# phys: a quantum gravity hypothesis on infalling matter (hunting for extreme Kerr black holes)

 << Quantum gravity refers to a group of theories—string theory, for example—that aims to reconcile the microscopic world of quantum physics with the macroscopic world of general relativity. >> 

 << Now theoretical work by Grant N.  Remmen (et al) shows that celestial objects called extremal Kerr black holes are highly sensitive to quantum gravity. >> 

 

  << A Kerr black hole is a rotating, electrically neutral black hole. It is said to be extremal if it has the highest possible angular momentum that is compatible with its mass.  Extremal Kerr black holes have yet to be detected, but many theories predict their existence. >> 

 

 They << point out that quantum corrections to general relativity would provide specific contributions to a quantity called the effective action, which describes the dynamics of a gravitational field. (..) under quantum gravity, the event horizon would develop curvature singularities—regions where the gravitational field is infinitely strong. >> 

 

 << the next step is to hunt for extremal Kerr black holes and to try to detect these curvature singularities through their effect on infalling matter. >> 

Ryan Wilkinson. New Physics Magnified in Spinning Black Holes. Physics 16, s117. Aug 31, 2023.

https://physics.aps.org/articles/v16/s117 

Gary T. Horowitz, Maciej Kolanowski, Grant N. Remmen, Jorge E. Santos. Extremal Kerr Black Holes as Amplifiers of New Physics. Phys. Rev. Lett. 131, 091402. Aug 31, 2023.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.091402

Also: Ingrid Fadelli. Theoretical study shows that Kerr black holes could amplify new physics. Phys.org. Sep 22, 2023. 

https://phys.org/news/2023-09-theoretical-kerr-black-holes-amplify.html

Also: astrophysics, black hole, in: https://www.inkgmr.net/kwrds.html

Keywords: astrophysics, black holes

# life: a proposito di '1or2achoos' (da Wuhan (?)), qui la cronologia

a proposito di '1or2achoos' (da Wuhan (?)), qui la cronologia di inizio dei 6 flu|covid che ho contratto dal gen2020 ad oggi con i relativi tempi di 'smorzamento' dell'infezione, trattati nebulizzando una miscela di alcool e H2O2 ( https://flashontrack.blogspot.com/2022/07/life-aproposito-di-1or2achoos-da-wuhan.html )

(1) 2020.04.11-16:04 ~12h (non vaccinato)

(2) 2021.09.01-07:40 ~12h (non vaccinato)

(3) 2022.06.11-08:26 18-36h (+1mese post vaccino, 3dosi)

(4) 2022.12.24-07:52 ~24h 

(5) 2023.02.28-12:09 ~24h 

(6) 2023.04.08-09:32 24-36h 

I tempi necessari per 'spegnere' questi  flu|covid sono tutti notevolmente inferiori (~80%) rispetto alle pregresse forme di flu che ho contratto delle quali ho memoria.

Invece non ho altre parole da aggiungere per commentare i diversi argomenti associabili a '1or2achoos' dal febbraio 2020 ad oggi.

Potrei (e.g. expectedepidemic, lockdown, greenpass, indicatori, statistiche, accademieacucciabili, sadichepredazioni, bucodibilancio, pastroky, ...) nelle bizzarre forme della poetica quasistocastica ( https://inkpi.blogspot.com/ ), ma mi astengo.

Anche: "Ricordo che quando si era ragazzi". in: "il pino di takata matsubara". Notes. Apr 1, 2011. https://inkpi.blogspot.com/2011/04/2157-il-pino-di-takata-matsubara.html

Anche: "e Da-Li' si sparse pell'aere". in: "cracker tendenziali". Notes. Apr 4, 2008. https://inkpi.blogspot.com/2008/04/cracker-tendenziali-around-matter.html

Anche: "in attesa del beffardo tsunami". in: "onda di carambola". Notes. Nov 29, 2004. 

https://inkpi.blogspot.com/2004/11/1619-onda-di-carambola.html

Anche: "aproposito di '1or2achoos' (da Wuhan (?)) ...". FonT. Jul 13, 2022. https://flashontrack.blogspot.com/2022/07/life-aproposito-di-1or2achoos-da-wuhan.html

Anche: 1or2achoos, sars, covid, virus, pastroky, in: 

https://www.inkgmr.net/kwrds.html

Keywords: life, virus, flu, coronavirus,  sarscov2, covid19, 1or2achoos, mask

# gst: anisotropic active depletion around a self-propelled non-interactive colloids; three characteristic states could be identified.

<< Active colloids in a bath of inert particles of smaller size cause anisotropic depletion. >>️

Here AA << combine mesoscale hydrodynamic simulation as well as theoretical analysis to examine the physical origin for the active depletion around a self-propelled noninteractive colloid. >>️

Their << results elucidate that the variable hydrodynamic effect critically governs the microstructure of the depletion zone. Three characteristic states of anisotropic depletion are identified, depending on the strength and stress of activity. >>️

<< Furthermore, (AA) demonstrate that such depletion in nonequilibrium results in various clusters with ordered organization of squirmers, which follows a distinct principle contrary to that of the entropy scenario of depletion in equilibrium. >>

️

Lijun Dai, Haixiao Wan, et al. Hydrodynamic Anisotropy of Depletion in Nonequilibrium. Phys. Rev. Lett. 131, 134002. Sep 27, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.134002

