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25.01.2022 Holographic Entanglement Entropy The holographic principle was introduced in the context of string theories by Susskind. In semi-classical considerations of quantum gravity, in (d + 1)-dimensions, it states that all the information contained in a volume Vd+1 is encoded on the surface of it’s boundary Vd+1. An explicit realization of the holographic principle is the AdS/CFT correspondence. This is a duality relating a quantum gravity theory on a certain spacetime to a non-gra...vitational quantum theory on a spacetime of one dimension lower. The gravity theory is a string theory on Anti-de Sitter (AdS) spacetime in (d + 1)-dimensions and the non-gravitational theory is a conformal field theory (CFT) living on the d-dimensional boundary of AdSd+1. The AdS/CFT correspondence is sometimes called gauge/gravity duality since it’s relating gauge theories to theories with gravity. In fact, the argument was initially introduced by t’Hooft for the case of the large N limit of gauge theories (or t’Hooft limit), where N is the dimension of the gauge group. Holographic entanglement entropy (HEE) is at the intersection of quantum gravity, quantum field theory and quantum information. Holographic entanglement entropy refers to the expression of entanglement of quantum field theories expressed holographically via a version of AdS-CFT Duality in terms of the geometry of higher dimensional bulk spacetime. Understanding quantum entanglement in interacting higher-dimensional conformal field theories is a challenging task, as direct analytical calculations are often impossible to perform. With holographic entanglement entropy, calculations of entanglement entropy turn into a problem of finding extremal surfaces in a curved spacetime, which we tackle with a numerical finite-element approach. Lets see how entanglement entropy is captured holographically. This question was first addressed by Ryu and Takayanagi (RT) in which they gave a prescription for static time-independent situations. This prescription was subsequently generalized by Hubeny, Rangamani, and Takayanagi (HRT) to general states, including arbitrary time dependence.

20.01.2022 What is Quantum Zeno Effect?

18.01.2022 What are Quasars ? What are quasars? Where do they come from? And what can these deep-space objects tell us about the universe at large? Quasars are one of the brightest member of a large class of active galactic nuclei or AGN in the universe, and are thought to be powered by supermassive black holes that form the centre of most galaxies.... These objects are powered by vast quantities of gas falling into these regions, fueling an enormous output of radiation. Under the right conditions, these objects can form jets, which race away from their source at great speeds, following powerful magnetic fields. Relativistic jets in active galactic nuclei (AGN) are believed to originate from the vicinity of a supermassive black hole (SMBH), which is located at the center of the galaxy. Understanding the detailed physical processes of jet formation, acceleration, collimation, and subsequent propagation has been one of the major quests in modern astrophysics, Quasars are immensely bright. From the central point in a galaxy, they emit as much energy as thousands of giant galaxies from a region as tiny as the Solar System. They radiate energy across the electromagnetic spectrum, from radio waves to -rays. Many expel jets of particles at near-light speed, which inflate vast particle clouds or 'lobes' that measure millions of light years across and emit radio waves. There is a limit as to how bright a quasar can be, called the Eddington limit, which depends on the mass of the black hole. If too much gas falls into the black hole at once, the gas heats up and creates pressure. This pressure slows down the flow of gas, keeping the luminosity of the quasar below the Eddington limit. Quasars are generally recognised by their unusually blue optical continua and resulting broad emission lines. They also are powerful X-ray sources. Roughly ten percent of these quasars are designated radio- loud, like the first example discovered, 3C 273, because they also possess powerful radio sources; the remainder are radio-quiet, Roughly ten percent of the radio-quiet quasars also exhibit broad absorption lines and are called BALQs.

17.01.2022 Randell Sundrum Model The Randall-Sundrum model was conceived in 1999 to address the Higgs Hierarchy Problem in particle physics. It arose enormous inter- est from theoreticians and phenomenologists ever since and revealed a fruitful tool to explore the physics of extra dimensions It is a class of string theory inspired models in combined cosmology and particle physics, which assume that the observable universe constitutes the asymptotic boundary of an ambient anti de Sitter ...spacetime: the force of gravity would pertain to the full anti de sitter bulk spacetime, but the gauge fields and fermion matter fields would be constrained to reside on that boundary, as would hence be all observations made via electromagnetic radiation by observers inside this cosmology. Hence the extra bulk dimensions in these models need not be small (technically: the fiber spaces need not be compact topological spaces with tiny Riemannian volume) in order to be unobservable for observers. This is in contrast to the (historically much older) Kaluza-Klein compactification models for physics with extra dimensions. Therefore Randall-Sumdrum-like models are also referred to as large extra dimension models. See more

12.01.2022 Entanglement Entropy Entanglement: Entanglement is arguably the most fundamental according to Schr odinger and potentially disturbing characteristic distinguishing the quantum from the classical world. One could describe it as follows: it implies that the measurement of an observable of a subsystem may affect drastically and instantaneously the possible outcome of a measurement on another part of the system, no matter how far apart it is spatially. This is to be distingu...Continue reading

