earlier times. Scientific inquiry into the wave nature of light began in the 17th and 18th centuries, when scientists such as Robert Hooke, Christiaan Huygens and Leonhard Euler proposed a wave theory of light based on experimental observations. In 1803 English polymath Thomas Young described the famous double-slit experiment. This experiment played a major role in the general acceptance of the wave theory of light. | https://en.wikipedia.org/wiki?curid=25202 |
9,523 | During the early 19th century, chemical research by John Dalton and Amedeo Avogadro lent weight to the atomic theory of matter, an idea that James Clerk Maxwell, Ludwig Boltzmann and others built upon to establish the kinetic theory of gases. The successes of kinetic theory gave further credence to the idea that matter is composed of atoms, yet the theory also had shortcomings that would only be resolved by the development of quantum mechanics. While the early conception of atoms from Greek philosophy had been that they were indivisible units the word "atom" deriving from the Greek for "uncuttable" the 19th century saw the formulation of hypotheses about subatomic structure. One important discovery in that regard was Michael Faraday's 1838 observation of a glow caused by an electrical discharge inside a glass tube containing gas at low pressure. Julius Plücker, Johann Wilhelm Hittorf and Eugen Goldstein carried on and improved upon Faraday's work, leading to the identification of cathode rays, which J. J. Thomson found to consist of subatomic particles that would be called electrons. | https://en.wikipedia.org/wiki?curid=25202 |
9,524 | The black-body radiation problem was discovered by Gustav Kirchhoff in 1859. In 1900, Max Planck proposed the hypothesis that energy is radiated and absorbed in discrete "quanta" (or energy packets), yielding a calculation that precisely matched the observed patterns of black-body radiation. The word "quantum" derives from the Latin, meaning "how great" or "how much". According to Planck, quantities of energy could be thought of as divided into "elements" whose size ("E") would be proportional to their frequency ("ν"): | https://en.wikipedia.org/wiki?curid=25202 |
9,525 | where "h" is Planck's constant. Planck cautiously insisted that this was only an aspect of the processes of absorption and emission of radiation and was not the "physical reality" of the radiation. In fact, he considered his quantum hypothesis a mathematical trick to get the right answer rather than a sizable discovery. However, in 1905 Albert Einstein interpreted Planck's quantum hypothesis realistically and used it to explain the photoelectric effect, in which shining light on certain materials can eject electrons from the material. Niels Bohr then developed Planck's ideas about radiation into a model of the hydrogen atom that successfully predicted the spectral lines of hydrogen. Einstein further developed this idea to show that an electromagnetic wave such as light could also be described as a particle (later called the photon), with a discrete amount of energy that depends on its frequency. In his paper "On the Quantum Theory of Radiation," Einstein expanded on the interaction between energy and matter to explain the absorption and emission of energy by atoms. Although overshadowed at the time by his general theory of relativity, this paper articulated the mechanism underlying the stimulated emission of radiation, which became the basis of the laser. | https://en.wikipedia.org/wiki?curid=25202 |
9,526 | This phase is known as the old quantum theory. Never complete or self-consistent, the old quantum theory was rather a set of heuristic corrections to classical mechanics. The theory is now understood as a semi-classical approximation to modern quantum mechanics. Notable results from this period include, in addition to the work of Planck, Einstein and Bohr mentioned above, Einstein and Peter Debye's work on the specific heat of solids, Bohr and Hendrika Johanna van Leeuwen's proof that classical physics cannot account for diamagnetism, and Arnold Sommerfeld's extension of the Bohr model to include special-relativistic effects. | https://en.wikipedia.org/wiki?curid=25202 |
9,527 | In the mid-1920s quantum mechanics was developed to become the standard formulation for atomic physics. In 1923, the French physicist Louis de Broglie put forward his theory of matter waves by stating that particles can exhibit wave characteristics and vice versa. Building on de Broglie's approach, modern quantum mechanics was born in 1925, when the German physicists Werner Heisenberg, Max Born, and Pascual Jordan developed matrix mechanics and the Austrian physicist Erwin Schrödinger invented wave mechanics. Born introduced the probabilistic interpretation of Schrödinger's wave function in July 1926. Thus, the entire field of quantum physics emerged, leading to its wider acceptance at the Fifth Solvay Conference in 1927. | https://en.wikipedia.org/wiki?curid=25202 |
