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62-649: The Neutrino Ettore Majorana Observatory ( NEMO experiment ) is an international collaboration of scientists searching for neutrinoless double beta decay (0νββ). The collaboration has been active since 1989. Observation of 0νββ would indicate neutrinos are Majorana particles and could be used to measure the neutrino mass. It is located in the Modane Underground Laboratory (LSM) in the Fréjus Road Tunnel . The experiment has (as of 2018) had 3 detectors, NEMO-1, NEMO-2, NEMO-3 (and

124-416: A 47 kg⋅y search for 0νββ of molybdenum-100 yielded T 1/2 > 1.1 × 10 years . This can be translated into an upper limit on the effective neutrino mass: m v < 0.3–0.9 eV , depending on the nuclear model. NEMO 2νββ Half-life Measurements NEMO Highest 0νββ Decay Lower Limits The Zr decay is particularly relevant because of its high Q and use in searches for time-dependence of

186-435: A mathematical theory , in the sense that the word "theory" has a different meaning in mathematical terms. R i c = k g {\displaystyle \mathrm {Ric} =kg} The equations for an Einstein manifold , used in general relativity to describe the curvature of spacetime A physical theory involves one or more relationships between various measurable quantities. Archimedes realized that

248-404: A certain economy and elegance (compare to mathematical beauty ), a notion sometimes called " Occam's razor " after the 13th-century English philosopher William of Occam (or Ockham), in which the simpler of two theories that describe the same matter just as adequately is preferred (but conceptual simplicity may mean mathematical complexity). They are also more likely to be accepted if they connect

310-481: A demonstrator module of SuperNEMO-detector) and is planning (as of 2018) to construct a new detector SuperNEMO. The NEMO-1 and NEMO-2 prototype detectors were used until 1997. Latest experiment NEMO-3 was under design and construction from 1994 onwards, took data from January 2003 to January 2011 and the final data analysis was published in 2018. The NEMO-2 and NEMO-3 detectors produced measurements for double neutrino decays and limits for neutrinoless double-beta decay for

372-500: A form of protoscience and others are a form of pseudoscience . The falsification of the original theory sometimes leads to reformulation of the theory. "Thought" experiments are situations created in one's mind, asking a question akin to "suppose you are in this situation, assuming such is true, what would follow?". They are usually created to investigate phenomena that are not readily experienced in every-day situations. Famous examples of such thought experiments are Schrödinger's cat ,

434-510: A friend and mentor of Heisenberg. "In the fall of 1933, Majorana returned to Rome in poor health, having developed acute gastritis in Germany and apparently suffering from nervous exhaustion. Put on a strict diet, he grew reclusive and became harsh in his dealings with his family. To his mother, with whom he had previously shared a warm relationship, he had written from Germany that he would not accompany her on their customary summer vacation by

496-448: A good account of experimentally-observed core electron energies of gadolinium and uranium , and of the fine structure splitting of caesium lines observed in optical spectra. In 1931, Majorana published the first paper on the phenomenon of autoionization in atomic spectra, which he called "spontaneous ionization"; an independent paper in the same year, published by Allen Shenstone of Princeton University , called it "auto-ionization",

558-766: A good example. For instance: " phenomenologists " might employ ( semi- ) empirical formulas and heuristics to agree with experimental results, often without deep physical understanding . "Modelers" (also called "model-builders") often appear much like phenomenologists, but try to model speculative theories that have certain desirable features (rather than on experimental data), or apply the techniques of mathematical modeling to physics problems. Some attempt to create approximate theories, called effective theories , because fully developed theories may be regarded as unsolvable or too complicated . Other theorists may try to unify , formalise, reinterpret or generalise extant theories, or create completely new ones altogether. Sometimes

620-561: A junior professor at the Institute of Physics in Rome. This work was an early quantitative application to atomic spectroscopy of Fermi's statistical model of atomic structure (now known as the Thomas–Fermi model , due to its contemporaneous description by Llewellyn Thomas ). In this paper, Majorana and Gentile performed first-principles calculations within the context of this model that gave

