Big Bang - Observational evidence

In physical cosmology, the Big Bang is the scientific theory that the Universe emerged from an enormously dense and hot state about 13.7 billion years ago. The Big Bang is a consequence of the observed Hubble's law velocities of distant galaxies that when taken together with the cosmological principle imply that space is expanding according to the Friedmann-Lemaître model of general relativity. Extrapolated into the past, these observations show that the Universe has expanded from a primeval state, in which all the matter and energy ...

Including:

• Big Bang - History
• Big Bang - Overview
• Big Bang - Theoretical underpinnings
• Big Bang - Observational evidence
• Big Bang - Hubble's law expansion
• Big Bang - Cosmic microwave background radiation
• Big Bang - Abundance of primordial elements
• Big Bang - Galactic evolution and distribution
• Big Bang - Features issues and problems
• Big Bang - Horizon problem
• Big Bang - Flatness problem
• Big Bang - Magnetic monopoles
• Big Bang - Baryon asymmetry
• Big Bang - Globular cluster age
• Big Bang - Dark matter
• Big Bang - Dark energy
• Big Bang - The future according to the Big Bang theory
• Big Bang - Speculative physics beyond the Big Bang
• Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia - Big Bang

A number of problems have arisen within the Big Bang theory throughout its history. Some of them are mainly of historical interest today, and have been avoided either through modifications to the theory or as the result of better observations. Other issues, such as the cuspy halo problem and the dwarf galaxy problem of cold dark matter, are not considered to be fatal as they can be addressed through refinements of the theory. There are a small number of proponents of non-standard cosmologies who doubt that there was a Big Bang at all. ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features, issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - Features, issues and problems

It is generally stated that there are three observational pillars that support the Big Bang theory of cosmology. These are the Hubble-type expansion seen in the redshifts of galaxies, the detailed measurements of the cosmic microwave background, and the abundance of light elements. (See Big Bang nucleosynthesis.) Additionally, the observed correlation function of large-scale structure of the cosmos fits well with standard Big Bang theory. ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - Observational evidence

A number of problems have arisen within the Big Bang theory throughout its history. Some of them are mainly of historical interest today, and have been avoided either through modifications to the theory or as the result of better observations. Other issues, such as the cuspy halo problem and the dwarf galaxy problem of cold dark matter, are not considered to be fatal as they can be addressed through refinements of the theory. There are a small number of proponents of non-standard cosmologies who doubt that there was a Big Bang at all. ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - Features issues and problems

The Big Bang theory developed from observations and theoretical considerations. Observationally, it was determined that most spiral nebulae were receding from Earth, but those who made the observation weren't aware of the cosmological implications, nor that the supposed nebulae were actually galaxies outside our own Milky Way. In 1927, the Belgian Catholic priest Georges Lemaître independently derived the Friedmann-Lemaître-Robertson-Walker equations and proposed, on the basis of the recession of spiral nebulae, that the Universe began with the "explosion" of a "primeval atom"†...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - History

Based on measurements of the expansion of the Universe using Type Ia supernovae, measurements of the lumpiness of the cosmic microwave background, and measurements of the correlation function of galaxies, the Universe has a calculated age of 13.7 ± 0.2 billion years. The agreement of these three independent measurements is considered strong evidence for the so-called ΛCDM model that describes the detailed na ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - Overview

As it stands today, the Big Bang is dependent on three assumptions: The universality of physical laws The cosmological principle The Copernican principle When first developed, these ideas were simply taken as postulates, but today there are efforts underway to test each of them. Tests of the universality of physical laws have found that the largest possible deviation of the fine structure constant over the age of the Universe is of order 10-5. The isotropy of the Universe that defines t ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - Theoretical underpinnings

Before observations of dark energy, cosmologists considered two scenarios for the future of the Universe. If the mass density of the universe is above the critical density, then the Universe would reach a maximum size and then begin to collapse. It would become denser and hotter again, ending with a state that was similar to that in which it started—a Big Crunch. Alternatively, if the density in the Universe is equal to or below the critical density, the expansion would slow down, but never stop. Star formation would cease as the Universe ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - The future according to the Big Bang theory

While the Big Bang model is well established in cosmology, it is likely to be refined in the future. Little is known about the earliest Universe, when inflation is hypothesized to have occurred. There may also be parts of the Universe well beyond what can be observed in principle. In the case of inflation this is required: exponential expansion has pushed large regions of space beyond our observable horizon. It may be possible to deduce what happened when we better understand physics at very high energy scales. Sp ...

See also:

Big Bang, Big Bang - History, Big Bang - Overview, Big Bang - Theoretical underpinnings, Big Bang - Observational evidence, Big Bang - Hubble's law expansion, Big Bang - Cosmic microwave background radiation, Big Bang - Abundance of primordial elements, Big Bang - Galactic evolution and distribution, Big Bang - Features issues and problems, Big Bang - Horizon problem, Big Bang - Flatness problem, Big Bang - Magnetic monopoles, Big Bang - Baryon asymmetry, Big Bang - Globular cluster age, Big Bang - Dark matter, Big Bang - Dark energy, Big Bang - The future according to the Big Bang theory, Big Bang - Speculative physics beyond the Big Bang, Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia II - Big Bang - Speculative physics beyond the Big Bang