|
Bharat Ratra
Bharat Vishnu Ratra (born 26 January 1960) is an Indian-American physicist, theoretical cosmologist and astroparticle physicist who is currently a university distinguished professor of Physics at Kansas State University. He is known for his work on dynamical dark energy and on the quantum-mechanical generation of energy density and magnetic field fluctuations during inflation. Biography Ratra was born in Bombay (Mumbai). He graduated with a Master of Science in physics from the Indian Institute of Technology Delhi in 1982 and completed his doctorate in physics at Stanford University in 1986 under the supervision of Leonard Susskind and Michael Peskin. Ratra was a postdoctoral fellow at the Stanford Linear Accelerator Center, Princeton University, the California Institute of Technology and the Massachusetts Institute of Technology. He joined Kansas State University in 1996 as an assistant professor of physics. He was promoted to associate professor in 2001 and professor in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mumbai
Mumbai (, ; also known as Bombay — the official name until 1995) is the capital city of the Indian state of Maharashtra and the ''de facto'' financial centre of India. According to the United Nations, as of 2018, Mumbai is the second-most populous city in India after Delhi and the eighth-most populous city in the world with a population of roughly 20 million (2 crore). As per the Indian government population census of 2011, Mumbai was the most populous city in India with an estimated city proper population of 12.5 million (1.25 crore) living under the Brihanmumbai Municipal Corporation. Mumbai is the centre of the Mumbai Metropolitan Region, the sixth most populous metropolitan area in the world with a population of over 23 million (2.3 crore). Mumbai lies on the Konkan coast on the west coast of India and has a deep natural harbour. In 2008, Mumbai was named an alpha world city. It has the highest number of millionaires and billionaires among all cities i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astroparticle Physics
Astroparticle physics, also called particle astrophysics, is a branch of particle physics that studies elementary particles of astronomical origin and their relation to astrophysics and cosmology. It is a relatively new field of research emerging at the intersection of particle physics, astronomy, astrophysics, detector physics, relativity, solid state physics, and cosmology. Partly motivated by the discovery of neutrino oscillation, the field has undergone rapid development, both theoretically and experimentally, since the early 2000s. History The field of astroparticle physics is evolved out of optical astronomy. With the growth of detector technology came the more mature astrophysics, which involved multiple physics subtopics, such as mechanics, electrodynamics, thermodynamics, plasma physics, nuclear physics, relativity, and particle physics. Particle physicists found astrophysics necessary due to difficulty in producing particles with comparable energy to those found in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Physical Society
The American Physical Society (APS) is a not-for-profit membership organization of professionals in physics and related disciplines, comprising nearly fifty divisions, sections, and other units. Its mission is the advancement and diffusion of knowledge of physics. The society publishes more than a dozen scientific journals, including the prestigious '' Physical Review'' and ''Physical Review Letters'', and organizes more than twenty science meetings each year. APS is a member society of the American Institute of Physics. Since January 2021 the organization has been led by chief executive officer Jonathan Bagger. History The American Physical Society was founded on May 20, 1899, when thirty-six physicists gathered at Columbia University for that purpose. They proclaimed the mission of the new Society to be "to advance and diffuse the knowledge of physics", and in one way or another the APS has been at that task ever since. In the early years, virtually the sole activity of the AP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Science Foundation
The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health. With an annual budget of about $8.3 billion (fiscal year 2020), the NSF funds approximately 25% of all federally supported basic research conducted by the United States' colleges and universities. In some fields, such as mathematics, computer science, economics, and the social sciences, the NSF is the major source of federal backing. The NSF's director and deputy director are appointed by the President of the United States and confirmed by the United States Senate, whereas the 24 president-appointed members of the National Science Board (NSB) do not require Senate confirmation. The director and deputy director are responsible for administration, planning, budgeting and day-to-day operations of the foundation, while t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Willy Fischler
Willy Fischler (born 1949 in Antwerp, Belgium) is a theoretical physicist. He is the Jane and Roland Blumberg Centennial Professor of Physics at the University of Texas at Austin, where he is affiliated with the Weinberg theory group. He is also a certified Flight Paramedic ( FP-C) and was a Licensed Paramedic with Marble Falls Area EMS and a volunteer EMT with the Westlake Fire Department. His contributions to physics include: * Early computation of the force between heavy quarks. * The DFSZ (Dine-Fischler-Srednicki-Zhitnisky) model, as a solution to the strong CP problem. * The cosmological effects of the invisible axion (with Michael Dine) and its role as a candidate for dark matter. * Pioneering work (with Michael Dine and Mark Srednicki) on the use of supersymmetry to solve outstanding problems in the standard model of particle physics. * The first formulation of what became known as the "moduli problem in cosmology" (with G.D. Coughlan, Edward Kolb, Stuart Raby an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inflation (cosmology)
