There are new hints that the fabric of space-time may be made of “memory cells” that record the whole history of the universe. If true, it could explain the nature of dark matter and much more
Category: cosmology
Binary neutron star mergers, cosmic collisions between two very dense stellar remnants made up predominantly of neutrons, have been the topic of numerous astrophysics studies due to their fascinating underlying physics and their possible cosmological outcomes. Most previous studies aimed at simulating and better understanding these events relied on computational methods designed to solve Einstein’s equations of general relativity under extreme conditions, such as those that would be present during neutron star mergers.
Researchers at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Yukawa Institute for Theoretical Physics, Chiba University, and Toho University recently performed the longest simulation of binary neutron star mergers to date, utilizing a framework for modeling the interactions between magnetic fields, high-density matter and neutrinos, known as the neutrino-radiation magnetohydrodynamics (MHD) framework.
Their simulation, outlined in Physical Review Letters, reveals the emergence of a magnetically dominated jet from the merger, followed by the collapse of the binary neutron star system into a black hole.
Back in 2019, the Event Horizon Telescope (EHT) team revealed the first-ever image of a supermassive black hole in the galaxy M87. In 2022, they followed up with the iconic image of Sagittarius A at the heart of the Milky Way. While these images were groundbreaking, the data behind them held even deeper insights that were hard to decode.
Neural Networks Meet Black Hole Physics
Previous studies by the EHT Collaboration used only a handful of realistic synthetic data files. Funded by the National Science Foundation (NSF) as part of the Partnership to Advance Throughput Computing (PATh) project, the Madison-based CHTC enabled the astronomers to feed millions of such data files into a so-called Bayesian neural network, which can quantify uncertainties. This allowed the researchers to make a much better comparison between the EHT data and the models.
A series of studies sheds light on the origins and characteristics of intermediate-mass black holes. In the world of black holes, there are generally three size categories: stellar-mass black holes (about five to 50 times the mass of the sun), supermassive black holes (millions to billions of times the mass of the sun), and intermediate-mass black holes with masses somewhere in between.
While we know that intermediate-mass black holes should exist, little is known about their origins or characteristics – they are considered the rare “missing links” in black hole evolution.
However, four new studies have shed new light on the mystery. The research was led by a team in the lab of Assistant Professor of Physics and Astronomy Karan Jani, who also serves as the founding director of the Vanderbilt Lunar Labs Initiative. The work was funded by the National Science Foundation and the Vanderbilt Office of the Vice Provost for Research and Innovation.
Thanks to observatories like the venerable Hubble Space Telescope (HST) and its next-generation cousin, the James Webb Space Telescope (JWST), astronomers are finally getting the chance to study galaxies that existed just one billion years after the Big Bang. This period is known as “Cosmic Dawn” because it was during this period that the first stars formed and came together to create the first galaxies in the Universe. The study of these galaxies has revealed some surprising and fascinating things that are allowing astronomers to learn how large-scale structures in the Universe came to be and how they’ve evolved since.
For the longest time, it was thought that this cosmological period could only be seen by space telescopes, as they don’t have to deal with interference from Earth’s atmosphere. With advanced technologies ranging from adaptive optics (AO) and coronagraphs to interferometry and spectrometers, ground-based telescopes are pushing the boundaries of what astronomers can see. In recent news, an international team of astronomers using the Cosmology Large Angular Scale Surveyor (CLASS) announced the first-ever detection of radiation from the cosmic microwave background (CMB) interacting with the first stars in the Universe. These findings shed light on one of the least understood periods in cosmological history.
The study that details their findings, which recently appeared in The Astrophysical Journal, was led by Yunyang Li — an observational cosmologist from the Kavli Institute for Cosmological Physics (University of Chicago) and The William H. Miller III Department of Physics and Astronomy at Johns Hopkins University (JHU). He was joined by many JHU colleagues, as well as astrophysicists from the National Institute of Standards and Technology, the Argonne National Laboratory, the Los Alamos National Laboratory, the Harvard-Smithsonian Center for Astrophysics, the Massachusetts Institute of Technology (MIT), the NASA Goddard Space Flight Center, and many prestigious universities.
The AI bot explained: If a black hole bomb were somehow constructed and detonated, the energy release could be comparable to that of a supernova, one of the most powerful explosions in the universe. Such an event would release vast amounts of radiation and could have devastating effects on its surroundings.
Dark matter constitutes about 27% of the universe, yet it remains one of the greatest mysteries in cosmology. Unlike normal matter, it does not emit, absorb, or reflect light, making it invisible and detectable only through its gravitational effects. Understanding dark matter is crucial for explaining galaxy formation and cosmic structure.
Accounting for approximately 68% of the universe, dark energy is a hypothetical form of energy proposed to explain the accelerated expansion of the universe. Its nature and properties remain unclear. Dark energy challenges our understanding of gravity and the ultimate fate of the cosmos.
Black holes are regions with a gravitational pull so strong that nothing, not even light, can escape. While we have theories describing their behavior, their interiors remain shrouded in mystery. The existence of black holes challenges the boundaries of our understanding of physics, including general relativity and quantum mechanics.
We’ve questioned that model and tackled questions from a different angle – by looking inward instead of outward.
Instead of starting with an expanding universe and asking how it began, we considered what happens when an over-density of matter collapses under gravity.
Prof Gaztanaga explained that the theory developed by his team of researchers worked within the principles of quantum mechanics and the model could be tested scientifically.
An international team of scientists has published a new report that moves toward a better understanding of the behavior of some of the heaviest particles in the universe under extreme conditions, which are similar to those just after the Big Bang.
The review article, published in the journal Physics Reports, is authored by physicists Juan M. Torres-Rincón, from the Institute of Cosmos Sciences at the University of Barcelona (ICCUB), Santosh K. Das, from the Indian Institute of Technology Goa (India), and Ralf Rapp, from Texas A&M University (United States).
The authors have published a comprehensive review that explores how particles containing heavy quarks (known as charm and bottom hadrons) interact in a hot, dense environment called hadronic matter. This environment is created in the last phase of high-energy collisions of atomic nuclei, such as those taking place at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC).
For the first time, scientists have used Earth-based telescopes to look back over 13 billion years to see how the first stars in the universe affect light emitted from the Big Bang.
Using telescopes high in the Andes mountains of northern Chile, astrophysicists have measured this polarized microwave light to create a clearer picture of one of the least understood epochs in the history of the universe, the Cosmic Dawn.
“People thought this couldn’t be done from the ground. Astronomy is a technology-limited field, and microwave signals from the Cosmic Dawn are famously difficult to measure,” said Tobias Marriage, project leader and a Johns Hopkins professor of physics and astronomy. “Ground-based observations face additional challenges compared to space. Overcoming those obstacles makes this measurement a significant achievement.”