682-577: A name first used by Pierre Auger . This name, without the hyphen, has since become the conventional term for the phenomenon. Majorana earned his Laurea in physics at the University of Rome La Sapienza in 1929. In 1932, he published a paper in the field of atomic spectroscopy concerning the behaviour of aligned atoms in time-varying magnetic fields. This problem, also studied by I. I. Rabi and others, led to development of an important sub-branch of atomic physics, that of radio-frequency spectroscopy. In

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744-498: A new branch of mathematics: infinite, orthogonal series . Modern theoretical physics attempts to unify theories and explain phenomena in further attempts to understand the Universe , from the cosmological to the elementary particle scale. Where experimentation cannot be done, theoretical physics still tries to advance through the use of mathematical models. Mainstream theories (sometimes referred to as central theories ) are

806-400: A number of elements, such as molybdenum-100 and selenium-82. These double beta decay times are important contributions to understanding the nucleus and are needed inputs for neutrinoless decay studies, which constrain neutrino mass. The NEMO collaboration remains active and is constructing an improved SuperNEMO detector. Planning of SuperNEMO and commissioning of SuperNEMO demonstrator module

868-486: A scientific colleague, but a warm personal friend." The Nazis had come to power in Germany as Majorana arrived there. He worked on a theory of the nucleus (published in German in 1933) which, in its treatment of exchange forces, represented a further development of Heisenberg's theory of the nucleus. Majorana also travelled to Copenhagen that year, where he worked with Niels Bohr , another Nobel Prize winner, and

930-498: A ship floats by displacing its mass of water, Pythagoras understood the relation between the length of a vibrating string and the musical tone it produces. Other examples include entropy as a measure of the uncertainty regarding the positions and motions of unseen particles and the quantum mechanical idea that ( action and) energy are not continuously variable. Theoretical physics consists of several different approaches. In this regard, theoretical particle physics forms

992-498: A ticket to travel by ship from Palermo to return to Naples. He never was seen again. Italian writer Leonardo Sciascia has summarized some of the results of investigations and hypotheses about the disappearance; however, some of Sciascia's conclusions were refuted by some of Majorana's former colleagues, including E. Amaldi and E. Segrè. Recami critically examines various hypotheses about Majorana's disappearance, including those advanced by Sciascia, and presents suggestive evidence for

1054-478: A trip from Naples to Palermo. He may have traveled to Palermo hoping to visit his friend Emilio Segrè , a professor at the university there, but Segrè was in California at that time. In Palermo, Majorana purchased a ticket on 25 March 1938 for a boat trip to return to Naples. He disappeared in unknown circumstances. Despite several investigations, his body was not found and his fate is still uncertain. On

1116-469: A wide range of phenomena. Testing the consequences of a theory is part of the scientific method . Physical theories can be grouped into three categories: mainstream theories , proposed theories and fringe theories . Theoretical physics began at least 2,300 years ago, under the Pre-socratic philosophy , and continued by Plato and Aristotle , whose views held sway for a millennium. During

1178-593: Is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict natural phenomena . This is in contrast to experimental physics , which uses experimental tools to probe these phenomena. The advancement of science generally depends on the interplay between experimental studies and theory . In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations. For example, while developing special relativity , Albert Einstein

1240-497: Is a model of physical events. It is judged by the extent to which its predictions agree with empirical observations. The quality of a physical theory is also judged on its ability to make new predictions which can be verified by new observations. A physical theory differs from a mathematical theorem in that while both are based on some form of axioms , judgment of mathematical applicability is not based on agreement with any experimental results. A physical theory similarly differs from

1302-399: Is on-going as of 2019. Other 0νββ experiments use the same material for the source of double beta decays and the detector. This allows a large mass of source material to be used and thereby maximizes the sensitivity of the experiment, but limits its flexibility. NEMO takes a different approach, using thin foils of source material surrounded by a separate tracking calorimeter . This allows