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from seconds after the conjectured Big Bang singularity to some time between and seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate. The acceleration of this expansion due to dark energy began after the universe was already over 7.7 billion years old (5.4 billion years ago). Inflation theory was developed in the late 1970s and early 80s, with notable contributions by several theoretical physicists, including Alexei Starobinsky at Landau Institute for Theoretical Physics, Alan Guth at Cornell University, and Andrei Linde at Lebedev Physical Institute. Alexei Starobinsky, Alan Guth, and Andrei Linde won the 2014 Kavli Prize "for pioneering the theory of cosmic inflation." It was developed further in the ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shape Of The Universe
The shape of the universe, in physical cosmology, is the local and global geometry of the universe. The local features of the geometry of the universe are primarily described by its curvature, whereas the topology of the universe describes general global properties of its shape as a continuous object. The spatial curvature is defined by general relativity, which describes how spacetime is curved due to the effect of gravity. The spatial topology cannot be determined from its curvature, due to the fact that there exist locally indistinguishable spaces that may be endowed with different topological invariants. Cosmologists distinguish between the observable universe and the entire universe, the former being a ball-shaped portion of the latter that can, in principle, be accessible by astronomical observations. Assuming the cosmological principle, the observable universe is similar from all contemporary vantage points, which allows cosmologists to discuss properties of the entire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble's Law
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving away from Earth. The velocity of the galaxies has been determined by their redshift, a shift of the light they emit toward the red end of the visible spectrum. Hubble's law is considered the first observational basis for the expansion of the universe, and today it serves as one of the pieces of evidence most often cited in support of the Big Bang model. The motion of astronomical objects due solely to this expansion is known as the Hubble flow. It is described by the equation , with ''H''0 the constant of proportionality—the Hubble constant—between the "proper distance" ''D'' to a galaxy, which can change over time, unlike the comoving distance, and its speed of separation ''v'', i.e. the derivative of proper distance with respect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quintessence (physics)
In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field, postulated as an explanation of the observation of an accelerating rate of expansion of the universe. The first example of this scenario was proposed by Ratra and Peebles (1988) and Wetterich (1988). The concept was expanded to more general types of time-varying dark energy, and the term "quintessence" was first introduced in a 1998 paper by Robert R. Caldwell, Rahul Dave and Paul Steinhardt. It has been proposed by some physicists to be a fifth fundamental force. Quintessence differs from the cosmological constant explanation of dark energy in that it is dynamic; that is, it changes over time, unlike the cosmological constant which, by definition, does not change. Quintessence can be either attractive or repulsive depending on the ratio of its kinetic and potential energy. Those working with this postulate believe that quintessence became repulsive about ten billion years ago, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scalar Field
In mathematics and physics, a scalar field is a function (mathematics), function associating a single number to every point (geometry), point in a space (mathematics), space – possibly physical space. The scalar may either be a pure Scalar (mathematics), mathematical number (dimensionless) or a scalar (physics), scalar physical quantity (with unit of measurement, units). In a physical context, scalar fields are required to be independent of the choice of reference frame, meaning that any two observers using the same units will agree on the value of the scalar field at the same absolute point in space (or spacetime) regardless of their respective points of origin. Examples used in physics include the temperature distribution throughout space, the pressure distribution in a fluid, and spin-zero quantum fields, such as the Higgs field. These fields are the subject of scalar field theory. Definition Mathematically, a scalar field on a Region (mathematical analysis), region ''U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Energy
In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the universe does not expand at a constant rate; rather, the universe's expansion is accelerating. Understanding the universe's evolution requires knowledge of its starting conditions and composition. Before these observations, scientists thought that all forms of matter and energy in the universe would only cause the expansion to slow down over time. Measurements of the cosmic microwave background (CMB) suggest the universe began in a hot Big Bang, from which general relativity explains its evolution and the subsequent large-scale motion. Without introducing a new form of energy, there was no way to explain how scientists could measure an accelerating universe. Since the 1990s, dark energy has been the most accepted premise to account for the acce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jim Peebles
Phillip James Edwin Peebles (born April 25, 1935) is a Canadian-American astrophysicist, astronomer, and theoretical cosmologist who is currently the Albert Einstein Professor in Science, Emeritus, at Princeton University. He is widely regarded as one of the world's leading theoretical cosmologists in the period since 1970, with major theoretical contributions to primordial nucleosynthesis, dark matter, the cosmic microwave background, and structure formation. Peebles was awarded half of the Nobel Prize in Physics in 2019 for his theoretical discoveries in physical cosmology. He shared the prize with Michel Mayor and Didier Queloz for their discovery of an exoplanet orbiting a sun-like star. While much of his work relates to the development of the universe from its first few seconds, he is more skeptical about what we can know about the very beginning, and stated, "It's very unfortunate that one thinks of the beginning whereas in fact, we have no good theory of such a thing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
