Quantum Physics Revealed As Non-Mysterious This is one of several shortened indices into the Quantum Physics Sequence. Hello! You may have been directed to this page because you said something along the lines of "Quantum physics shows that reality doesn't exist apart from our observation of it," or "Science has disproved the idea of an objective reality," or even just "Quantum physics is one of the great mysteries of modern science; no one understands how it works." There was a time, roughly the first half-century after quantum physics was invented, when this was more or less true. The series of posts indexed below will show you - not just tell you - what's really going on down there. Some optional preliminaries you might want to read: Reductionism: We build models of the universe that have many different levels of description. And here's the main sequence: Quantum Explanations: Quantum mechanics doesn't deserve its fearsome reputation.
Cosmological Interpretations of Quantum Mechanics It seems that there’s now a new burgeoning field bringing together multiverse studies and interpretational issues in quantum mechanics. Last year Aguirre, Tegmark and Layzer came out with with Born in an Infinite Universe: a Cosmological Interpretation of Quantum Mechanics, which claimed: This analysis unifies the classical and quantum levels of parallel universes that have been discussed in the literature, and has implications for several issues in quantum measurement theory… the analysis suggests a “cosmological interpretation” of quantum theory in which the wave function describes the actual spatial collection of identical quantum systems, and quantum uncertainty is attributable to the observer’s inability to self-locate in this collection. Our framework provides a fully unified treatment of quantum measurement processes and the multiverse. We conclude that the eternally inflating multiverse and many worlds in quantum mechanics are the same.
10 Enormous Numbers Technology One of the first questions that kids often ask is “What is the biggest number?” This question is an important step in transitioning to a world of abstract concepts. The answer is of course that numbers are generally considered endless, but there gets to be a point were numbers become so big that there really is no point in having them, they have no real importance outside of the fact that yes technically they do exist. Ten to the eightieth power – a 1 with 80 zeros after it – is quite massive but somewhat tangible at least from a relatively concrete point of view. The word googol, with a slightly different spelling, has become a frequently used verb in modern times, thanks to a highly popular search engine. A Plank length is extremely small, approximately 1.616199 x 10-35 meters, or in long form 0.00000000000000000000000000000616199 meters. The third largest number on this list, the number of all the plank volumes in the universe, consists of 185 digits. Sorry, had to do it.
Scalar field theory In theoretical physics, scalar field theory can refer to a classical or quantum theory of scalar fields. A field which is invariant under any Lorentz transformation is called a "scalar", in contrast to a vector or tensor field. The quanta of the quantized scalar field are spin-zero particles, and as such are bosons. The only fundamental scalar field that has been observed in nature is the Higgs field. However, scalar fields appear in the effective field theory descriptions of many physical phenomena. An example is the pion, which is actually a "pseudoscalar", which means it is not invariant under parity transformations which invert the spatial directions, distinguishing it from a true scalar, which is parity-invariant. , has a particularly simple form: it is diagonal, and here we use the + − − − sign convention. Classical scalar field theory[edit] Linear (free) theory[edit] where is known as a Lagrangian density, dD-1 ≝ dx⋅dy⋅dz ≝ dx1⋅dx2⋅dx3 for the three spatial coordinates, . The n! . .
Applications Gravitation quantique à boucles - LQG - Loop Quantum Gravity - Gravitation quantique La gravitation quantique à boucles est l'une des principales voies de recherche concernant le problème de l'élaboration d'une théorie capable de décrire l'aspect quantique de la gravitation. Il faut en effet une théorie quantique de la gravitation lorsque l'on veut comprendre la naissance de l'univers et ce qui se passe à l'intérieur des trous noirs. Dans le cadre de la relativité générale classique, il apparaît alors dans ces situations des singularités avec des divergences de certaines quantités physiques indésirables. Le sujet de la gravitation quantique est extrêmement vaste et il faudrait probablement des centaines de pages pour lui rendre justice. La cosmologie quantique En résumé, on cherche à appliquer les règles de quantification standards dites canoniques aux équations d’Einstein, ce qui veut dire qu’on cherche à mettre ces dernières sous une forme dite hamiltonienne bien connue avec la mécanique analytique. décrit par une équation de Klein-Gordon avec un potentiel V( ).
