Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize and predict natural phenomena. This is in contrast to experimental physics; the advancement of science 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 was concerned with the Lorentz transformation which left Maxwell's equations invariant, but was 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 an experimental result lacking a theoretical formulation. A physical theory is a model of physical events, it is judged by the extent. The quality of a physical theory is 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 differs from a mathematical theory, in the sense that the word "theory" has a different meaning in mathematical terms. A physical theory involves one or more relationships between various measurable quantities. Archimedes realized that 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 energy are not continuously variable. Theoretical physics consists of several different approaches. In this regard, theoretical particle physics forms a good example. For instance: "phenomenologists" might employ empirical formulas and heuristics to agree with experimental results without deep physical understanding.
"Modelers" appear much like phenomenologists, but try to model speculative theories that have certain desirable features, or apply the techniques of mathematical modeling to physics problems. Some attempt to create approximate theories, called effective theories, because developed theories may be regarded as unsolvable or too complicated. Other theorists may try to unify, reinterpret or generalise extant theories, or create new ones altogether. Sometimes the vision provided by pure mathematical systems can provide clues to how a physical system might be modeled. Theoretical problems that need computational investigation are the concern of computational physics. Theoretical advances may consist in setting aside old, incorrect paradigms or may be an alternative model that provides answers that are more accurate or that can be more applied. In the latter case, a correspondence principle will be required to recover the known result. Sometimes though, advances may proceed along different paths. For example, an correct theory may need some conceptual or factual revisions.
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 incorrect ones; the theory should have, at least as a secondary objective, a certain economy and elegance, a notion sometimes called "Occam's razor" after the 13th-century English philosopher William of Occam, in which the simpler of two theories that describe the same matter just as adequately is preferred. They are more to be accepted if they connect 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, continued by Plato and Aristotle, whose views held sway for a millennium. During the rise of medieval universities, the only acknowledged intellectual disciplines were the seven liberal arts of the Trivium like grammar and rhetoric and of the Quadrivium like arithmetic, geometry 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 the Scientific Revolution gathered pace, the concepts of matter, space and causality began to acquire the form we know today, 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.
Filippo Picinelli was an Augustinian canon. Picinelli was born in Milan, Italy in 1604 and joined the Augustinian Order in 1614, he studied philosophy and theology at Cremona and Piacenza, lived in Milan. Picinelli believed; this led him to assemble an encyclopaedia of emblems extending to more than a thousand pages, his Mondo simbolico. Ateneo dei letterati milanesi, Milan, 1670 Ateneo dei letterati milanesi. Foeminarum S. Scripturae Elogia, 1694 Latin edition Foeminarum S. Scripturae Elogia: Centuria Singularis Labores Apostolici (1711 Latin edition, Vol. 1 Labores Apostolici: Quibus accessêre Sermonis geminati in sesto Nativitatis Domini... Cum Indicibus Copiosis Sermonum, Rerum, & Applicationum ad singgulos does Quadragesimae. Labores Apostolici, Exhibiti in Secundo Quadragesimali Lumi riflessi, 1667 Mondo simbolico, 1635 Sacrarum religionum Symbola virginea Tributa encomiorum 4 Enoch
Lactarius turpis is known as the Ugly Milk-cap in English. It is found in Europe and Siberia, has been introduced to Australia and New Zealand. While associated with birch, it is found with spruce and other trees in mixed woodland; the messy, dirty appearance, seen in the photograph, is characteristic of the species and gives it its English name and the Latin species epithet, turpis. It seems to collect debris on top and the gills acquire a dirty brownish stain due to discoloured milk; this variable mushroom demonstrates a common phenomenon in mycology as there is much disagreement over naming. The three main scientific designations: Lactarius turpis Fr. Lactarius necator Karsten, Lactarius plumbeus S. F. Gray,are but not always, considered to be synonyms for same species; the epithets necator and plumbeus were both coined by Pierre Bulliard as Agaricus necator and Agaricus plumbeus, but there is and was confusion as to which mushrooms were meant. The name turpis, derived from the Latin term turpis "ugly", was originated by Johann Anton Weinmann and taken over by Elias Magnus Fries in 1838.
Plumbeus too referred to the milk-cap's appearance, derived from the Latin for plumbeus "lead-coloured". The cap is 8–20 cm in diameter. At first it has a somewhat depressed centre; the upper surface is olive brown or yellow-green and is sticky or slimy in the middle. When young it has velvety zones and may be shaggy at the rim, it becomes funnel-shaped and the colour darkens to blackish. The gills are dirty white, stained olive-brown by old milk, white on contact with the air, they are somewhat decurrent. With potassium hydroxide or ammonia there is a purple reaction; the stipe is up to about 7 cm tall by 3 cm in diameter and it is similar in colour to the cap, but much lighter. It may have shallow pits; the flesh tends to turn brown. The taste is acrid. There is little smell; the spores are ornamented with a pattern of ridges. This species is reported to contain the mutagen necatorin, so it cannot be recommended for eating. Boiling reduces the concentration of this compound, but does not eliminate it.
Due to the acrid taste, most western European authorities classify this mushroom as inedible or poor. However, it has popularly been used as a spice in mushroom dishes in northern and eastern Europe and Siberia, it is commercially available preserved in salt. Considered a choice mushroom in Russia, one of the best for pickling. List of Lactarius species