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1364-539: The EPR thought experiment , simple illustrations of time dilation , and so on. These usually lead to real experiments designed to verify that the conclusion (and therefore the assumptions) of the thought experiments are correct. The EPR thought experiment led to the Bell inequalities , which were then tested to various degrees of rigor , leading to the acceptance of the current formulation of quantum mechanics and probabilism as

1426-572: The Scientific Revolution gathered pace, the concepts of matter , energy, space, time and causality slowly began to acquire the form we know today, and other sciences spun off from the rubric of natural philosophy . Thus began the modern era of theory with the Copernican paradigm shift in astronomy, soon followed by Johannes Kepler 's expressions for planetary orbits, which summarized the meticulous observations of Tycho Brahe ;

1488-461: The two-fluid theory of electricity are two cases in this point. However, an exception to all the above is the wave–particle duality , a theory combining aspects of different, opposing models via the Bohr complementarity principle . Physical theories become accepted if they are able to make correct predictions and no (or few) incorrect ones. The theory should have, at least as a secondary objective,

1550-429: The 19th century. Another important event in the 19th century was the discovery of electromagnetic theory , unifying the previously separate phenomena of electricity, magnetism and light. The pillars of modern physics , and perhaps the most revolutionary theories in the history of physics, have been relativity theory and quantum mechanics . Newtonian mechanics was subsumed under special relativity and Newton's gravity

1612-588: The 2006 Majorana Prize were Erasmo Recami  [ it ] ( University of Bergamo and INFN ) and George Sudarshan ( University of Texas ); of the 2007 Majorana Prize: Lee Smolin ( Perimeter Institute for Theoretical Physics , Canada), Eliano Pessa  [ it ] (Centro Interdipartimentale di Scienze Cognitive, Università di Pavia and Dipartimento di Psicologia, Università di Pavia Piazza Botta, Italy) and Marcello Cini  [ it ] (Dipartimento di Fisica, Università La Sapienza, Roma, Italy). Theoretical physicist Theoretical physics

1674-476: The Dutchmen Snell and Huygens. In the 18th and 19th centuries Joseph-Louis Lagrange , Leonhard Euler and William Rowan Hamilton would extend the theory of classical mechanics considerably. They picked up the interactive intertwining of mathematics and physics begun two millennia earlier by Pythagoras. Among the great conceptual achievements of the 19th and 20th centuries were the consolidation of

1736-587: The Earth ) or may be an alternative model that provides answers that are more accurate or that can be more widely applied. In the latter case, a correspondence principle will be required to recover the previously known result . Sometimes though, advances may proceed along different paths. For example, an essentially correct theory may need some conceptual or factual revisions; atomic theory , first postulated millennia ago (by several thinkers in Greece and India ) and

1798-473: The age of 32, he became a full professor of theoretical physics at the University of Naples independently of the competition rules, without needing to take an examination because of his "high fame of singular expertise reached in the field of theoretical physics". Majorana did prescient theoretical work on neutrino masses , an active subject of research as of 2017 . Reportedly, Majorana had withdrawn all of his money from his bank account prior to making

1860-419: The applications of relativity to problems in astronomy and cosmology respectively . All of these achievements depended on the theoretical physics as a moving force both to suggest experiments and to consolidate results — often by ingenious application of existing mathematics, or, as in the case of Descartes and Newton (with Leibniz ), by inventing new mathematics. Fourier's studies of heat conduction led to

1922-514: The body of knowledge of both factual and scientific views and possess a usual scientific quality of the tests of repeatability, consistency with existing well-established science and experimentation. There do exist mainstream theories that are generally accepted theories based solely upon their effects explaining a wide variety of data, although the detection, explanation, and possible composition are subjects of debate. The proposed theories of physics are usually relatively new theories which deal with

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1984-739: The centennial of Majorana's birth in Catania, 5–6 October 2006. The conference proceedings with articles of highly ranked international scientists A. Bianconi, D. Brink, N. Cabibbo , R. Casalbuoni, G. Dragoni, S. Esposito, E. Fiorini, M. Inguscio, R. W. Jackiw, L. Maiani , R. Mantegna, E. Migneco, R. Petronzio, B. Preziosi, R. Pucci, E. Recami, and Antonino Zichichi have been published by POS Proceedings of Science of SISSA , edited by Andrea Rapisarda (chairman), Paolo Castorina, Francesco Catara, Salvatore Lo Nigro, Emilio Migneco, Francesco Porto, and Emanuele Rimini. A commemorative book of his nine collected papers, with commentary and English translations,

