The universe appears normal to an observer falling into a supermassive black hole
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The retrieved physics literature discusses numerical simulations and quantum path integrals concerning observers near or falling past a black hole horizon, providing partial insight into infalling perspectives while contrasting them with distant observers who perceive time dilation effects.
We present a 360∘ (i.e., 4π steradian) general-relativistic ray-tracing and radiative transfer calculations of accreting supermassive black holes. We perform state-of-the-art three-dimensional general-relativistic magnetohydrodynamical simulations using the BHAC code, subsequently post-processing this data with the radiative transfer code RAPTOR. All relativistic and general-relativistic effects, such as Doppler boosting and gravitational redshift, as well as geometrical effects due to the local gravitational field and the observer’s changing position and state of motion, are therefore calculated self-consistently. Synthetic images at four astronomically-relevant observing frequencies are generated from the perspective of an observer with a full 360∘ view inside the accretion flow, who is advected with the flow as it evolves. As an example we calculated images based on recent best-fit models of observations of Sagittarius A*. These images are combined to generate a complete 360∘ Virtual Reality movie of the surrounding environment of the black hole and its event horizon. Our approach also enables the calculation of the local luminosity received at a given fluid element in the accretion flow, providing important applications in, e.g., radiation feedback calculations onto black hole accretion flows. In addition to scientific applications, the 360∘ Virtual Reality movies we present also represent a new medium through which to interactively communicate black hole physics to a wider audience, serving as a powerful educational tool.
The viewer can then look in any direction during the animation; this is also known as 360 ∘ VR. Another important feature of VR, stereographic rendering, presents different images to each eye, so that the viewer experiences stereoscopic depth. For our application, however, this technique is not relevant, since the physical distance between the eyes of the observer is much smaller than the typical length scale of a supermassive black hole (which is \(6.645\times10^{11}\) cm for Sagittarius A*), and therefore we would not see any depth in the image (just as we do not see stereoscopic depth when looking at the Moon).
Interactive visualisations, where the viewer also has the freedom to change his or her position, would require real-time rendering of the environment, which is beyond the reach of current computational resources. Our new way of visualising black holes enables the study of accretion from the point of view of an observer close to the black hole event horizon, with the freedom to image in all directions, as opposed to the perspective of an observer far away from the source with a fixed position and narrow field of view. In the case of a distant observer, the source appears projected onto the celestial sphere (thus appearing two-dimensional).
Several researchers have previously considered an observer moving around, or falling into a black hole, e.g., (1) falling through the event horizon as illustrated through the gravitational lensing distortions of different regions (e.g., the ergo-region and event horizon), represented as chequerboard patterns projected onto an observer’s image plane (Madore 2011 ), (2) a flight through a simulation of a non-rotating black hole (Hamilton 1998 ), (3) a flight through an accretion disk of a black hole using an observer with a narrow field of view camera (Luminet 2011 ), (4) a 360 ∘
2 Methods In this section, we introduce the virtual camera setup, present black hole shadow vacuum lensing tests using both stationary and free-falling observers at different radial positions, discuss the different camera trajectories used in the VR movie shown later in this article and introduce the GRMHD plasma model that is used as an input for the geometry of the accretion flow onto the black hole. 2.1 VR camera The original RAPTOR code (Bronzwaer et al. 2018 ) initialises rays (i.e., photon geodesics) using impact parameters determined form coordinate locations on the observer’s image plane (Bardeen et al. 1972 ).
\end{aligned}$$ (18) The free-falling velocities were obtained by numerically integrating the geodesic equation for a free-falling massive particle. To visualise the effect of the observer’s motion on the observed field of view, we place a sphere around both the observer and the black hole, which is centred on the black hole. This is what we subsequently refer to as the “celestial sphere”. The black hole spin is taken to be \(a=0.9375\) , the exact value of the spin parameter for Sgr A* is unknown, the chosen value was the best fit of a parameter survey (Mościbrodzka et al. 2009 ).
The different colors represent different quadrants of the sky, yellow and blue being behind the observer, while red and green are in front of the observer. The black lines represent lines of constant longitude and lattitude while the black, circular region in the center is the black-hole shadow. Middle panel: as top panel, but seen by a radially in-falling observer. Bottom-left panel: photons originating from a stationary observer’s camera, as used to generate the top panel. Bottom-right panel: photons originating from a radially in-falling observer’s camera, as used to generate the middle panel. The black hole event horizon is shown as the black region in both bottom panels.