11.01.2022 What Is Quantum Atom Theory? French physicist named Louis de Broglie suggested that, like light, electrons could act as both particles and wave. De Broglie's hypothesis was soon confirmed in experiments that showed electron beams could be diffracted or bent as they passed through a slit much like light could. So, the waves produced by an electron confined in its orbit about the nucleus sets up a standing waves of specific wavelength, energy and frequency (i.e., Bohr's energy ...levels) much like a guitar string sets up a standing wave when plucked. If an electron traveled as a wave, could you locate the precise position of the electron within the wave? A German physicist, Werner Heisenberg, answered no in what he called the uncertainty principle. We can never know both the momentum and position of an electron in an atom. Therefore, Heisenberg said that we shouldn't view electrons as moving in well-defined orbits about the nucleus. With de Broglie's hypothesis and Heisenberg's uncertainty principle in mind, an Austrian physicist named Erwin Schrodinger derived a set of equations or wave functions in 1926 for electrons. The quantum mechanical model of the atom comes from the solution to Schrödinger’s equation. Quantization of electron energies is a requirement in order to solve the equation. This is unlike the Bohr model, in which you quantization was simply assumed with no mathematical basis. Recall that in the Bohr model, the exact path of the electron was restricted to very well-defined circular orbits around the nucleus. The quantum mechanical model is a radical departure from that. Solutions to the Schrödinger wave equation, called wave functions , give only the probability of finding an electron at a given point around the nucleus. Electrons do not travel around the nucleus in simple circular orbits. The location of the electrons in the quantum mechanical model of the atom is often referred to as an electron cloud. The darker region nearer the nucleus has high probability of finding the electron, while the lighter region further from the nucleus has a lower probability of finding the electron.

10.01.2022 Upcoming post is on supernova# writing in progress#

10.01.2022 Gauge/Gravity Duality The gauge/gravity duality is an equality between two theories: On one side we have a quantum field theory in d spacetime dimensions. On the other side we have a gravity theory on a d+1 dimensional spacetime that has an asymptotic boundary which is d dimensional. It is also sometimes called AdS/CFT , because the simplest examples involve anti-de-Sitter spaces and conformal field theories. It is often called gauge-string duality. This is be- cause the grav...ity theories are string theories and the quantum field theories are gauge theories. It is also referred to as holography because one is de- scribing a d + 1 dimensional gravity theory in terms of a lower dimensional system, in a way that is reminiscent of an optical hologram which stores a three dimensional imagine on a two dimensional photographic plate. It is called a conjecture, but by now there is a lot of evidence that it is correct. In addition, there are some derivations based on physical arguments. The simplest example involves an anti-de-Sitter spacetime. So, let us start describing this spacetime in some detail. Anti-de-Sitter is the simplest so- lution of Einstein’s equations with a negative cosmological constant. It is the lorentzian analog of hyperbolic space, which was historically the first example of a non-Euclidean geometry. In a similar way, AdS/CFT gives the simplest example of a quantum mechanical spacetime. The AdS/CFT duality is a powerful tool for analyzing strongly-coupled gauge theories using classical gravitational theories. The duality originated from string theory, so it has been actively investigated in particle physics. In recent years, however, the duality has been discussed beyond theoretical particle physics. This is because the duality is becoming a powerful tool to analyze the real world. For ex- ample, it turns out that one prediction of AdS/CFT is indeed close to the experimental results of the real quark-gluon plasma. Since then, the duality has been applied to various fields of physics; examples are QCD, nuclear physics, nonequilibrium physics, and condensed-matter physics. Roughly speaking, the AdS/CFT duality claims the following equivalence be- tween two theories: Strongly-coupled 4-dimensional gauge theory = Gravitational theory in 5-dimensional AdS spacetime

09.01.2022 Hello, please consider my theory and let me know if you think I'm onto something! The "speed of light" is really just the speed of the domino effect between qua...ntized (unmeasurable) spaces looped together a point of contact as it moves through space and it is not the speed of one particle traversing space. Two or more dominoes standing apart at a distance will each take their time to fall, and this may be visibly acknowledged as a delayed point of contact moving through space. Likewise, when Newton's balls crack together that same chain reaction of kinetic energy takes place but this time its in a line of several balls already touching, allowing the point of contact to move relatively instantly as a pressure wave, aka sound, only Newton's cradle moves so quickly that the delay is beyond human detection. Light is no different but at an even shorter delay (wave length), a tighter pressure wave along the quantized fabric of space the shortest delay possible because of its unmeasurable quantum nature being too small to possibly detect, a half decillionth of an inch. Quantum dominoes are the fastest in existence. So, when you turn the dimmer up it's kinda like yelling but with light. I offer a more visual description here: https://stephenkronstein.wordpress.com//light-as-a-chain-r Consider this: https://science.howstuffworks.com/light4.htm "The frequency of visible light is referred to as color, and ranges from 430 trillion hertz, seen as red, to 750 trillion hertz, seen as violet." If I am right about light as a chain reaction then these high frequencies tell us something about the nature of the quantum fabric of space. There must be a dielectric constant of the Universe that accounts for the delay (slight resistance) in the fabric, what limits the speed of light. I envision all waves travelling on this quantum fabric with lower frequencies travelling like bigger waves on the open sea. Sound waves travel on this same quantum fabric but with a bigger splash/frequency/wave/wobble on the surface of the pond. As a point of reference, human voices are around 100-200 hz. The mass of a planet with its electromagnetic frequency of ~8hz or so warps this same fabric to create its sense of gravity. So how about it? Am I on to something? Does light as a daisy chain provide a way to connect all of the leading theories about the Universe?