2046-497: The day of his disappearance, Majorana sent the following note from Palermo to Antonio Carrelli, director of the Naples Physics Institute: Dear Carrelli, I made a decision that has become unavoidable. There isn't a bit of selfishness in it, but I realize what trouble my sudden disappearance will cause you and the students. For this as well, I beg your forgiveness, but especially for betraying

2108-750: The double beta decay. They are identified by their curvature in a magnetic field and particle energy is measured in a calorimeter. In 0νββ, the sum of the electron and positron energies will be the( Q value ) released in double beta decay. For standard double beta decay the neutrinos, which cannot be observed directly, reduce the detected energy. Neutrinoless double beta decay (0νββ) has not been observed in 5 years of data taking and limits have been set for several isotopes. NEMO-2 reported 0νββ limits for Majoron models of Mo, Cd, Se and Zr. NEMO-3 reported precision 2νββ half-lives for its 7 isotopes and 0νββ limits for Zr, Ca, Nd at Neutrino08. NEMO-3 reported 2νββ and more 0νββ limits at SUSY08. In 2014, NEMO-3 reported

2170-432: The existence of an unknown particle that they suggested was a gamma ray . Majorana was the first to interpret correctly the experiment as requiring a new particle that had a neutral charge and a mass about the same as the proton ; this particle is the neutron . Fermi advised him to write an article on the topic, but Majorana did not. James Chadwick proved the existence of the neutron by experiment later that year, and he

2232-685: The form of a thin foil. The installation of a first module (using selenium-82) in the LSM is under way, with data taking expected in the second half of 2015. As of 2019, the commissioning of the SuperNEMO demonstration module (basically one of the 20 modulus of the whole SuperNEMO) is underway, and the collaboration continues to plan to construct the whole 20-module SuperNEMO detector. Ettore Majorana Ettore Majorana ( / m aɪ ə ˈ r ɑː n ə / , Italian: [ˈɛttore majoˈraːna] ; born on 5 August 1906 – likely dying in or after 1959)

2294-527: The foundation for the office to declare the disappearance case officially closed, having found no criminal evidence related to his disappearance, determining that it probably was a personal choice, and a presumption that he had emigrated to Venezuela. The year 2006 marked Majorana's centenary. An international conference on "Ettore Majorana's legacy and the Physics of the XXI century" was held in commemoration of

2356-416: The highest order, writing Principia Mathematica . In it contained a grand synthesis of the work of Copernicus, Galileo and Kepler; as well as Newton's theories of mechanics and gravitation, which held sway as worldviews until the early 20th century. Simultaneously, progress was also made in optics (in particular colour theory and the ancient science of geometrical optics ), courtesy of Newton, Descartes and

2418-455: The idea of energy (as well as its global conservation) by the inclusion of heat , electricity and magnetism , and then light . The laws of thermodynamics , and most importantly the introduction of the singular concept of entropy began to provide a macroscopic explanation for the properties of matter. Statistical mechanics (followed by statistical physics and Quantum statistical mechanics ) emerged as an offshoot of thermodynamics late in

2480-675: The late 1920s. In the aftermath of World War 2, more progress brought much renewed interest in QFT, which had since the early efforts, stagnated. The same period also saw fresh attacks on the problems of superconductivity and phase transitions, as well as the first applications of QFT in the area of theoretical condensed matter. The 1960s and 70s saw the formulation of the Standard model of particle physics using QFT and progress in condensed matter physics (theoretical foundations of superconductivity and critical phenomena , among others ), in parallel to

2542-406: The neutrinoless double beta decay search are about 7 kg of enriched molybdenum-100 and about 1 kg of selenium-82 . The experiment also contains smaller amounts of cadmium-116 , neodymium-150 , zirconium-96 and calcium-48 foils. Tellurium and copper foils are used for background measurements. A tracking detector on each side of the foil detects electrons and positrons from