As the observer is advected further away, by frame 8599 the angular size of the black hole and the surrounding accretion flow is greatly reduced and appears almost point-like To obtain a better quantitative understanding of the movie we also calculate the total bolometric luminosity as received by the observer’s camera. This is shown in the top panel of Fig. 11 . At 6150 a decrease in luminosity is evident at the three lowest frequencies, which corresponds to where the observer is closest to the black hole event horizon and has entered the optically-thick accretion disk. A magnified version of this Figure in the optically-thick part is shown in the bottom panel of Fig. 11 .
These stars were so large that their cores collapsed into black holes. The black hole at the center of these stars slowly consumed the star from within making black holes of up to 103 solar masses. These black holes may be the seeds of the supermassive black holes found in the centers of most galaxies.[24] If these stars really existed, they may even explain where supermassive black holes come from. Most of the energy released in gravitational collapse is given off very quickly. A distant observer sees the material falling in slowly and then stop just above the event horizon because of gravitational time dilation. The light given off just before the event horizon is delayed an infinite amount of time. So the observer never sees the formation of the event horizon. Instead, the collapsing material seems to become dimmer and increasingly red-shifted, eventually fading away.[25]
Supermassive black holes
Black holes have also been found in the middle of almost every galaxy in the known universe. These are called supermassive black holes (SBH), and are the biggest black holes of all. They formed when the Universe was very young, and also helped to form all the galaxies.
One of the fundamental problems in quantum gravity is to describe the experience of a gravitating observer in generic spacetimes. In this paper, we develop a framework for describing non-perturbative physics relative to an observer using the gravitational path integral. We apply our proposal to an observer that lives in a closed universe and one that falls behind a black hole horizon. We find that the Hilbert space that describes the experience of the observer is much larger than the Hilbert space in the absence of an observer. In the case of closed universes, the Hilbert space is not one-dimensional, as calculations in the absence of the observer suggest. Rather, its dimension scales exponentially with ${G}_{N}^{-1}$. Similarly, from an observer’s perspective, the dimension of the Hilbert space in a two-sided black hole is increased. We compute various observables probing the experience of a gravitating observer in this Hilbert space. We find that an observer experiences non-trivial physics in the closed universe in contrast to what it would see in a one-dimensional Hilbert space. In the two-sided black hole setting, our proposal implies that non-perturbative corrections to effective field theory for an infalling observer are suppressed until times exponential in the black hole entropy, resolving a recently-raised puzzle in black hole physics. While the framework that we develop is exemplified in the toy-model of JT gravity, most of our analysis can be extended to higher dim
In this paper, we develop a framework for describing non-perturbative physics relative to an observer using the gravitational path integral. We apply our proposal to an observer that lives in a closed universe and one that falls behind a black hole horizon. We find that the Hilbert space that describes the experience of the observer is much larger than the Hilbert space in the absence of an observer. In the case of closed universes, the Hilbert space is not one-dimensional, as calculations in the absence of the observer suggest. Rather, its dimension scales exponentially with \({G}_{N}^{-1}\) .
Similarly, from an observer’s perspective, the dimension of the Hilbert space in a two-sided black hole is increased. We compute various observables probing the experience of a gravitating observer in this Hilbert space. We find that an observer experiences non-trivial physics in the closed universe in contrast to what it would see in a one-dimensional Hilbert space. In the two-sided black hole setting, our proposal implies that non-perturbative corrections to effective field theory for an infalling observer are suppressed until times exponential in the black hole entropy, resolving a recently-raised puzzle in black hole physics.
While the framework that we develop is exemplified in the toy-model of JT gravity, most of our analysis can be extended to higher dimensions and, in particular, to generic spacetimes not admitting a conventional holographic description, such as cosmological universes or black hole interiors.
Maldacena, Quantum corrections to holographic entanglement entropy , JHEP 11 (2013) 074 [ arXiv:1307.2892 ] [ INSPIRE ]. Article ADS Google Scholar D. Marolf and H. Maxfield, Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information , JHEP 08 (2020) 044 [ arXiv:2002.08950 ] [ INSPIRE ]. Article ADS MathSciNet Google Scholar P. Saad, S.H. Shenker and D. Stanford, A semiclassical ramp in SYK and in gravity , arXiv:1806.06840 [ INSPIRE ]. P. Saad, S.H. Shenker and D. Stanford, JT gravity as a matrix integral , arXiv:1903.11115 [ INSPIRE ]. P. Saad, S.H. Shenker, D. Stanford and S.
Boruch, L.V. Iliesiu, G. Lin and C. Yan, How the Hilbert space of two-sided black holes factorises , arXiv:2406.04396 [ INSPIRE ]. S. Antonini, M. Sasieta and B. Swingle, Cosmology from random entanglement , JHEP 11 (2023) 188 [ arXiv:2307.14416 ] [ INSPIRE ]. Article ADS MathSciNet Google Scholar M. Usatyuk, Z.-Y. Wang and Y. Zhao, Closed universes in two dimensional gravity , SciPost Phys. 17 (2024) 051 [ arXiv:2402.00098 ] [ INSPIRE ]. Article MathSciNet Google Scholar M. Usatyuk and Y. Zhao, Closed universes, factorization, and ensemble averaging , JHEP 02 (2025) 052 [ arXiv:2403.13047 ] [ INSPIRE ]. Article MathSciNet Google Scholar J. McNamara and C.
