The eROSITA telescope’s detailed pictures are among the most precise cosmological measurements ever made.
Category: cosmology – Page 133
Revisiting the dynamics of interacting vector-like dark energy
We revise the dynamics of interacting vector-like dark energy, a theoretical framework proposed to explain the accelerated expansion of the universe. By investigating the interaction between vector-like dark energy and dark matter, we analyze its effects on the cosmic expansion history and the thermodynamics of the accelerating universe. Our results demonstrate that the presence of interaction significantly influences the evolution of vector-like dark energy, leading to distinct features in its equation of state and energy density. We compare our findings with observational data and highlight the importance of considering interactions in future cosmological studies.
Loosening the Hubble Tension
New James Webb Space Telescope observations may have done with one of the longest-standing tensions in cosmology.
For almost a decade, astronomers have been struggling with a nagging mismatch between two different ways of determining the Hubble constant — a measure of the current expansion rate of the universe. This mismatch, known as the Hubble tension, has led to claims that new physics might be needed to solve the issue. (Read about the “constant controversy” in the June 2019 issue of Sky & Telescope.)
But a detailed analysis of a new set of James Webb Space Telescope (JWST) observations now suggests that the problem may not exist. “As Carl Sagan said, extraordinary claims require extraordinary evidence,” says Wendy Freedman (University of Chicago), “and I don’t see extraordinary evidence.”
Why are black holes stable against their own gravity?
Neutron stars are timelike matter with a maximum mass of about 2.34 solar masses in quantum chromodynamics (the strong color force). Black holes are spacelike matter that have no maximum mass, but a minimum mass of 2.35 solar masses. Indeed, black holes have been identified with millions or billions of solar masses.
AI helps distinguish dark matter from cosmic noise
Dark matter is the invisible force holding the universe together—or so we think. It makes up about 85% of all matter and around 27% of the universe’s contents, but since we can’t see it directly, we have to study its gravitational effects on galaxies and other cosmic structures. Despite decades of research, the true nature of dark matter remains one of science’s most elusive questions.
Can Space and Time Exist as Two Shapes at Once? Mind-Bending Experiments Aim to Find Out
Proposed experiments will search for signs that spacetime is quantum and can exist in a superposition of multiple shapes at once.
By Nick Huggett & Carlo Rovelli
There is a glaring gap in our knowledge of the physical world: none of our well-established theories describe gravity’s quantum nature. Yet physicists expect that this quantum nature is essential for explaining extreme situations such as the very early universe and the deep interior of black holes. The need to understand it is called the problem of “quantum gravity.”