9,528 | By 1930 quantum mechanics had been further unified and formalized by David Hilbert, Paul Dirac and John von Neumann with greater emphasis on measurement, the statistical nature of our knowledge of reality, and philosophical speculation about the 'observer'. It has since permeated many disciplines, including quantum chemistry, quantum electronics, quantum optics, and quantum information science. It also provides a useful framework for many features of the modern periodic table of elements, and describes the behaviors of atoms during chemical bonding and the flow of electrons in computer semiconductors, and therefore plays a crucial role in many modern technologies. While quantum mechanics was constructed to describe the world of the very small, it is also needed to explain some macroscopic phenomena such as superconductors and superfluids. | https://en.wikipedia.org/wiki?curid=25202 |
9,529 | The following titles, all by working physicists, attempt to communicate quantum theory to lay people, using a minimum of technical apparatus. | https://en.wikipedia.org/wiki?curid=25202 |
9,530 | The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum known depth is at the southern end of a small slot-shaped valley in its floor known as the Challenger Deep. If Mount Everest were hypothetically placed into the trench at this point, its peak would still be underwater by more than . | https://en.wikipedia.org/wiki?curid=19036 |
9,531 | At the bottom of the trench, the water column above exerts a pressure of , more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%. The temperature at the bottom is . | https://en.wikipedia.org/wiki?curid=19036 |
9,532 | In 2009, the Mariana Trench was established as a US National Monument. Monothalamea have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of below the sea surface. Data has also suggested that microbial life forms thrive within the trench. | https://en.wikipedia.org/wiki?curid=19036 |
9,533 | The Mariana Trench is named after the nearby Mariana Islands, which are named Las Marianas in honor of Spanish Queen Mariana of Austria, widow of Philip IV of Spain. The islands are part of the island arc that is formed on an over-riding plate, called the Mariana Plate (also named for the islands), on the western side of the trench. | https://en.wikipedia.org/wiki?curid=19036 |
9,534 | The Mariana Trench is part of the Izu–Bonin–Mariana subduction system that forms the boundary between two tectonic plates. In this system, the western edge of one plate, the Pacific Plate, is subducted (i.e., thrust) beneath the smaller Mariana Plate that lies to the west. Crustal material at the western edge of the Pacific Plate is some of the oldest oceanic crust on Earth (up to 170 million years old), and is, therefore, cooler and denser; hence its great height difference relative to the higher-riding (and younger) Mariana Plate. The deepest area at the plate boundary is the Mariana Trench proper. | https://en.wikipedia.org/wiki?curid=19036 |
9,535 | The movement of the Pacific and Mariana plates is also indirectly responsible for the formation of the Mariana Islands. These volcanic islands are caused by flux melting of the upper mantle due to the release of water that is trapped in minerals of the subducted portion of the Pacific Plate. | https://en.wikipedia.org/wiki?curid=19036 |
9,536 | The trench was first sounded during the "Challenger" expedition in 1875 using a weighted rope, which recorded a depth of . In 1877, a map was published called "Tiefenkarte des Grossen Ozeans" ("Depth map of the Great Ocean") by Petermann, which showed a "Challenger Tief" ("Challenger deep") at the location of that sounding. In 1899, , a converted collier, recorded a depth of . | https://en.wikipedia.org/wiki?curid=19036 |
9,537 | In 1951, "Challenger II" surveyed the trench using echo sounding, a much more precise and vastly easier way to measure depth than the sounding equipment and drag lines used in the original expedition. During this survey, the deepest part of the trench was recorded when the "Challenger II" measured a depth of at , known as the Challenger Deep. | https://en.wikipedia.org/wiki?curid=19036 |
9,538 | In 1962, the surface ship M.V. "Spencer F. Baird" recorded a maximum depth of using precision depth gauges. | https://en.wikipedia.org/wiki?curid=19036 |
9,539 | In 1984, the Japanese survey vessel "Takuyō" (拓洋) collected data from the Mariana Trench using a narrow, multi-beam echo sounder; it reported a maximum depth of , also reported as . Remotely Operated Vehicle "KAIKO" reached the deepest area of the Mariana Trench and made the deepest diving record of on 24 March 1995. | https://en.wikipedia.org/wiki?curid=19036 |
