The Architecture of the Cosmos

2021 ◽  
pp. 1-10
Author(s):  
Gianfranco Bertone

In the first part of the book, I discuss the discovery of gravitational waves and the birth of multimessenger astronomy. Borrowing the structure of Dante’s Paradise and Inferno, I illustrate the biggest mysteries of modern cosmology and argue that multimessenger astronomy, and in particular gravitational waves, may hold the key to unlock these mysteries, and may thus help a bridge between the realm of gravity, and that of quantum physics. Stars. Black holes. Galaxies. Even the most well-known celestial objects are so removed from our daily experience that we might almost mistake them for abstract entities. Yet they are no less real than the objects that surround you as you read these lines.

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.


2021 ◽  
pp. 79-88
Author(s):  
Gianfranco Bertone

I discuss here black holes, extreme astronomical objects that swallow all forms of matter and radiation surrounding them, and leave behind, as physicist John A. Wheeler said, only their ‘gravitational aura’. These endlessly fascinating objects are the gates where gravity meets quantum physics. Since the pioneering work of scientists like S. Hawking, black holes have become ‘theoretical laboratories’ to explore new physics theories. I discuss how the discovery of gravitational waves from black holes, and the first image of a black hole revealed in 2019, have transformed the study of black holes, and may soon lead to new ground-breaking discoveries. The Universe will disappear. Slowly, it will grow dimmer and dimmer, until it disappears completely.


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.


Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 358
Author(s):  
Roberto Casadio ◽  
Andrea Giusti

Bootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces. We further discuss how such models of quantum cosmology can lead to a natural solution to the cosmological constant problem.


2021 ◽  
Vol 812 ◽  
pp. 136011
Author(s):  
Daniel Flores-Alfonso ◽  
Blanca Angélica González-Morales ◽  
Román Linares ◽  
Marco Maceda

2021 ◽  
pp. 100836
Author(s):  
Andrew L. Miller ◽  
Sébastien Clesse ◽  
Federico De Lillo ◽  
Giacomo Bruno ◽  
Antoine Depasse ◽  
...  

2021 ◽  
Author(s):  
Rui feng Zheng ◽  
Jia ming Shi ◽  
Taotao Qiu

Abstract It is well known that primordial black hole (PBH) can be generated in inflation process of the early universe, especially when the inflaton field has some non-trivial features that could break the slow-roll condition. In this paper, we investigate a toy model of inflation with bumpy potential, which has one or several bumps. We found that potential with multi-bump can give rise to power spectra with multi peaks in small-scale region, which can in turn predict the generation of primordial black holes in various mass ranges. We also consider the two possibilities of PBH formation by spherical collapse and elliptical collapse. And discusses the scalar-induced gravitational waves (SIGWs) generated by the second-order scalar perturbations.


Author(s):  
Ram Brustein ◽  
Yotam Sherf

The response of a gravitating object to an external tidal field is encoded in its Love numbers, which identically vanish for classical black holes (BHs). Here we show, using standard time-independent quantum perturbation theory, that for a quantum BH, generically, the Love numbers are nonvanishing and negative. We calculate the quadrupolar electric quantum Love number of slowly rotating BHs and show that it depends most strongly on the first excited level of the quantum BH. Finally, we discuss the detectability of the quadrupolar quantum Love number in future precision gravitational-wave observations and show that, under favourable circumstances, its magnitude is large enough to imprint an observable signature on the gravitational waves emitted during the inspiral. Phase of two moderately spinning BHs.


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