A RUDN University physicist has developed a formula for calculating Hawking radiation on the event horizon of a black hole, which allows physicists to determine how this radiation would be changed with quantum corrections ...
General Physics
Jan 31, 2020
7
3045
Galaxies. Amalgamations of stars, interstellar gas, dust, stellar debris and dark matter. They waltz through the cold universe, gravity nurturing their embrace. Occasionally, galaxies snowball into enormous galaxy clusters ...
Astronomy
Jan 14, 2020
0
154
The most direct and strongest evidence for the accelerating universe with dark energy is provided by the distance measurements using type Ia supernovae (SN Ia) for the galaxies at high redshift. This result is based on the ...
Astronomy
Jan 06, 2020
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19876
The observed acceleration of the Hubble expansion rate has been attributed to a mysterious "dark energy" which supposedly makes up about 70% of the universe. Professor Subir Sarkar from the Rudolf Peierls Centre for Theoretical ...
Astronomy
Nov 27, 2019
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2428
One of the biggest mysteries in science began with a dying star.
Astronomy
Nov 25, 2019
1
39
No matter how elegant your theory is, experimental data will have the last word. Observations of the retrograde motion of the planets were fundamental to the Copernican revolution, in which the sun replaced Earth at the centre ...
Astronomy
Nov 13, 2019
45
181
Wielding state-of-the-art technologies and techniques, a team of Clemson University astrophysicists has added a novel approach to quantifying one of the most fundamental laws of the universe.
Astronomy
Nov 08, 2019
34
1555
A trio of researchers with the University of Manchester, Università di Roma 'La Sapienza' and Sorbonne Universities has sparked a major debate among cosmologists by claiming that data from the Planck space observatory suggests ...
As an astronomer, there is no better feeling than achieving "first light" with a new instrument or telescope. It is the culmination of years of preparations and construction of new hardware, which for the first time collects ...
Astronomy
Oct 29, 2019
33
232
A new instrument on the 4-m Mayall telescope has opened its array of thousands of fiber-optic "eyes" to the cosmos and successfully captured the light from distant galaxies. The milestone marks the beginning of final testing ...
Astronomy
Oct 28, 2019
7
63
In physical cosmology and astronomy, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 74% of the total mass-energy of the universe.
Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant is physically equivalent to vacuum energy. Scalar fields which do change in space can be difficult to distinguish from a cosmological constant because the change may be extremely slow.
High-precision measurements of the expansion of the universe are required to understand how the expansion rate changes over time. In general relativity, the evolution of the expansion rate is parameterized by the cosmological equation of state. Measuring the equation of state of dark energy is one of the biggest efforts in observational cosmology today.
Adding the cosmological constant to cosmology's standard FLRW metric leads to the Lambda-CDM model, which has been referred to as the "standard model" of cosmology because of its precise agreement with observations. Dark energy has been used as a crucial ingredient in a recent attempt to formulate a cyclic model for the universe.
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