9,540 | During surveys carried out between 1997 and 2001, a spot was found along the Mariana Trench that had a depth similar to the Challenger Deep, possibly even deeper. It was discovered while scientists from the Hawaii Institute of Geophysics and Planetology were completing a survey around Guam; they used a sonar mapping system towed behind the research ship to conduct the survey. This new spot was named the HMRG (Hawaii Mapping Research Group) Deep, after the group of scientists who discovered it. | https://en.wikipedia.org/wiki?curid=19036 |
9,541 | On 1 June 2009, mapping aboard the (mothership of the Nereus vehicle), indicated a spot with a depth of . The sonar mapping of the Challenger Deep was possible by its Simrad EM120 sonar multibeam bathymetry system for deep water. The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth across the entire swath (implying that the depth figure is accurate to ± ).<ref name="Daily Reports for R/V KILO MOANA"></ref><ref name="Scientic Equipment aboard the R/V KILO MOANA"></ref> | https://en.wikipedia.org/wiki?curid=19036 |
9,542 | In 2011, it was announced at the American Geophysical Union Fall Meeting that a US Navy hydrographic ship equipped with a multibeam echosounder conducted a survey which mapped the entire trench to resolution. The mapping revealed the existence of four rocky outcrops thought to be former seamounts. | https://en.wikipedia.org/wiki?curid=19036 |
9,543 | The Mariana Trench is a site chosen by researchers at Washington University and the Woods Hole Oceanographic Institution in 2012 for a seismic survey to investigate the subsurface water cycle. Using both ocean-bottom seismometers and hydrophones, the scientists are able to map structures as deep as beneath the surface. | https://en.wikipedia.org/wiki?curid=19036 |
9,544 | As of 2022, twenty-two crewed descents and seven uncrewed descents have been achieved. The first was the crewed descent by Swiss-designed, Italian-built, United States Navy-owned bathyscaphe "Trieste", which reached the bottom at 1:06 pm on 23 January 1960, with Don Walsh and Jacques Piccard on board. Iron shot was used for ballast, with gasoline for buoyancy. The onboard systems indicated a depth of , but this was later revised to . The depth was estimated from a conversion of pressure measured and calculations based on the water density from sea surface to seabed. | https://en.wikipedia.org/wiki?curid=19036 |
9,545 | This was followed by the uncrewed ROVs "Kaikō" in 1996 and "Nereus" in 2009. The first three expeditions directly measured very similar depths of . The fourth was made by Canadian film director James Cameron on 26 March 2012. He reached the bottom of the Mariana Trench in the submersible vessel "Deepsea Challenger", diving to a depth of . | https://en.wikipedia.org/wiki?curid=19036 |
9,546 | In July 2015, members of the National Oceanic and Atmospheric Administration, Oregon State University, and the Coast Guard submerged a hydrophone into the deepest part of the Mariana Trench, the Challenger Deep, never having previously deployed one past a mile. The titanium-shelled hydrophone was designed to withstand the immense pressure 7 miles under. Although researchers were unable to retrieve the hydrophone until November, the data capacity was full within the first 23 days. After months of analyzing the sounds, the experts were surprised to pick up natural sounds like earthquakes, typhoons, baleen whales, and machine-made sounds such as boats. Due to the mission's success, the researchers announced plans to deploy a second hydrophone in 2017 for an extended period of time. | https://en.wikipedia.org/wiki?curid=19036 |
9,547 | Victor Vescovo achieved a new record descent to on 28 April 2019 using the DSV "Limiting Factor", a Triton 36000/2 model manufactured by Florida-based Triton Submarines. He dived four times between 28 April and 5 May 2019, becoming the first person to dive into Challenger Deep more than once. | https://en.wikipedia.org/wiki?curid=19036 |
9,548 | On 8 May 2020, a joint project between the Russian shipbuilders, scientific teams of the Russian Academy of Sciences with the support of the Russian Foundation for Advanced Research Projects and the Pacific Fleet submerged the autonomous underwater vehicle "Vityaz-D" to the bottom of the Mariana Trench at a depth of . "Vityaz-D" is the first underwater vehicle to operate autonomously at the extreme depths of the Mariana Trench. The duration of the mission, excluding diving and surfacing, was more than 3 hours. | https://en.wikipedia.org/wiki?curid=19036 |
9,549 | On 10 November 2020, the Chinese submersible "Fendouzhe" reached the bottom of the Mariana Trench at a depth of . | https://en.wikipedia.org/wiki?curid=19036 |