How to Find and Care for a Pet Tardigrade ( Water Bear ) 'Water bears' is a colloquial name for tiny multicellular critters (typically 0.05-1.5mm long, depending on the species) that have always delighted microscopists. They are properly called tardigrades, and with four pairs of stumpy legs with a slow lumbering gait they do look like a microscopic bear (an eight legged, microscopic bear, that is). Tardigrades ( Water Bears ) live in moss and ferns. They are some of the most amazing animals on Earth. They can survive: Temperatures as low as -200 °C (-328 °F) and as high as 151 °C (304 °F);Freezing in a block of ice,Lack of oxygen,Lack of water for as long as decade(s).Levels of X-ray radiation 1000x the lethal human dose,Most noxious chemicals,Boiling alcohol,Low pressure of a vacuum; like that of space,And high pressure (up to 6x the pressure of the deepest part of the ocean). They may be microscopic, but are very cool! Ad Steps Give us 3 minutes of knowledge! Can you tell us about Painting doors? Removing paint? Mosquito control? Tips Warnings
Lagrangian The Lagrangian, L, of a dynamical system is a function that summarizes the dynamics of the system. The Lagrangian is named after Italian-French mathematician and astronomer Joseph Louis Lagrange. The concept of a Lagrangian was introduced in a reformulation of classical mechanics introduced by Lagrange known as Lagrangian mechanics. Definition[edit] In classical mechanics, the natural form of the Lagrangian is defined as the kinetic energy, T, of the system minus its potential energy, V.[1] In symbols, If the Lagrangian of a system is known, then the equations of motion of the system may be obtained by a direct substitution of the expression for the Lagrangian into the Euler–Lagrange equation. , but solving any equivalent Lagrangians will give the same equations of motion.[2][3] The Lagrangian formulation[edit] Simple example[edit] The trajectory of a thrown ball is characterized by the sum of the Lagrangian values at each time being a (local) minimum. Importance[edit] does not depend on . . .
EPR paradox Albert Einstein The EPR paradox is an early and influential critique leveled against the Copenhagen interpretation of quantum mechanics. Albert Einstein and his colleagues Boris Podolsky and Nathan Rosen (known collectively as EPR) designed a thought experiment which revealed that the accepted formulation of quantum mechanics had a consequence which had not previously been noticed, but which looked unreasonable at the time. The scenario described involved the phenomenon that is now known as quantum entanglement. According to quantum mechanics, under some conditions, a pair of quantum systems may be described by a single wave function, which encodes the probabilities of the outcomes of experiments that may be performed on the two systems, whether jointly or individually. At the time the EPR article discussed below was written, it was known from experiments that the outcome of an experiment sometimes cannot be uniquely predicted. History of EPR developments[edit] Einstein's opposition[edit]
Théorie de la Double Causalité La Théorie de la Double Causalité (TDC) vient de recevoir un soutien très inattendu de la part d'un physicien de renom - Stephen Hawking - qui dans son dernier livre "The Great Design" traduit en français sous le titre "Y a-t-il un grand architecte dans l'univers ?" reprend tous ses arguments de base, y compris celui qui pouvait sembler le plus stupéfiant: le concept de déterminisme inversé, qui s'avère tout à fait équivalent à la Cosmologie Descendante - ou Cosmologie Top-Down - avancée par Stephen Hawking, puisqu'il écrit page 171: <<En cosmologie, il faut renoncer à voir l'histoire de l'univers selon une approche ascendante supposant une histoire unique avec un point de départ et une évolution, mais au contraire adopter une approche descendante en remontant le cours des histoires possibles à partir du présent.... Mais ce n'est pas tout ! En prétendant donc répondre à la question "Y-a t-il un grand architecte dans l'univers ?" Pour conclure, voici deux petites distractions:
The tardigrade genome has been sequenced, and it has the most foreign DNA of any animal Scientists have sequenced the entire genome of the tardigrade, AKA the water bear, for the first time. And their results suggest that this weird little creature has the most foreign genes of any animal studied so far – or to put it another way, roughly one-sixth of the tardigrade's genome was stolen from other species. We have to admit, we're kinda not surprised. A little background here for those who aren’t familiar with the strangeness that is the tardigrade – the microscopic water creature grows to just over 1 mm on average, and is the only animal that can survive in the harsh environment of space. It can also withstand temperatures from just above absolute zero to well above the boiling point of water, can cope with ridiculous amounts of pressure and radiation, and can live for more than 10 years without food or water. Basically, it's nearly impossible to kill, and now scientists have shown that its DNA is just as bizarre as it is.