Black Holes

2021 ◽  
pp. 53-65
Author(s):  
Gianfranco Bertone

In the second part of the book, I argue that the four biggest mysteries of modern physics and astronomy—dark matter, dark energy, black holes, and the Big Bang—sink their roots into the physics of the infinitely small. And I argue that gravitational waves may shed new light on, and possibly solve, each of these four mysteries. I start here by introducing the problem of dark matter, the mysterious substance that permeates the Universe at all scales and describe the gravitational waves observations that might soon elucidate its nature. The next time you see the Sun shining in the sky, consider this: what blinds your eyes and warms your skin is an immense nuclear furnace, which transforms millions of tons of nuclear fuel into energy every second. And when you contemplate the night sky, try to visualize it for what it essentially is: an endless expanse of colossal natural reactors, forging the atoms that we, and everything that surrounds us, are made of.

2021 ◽  
Author(s):  
Carlos A. Melendres

Abstract We present a physico-chemical approach towards understanding the mysteries associated with the Inflationary Big Bang model of Cosmic evolution based on a theory that space consists of energy quanta. We use thermodynamics to elucidate the expansion of the universe, its composition, and the nature of dark energy and dark matter. The universe started from an atomic size volume of space quanta at very high temperature. Upon expansion and cooling, phase transitions resulted in the formation of fundamental particles, and matter which grow into stars, galaxies, and clusters due to gravity. From cooling data on the universe, we constructed a thermodynamic phase diagram of composition of the universe, from which we obtained a correlation between dark energy and the energy of space. Using Friedmann’s equations, our Quantum Space model fitted well the WMAP data on cosmic composition with an equation of state parameter, w= -0.7. The expansion of the universe was adiabatic and decelerating during the first 7 billion years after the Big Bang. It accelerated due to the dominance of dark energy at 7.25 x 109 years, in good agreement with BOSS measurements. Dark Matter is identified as a plasma form of matter similar to that which existed before recombination and during reionization.


2002 ◽  
Vol 10 (2) ◽  
pp. 221-236 ◽  
Author(s):  
ANDREW R. LIDDLE

The 20th century saw the establishment of the first quantitative theory seeking to describe the behaviour of the Universe as a whole – the Big Bang. This sets up a framework within which there has been great success in interpreting a wide range of observations, including the abundances of light chemical elements, the existence and spectrum of the cosmic microwave radiation, and the formation and evolution of galaxies. At the end of the 20th century, the surprising conclusion of the Big Bang theory is that 95% of the Universe is made of two different unknown types of material whose nature remains unclear: dark matter and dark energy. Needless to say, this is a major challenge for science. At the beginning of the 21st century, cosmology appears poised to enter a high-precision era, where the key quantities of cosmology will be determined to two or more significant figures. If cosmologists are on the right track, this will confirm the existence of dark matter and dark energy; if not, it will force us to revise our current picture of the Universe. Either way, the prospect is for exciting years ahead in cosmology.


2021 ◽  
pp. 1-13
Author(s):  
Raymond T. Pierrehumbert

‘Beginnings’ discusses the general processes that form planetary systems, particularly the Solar System. Most of the Universe is made of a mysterious substance called ‘dark matter’, and an even more mysterious substance called ‘dark energy’. After the birth of the Universe in the Big Bang, the tiny bits of stardust which have accumulated contain the heavier elements (baryonic matter) that make it possible to form beings like ourselves, and the planets on which we live. We mustn't forget the importance of the formation of protostars, as well as gas and ice giant planets, the evolution of the proto-Sun, and the formation of inner rocky planets.


Author(s):  
Geoff Cottrell

Matter: A Very Short Introduction explains matter—the stuff of which your body and the universe is made—from elementary particles, to atoms, humans, planets, up to the superclusters of galaxies. Familiar solids, liquids, and gases are described, as well as plasmas, exotic forms of quantum matter, and antimatter. This VSI outlines the quantum properties of atoms, the fundamental forces of nature, and how the different forms of matter arise. The origins of matter are traced to the Big Bang, 13.8 billion years ago. However, all the familiar normal matter constitutes only 5% of the matter that exists. The remainder comes in two mysterious forms: dark matter and dark energy, which are discussed.


