Particle chauvinism is the term used by British astrophysicist Martin Rees to describe the (allegedly erroneous) assumption that what we think of as normal matter – atoms, quarks, electrons, etc. (excluding dark matter or other matter) – is the basis of matter in the universe, rather than a rare phenomenon. [1]
With the growing recognition in the late 20th century of the presence of dark matter in the universe, ordinary baryonic matter has come to be seen as something of a cosmic afterthought. [2] As J.D. Barrow put it:
The 21st century saw the share of baryonic matter in the total mass-energy of the universe downgraded further, to perhaps as low as 1%, [4] further extending what has been called the demise of particle-chauvinism, [5] before being revised up to some 5% of the contents of the universe. [6]
The anthropic principle, also known as the "observation selection effect", is the hypothesis, first proposed in 1957 by Robert Dicke, that the range of possible observations that could be made about the universe is limited by the fact that observations could happen only in a universe capable of developing intelligent life. Proponents of the anthropic principle argue that it explains why the universe has the age and the fundamental physical constants necessary to accommodate conscious life, since if either had been different, no one would have been around to make observations. Anthropic reasoning is often used to deal with the idea that the universe seems to be finely tuned for the existence of life.
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. It was first proposed in 1927 by Roman Catholic priest and physicist Georges Lemaître. Various cosmological models of the Big Bang explain the evolution of the observable universe from the earliest known periods through its subsequent large-scale form. These models offer a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure. The overall uniformity of the universe, known as the flatness problem, is explained through cosmic inflation: a sudden and very rapid expansion of space during the earliest moments. However, physics currently lacks a widely accepted theory of quantum gravity that can successfully model the earliest conditions of the Big Bang.
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood.
In astronomy, dark matter is a hypothetical form of matter that appears not to interact with light or the electromagnetic field. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be seen. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.
Proclus Lycius, called Proclus the Successor, was a Greek Neoplatonist philosopher, one of the last major classical philosophers of late antiquity. He set forth one of the most elaborate and fully developed systems of Neoplatonism and, through later interpreters and translators, exerted an influence on Byzantine philosophy, Early Islamic philosophy, Scholastic philosophy, and German Idealism, especially G.W.F. Hegel, who called Proclus's Platonic Theology "the true turning point or transition from ancient to modern times, from ancient philosophy to Christianity."
In cosmology and physics, cold dark matter (CDM) is a hypothetical type of dark matter. According to the current standard model of cosmology, Lambda-CDM model, approximately 27% of the universe is dark matter and 68% is dark energy, with only a small fraction being the ordinary baryonic matter that composes stars, planets, and living organisms. Cold refers to the fact that the dark matter moves slowly compared to the speed of light, giving it a vanishing equation of state. Dark indicates that it interacts very weakly with ordinary matter and electromagnetic radiation. Proposed candidates for CDM include weakly interacting massive particles, primordial black holes, and axions.
In astronomy and cosmology, baryonic dark matter is hypothetical dark matter composed of baryons. Only a small proportion of the dark matter in the universe is likely to be baryonic.
In physics, a dimensionless physical constant is a physical constant that is dimensionless, i.e. a pure number having no units attached and having a numerical value that is independent of whatever system of units may be used.
In physical cosmology, baryogenesis is the physical process that is hypothesized to have taken place during the early universe to produce baryonic asymmetry, i.e. the imbalance of matter (baryons) and antimatter (antibaryons) in the observed universe.
The characterization of the universe as finely tuned intends to explain why the known constants of Nature, such as the electron charge, the gravitational constant, etc., have the values that we measure rather than some other (arbitrary) values. According to the "fine-tuned universe" hypothesis, if these constants' values were too different from what they are, "life as we know it" could not exist. In practice, this hypothesis is formulated in terms of dimensionless physical constants.
Samuel Rutherford Crockett, who published under the name "S. R. Crockett", was a Scottish novelist.
Lindisfarne Castle is a 16th-century castle located on Holy Island, near Berwick-upon-Tweed, Northumberland, England, much altered by Sir Edwin Lutyens in 1901. The island is accessible from the mainland at low tide by means of a causeway.
A colloid mill is a machine that is used to reduce the particle size of a solid in suspension in a liquid, or to reduce the droplet size in emulsions. Colloid mills work on the rotor-stator principle: a rotor turns at high speeds. A high level of hydraulic shear stress is applied on the fluid which results in disrupting and breaking down the structure. Colloid mills are frequently used to increase the stability of suspensions and emulsions, but can also be used to reduce the particle size of solids in suspensions. Higher shear rates lead to smaller droplets, down to approximately 1 μm which are more resistant to emulsion separation.
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, matter generally includes atoms and anything made up of them, and any particles that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or other energy phenomena or waves such as light or heat. Matter exists in various states. These include classical everyday phases such as solid, liquid, and gas – for example water exists as ice, liquid water, and gaseous steam – but other states are possible, including plasma, Bose–Einstein condensates, fermionic condensates, and quark–gluon plasma.
The warm–hot intergalactic medium (WHIM) is the sparse, warm-to-hot (105 to 107 K) plasma that cosmologists believe to exist in the spaces between galaxies and to contain 40–50% of the baryonic 'normal matter' in the universe at the current epoch. The WHIM can be described as a web of hot, diffuse gas stretching between galaxies, and consists of plasma, as well as atoms and molecules, in contrast to dark matter. The WHIM is a proposed solution to the missing baryon problem, where the observed amount of baryonic matter does not match theoretical predictions from cosmology.
Hylogenesis is a physical theory about the mechanism behind the origins of dark matter and antimatter. It was proposed in August 2010 in a paper by Hooman Davoudiasl, David E. Morrissey, Kris Sigurdson and Sean Tulin.
In astrophysics and cosmology scalar field dark matter is a classical, minimally coupled, scalar field postulated to account for the inferred dark matter.
Abell 222 is a galaxy cluster in the constellation of Cetus. It holds thousands of galaxies together. It is located at a distance of 2.4 billion light-years from Earth.
In cosmology, the missing baryon problem is an observed discrepancy between the amount of baryonic matter detected from shortly after the Big Bang and from more recent epochs. Observations of the cosmic microwave background and Big Bang nucleosynthesis studies have set constraints on the abundance of baryons in the early universe, finding that baryonic matter accounts for approximately 4.8% of the energy contents of the Universe. At the same time, a census of baryons in the recent observable universe has found that observed baryonic matter accounts for less than half of that amount. This discrepancy is commonly known as the missing baryon problem. The missing baryon problem is different from the dark matter problem, which is non-baryonic in nature.
Marc S. Seigar is an astrophysicist, academic and author. He is the Dean of the College of Natural Sciences and Mathematics, and a Professor of Physics and Astronomy at the University of Toledo.
{{cite book}}
: CS1 maint: location missing publisher (link){{cite book}}
: CS1 maint: location missing publisher (link){{cite book}}
: CS1 maint: location missing publisher (link)