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Quantum field theory reveals potential flaws in models predicting numerous primordial black holes, suggesting fewer exist, which may impact theories of dark matter and the universe’s structure.

Researchers have applied the well-understood and highly verified quantum field theory, usually applied to the study of the very small, to a new target, the early universe. Their exploration led to the conclusion that there ought to be far fewer miniature black holes than most models suggest, though observations to confirm this should soon be possible. The specific kind of black hole in question could be a contender for dark matter.

The study, which was published recently in Physical Review Letters, was conducted by researchers at the Research Center for the Early Universe (RESCEU) and Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI) at the University of Tokyo.

The DESI collaboration is conducting a groundbreaking experiment to understand the universe’s expansion and acceleration. Their work with the DESI instrument has enabled them to map the cosmos from its early stages to the present, challenging existing models of the universe. Initial findings suggest there may be more to discover about dark energy and cosmic acceleration. The project’s innovative approach, including a fully blinded analysis, ensures that their conclusions are based on unbiased data, paving the way for future discoveries in astrophysics. Credit: SciTechDaily.com.

The DESI collaboration is examining the universe’s accelerating expansion through comprehensive mapping from its early stages to the present. Their findings challenge traditional cosmic models and suggest new insights into dark energy, all while utilizing groundbreaking, unbiased research methods.

Continue reading “Beyond Einstein: Groundbreaking Map of the Universe Redefines Cosmic Models” »

In the vast expanse of the cosmos, there is much more than meets the eye. For every kilogram of visible matter in the universe, from the computer on your desk to the distant stars and galaxies, there are 5 kilograms of invisible “dark matter” that permeate our surroundings.

This enigmatic dark matter evades direct observation yet exerts its invisible pull on the visible objects around us.

Fifty years ago, renowned physicist Stephen Hawking proposed a fascinating idea about the nature of dark matter. He suggested that it might consist of a population of black holes that formed in the early stages of the universe, mere moments after the Big Bang.

Primordial black holes (PBHs)—hypothetical objects formed by the gravitational collapse of dense regions in the early Universe—have been invoked as dark-matter candidates. But for PBHs to constitute all dark matter, they’d have to be extremely light, possibly weighing less than small asteroids. Now Elba Alonso-Monsalve and David Kaiser of the Massachusetts Institute of Technology show that these diminutive PBHs could possess an exotic property—a net color charge (such a charge characterizes quarks and gluons in quantum chromodynamics theory) [1]. Such color-charged PBHs might have left potentially observable signatures, says Kaiser.

Observations rule out that stellar-mass PBHs could fully explain dark matter, but PBHs weighing between 10¹⁷ and 10²² g remain viable candidates. Since a PBH’s mass should relate to its age, this mass range corresponds to PBH formation immediately after the big bang, when the Universe was still a hot plasma of unconfined quarks and gluons. Most PBHs would have formed by engulfing large numbers of quarks and gluons having a distribution of color charges. These PBHs would be color-charge neutral and sufficiently massive to live until today. However, the duo’s calculations show that a few PBHs could have formed from regions so tiny that the charges of the absorbed gluons would be correlated, giving these PBHs a net charge.

Color-charged black holes have long been considered to be mathematically possible, but the new study is the first to propose a realistic formation mechanism, says Kaiser. The small sizes imply that they would have since evaporated. Yet their presence in the early Universe might have disrupted the distribution of protons and neutrons when the big bang created the first nuclear isotopes, leaving subtle traces in the cosmic abundance of the elements.

For every kilogram of matter that we can see—from the computer on your desk to distant stars and galaxies—there are 5 kilograms of invisible matter that suffuse our surroundings. This “dark matter” is a mysterious entity that evades all forms of direct observation yet makes its presence felt through its invisible pull on visible objects.

New findings reveal magnetic fields in three massive stars in the Magellanic Clouds, shedding light on the influence of magnetism on stellar evolution and the formation of neutron stars and black holes. The use of advanced spectropolarimetry techniques was crucial to overcome past observational challenges.

Magnetic fields have been discovered in three massive, hot stars within our neighboring galaxies, the Large and Small Magellanic Clouds, for the first time. Although magnetic fields in massive stars are not new to our own galaxy, their detection in the Magellanic Clouds is particularly significant due to the abundance of young, massive stars in these galaxies. This discovery offers a rare chance to investigate actively forming stars and explore the maximum mass a star can achieve while maintaining stability.

Impact of magnetism on star evolution.

Researchers for the first time showed, how gravity can exist without mass, providing an alternative theory that could potentially mitigate the need for dark matter…

Dark matter is a hypothetical form of matter that is implied by gravitational effects that can’t be explained by general relativity unless more matter is present in the universe than can be seen. It remains virtually as mysterious as it was nearly a century ago when first suggested by Dutch astronomer Jan Oort in 1932 to explain the so-called “missing mass” necessary for things like galaxies to clump together.

Now Dr. Richard Lieu at The University of Alabama in Huntsville (UAH) has published a paper in the Monthly Notices of the Royal Astronomical Society that shows, for the first time, how gravity can exist without mass, providing an alternative theory that could potentially mitigate the need for dark matter.

Continue reading “Researcher suggests that gravity can exist without mass, mitigating the need for hypothetical dark matter” »

The American theoretical physicist, Brian Greene explains various hypotheses about the causation of the big bang. Brian Greene is an excellent science communicator and he makes complex cosmological concepts more easy to understand.

The Big Bang explains the evolution of the universe from a starting density and temperature that is currently well beyond humanity’s capability to replicate. Thus the most extreme conditions and earliest times of the universe are speculative and any explanation for what caused the big bang should be taken with a grain of salt. Nevertheless that shouldn’t stop us to ask questions like what was there before the big bang.

Continue reading “Brian Greene — What Was There Before The Big Bang?” »

Primordial black holes are hypothetical objects formed during the earliest moments of the universe. According to the models, they formed from micro-fluctuations in matter density and spacetime to become sand grain-sized mountain-massed black holes.