Also: particle, colloids, in https://www.inkgmr.net/kwrds.html

Keywords: gst, particles, colloids, depletion, squirmers, self-propulsion systems

# gst: wandering domains: a hypothetical scenario with bounded orbits.

<< A significant open question in transcendental dynamics asks if it is possible for a point, and thus all points, of a wandering domain to have a bounded orbit. >>

<< In other words, is there a transcendental entire function f with a wandering domain U such that its forward orbit, U_n≥0 f^n(U), is bounded? >>

AA << give a partial answer to this question by constructing an example of a such a wandering domain U which has a nearly bounded orbit; >>

<< In other words, the set of natural numbers n for which f^n(U) is contained in D has upper (and lower) natural density one. >>

<< This is in particularly strong contrast to all existing examples of wandering domains, for which the quantity (..) is equal to zero for any choice of bounded domain D. >>

Leticia Pardo-Simon, David J. Sixsmith. Wandering domains with nearly bounded orbits. arXiv: 2307.16682v1 [math.DS]. Jul 31, 2023. 

https://arxiv.org/abs/2307.16682

Also: Unbounded fast escaping wandering domains. https://arxiv.org/abs/2210.13350 ; Escaping sets of continuous functions. https://arxiv.org/abs/1601.04010 

Also: 'escape', in FonT: https://flashontrack.blogspot.com/search?q=escape

Also: 'fuga', in Notes (quasi-stochastic poetry): https://inkpi.blogspot.com/search?q=fuga 

Keywords: gst, wandering domain, escape 

# gst: reconfiguration and oscillations of sheets subject to vortex

<< The dynamics of a thin low-density polyethylene sheet subject to periodic forcing due to Bénard-Kàrmàn vortices in a long narrow water channel is investigated here. In particular, the time-averaged sheet deflection and its oscillation amplitude are considered. >>

<< The former is first illustrated to be well-approximated by the static equilibrium between the buoyancy force, the elastic restoring force, and the profile drag based on the depth-averaged water speed. >>

AA << observations also indicate that the presence of upstream vortices hinder the overall reconfiguration effect, well-known in an otherwise steady flow. For the sheet-tip oscillations, a simple model based on a torsional-spring-mounted flat plate correctly captures the measured tip amplitude δb over a wide range of sheet physical properties and flow conditions. >>

<< Furthermore, a rich phenomenology of structural dynamics including vortex-forced-vibration, lock-in with the sheet natural frequency, and flow-induced vibration due to the sheet wake, multiple-frequency, and modal response is reported. >>

️

J. John Soundar Jerome, Yohann Bachelier, et al. Reconfiguration and oscillations of a vertical, cantilevered sheet subject to vortex shedding behind a cylinder. Phys. Rev. Fluids 8, 093801. Sep 15, 2023. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.093801

Also: vortex, in https://www.inkgmr.net/kwrds.html

Keywords: gst, sheet, vortex, Benard-Karman vortices

# gst: apropos of transitions, three distinct new families of long-wave instabilities and potential new pathways to turbulence.

AA << reveal three previously unknown instabilities, distinct from the well-known Kelvin-Helmholtz Instability (KHI) and Holmboe Wave Instability (HWI), in that they have longer wavelengths (..) and often slower growth rates. >>

<< The circumstances under which turbulence can persist in strongly stratified flows remains a fascinating debate within the community. [AA] demonstrated that weakly unstable (very) long waves may trigger turbulence and mixing after long periods of time, even under initially very strongly stratified conditions. >>

Lu Zhu, Amir Atoufi, Adrien Lefauve, Rich R. Kerswell, P. F. Linden. Long-wave instabilities of sloping stratified exchange flows. arXiv:2309.10056v1 [physics.flu-dyn]. Sep 18, 2023.

https://doi.org/10.48550/arXiv.2309.10056

Also: waves, instability, transition, turbulence, chaos, in https://www.inkgmr.net/kwrds.html

Keywords: gst, waves, instability, long-wave instability, transition, turbulence, chaos

# gst: apropos of collisions of a vortex dipoles, vortex unbinding, vortex pinning to the edge, and emission of rarefaction pulses.

<< Vortices and dark solitons are fundamental defects that appear in nonlinear physics at all scales, from nonlinear optics to cosmic fluids. In two or three dimensions, dark solitons are fundamentally connected to highly ordered vortex states through an intrinsic modulation instability in the surrounding matter. >>️

<< Here, [AA] report an experimental realization of ring dark soliton (RDS)  generation in a two-dimensional atomic superfluid trapped in a circular box. By quenching the confining box potential, [they] observe an RDS emitted from the edge and its peculiar signature in the radial motion. As an RDS evolves, [they] observe transverse modulations at discrete azimuthal angles, which clearly result in a patterned formation of a circular vortex dipole array. Through collisions of the vortex dipoles with the box trap, [they] observe vortex unbinding, vortex pinning to the edge, and emission of rarefaction pulses. >>

Hikaru Tamura, Cheng-An Chen, Chen-Lung Hung. Observation of Self-Patterned Defect Formation in Atomic Superfluids–from Ring Dark Solitons to Vortex Dipole Necklaces. Phys. Rev. X 13, 031029. Sep 14, 2023. 

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.13.031029

Also: soliton, vortex, turbulence, waves, in: https://www.inkgmr.net/kwrds.html  

Keywords: gst, soliton, dark soliton, vortex, turbulence, waves.