9,550 | The expedition conducted in 1960 claimed to have observed, with great surprise because of the high pressure, large creatures living at the bottom, such as a flatfish about long, and shrimp. According to Piccard, "The bottom appeared light and clear, a waste of firm diatomaceous ooze". Many marine biologists are now skeptical of the supposed sighting of the flatfish, and it is suggested that the creature may instead have been a sea cucumber. During the second expedition, the uncrewed vehicle "Kaikō" collected mud samples from the seabed. Tiny organisms were found to be living in those samples. | https://en.wikipedia.org/wiki?curid=19036 |
9,551 | In July 2011, a research expedition deployed untethered landers, called drop cams, equipped with digital video cameras and lights to explore this deep-sea region. Among many other living organisms, some gigantic single-celled foraminiferans with a size of more than , belonging to the class of monothalamea, were observed. Monothalamea are noteworthy for their size, their extreme abundance on the seafloor, and their role as hosts for a variety of organisms. | https://en.wikipedia.org/wiki?curid=19036 |
9,552 | In December 2014, a new species of snailfish was discovered at a depth of , breaking the previous record for the deepest living fish seen on video. | https://en.wikipedia.org/wiki?curid=19036 |
9,553 | During the 2014 expedition, several new species were filmed, including huge amphipods known as supergiants. Deep-sea gigantism is the process where species grow larger than their shallow-water relatives. | https://en.wikipedia.org/wiki?curid=19036 |
9,554 | In 2016, a research expedition looked at the chemical makeup of crustacean scavengers collected from the range of within the trench. Within these organisms, the researchers found extremely elevated concentrations of PCBs, a chemical toxin banned in the 1970s for its environmental harm, concentrated at all depths within the sediment of the trench. Further research has found that amphipods also ingest microplastics, with 100% of amphipods having at least one piece of synthetic material in their stomachs. | https://en.wikipedia.org/wiki?curid=19036 |
9,555 | In 2019, Victor Vescovo reported finding a plastic bag and candy wrappers at the bottom of the trench. That year, "Scientific American" also reported that carbon-14 from nuclear bomb testing has been found in the bodies of aquatic animals found in the trench. | https://en.wikipedia.org/wiki?curid=19036 |
9,556 | Like other oceanic trenches, the Mariana Trench has been proposed as a site for nuclear waste disposal in the hope that tectonic plate subduction occurring at the site might eventually push the nuclear waste deep into the Earth's mantle, the second layer of the Earth. However, ocean dumping of nuclear waste is prohibited by international law. Furthermore, plate subduction zones are associated with very large megathrust earthquakes, the effects of which are unpredictable for the safety of long-term disposal of nuclear wastes within the hadopelagic ecosystem. | https://en.wikipedia.org/wiki?curid=19036 |
9,557 | Microsoft Excel is a spreadsheet developed by Microsoft for Windows, macOS, Android and iOS. It features calculation or computation capabilities, graphing tools, pivot tables, and a macro programming language called Visual Basic for Applications (VBA). Excel forms part of the Microsoft Office suite of software. | https://en.wikipedia.org/wiki?curid=20268 |
9,558 | Microsoft Excel has the basic features of all spreadsheets, using a grid of "cells" arranged in numbered "rows" and letter-named "columns" to organize data manipulations like arithmetic operations. It has a battery of supplied functions to answer statistical, engineering, and financial needs. In addition, it can display data as line graphs, histograms and charts, and with a very limited three-dimensional graphical display. It allows sectioning of data to view its dependencies on various factors for different perspectives (using "pivot tables" and the "scenario manager"). A PivotTable is a tool for data analysis. It does this by simplifying large data sets via PivotTable fields. It has a programming aspect, "Visual Basic for Applications", allowing the user to employ a wide variety of numerical methods, for example, for solving differential equations of mathematical physics, and then reporting the results back to the spreadsheet. It also has a variety of interactive features allowing user interfaces that can completely hide the spreadsheet from the user, so the spreadsheet presents itself as a so-called "application", or "decision support system" (DSS), via a custom-designed user interface, for example, a stock analyzer, or in general, as a design tool that asks the user questions and provides answers and reports. In a more elaborate realization, an Excel application can automatically poll external databases and measuring instruments using an update schedule, analyze the results, make a Word report or PowerPoint slide show, and e-mail these presentations on a regular basis to a list of participants. Excel was not designed to be used as a database. | https://en.wikipedia.org/wiki?curid=20268 |