Author(s):  
Carlos Melendres

We present a thermodynamic approach in modeling the evolution of the universe based on a theory that space consists of energy quanta, the spaceons. From wave-particle duality, they can be treated as an ideal gas. The model is similar to the Big Bang but without Inflation. It provides an insight into the nature of dark energy and dark matter, and an explanation for the accelerated expansion of the universe. The universe started from an atomic size volume of spaceons at very high temperature and pressure. Upon expansion and cooling, phase transitions occurred resulting in the formation of fundamental particles, and matter. These nucleate and grow into stars, galaxies, and clusters due to the action of gravity. From the cooling curve of the universe we constructed a thermodynamic phase diagram of cosmic composition, from which we obtained the correlation between dark energy and the energy of space. Using Friedmann’s equations, our model fits well the WMAP data on cosmic composition with an equation of state parameter, w= -0.7. The dominance of dark energy started at 7.25 x 109 years, in good agreement with BOSS measurements. The expansion of space is attributed to a scalar quantum space field. Dark Matter is identified as a plasma form of matter similar to that which existed during the photon epoch, prior to recombination. The thermodynamics of expansion of the universe was adiabatic and decelerating during the first 7 billion years after the Big Bang; it accelerated thereafter. A negative pressure for Dark Energy is required to sustain the latter. This is consistent with the theory of General Relativity and the law of conservation of energy. We propose a mechanism for the acceleration as due to consolidation of matter forming Dark Energy Stars (DES) and other compact objects. The resulting reduction in gravitational potential energy feeds back energy for the expansion. Space will continue to expand and dark energy will undergo phase transition to a Bose-Einstein condensate, a superfluid form of matter. Self-gravitation can cause a bounce and start a new Big Bang. We show how the interplay of gravitational and space forces leads to a cyclic, maybe eternal, universe.


Author(s):  
David M. Wittman

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.


Author(s):  
Gianfranco Bertone

The spectacular advances of modern astronomy have opened our horizon on an unexpected cosmos: a dark, mysterious Universe, populated by enigmatic entities we know very little about, like black holes, or nothing at all, like dark matter and dark energy. In this book, I discuss how the rise of a new discipline dubbed multimessenger astronomy is bringing about a revolution in our understanding of the cosmos, by combining the traditional approach based on the observation of light from celestial objects, with a new one based on other ‘messengers’—such as gravitational waves, neutrinos, and cosmic rays—that carry information from otherwise inaccessible corners of the Universe. Much has been written about the extraordinary potential of this new discipline, since the 2017 Nobel Prize in physics was awarded for the direct detection of gravitational waves. But here I will take a different angle and explore how gravitational waves and other messengers might help us break the stalemate that has been plaguing fundamental physics for four decades, and to consolidate the foundations of modern cosmology.


2018 ◽  
Vol 27 (14) ◽  
pp. 1846005 ◽  
Author(s):  
Tom Banks ◽  
W. Fischler

This essay outlines the Holographic Spacetime (HST) theory of cosmology and its relation to conventional theories of inflation. The predictions of the theory are compatible with observations, and one must hope for data on primordial gravitational waves or non-Gaussian fluctuations to distinguish it from conventional models. The model predicts an early era of structure formation, prior to the Big Bang. Understanding the fate of those structures requires complicated simulations that have not yet been done. The result of those calculations might falsify the model, or might provide a very economical framework for explaining dark matter and the generation of the baryon asymmetry.


2014 ◽  
Vol 29 (37) ◽  
pp. 1440001 ◽  
Author(s):  
Jordi Casanellas ◽  
Ilídio Lopes

During the last century, with the development of modern physics in such diverse fields as thermodynamics, statistical physics, and nuclear and particle physics, the basic principles of the evolution of stars have been successfully well understood. Nowadays, a precise diagnostic of the stellar interiors is possible with the new fields of helioseismology and astroseismology. Even the measurement of solar neutrino fluxes, once a problem in particle physics, is now a powerful probe of the core of the Sun. These tools have allowed the use of stars to test new physics, in particular the properties of the hypothetical particles that constitute the dark matter (DM) of the Universe. Here we present recent results obtained using this approach.


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