One of the great challenges of modern cosmology is to reveal the nature of dark matter. We know it exists (it constitutes more than 85% of the matter in the universe), but we have never seen it directly and still do not know what it is.
Category: cosmology – Page 96
Holographic Dark Energy: A New Model for Understanding the Universe’s Expansion
Following the accelerated expansion discovery of the Universe, scientists introduced dark energy concepts, which faced issues like the cosmological constant problem.
Researchers at IKBFU developed a holographic dark energy model based on quantum gravity, which views the Universe as a hologram. This model, initially unstable, was refined to treat dark energy as perturbations, stabilizing it. It is now being tested against observational data for accuracy.
Discovery of Accelerated Universe Expansion.
Hubble Tension Solved? Astronomers Race To Save Standard Model Of Cosmology
The right value for the expansion rate of the universe continues to elude astronomers.
First-ever experimental evidence of rare kaon decay found at CERN
In the popular tv show big bang theory kaon decay was discovered at cern that won sheldon cooper and Amy the Nobel prize in super asymmetry and this elusive particle has been discovered. What a remarkable discovery face_with_colon_three
Researchers at CERN have observed an exceptionally rare particle decay event, potentially paving the way to uncover new physics beyond the current understanding of fundamental particles and their interactions.
This decay is extraordinarily uncommon—according to the Standard Model ℠ of particle physics, which describes particle interactions, fewer than one in every 10 billion kaons undergo this specific decay.
The NA62 experiment was developed and optimized precisely to detect and study this elusive kaon decay process.
Cosmology Is at a Tipping Point—We May Be on the Verge of Discovering New Physics
For the past few years, a series of controversies have rocked the well-established field of cosmology. In a nutshell, the predictions of the standard model of the universe appear to be at odds with some recent observations.
There are heated debates about whether these observations are biased, or whether the cosmological model, which predicts the structure and evolution of the entire universe, may need a rethink. Some even claim that cosmology is in crisis. Right now, we do not know which side will win. But excitingly, we are on the brink of finding that out.
To be fair, controversies are just the normal course of the scientific method. And over many years, the standard cosmological model has had its share of them. This model suggests the universe is made up of 68.3 percent “dark energy” (an unknown substance that causes the universe’s expansion to accelerate), 26.8 percent dark matter (an unknown form of matter) and 4.9 percent ordinary atoms, very precisely measured from the cosmic microwave background —the afterglow of radiation from the Big Bang.
Can Information Escape a Black Hole?
Episode · The Joy of Why · Nothing escapes a black hole… or does it? In the 1970s, Stephen Hawking described a subtle process by which black holes can “evaporate,” with some particles evading gravitational oblivion. This phenomenon, now dubbed “Hawking radiation,” seems inherently at odds with general relativity, but it gets weirder still: If particles can escape, do they preserve some information about the matter that was obliterated? Leonard Susskind, a physicist at Stanford University, found himself at odds with Hawking when it came to answering this question. In this episode, co-host Janna Levin speaks with Susskind about the “black hole war” that ensued and the powerful scientific lessons that have radiated from one of the most famous paradoxes in physics.
Thermodynamics of frozen stars
New study suggests that black holes may not be the featureless, structureless entities that Einstein’s general theory of relativity predicts them to be.
The frozen star is a recent proposal for a nonsingular solution of Einstein’s equations that describes an ultracompact object which closely resembles a black hole from an external perspective. The frozen star is also meant to be an alternative, classical description of an earlier proposal, the highly quantum polymer model. Here, we show that the thermodynamic properties of frozen stars closely resemble those of black holes: frozen stars radiate thermally, with a temperature and an entropy that are perturbatively close to those of black holes of the same mass. Their entropy is calculated using the Euclidean-action method of Gibbons and Hawking. We then discuss their dynamical formation by estimating the probability for a collapsing shell of “normal’’ matter to transition, quantum mechanically, into a frozen star.