9,559 | Microsoft allows for a number of optional command-line switches to control the manner in which Excel starts. | https://en.wikipedia.org/wiki?curid=20268 |
9,560 | Excel 2016 has 484 functions. Of these, 360 existed prior to Excel 2010. Microsoft classifies these functions in 14 categories. Of the 484 current functions, 386 may be called from VBA as methods of the object "WorksheetFunction" and 44 have the same names as VBA functions. | https://en.wikipedia.org/wiki?curid=20268 |
9,561 | The Windows version of Excel supports programming through Microsoft's Visual Basic for Applications (VBA), which is a dialect of Visual Basic. Programming with VBA allows spreadsheet manipulation that is awkward or impossible with standard spreadsheet techniques. Programmers may write code directly using the Visual Basic Editor (VBE), which includes a window for writing code, debugging code, and code module organization environment. The user can implement numerical methods as well as automating tasks such as formatting or data organization in VBA and guide the calculation using any desired intermediate results reported back to the spreadsheet. | https://en.wikipedia.org/wiki?curid=20268 |
9,562 | VBA was removed from Mac Excel 2008, as the developers did not believe that a timely release would allow porting the VBA engine natively to Mac OS X. VBA was restored in the next version, Mac Excel 2011, although the build lacks support for ActiveX objects, impacting some high level developer tools. | https://en.wikipedia.org/wiki?curid=20268 |
9,563 | A common and easy way to generate VBA code is by using the Macro Recorder. The Macro Recorder records actions of the user and generates VBA code in the form of a macro. These actions can then be repeated automatically by running the macro. The macros can also be linked to different trigger types like keyboard shortcuts, a command button or a graphic. The actions in the macro can be executed from these trigger types or from the generic toolbar options. The VBA code of the macro can also be edited in the VBE. Certain features such as loop functions and screen prompt by their own properties, and some graphical display items, cannot be recorded but must be entered into the VBA module directly by the programmer. Advanced users can employ user prompts to create an interactive program, or react to events such as sheets being loaded or changed. | https://en.wikipedia.org/wiki?curid=20268 |
9,564 | Macro Recorded code may not be compatible with Excel versions. Some code that is used in Excel 2010 cannot be used in Excel 2003. Making a Macro that changes the cell colors and making changes to other aspects of cells may not be backward compatible. | https://en.wikipedia.org/wiki?curid=20268 |
9,565 | VBA code interacts with the spreadsheet through the Excel "Object Model", a vocabulary identifying spreadsheet objects, and a set of supplied functions or "methods" that enable reading and writing to the spreadsheet and interaction with its users (for example, through custom toolbars or "command bars" and "message boxes"). User-created VBA subroutines execute these actions and operate like macros generated using the macro recorder, but are more flexible and efficient. | https://en.wikipedia.org/wiki?curid=20268 |
9,566 | From its first version Excel supported end-user programming of macros (automation of repetitive tasks) and user-defined functions (extension of Excel's built-in function library). In early versions of Excel, these programs were written in a macro language whose statements had formula syntax and resided in the cells of special-purpose macro sheets (stored with file extension .XLM in Windows.) XLM was the default macro language for Excel through Excel 4.0. Beginning with version 5.0 Excel recorded macros in VBA by default but with version 5.0 XLM recording was still allowed as an option. After version 5.0 that option was discontinued. All versions of Excel, including Excel 2021 are capable of running an XLM macro, though Microsoft discourages their use. | https://en.wikipedia.org/wiki?curid=20268 |
9,567 | Excel supports charts, graphs, or histograms generated from specified groups of cells. It also supports Pivot Charts that allow for a chart to be linked directly to a Pivot table. This allows the chart to be refreshed with the Pivot Table. The generated graphic component can either be embedded within the current sheet or added as a separate object. | https://en.wikipedia.org/wiki?curid=20268 |
