PhDcomics TV releases new physics videos on black holes, gravitational waves, Hawking interview, entanglement

2016 ◽  
Vol 54 (5) ◽  
pp. 318-318
Author(s):  
Dan MacIsaac
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):  
Jonathan R Gair

The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics.


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.


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 ◽  
Vol 812 ◽  
pp. 136026
Author(s):  
Zihan Zhou ◽  
Jun Yan ◽  
Andrea Addazi ◽  
Yi-Fu Cai ◽  
Antonino Marciano ◽  
...  

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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