Penrose process: its variants and astrophysical applications

• Zdeněk Stuchlík (Institute of Physics, Silesian University in Opava)

The Penrose process governing extraction of energy from black holes by the simple effects related to uncharged or charged particles is discussed in most of the known variants related to Kerr black holes and Kerr naked singularities, or to electrically charged static black holes. Attention is focused on the magnetic Penrose process in its extremely efficient version enabling extreme acceleration of charged particles after ionization of uncharged matter, giving explanation of the ultra-high energy cosmic rays. The effect of radiative self-force of accelerated particles is briefly discussed. It is shown that in the ergosphere of Kerr black holes it could lead to a new verion of radiative Penrose process due to radiation of photons with negative energy as related to distant static observers that cause the extraction of black hole rotational energy in this version of the Penrose process.

Freeman Dyson on Quantum Gravity

• Marek Abramowicz (Silesian University, Opava)

Freeman Dyson made these points on Quantum Gravity: (1.) A single graviton cannot be detected, because a measuring two-body apparatus size should be smaller that its gravitational radius. (2.) With no possibility of detecting a single graviton the very concept of Quantum Gravity is practically meaningless. (3.) There is nothing wrong with having separate theories for the large scale (gravity) and for the small scale (quanta). A unification may be in practice (and in principle) unhelpful or even meaningless.

Derivation of the existence of the Black Holic Quantum from GRBs

• Remo Ruffini

Quantifying the Blackholic Quantum in GRBs and AGN

• Jorge Rueda (ICRANET)

The concept of blackholic quantum is at the base of the emission of high-energy (GeV) electromagnetic radiation and ultrahigh-energy cosmic rays from long GRBs and AGN. I assess from the quantitative viewpoint the blackholic quantum in specific sources and outline astrophysical consequences.

Projects in Strong-Field General Relativity: my worldline with Pavel Bakala

• Luigi Stella (Luigi Stella - INAF Astronomical Observatory of Rome )

In this presentation I will survey the projects that Pavel Bakala and I, together with students and collaborators, carried out in recent years, especially during Pavel's sabbatical at the Astronomical Observatory of Rome in 2019. Strong-field GR in application to astrophysical effects and problems was the leitmotiv of the projects, with extreme light bending playing an especially prominent role.