9,568 | These displays are dynamically updated if the content of cells changes. For example, suppose that the important design requirements are displayed visually; then, in response to a user's change in trial values for parameters, the curves describing the design change shape, and their points of intersection shift, assisting the selection of the best design. | https://en.wikipedia.org/wiki?curid=20268 |
9,569 | Versions of Excel up to 7.0 had a limitation in the size of their data sets of 16K (2 = ) rows. Versions 8.0 through 11.0 could handle 64K (2 = ) rows and 256 columns (2 as label 'IV'). Version 12.0 onwards, including the current Version 16.x, can handle over 1M (2 = ) rows, and (2, labeled as column 'XFD') columns. | https://en.wikipedia.org/wiki?curid=20268 |
9,570 | Microsoft Excel up until 2007 version used a proprietary binary file format called Excel Binary File Format (.XLS) as its primary format. Excel 2007 uses Office Open XML as its primary file format, an XML-based format that followed after a previous XML-based format called "XML Spreadsheet" ("XMLSS"), first introduced in Excel 2002. | https://en.wikipedia.org/wiki?curid=20268 |
9,571 | Although supporting and encouraging the use of new XML-based formats as replacements, Excel 2007 remained backwards-compatible with the traditional, binary formats. In addition, most versions of Microsoft Excel can read CSV, DBF, SYLK, DIF, and other legacy formats. Support for some older file formats was removed in Excel 2007. The file formats were mainly from DOS-based programs. | https://en.wikipedia.org/wiki?curid=20268 |
9,572 | OpenOffice.org has created documentation of the Excel format. Two epochs of the format exist: the 97-2003 OLE format, and the older stream format. Microsoft has made the Excel binary format specification available to freely download. | https://en.wikipedia.org/wiki?curid=20268 |
9,573 | The "XML Spreadsheet" format introduced in Excel 2002 is a simple, XML based format missing some more advanced features like storage of VBA macros. Though the intended file extension for this format is ".xml", the program also correctly handles XML files with ".xls" extension. This feature is widely used by third-party applications (e.g. "MySQL Query Browser") to offer "export to Excel" capabilities without implementing binary file format. The following example will be correctly opened by Excel if saved either as "Book1.xml" or "Book1.xls": | https://en.wikipedia.org/wiki?curid=20268 |
9,574 | Microsoft Excel 2007, along with the other products in the Microsoft Office 2007 suite, introduced new file formats. The first of these (.xlsx) is defined in the Office Open XML (OOXML) specification. | https://en.wikipedia.org/wiki?curid=20268 |
9,575 | Windows applications such as Microsoft Access and Microsoft Word, as well as Excel can communicate with each other and use each other's capabilities. The most common are Dynamic Data Exchange: although strongly deprecated by Microsoft, this is a common method to send data between applications running on Windows, with official MS publications referring to it as "the protocol from hell". As the name suggests, it allows applications to supply data to others for calculation and display. It is very common in financial markets, being used to connect to important financial data services such as Bloomberg and Reuters. | https://en.wikipedia.org/wiki?curid=20268 |
9,576 | OLE Object Linking and Embedding allows a Windows application to control another to enable it to format or calculate data. This may take on the form of "embedding" where an application uses another to handle a task that it is more suited to, for example a PowerPoint presentation may be embedded in an Excel spreadsheet or vice versa. | https://en.wikipedia.org/wiki?curid=20268 |
9,577 | Excel users can access external data sources via Microsoft Office features such as (for example) connections built with the Office Data Connection file format. Excel files themselves may be updated using a Microsoft supplied ODBC driver. | https://en.wikipedia.org/wiki?curid=20268 |
9,578 | Excel can accept data in real-time through several programming interfaces, which allow it to communicate with many data sources such as Bloomberg and Reuters (through addins such as Power Plus Pro). | https://en.wikipedia.org/wiki?curid=20268 |
9,579 | Programmers have produced APIs to open Excel spreadsheets in a variety of applications and environments other than Microsoft Excel. These include opening Excel documents on the web using either ActiveX controls, or plugins like the Adobe Flash Player. The Apache POI opensource project provides Java libraries for reading and writing Excel spreadsheet files. | https://en.wikipedia.org/wiki?curid=20268 |
