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Zero-energy Universe
The zero-energy universe hypothesis proposes that the total amount of energy in the universe is exactly zero: its amount of positive energy in the form of matter is exactly canceled out by its negative energy in the form of gravity. Some physicists, such as Lawrence Krauss, Stephen Hawking or Alexander Vilenkin, call or called this state "a universe from nothingness", although the zero-energy universe model requires both a matter field with positive energy and a gravitational field with negative energy to exist. The hypothesis is broadly discussed in popular sources. Edward P. Tryon, "Is the Universe a Vacuum Fluctuation?", ''Nature'', vol. 246, p. 396–397, 1973. Other cancellation examples include the expected symmetric prevalence of right- and left-handed angular momenta of objects ("spin" in the common sense), the observed flatness of the universe, the equal prevalence of positive and negative charges, opposing particle spin in quantum mechanics, as well as the crests and trou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy
Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and light. Energy is a Conservation law, conserved quantity—the law of conservation of energy states that energy can be Energy transformation, converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J). Forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a Classical field theory, field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, the internal energy contained within a thermodynamic system, and rest energy associated with an object's rest mass. These are not mutual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Tryon
Edward P. Tryon (September 4, 1940 – December 11, 2019) was an American scientist and a professor emeritus of physics at Hunter College of the City University of New York (CUNY). He was the first physicist to propose that our universe originated as a quantum fluctuation of the vacuum. Early life Tryon was born and raised in Terre Haute, Indiana.gribbin, p.303 He took his first physics course in his junior year at Wiley High School. Academia and intellectual influences Tryon entered Cornell University in 1958. He was influenced by Nobel Laureate Hans Bethe, who was one of his professors. He was especially affected by advice that Bethe gave him: "Our intuition is based on our experiences in the macroscopic world. There is no reason to expect our intuition to be valid for microscopic phenomena." He graduated from Cornell University in 1962, earning a bachelor's degree in physics. He would then go on to do his graduate work at the University of California, Berkeley. There he was ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Cosmology
Quantum cosmology is the attempt in theoretical physics to develop a quantum theory of the universe. This approach attempts to answer open questions of classical physical cosmology, particularly those related to the first phases of the universe. Classical cosmology is based on Albert Einstein's general theory of relativity (GTR or simply GR) which describes the evolution of the universe very well, as long as you do not approach the Big Bang. It is the gravitational singularity and the Planck time where relativity theory fails to provide what must be demanded of a final theory of space and time. Therefore, a theory is needed that integrates relativity theory and quantum theory. Such an approach is attempted for instance with loop quantum cosmology, loop quantum gravity, string theory and causal set theory. In quantum cosmology, the universe is treated as a wave function instead of classical spacetime. See also * String cosmology * Brane cosmology * Loop quantum cosm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science
Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which study the physical world, and the social sciences, which study individuals and societies. While referred to as the formal sciences, the study of logic, mathematics, and theoretical computer science are typically regarded as separate because they rely on deductive reasoning instead of the scientific method as their main methodology. Meanwhile, applied sciences are disciplines that use scientific knowledge for practical purposes, such as engineering and medicine. The history of science spans the majority of the historical record, with the earliest identifiable predecessors to modern science dating to the Bronze Age in Ancient Egypt, Egypt and Mesopotamia (). Their contributions to mathematics, astronomy, and medicine entered and shaped the Gree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Big Bang
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure. The uniformity of the universe, known as the horizon and flatness problems, is explained through cosmic inflation: a phase of accelerated expansion during the earliest stages. A wide range of empirical evidence strongly favors the Big Bang event, which is now essentially universally accepted.: "At the same time that observations tipped the balance definitely in favor of the relativistic big-bang theory, ..." Detailed measurements of the expansion rate of the universe place the Big Bang singularity at an estimated billion years ago, which is considered the age of the universe. Extrapolating this cosmic expansion backward in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brief Answers To The Big Questions
''Brief Answers to the Big Questions'' is a popular science book written by physicist Stephen Hawking, and published by Hodder & Stoughton (hardcover) and Bantam Books (paperback) on 16 October 2018. The book examines some of the universe greatest mysteries, and promotes the view that science is very important in helping to solve problems on planet Earth. The publisher describes the book as "a selection of awking'smost profound, accessible, and timely reflections from his personal archive", and is based on, according to a book reviewer, "half a million or so words" from his essays, lectures and keynote speeches. The book was incomplete at the time of the author's passing in March 2018, but was completed with "his academic colleagues, his family and the Stephen Hawking Estate". The book includes a foreword written by Eddie Redmayne, who won an Academy Award for his portrayal of Hawking in the 2014 film ''The Theory of Everything''; an introduction by Nobel Prize-winning physicis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minkowski Space