B 252 (1985) 343 [ INSPIRE ]. C. Teitelboim, Gravitation and Hamiltonian Structure in Two Space-Time Dimensions , Phys. Lett. B 126 (1983) 41 [ INSPIRE ]. P.-S. Hsin, L.V. Iliesiu and Z. Yang, A violation of global symmetries from replica wormholes and the fate of black hole remnants , Class. Quant. Grav. 38 (2021) 194004 [ arXiv:2011.09444 ] [ INSPIRE ]. Article ADS MathSciNet Google Scholar C. Akers and G. Penington, Quantum minimal surfaces from quantum error correction , SciPost Phys. 12 (2022) 157 [ arXiv:2109.14618 ] [ INSPIRE ]. Article ADS MathSciNet Google Scholar C.
Raju, An Infalling Observer in AdS/CFT , JHEP 10 (2013) 212 [ arXiv:1211.6767 ] [ INSPIRE ]. Article ADS Google Scholar K. Papadodimas and S. Raju, State-Dependent Bulk-Boundary Maps and Black Hole Complementarity , Phys. Rev. D 89 (2014) 086010 [ arXiv:1310.6335 ] [ INSPIRE ]. Article ADS Google Scholar D. Marolf and J. Polchinski, Violations of the Born rule in cool state-dependent horizons , JHEP 01 (2016) 008 [ arXiv:1506.01337 ] [ INSPIRE ]. Article ADS MathSciNet Google Scholar D. Stanford and L. Susskind, Complexity and Shock Wave Geometries , Phys. Rev. D 90 (2014) 126007 [ arXiv:1406.2678 ] [ INSPIRE ]. Article ADS Google Scholar D. Harlow and D.
Jafferis, The Factorization Problem in Jackiw-Teitelboim Gravity , JHEP 02 (2020) 177 [ arXiv:1804.01081 ] [ INSPIRE ]. Article ADS MathSciNet Google Scholar T.G. Mertens and G.J. Turiaci, Solvable models of
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Stereoscopic visualization adds an additional dimension to the viewer's experience, giving them a sense of distance. In a general relativistic visualization, distance can be measured in a variety of ways. We argue that the affine distance, which matches the usual notion of distance in flat spacetime, is a natural distance to use in curved spacetime. As an example, we apply affine distance to the visualization of the interior of a black hole. Affine distance is not the distance perceived with normal binocular vision in curved spacetime. However, the failure of binocular vision is simply a limitation of animals who have evolved in flat spacetime, not a fundamental obstacle to depth perception in curved spacetime. Trinocular vision would provide superior depth perception.
Stereoscopic visualization in curved spacetime: seeing deep inside a black hole - IOPscience The Deutsche Physikalische Gesellschaft (DPG) with a tradition extending back to 1845 is the largest physical society in the world with more than 61,000 members. The DPG sees itself as the forum and mouthpiece for physics and is a non-profit organisation that does not pursue financial interests. It supports the sharing of ideas and thoughts within the scientific community, fosters physics teaching and would also like to open a window to physics for all those with a healthy curiosity.
The following article is Open access Stereoscopic visualization in curved spacetime: seeing deep inside a black hole Andrew J S Hamilton and Gavin Polhemus Published 16 December 2010 • Published under licence by IOP Publishing Ltd New Journal of Physics , Volume 12 , December 2010 Citation Andrew J S Hamilton and Gavin Polhemus 2010 New J. Phys. 12 123027 DOI 10.1088/1367-2630/12/12/123027 PDF Opens in a new tab. Authors Andrew J S Hamilton AFFILIATIONS JILA, Box 440, U. Colorado, Boulder, CO 80309, USA Department of Astrophysical and Planetary Sciences, Box 391, U. Colorado, Boulder, CO, USA Gavin Polhemus AFFILIATIONS JILA, Box 440, U.
We argue that the affine distance, which matches the usual notion of distance in flat spacetime, is a natural distance to use in curved spacetime. As an example, we apply affine distance to the visualization of the interior of a black hole. Affine distance is not the distance perceived with normal binocular vision in curved spacetime. However, the failure of binocular vision is simply a limitation of animals that have evolved in flat spacetime, not a fundamental obstacle to depth perception in curved spacetime. Trinocular vision would provide superior depth perception.
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