9,580 | All passwords except "password to open a document" can be removed instantly regardless of the Microsoft Excel version used to create the document. These types of passwords are used primarily for shared work on a document. Such password-protected documents are not encrypted, and a data sources from a set password is saved in a document's header. "Password to protect workbook" is an exception – when it is set, a document is encrypted with the standard password “"VelvetSweatshop"”, but since it is known to the public, it actually does not add any extra protection to the document. The only type of password that can prevent a trespasser from gaining access to a document is "password to open a document". The cryptographic strength of this kind of protection depends strongly on the Microsoft Excel version that was used to create the document. | https://en.wikipedia.org/wiki?curid=20268 |
9,581 | In "Microsoft Excel 95" and earlier versions, the password to open is converted to a 16-bit key that can be instantly cracked. In "Excel 97/2000" the password is converted to a 40-bit key, which can also be cracked very quickly using modern equipment. As regards services that use rainbow tables (e.g. Password-Find), it takes up to several seconds to remove protection. In addition, password-cracking programs can brute-force attack passwords at a rate of hundreds of thousands of passwords a second, which not only lets them decrypt a document but also find the original password. | https://en.wikipedia.org/wiki?curid=20268 |
9,582 | In "Excel 2003/XP" the encryption is slightly better – a user can choose any encryption algorithm that is available in the system (see Cryptographic Service Provider). Due to the CSP, an "Excel" file can't be decrypted, and thus the "password to open" can't be removed, though the brute-force attack speed remains quite high. Nevertheless, the older "Excel 97/2000" algorithm is set by the default. Therefore, users who do not change the default settings lack reliable protection of their documents. | https://en.wikipedia.org/wiki?curid=20268 |
9,583 | The situation changed fundamentally in "Excel 2007", where the modern AES algorithm with a key of 128 bits started being used for decryption, and a 50,000-fold use of the hash function SHA1 reduced the speed of brute-force attacks down to hundreds of passwords per second. In "Excel 2010", the strength of the protection by the default was increased two times due to the use of a 100,000-fold SHA1 to convert a password to a key. | https://en.wikipedia.org/wiki?curid=20268 |
9,584 | Excel Mobile is a spreadsheet program that can edit XLSX files. It can edit and format text in cells, calculate formulas, search within the spreadsheet, sort rows and columns, freeze panes, filter the columns, add comments, and create charts. It can't add columns or rows except at the edge of the document, rearrange columns or rows, delete rows or columns, or add spreadsheet tabs. The 2007 version has the ability to use a full-screen mode to deal with limited screen resolution, as well as split panes to view different parts of a worksheet at one time. Protection settings, zoom settings, autofilter settings, certain chart formatting, hidden sheets, and other features are not supported on Excel Mobile, and will be modified upon opening and saving a workbook. In 2015, Excel Mobile became available for Windows 10 and Windows 10 Mobile on Windows Store. | https://en.wikipedia.org/wiki?curid=20268 |
9,585 | Excel for the web is a free lightweight version of Microsoft Excel available as part of Office on the web, which also includes web versions of Microsoft Word and Microsoft PowerPoint. | https://en.wikipedia.org/wiki?curid=20268 |
9,586 | Excel for the web can display most of the features available in the desktop versions of Excel, although it may not be able to insert or edit them. Certain data connections are not accessible on Excel for the web, including with charts that may use these external connections. Excel for the web also cannot display legacy features, such as Excel 4.0 macros or Excel 5.0 dialog sheets. There are also small differences between how some of the Excel functions work. | https://en.wikipedia.org/wiki?curid=20268 |
9,587 | Microsoft Excel Viewer was a freeware program for Microsoft Windows for viewing and printing spreadsheet documents created by Excel. Microsoft retired the viewer in April 2018 with the last security update released in February 2019 for Excel Viewer 2007 (SP3). | https://en.wikipedia.org/wiki?curid=20268 |
