ⓘ Physical universe


Accelerating expansion of the universe

The accelerating expansion of the universe is the observation that the expansion of the universe is such that the velocity at which a distant galaxy is receding from the observer is continuously increasing with time. The accelerated expansion was discovered during 1998, by two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team, which both used distant type Ia supernovae to measure the acceleration. The idea was that as type 1a supernovae have almost the same intrinsic brightness a standard candle, and since objects that are further away appear dimmer ...


Age of the universe

In physical cosmology, the age of the universe is the time elapsed since the Big Bang. The current measurement of the age of the universe is around 13.8 billion years – 13.799 ± 0.021 billion years within the Lambda-CDM concordance model. The uncertainty has been narrowed down to 20 million years, based on a number of studies which all gave extremely similar figures for the age. These include studies of the microwave background radiation by the Planck spacecraft, the Wilkinson Microwave Anisotropy Probe and other space probes. Measurements of the cosmic background radiation give the coolin ...


Big Bang

The Big Bang theory is a cosmological model of the observable universe from the earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from an initial state of very high-density and high-temperature, and offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background radiation, large-scale structure, and Hubbles law – the farther away galaxies are, the faster they are moving away from Earth. If the observed conditions are extrapolated backwards ...


Clockwork universe

In the history of science, the clockwork universe compares the universe to a mechanical clock. It continues ticking along, as a perfect machine, with its gears governed by the laws of physics, making every aspect of the machine predictable.


Cosmic age problem

The cosmic age problem is a historical problem in astronomy concerning the age of the universe. The problem was that at various times in the 20th century, some objects in the universe were estimated to be older than the time elapsed since the Big Bang, as estimated from measurements of the expansion rate of the universe known as the Hubble constant, denoted H 0. If so, this would represent a contradiction, since objects such as galaxies, stars and planets could not have existed in the extreme temperatures and densities shortly after the Big Bang. Since around 1997–2003, the problem is beli ...


Cosmic latte

Cosmic latte is the average color of the universe, found by a team of astronomers from Johns Hopkins University. In 2001, Karl Glazebrook and Ivan Baldry determined that the average color of the universe was a greenish white, but they soon corrected their analysis in a 2002 paper in which they reported that their survey of the light from over 200.000 galaxies averaged to a slightly beigeish white. The hex triplet value for cosmic latte is #FFF8E7.


Cosmic time

Cosmic time is the time coordinate commonly used in the Big Bang models of physical cosmology. Such time coordinate may be defined for a homogeneous, expanding universe so that the universe has the same density everywhere at each moment in time. The clocks measuring cosmic time should move along the Hubble flow. Cosmic time t {\displaystyle t} is a measure of time by a physical clock with zero peculiar velocity in the absence of matter over-/under-densities to prevent time dilation due to relativistic effects or confusions caused by expansion of the universe. Unlike other measures of time ...



Cosmogony and the root of γίνομαι / γέγονα) is any model concerning the origin of either the cosmos or the universe.


Cosmological horizon

A cosmological horizon is a measure of the distance from which one could possibly retrieve information. This observable constraint is due to various properties of general relativity, the expanding universe, and the physics of Big Bang cosmology. Cosmological horizons set the size and scale of the observable universe. This article explains a number of these horizons.


Location of Earth

Knowledge of the location of Earth has been shaped by 400 years of telescopic observations, and has expanded radically since the start of the 20th century. Initially, Earth was believed to be the center of the Universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. After the acceptance of the heliocentric model in the 17th century, observations by William Herschel and others showed that the Sun lay within a vast, disc-shaped galaxy of stars. By the 20th century, observations of spiral nebulae revealed that the Milky Way galaxy was o ...


Gold universe

A Gold universe is a cosmological model of the universe. In these models, the universe starts with a Big Bang and expands for some time, with increasing entropy and a thermodynamic arrow of time pointing in the direction of the expansion. After the universe reaches a low-density state, it recontracts, but entropy now decreases, pointing the thermodynamic arrow of time in the opposite direction, until the universe ends in a low-entropy, high-density Big Crunch. There are two models of the universe which support the possibility of a reversed direction of time. The first begins with a state o ...


Graphical timeline from Big Bang to Heat Death

This is the timeline of the Universe from Big Bang to Heat Death scenario. The different eras of the universe are shown. The heat death will occur in 10 100 years, if protons decay. Usually the logarithmic scale is used for such timelines but it compresses the most interesting Stelliferous Era too much as this example shows. Therefore, a double-logarithmic scale s s*100 in the graphics is used instead. The minimum of it is only 1, not 0 as needed, and the negative outputs for inputs smaller than 10 are useless. Therefore, the time from 0.1 to 10 years is collapsed to a single point 0, but ...


