The large-scale structure of the universe—the gigantic, hierarchical cosmic web of structures bound by gravity—is mostly made up of dark matter. The growth of the large-scale structure, from individual galaxies to galaxy ...
For the first time, scientists have observed antimatter particles—the mysterious twins of the visible matter all around us—falling downwards due to the effect of gravity, Europe's physics lab CERN announced on Wednesday.
General Physics
Sep 30, 2023
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Einstein's theory of gravity—general relativity—has been very successful for more than a century. However, it has theoretical shortcomings. This is not surprising: the theory predicts its own failure at spacetime singularities ...
General Physics
Sep 25, 2023
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Astronomers have found a striking link between the amount of dust surrounding a supermassive black hole and the strength of the radio emission produced in extremely bright galaxies.
Astronomy
Sep 25, 2023
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A team of engineers and technicians at Ball Aerospace, one of the industry partners for NASA's Nancy Grace Roman Space Telescope, and NASA's Goddard Space Flight Center in Greenbelt, Maryland, has finished assembling the ...
Space Exploration
Sep 13, 2023
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As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.
General Physics
Sep 11, 2023
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Our best understanding of the universe is rooted in a cosmological model known as LCDM. The CDM stands for cold dark matter, where most of the matter in the universe isn't stars and planets, but a strange form of matter that ...
Astronomy
Sep 5, 2023
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NASA's Nancy Grace Roman Space Telescope team has begun integrating and testing the spacecraft's electrical cabling, or harness, which enables different parts of the observatory to communicate with one another. Additionally, ...
Astronomy
Aug 23, 2023
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Astrophysicists can use measurements of the cosmic microwave background, radiation formed 380,000 years after the Big Bang, to understand what the universe was like in its infancy. And by observing light emitted from galaxies ...
Astronomy
Aug 14, 2023
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Researchers have found a new way to measure dark energy—the mysterious force that makes up more than two-thirds of the universe and is responsible for its accelerating expansion—in our own cosmic backyard.
Astronomy
Aug 14, 2023
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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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