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2604-565: The physical constants. Geochemical measurements of ZrSiO 4 allow comparison of its historic and present rates, by extracting the resultant Mo. The final results of NEMO-3 were published in 2018. A next generation experiment, SuperNEMO, is under construction. It is based on technology used by the NEMO-3 experiment, but will be more than a factor of ten bigger. The SuperNEMO detector will consist of 20 modules each containing approximately 5 kg of enriched double beta decay emitting isotope in

2666-419: The process of becoming established and some proposed theories. It can include speculative sciences. This includes physics fields and physical theories presented in accordance with known evidence, and a body of associated predictions have been made according to that theory. Some fringe theories go on to become a widely accepted part of physics. Other fringe theories end up being disproven. Some fringe theories are

2728-541: The proposal that Majorana travelled to Argentina . Italian philosopher Giorgio Agamben published a book in 2016 that examines the case of Majorana's disappearance. Several proposed explanations for his disappearance include: In March 2011, Italian media reported that the Rome Attorney's Office had announced an inquiry into the statement made by a witness about meeting with Majorana in Buenos Aires in

2790-607: The rise of medieval universities , the only acknowledged intellectual disciplines were the seven liberal arts of the Trivium like grammar , logic , and rhetoric and of the Quadrivium like arithmetic , geometry , music and astronomy . During the Middle Ages and Renaissance , the concept of experimental science, the counterpoint to theory, began with scholars such as Ibn al-Haytham and Francis Bacon . As

2852-581: The same year, Majorana published his paper on a relativistic theory of particles with arbitrary intrinsic momentum, in which he developed and applied infinite dimensional representations of the Lorentz group , and gave a theoretical basis for the mass spectrum of elementary particles. Like most of Majorana's papers, written in Italian, it languished in relative obscurity for several decades. Experiments in 1932 by Irène Joliot-Curie and Frédéric Joliot showed

2914-676: The sea. Appearing at the institute less frequently, he soon was scarcely leaving his home; the promising young physicist had become a hermit. For nearly four years he shut himself off from friends and stopped publishing." During these years, in which he published few articles, Majorana wrote many small works on geophysics , electrical engineering , mathematics , and relativity . These unpublished papers, preserved in Domus Galileiana in Pisa , have been edited by Erasmo Recami and Salvatore Esposito. Majorana's last-published paper, in 1937,

2976-484: The study of physics which include scientific approaches, means for determining the validity of models and new types of reasoning used to arrive at the theory. However, some proposed theories include theories that have been around for decades and have eluded methods of discovery and testing. Proposed theories can include fringe theories in the process of becoming established (and, sometimes, gaining wider acceptance). Proposed theories usually have not been tested. In addition to

3038-472: The theories like those listed below, there are also different interpretations of quantum mechanics , which may or may not be considered different theories since it is debatable whether they yield different predictions for physical experiments, even in principle. For example, AdS/CFT correspondence , Chern–Simons theory , graviton , magnetic monopole , string theory , theory of everything . Fringe theories include any new area of scientific endeavor in

3100-424: The trust, the sincere friendship, and the sympathy you gave me over the past months. I ask you to remember me to all those I learned to know and appreciate in your Institute, especially Sciuti: I will keep a fond memory of them all at least until 11 pm tonight, possibly later too. — E. Majorana This was followed rapidly by a telegram from Majorana cancelling earlier travel plans. Apparently, he then bought

3162-451: The urging of Emilio Segrè . He was very young when he joined Enrico Fermi 's team in Rome as one of the " Via Panisperna boys ", who took their name from the street address of their laboratory. Majorana's first papers dealt with problems in atomic spectroscopy . His first paper, published in 1928, was written when he was an undergraduate and it was coauthored by Giovanni Gentile, Jr.,

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3224-422: The use of any source material which can be formed into a thin foil. Also, because its tracking is more accurate, it can reliably detect if two electrons come from the same place, thereby reducing false detections of double beta decays. The experiment has a cylindrical shape with 20 sectors that contain different isotopes in the form of thin foils with a total surface of about 20 m. The main isotopes used for

