Journey into a realistic black hole.
This journey into a black hole
is a general relativistic volume-rendering with the BHFS
of a general relativistic magnetohydrodynamic simulation of a disk and jet
supercomputed by John Hawley at the University of Virginia.
The movie is similar to one I did for the NOVA documentary
“Monster of the Milky Way”,
which premiered on PBS in 2006.
The black hole
is intended to model the
4 million solar mass
supermassive black hole at the center of our Galaxy, the Milky Way.
The clock shows your proper time,
in seconds until vaporization by the inflationary instability at the inner horizon.
The tidal force from the supermassive black hole is weak enough
that you can survive all the way down to the inner horizon without being torn apart.
Caveats
The claim is that all the movies on this website are
“scientifically accurate”,
if general relativity is the correct theory of gravity.
But of course it is impossible to make a movie that is
scientifically accurate in all respects.
Realistic elements:
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The disk and jet are from a
general relativistic magnetohydrodynamic
supercomputer simulation.
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The ray-tracing and volume-rendering are general relativistic.
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You, the observer,
fall on a real free-fall geodesic.
The relativistic beaming effects
from your motion are included.
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Semi-realistic elements:
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The coloring has scientific significance,
in that the various parts of the disk and jet are colored with
an appropriately red- or blue-shifted blackbody color.
The reddish color of the jet
is caused by the large special relativistic transverse Doppler shift.
While meaningful,
the coloring is not realistic.
In reality
the disk and jet would be hotter
than any optical blackbody temperature,
and they would not emit as a blackbody.
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Unrealistic elements:
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The geometry is that of a charged (Reissner-Nordström) black hole
(with charge-to-mass 0.9),
not a rotating (Kerr) black hole.
That is simply because I have not yet implemented rotating black holes
in the BHFS.
It is not a limitation of Hawley's simulation,
which was done with a Kerr geometry.
The excuse is that the interior structure of a non-rotating charged black hole
resembles that of a rotating black hole
in that both have an inner horizon
where the mass inflation instability takes place.
One day I hope to implement rotating black holes in the BHFS,
but it will require a major investment of time and effort.
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Hawley stopped his simulation at the outer horizon of the black hole.
His simulation was done in Boyer-Linquist coordinates,
so layers piled up at the outer horizon.
To allow the visualization to continue inside the horizon,
I took the piled-up layers and spread them inward inside the horizon.
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The movie uses only a single frame from Hawley's simulation.
In effect, the black hole is in solid body rotation.
Hawley provided me with a full set of 5000 frames,
but near the horizon the time resolution is insufficient.
Interpolating between frames produced distracting visual artifacts.
If you are surprised by the fact that the visualization
still gives the impression of outflow, so was I.
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The movie does not take into account the different time delays
from various parts of the scene.
The absence of differential time delays
is a side-effect of using a single frame of the simulation.
Taking into account time delays would pose the challenge of
using 4D instead of 3D textures for volume-rendering.
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The solid body rotation continues
near the inner horizon?
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The quantity rendered is the radial Poynting flux
(the radial flux of electromagnetic energy-momentum).
This is not what a human observer would “actually” see,
whatever that might be.
Hawley recommended (and I agree)
the Poynting flux because
(a) it shows nicely the fine scale structure in the disk
caused by the turbulent magnetic field,
and
(b) it reveals the jet prominently.
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The geometry is Reissner-Nordström throughout.
I did not attempt to take into account the modification
of the geometry caused by the inflationary instability at the inner horizon.
Actually this should be an excellent approximation
for an astronomically realistic black hole,
whose accretion rate is tiny.
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Penrose diagram illustrating the cause of mass inflation
The infinite blueshift at the inner horizon
of the Reissner-Nordström geometry
was first pointed out by Roger Penrose in 1968.
Penrose suggested that the infinite blueshift would destabilize the Reissner-Nordström.
The full nonlinear character of the instability at the inner horizon
was eventually clarified in a seminal paper by Eric Poisson & Werner Israel in 1990.