In physics, Minkowski space (or Minkowski spacetime) () is the main mathematical description of spacetime in the absence of gravitation. It combines inertial space and time manifolds into a four-dimensional model. The model helps show how a spacetime interval between any two events is independent of the inertial frame of reference in which they are recorded. Mathematician Hermann Minkowski developed it from the work of Hendrik Lorentz, Henri Poincaré, and others said it "was grown on experimental physical grounds". Minkowski space is closely associated with Einstein's theories of special relativity and general relativity and is the most common mathematical structure by which special relativity is formalized. While the individual components in Euclidean space and time might differ due to length contraction and time dilation, in Minkowski spacetime, all frames of reference will agree on the total interval in spacetime between events.This makes spacetime distance an inva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedmann–Lemaître–Robertson–Walker Metric
The Friedmann–Lemaître–Robertson–Walker metric (FLRW; ) is a metric that describes a homogeneous, isotropic, expanding (or otherwise, contracting) universe that is path-connected, but not necessarily simply connected. The general form of the metric follows from the geometric properties of homogeneity and isotropy. Depending on geographical or historical preferences, the set of the four scientists – Alexander Friedmann, Georges Lemaître, Howard P. Robertson and Arthur Geoffrey Walker – are variously grouped as Friedmann, Friedmann–Robertson–Walker (FRW), Robertson–Walker (RW), or Friedmann–Lemaître (FL). When combined with Einstein's field equations the metric gives the Friedmann equation which has been developed into the ''Standard Model'' of modern cosmology, and the further developed Lambda-CDM model. Concept The metric is a consequence of assuming that the mass in the universe has constant density – homogeneity – and is the same in all direc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nathan Rosen
Nathan Rosen (; March 22, 1909 – December 18, 1995) was an American and Israeli physicist noted for his study on the structure of the hydrogen molecule and his collaboration with Albert Einstein and Boris Podolsky on entangled wave functions and the EPR paradox. He is also remembered for the Einstein–Rosen bridge, the first known kind of wormhole. Background Nathan Rosen was born into a Jewish family in Brooklyn, New York (state), New York. He attended MIT during the Great Depression, where he received a bachelor's degree in electromechanical engineering and later a master's and a doctorate in physics. As a student he published several papers of note, one being "The Neutron," which attempted to explain the structure of the atomic nucleus a year before their discovery by James Chadwick. He also developed an interest in wave functions, and later, gravitation, when he worked as a fellow at the University of Michigan and Princeton University. State of science At the beginning of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Scientist (magazine)
''The Scientist'' is a professional magazine intended for life scientists. ''The Scientist'' covers recently published research papers, current research, techniques, and other columns and reports of interest to its readers. The magazine is published monthly and is available in print and digital formats. Overview The main purpose of the magazine is to provide print and online coverage of the latest developments in life sciences research, technology, careers, and business. Subject matters covered by the magazine include groundbreaking research, industry innovations, careers, financial topics, the economics of science, scientific ethics, profiles of scientists, lab tools, scientific publishing, techniques, product spotlight, and guides. History ''The Scientist'' was founded in 1986 by American businessman Eugene Garfield as part of his academic publishing service ''Institute for Scientific Information.'' The publishing house was sold two years later to ''JPT Publishing'', but Eug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Brief History Of Time
''A Brief History of Time: From the Big Bang to Black Holes'' is a book on cosmology by the physicist Stephen Hawking, first published in 1988. Hawking writes in non-technical terms about the structure, origin, development and eventual fate of the universe. He talks about basic concepts like space and time, building blocks that make up the universe (such as quarks) and the fundamental forces that govern it (such as gravity). He discusses two theories, general relativity and quantum mechanics that form the foundation of modern physics. Finally, he talks about the search for a unified theory that consistently describes everything in the universe. The book became a bestseller and has sold more than 25 million copies in 40 languages. It was included on ''Time'''s list of the 100 best nonfiction books since the magazine's founding. Errol Morris made a documentary, '' A Brief History of Time'' (1991) which combines material from Hawking's book with interviews featuring Hawking, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alan Guth
Alan Harvey Guth (; born February 27, 1947) is an American theoretical physicist and cosmologist who is the Victor Weisskopf Professor of Physics at the Massachusetts Institute of Technology. Along with Alexei Starobinsky and Andrei Linde, he won the 2014 Kavli Prize "for pioneering the theory of cosmic inflation." Guth's research focuses on elementary particle theory and how particle theory is applicable to the early universe. [Baidu] |