07.01.2022 Quantum Error Correction Quantum error correction (QEC) is used in quantum computing to protect quantum information from errors due to decoherence and other quantum noises. Quantum error correction is essential if one is to achieve fault-tolerant quantum computation that can deal not only with noise on stored quantum information, but also with faulty quantum gates, faulty quantum preparation, and faulty measurements. Qubit systems become more and more susceptible to noise a...s they scale up in number. Error-correcting codes that can fix bit-flip errors are important in outputting accurate results from our quantum computers. The fabric of space-time is surprisingly robust for being woven out of fragile quantum stuff. The explanation may lie in a deep connection between the nature of space-time and quantum error correction the method of protecting information in quantum computers. Recent research in quantum gravity has suggested that nature implements a quantum error-correcting code to keep space-time intact. Understanding which code is used could unravel the mysteries of black holes and help in the quest to scale up quantum computing.

07.01.2022 What is Supernova Explosion?

07.01.2022 Neutron Star A neutron star is the compressed core of a massive star the super dense cinders left over after a supernova. It has the mass of the sun, but squeezed into a space the width of a city. Gravity presses the material in on itself so tightly that protons and electrons combine to make neutrons, yielding the name "neutron star." Neutron stars are the densest reservoirs of matter in the universe the last stuff on the line before a black hole, said Mark Alfrod a phy...Continue reading

06.01.2022 Supernova A supernova is the name given to the cataclysmic explosion of a massive star at the end of its life. It can emit more energy in a few seconds than our sun will radiate in its lifetime of billions of years. There are two types of supernova. Type I and Type II. Basically, supernovae arise from two very different classes of stars: massive ones and old, non-massive ones. The Type II supernovae very strongly show the presence of the element hydrogen in their spectra. T...ype I supernovae do not show any hydrogen in their spectra. The astronomer Rudolf Minkowski discovered this distinction in 1941. Type I supernovae can be further subclassified into those with the silicon spectral feature, and these were called Type Ia supernovae, and those that do not show this feature; this latter group were called Type Ib supernovae. Supernovae are not just beautiful cosmic fireworksmany of the elements that are essential for life, such as calcium and iron, are believed to have been produced by supernovae.

06.01.2022 Bose Einstein Condensate A BoseEinstein condensate is a state of matter which is typically formed when a gas of bosons at low densities is cooled to temperatures very close to absolute zero. It formed at a fraction above absolute zero and only in atoms that act like bosons, one of two types of fundamental particles. Bosons don’t follow the Pauli exclusion principle, which prohibits two particles from existing in the same quantum state. When bosonic atoms are cooled to form a condensate, they can lose their individuality. They behave like one big collective superatom, analogous to how photons become indistinguishable in a laser beam.

05.01.2022 What is Nuclear Pasta? Nuclear pasta In astrophysics and nuclear physics, nuclear pasta is a theoretical type of degenerate matter that is postulated to exist within the crusts of neutron stars. If it does in fact exist, nuclear pasta is the strongest material in the universe. Between the surface of a neutron star and the quarkgluon plasma at the core, at matter densities of 1014 g/cm3, nuclear attraction and Coulomb repulsion forces are of similar magnitude. The competition between the forces leads to the formation of a variety of complex structures assembled from neutrons and protons. Astrophysicists call these types of structures nuclear pasta because the geometry of the structures resembles various types of pasta.

04.01.2022 Entanglement Hamiltonian While entanglement entropy and entanglement spectrum are important measures of quantum information, the entanglement Hamiltonian (EH) is a more fundamental object. The EH is a sum of the local energy density weighted by a local inverse of entanglement temperature. Knowledge of the EH could offer an alternative picture of how subsystem A behaves by appealing to our thermodynamic intuition. However, precise knowledge about the EH is rare, even for static systems. Recently, numerical efforts have attempted to obtain the EH in static interacting systems prequench state. In addition, as notable byproducts, CFT also gives time dependence of entanglement entropy to the leading order.

02.01.2022 Cosmic Microwave Background The CMB is thermal microwave radiation at a temperature of approximately 2.7 degrees above absolute zero (about 270 degree C 455 F). Its discovery transformed the hot Big Bang model into the standard model for the origin of the universe. The Big Bang model naturally explains the CMB as red-shifted remnant radiation from a time 380,000 years after the Big Bang when the universe was made up of a hot plasma of photons, electrons and baryons. The phot...Continue reading

01.01.2022 What is one electron theory?