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The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 5 billion years ago. [ 8 ] [ notes 1 ] Within the framework of general relativity , an accelerated expansion can be accounted for by a positive value of the cosmological constant Λ , equivalent to the presence of ...
The expansion of the universe can be understood as a consequence of an initial impulse (possibly due to inflation), which sent the contents of the universe flying apart. The mutual gravitational attraction of the matter and radiation within the universe gradually slows this expansion over time, but expansion nevertheless continues due to ...
In using Hubble's law to determine distances, only the velocity due to the expansion of the universe can be used. Since gravitationally interacting galaxies move relative to each other independent of the expansion of the universe, [43] these relative velocities, called peculiar velocities, need to be accounted for in the application of Hubble's ...
"Yes, it appears there is something missing in our understanding of the universe," added Riess, a 2011 Nobel laureate in physics for the co-discovery of the universe's accelerating expansion.
Gravity is one of the universe's fundamental forces. Einstein's theory linked space, time and gravity. It holds that concentrations of mass and energy curve the structure of space-time ...
In the widely accepted ΛCDM cosmological model, dark matter accounts for about 25.8% ± 1.1% of the mass and energy in the universe while about 69.2% ± 1.2% is dark energy, a mysterious form of energy responsible for the acceleration of the expansion of the universe. [17] Ordinary ('baryonic') matter therefore composes only 4.84% ± 0.1% of ...
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The notion of an expanding universe was first scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.
The Big Crunch is a hypothetical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach absolute zero, an event potentially followed by a reformation of the universe starting with another Big Bang.