Graphical timeline of the universe

This more than 20-billion-year timeline of our universe shows the best estimates of major events from the universes beginning to anticipated future events. Zero on the scale is the present day. A large step on the scale is one billion years; a small step, one hundred million years. The past is denoted by a minus sign: e.g., the oldest rock on Earth was formed about four billion years ago and this is marked at -4e+09 years, where 4e+09 represents 4 times 10 to the power of 9. The "Big Bang" event most likely happened 13.8 billion years ago; see age of the universe.


Graphical timeline of the Big Bang

This timeline of the Big Bang shows a sequence of events as currently theorized by scientists. It is a logarithmic scale that shows 10 ⋅ log 10 {\displaystyle 10\cdot \log _{10}} second instead of second. For example, one microsecond is 10 ⋅ log 10 ⁡ 0.000001 = 10 ⋅ − 6 = − 60 {\displaystyle 10\cdot \log _{10}0.000001=10\cdot -6=-60}. To convert −30 read on the scale to second calculate 10 − 30 10 = 10 − 3 = 0.001 {\displaystyle 10^{-{\frac {30}{10}}}=10^{-3}=0.001} second = one millisecond. On a logarithmic time scale a step lasts ten times longer than the previous step.


Graphical timeline of the Stelliferous Era

This is the timeline of the stelliferous era but also partly charts the primordial era, and charts more of the degenerate era of the heat death scenario. The scale is 10 × log 10 ⁡ { t } {\displaystyle 10\times \log _{10}\{t\}} where { t } {\displaystyle \{t\}} is the time since the Big Bang expressed in years. Example: one million years is { t } = 1.000.000 ; 10 × log 10 ⁡ { t } = 10 × 6 = 60 {\displaystyle \{t\}=1{,}000{,}000;\ \ 10\times \log _{10}\{t\}=10\times 6=60}.


Lambda-CDM model

The ΛCDM or Lambda-CDM model is a parametrization of the Big Bang cosmological model in which the universe contains three major components: first, a cosmological constant denoted by Lambda and associated with dark energy; second, the postulated cold dark matter ; and third, ordinary matter. It is frequently referred to as the standard model of Big Bang cosmology because it is the simplest model that provides a reasonably good account of the following properties of the cosmos: the large-scale structure in the distribution of galaxies the observed abundances of hydrogen including deuterium, ...


Observable universe

The observable universe is a spherical region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. There are at least 2 trillion galaxies in the observable universe. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe has a spherical volume ce ...


Particle horizon

The particle horizon, or the cosmic light horizon) is the maximum distance from which light from particles could have traveled to the observer in the age of the universe. Much like the concept of a terrestrial horizon, it represents the boundary between the observable and the unobservable regions of the universe, so its distance at the present epoch defines the size of the observable universe. Due to the expansion of the universe, it is not simply the age of the universe times the speed of light, but rather the speed of light times the conformal time. The existence, properties, and signifi ...


Three-torus model of the universe

The three-Torus model is a cosmological model proposed in 1984 by Alexei Starobinsky and Yakov Borisovich Zeldovich at the Landau Institute in Moscow. The theory describes the shape of the universe as a three-dimensional torus.



Ylem is a term that was used by George Gamow, his student Ralph Alpher, and their associates in the late 1940s for a hypothetical original substance or condensed state of matter, which became subatomic particles and elements as we understand them today. The term ylem was actually resuscitated by Ralph Alpher. In modern understanding, the "ylem" as described by Gamow was the primordial plasma, formed in baryogenesis, which underwent Big Bang nucleosynthesis and was opaque to radiation. Recombination of the charged plasma into neutral atoms made the Universe transparent at the age of 380.000 ...


ⓘ Physical universe

  • static universe also referred to as a stationary or infinite or static infinite universe is a cosmological model in which the universe is both
  • A Gold universe is a cosmological model of the universe In these models, the universe starts with a Big Bang and expands for some time, with increasing
  • of the universe also known as the Big Chill or Big Freeze, is a conjecture on the ultimate fate of the universe which suggests the universe would evolve
  • Universe Today U.T. is a popular North American - based non - commercial space and astronomy news website. The domain was registered on December 30, 1998
  • Tegmark. Tegmark s MUH is: Our external physical reality is a mathematical structure. That is, the physical universe is not merely described by mathematics
  • A physical paradox is an apparent contradiction in physical descriptions of the universe While many physical paradoxes have accepted resolutions, others
  • In the case where two fictional universes covering entire actual universes cross over, physical travel from one universe to another may actually occur in
  • remains constant, the physical distance between two such co - moving points expands proportionally with the scale factor of the universe The Big Bang is not

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