9,588 | The first version released by Microsoft was Excel 97 Viewer. Excel 97 Viewer was supported in Windows CE for Handheld PCs. In October 2004, Microsoft released Excel Viewer 2003. In September 2007, Microsoft released Excel Viewer 2003 Service Pack 3 (SP3). In January 2008, Microsoft released Excel Viewer 2007 (featuring a non-collapsible Ribbon interface). In April 2009, Microsoft released Excel Viewer 2007 Service Pack 2 (SP2). In October 2011, Microsoft released Excel Viewer 2007 Service Pack 3 (SP3). | https://en.wikipedia.org/wiki?curid=20268 |
9,589 | Microsoft advises to view and print Excel files for free to use the Excel Mobile application for Windows 10 and for Windows 7 and Windows 8 to upload the file to OneDrive and use Excel for the web with a Microsoft account to open them in a browser. | https://en.wikipedia.org/wiki?curid=20268 |
9,590 | In addition to issues with spreadsheets in general, other problems specific to Excel include numeric precision, misleading statistics functions, mod function errors, date limitations and more. | https://en.wikipedia.org/wiki?curid=20268 |
9,591 | Despite the use of 15-figure precision, Excel can display many more figures (up to thirty) upon user request. But the displayed figures are "not" those actually used in its computations, and so, for example, the difference of two numbers may differ from the difference of their displayed values. Although such departures are usually beyond the 15th decimal, exceptions do occur, especially for very large or very small numbers. Serious errors can occur if decisions are made based upon automated comparisons of numbers (for example, using the Excel "If" function), as equality of two numbers can be unpredictable. | https://en.wikipedia.org/wiki?curid=20268 |
9,592 | In the figure, the fraction 1/9000 is displayed in Excel. Although this number has a decimal representation that is an infinite string of ones, Excel displays only the leading 15 figures. In the second line, the number one is added to the fraction, and again Excel displays only 15 figures. In the third line, one is subtracted from the sum using Excel. Because the sum in the second line has only eleven 1's after the decimal, the difference when 1 is subtracted from this displayed value is three 0's followed by a string of eleven 1's. However, the difference reported by Excel in the third line is three 0's followed by a string of "thirteen" 1's and two extra erroneous digits. This is because Excel calculates with about half a digit more than it displays. | https://en.wikipedia.org/wiki?curid=20268 |
9,593 | Excel works with a modified 1985 version of the IEEE 754 specification. Excel's implementation involves conversions between binary and decimal representations, leading to accuracy that is on average better than one would expect from simple fifteen digit precision, but that can be worse. See the main article for details. | https://en.wikipedia.org/wiki?curid=20268 |
9,594 | Besides accuracy in user computations, the question of accuracy in Excel-provided functions may be raised. Particularly in the arena of statistical functions, Excel has been criticized for sacrificing accuracy for speed of calculation. | https://en.wikipedia.org/wiki?curid=20268 |
9,595 | As many calculations in Excel are executed using VBA, an additional issue is the accuracy of VBA, which varies with variable type and user-requested precision. | https://en.wikipedia.org/wiki?curid=20268 |
9,596 | The accuracy and convenience of statistical tools in Excel has been criticized, as mishandling missing data, as returning incorrect values due to inept handling of round-off and large numbers, as only selectively updating calculations on a spreadsheet when some cell values are changed, and as having a limited set of statistical tools. Microsoft has announced some of these issues are addressed in Excel 2010. | https://en.wikipedia.org/wiki?curid=20268 |
9,597 | Excel has issues with modulo operations. In the case of excessively large results, Excel will return the error warning instead of an answer. | https://en.wikipedia.org/wiki?curid=20268 |
9,598 | Excel includes February 29, 1900, incorrectly treating 1900 as a leap year, even though e.g. 2100 is correctly treated as a non-leap year. The bug originated from Lotus 1-2-3 (deliberately implemented to save computer memory), and was also purposely implemented in Excel, for the purpose of bug compatibility. This legacy has later been carried over into Office Open XML file format. | https://en.wikipedia.org/wiki?curid=20268 |
9,599 | Thus a (not necessarily whole) number greater than or equal to 61 interpreted as a date and time are the (real) number of days after December 30, 1899, 0:00, a non-negative number less than 60 is the number of days after December 31, 1899, 0:00, and numbers with whole part 60 represent the fictional day. | https://en.wikipedia.org/wiki?curid=20268 |
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