3286-539: The vision provided by pure mathematical systems can provide clues to how a physical system might be modeled; e.g., the notion, due to Riemann and others, that space itself might be curved. Theoretical problems that need computational investigation are often the concern of computational physics . Theoretical advances may consist in setting aside old, incorrect paradigms (e.g., aether theory of light propagation, caloric theory of heat, burning consisting of evolving phlogiston , or astronomical bodies revolving around

3348-530: The works of these men (alongside Galileo's) can perhaps be considered to constitute the Scientific Revolution. The great push toward the modern concept of explanation started with Galileo , one of the few physicists who was both a consummate theoretician and a great experimentalist . The analytic geometry and mechanics of Descartes were incorporated into the calculus and mechanics of Isaac Newton , another theoretician/experimentalist of

3410-553: The world; those of second or third rank do their best but never get very far. Then there is the first rank, those who make important discoveries, fundamental to scientific progress. But then there are the geniuses, like Galilei and Newton . Majorana was one of these." Majorana was born in Catania , Sicily . Majorana's uncle Quirino Majorana also was a physicist. Mathematically gifted, Majorana began his university studies in engineering in 1923, but switched to physics in 1928 at

3472-621: The years after World War II. On 7 June 2011 Italian media reported that the Carabinieri 's RIS had analyzed a photograph of a man taken in Argentina in 1955, finding ten points of similarity with Majorana's face. On 4 February 2015, the Rome Attorney's Office released a statement declaring that Majorana had been alive between 1955 and 1959, living in Valencia, Venezuela . Based upon new evidence, these last findings were

3534-518: Was an Italian theoretical physicist who worked on neutrino masses. On 25 March 1938, he disappeared under mysterious circumstances after purchasing a ticket to travel by ship from Naples to Palermo . The Majorana equation and Majorana fermions are named after him. In 2006, the Majorana Prize was established in his memory. In 1938, Enrico Fermi was quoted as saying about Majorana: "There are several categories of scientists in

3596-578: Was an elaboration of a symmetrical theory of electrons and positrons . He predicted that in the class of particles known as fermions, there should be particles that are their own antiparticles. Solution of the Majorana equation yields those particles, now referred to as Majorana fermions . There has been speculation that at least some part of the "missing mass" in the universe, which cannot be detected except by inference from its gravitational influence, may be composed of Majorana particles. In 1938, at

3658-587: Was awarded the Nobel Prize for this discovery. Majorana was known for not seeking credit for his discoveries, considering his work to be trivial. He wrote only nine papers in his lifetime. "At Fermi's urging, Majorana left Italy early in 1933 on a grant from the National Research Council. In Leipzig , Germany, he met Werner Heisenberg . In letters he subsequently wrote to Heisenberg, Majorana revealed that he had found in him, not only

3720-456: Was concerned with the Lorentz transformation which left Maxwell's equations invariant, but was apparently uninterested in the Michelson–Morley experiment on Earth 's drift through a luminiferous aether . Conversely, Einstein was awarded the Nobel Prize for explaining the photoelectric effect , previously an experimental result lacking a theoretical formulation. A physical theory

3782-422: Was given a kinematic explanation by general relativity . Quantum mechanics led to an understanding of blackbody radiation (which indeed, was an original motivation for the theory) and of anomalies in the specific heats of solids — and finally to an understanding of the internal structures of atoms and molecules . Quantum mechanics soon gave way to the formulation of quantum field theory (QFT), begun in

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3844-681: Was published by the Italian Physical Society in 2006. Also to commemorate the centenary, the Electronic Journal of Theoretical Physics (EJTP) published a special issue of twenty articles dedicated to the modern development of Majorana's legacy. The EJTP also established a prize in his memory to mark his centenary. The Majorana Medal or Majorana Prize is an annual prize for researchers who have shown peculiar creativity, critical sense, and mathematical rigour in theoretical physics—in its broadest sense. The recipients of

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