Black Holes

John K Clark (
Wed, 15 Apr 1998 11:21:25 -0700 (PDT)


Anders Sandberg <> On 14 Apr 1998 Wrote:

>I wonder if one could get destabilizing effects by anisotropic
>evaporation that makes the peaks accelerate or grow? Sounds like a
>wonderfully hard problem in numerical black hole thermodynamics
>(if true, then black holes would likely destabilize and radiate away
>very quickly

I've never heard of anisotropic evaporation, but if a Neutron star were to
fall in or two black holes were to merge the event horizon would pulsate,
it would ring like a bell. If the holes was spinning rapidly the pulsations
would extract energy from the rotations and many people thought that the
pulsations would keep growing until the hole was torn apart. However in 1971
Saul Teukolsky proved that regardless of its rotational speed the hole would
remain stable, the pulsations do extract energy from rotation but they do not
grow without limit because they radiate even more energy away as gravitational
waves so the pulsations damp down.

On Tue, 14 Apr 1998 Michael Lorrey <> Wrote:

>I have been wondering if the acceleration you experience in falling
>into the hole, especially at near relativistic velocities, would
>provide sufficient frame dragging to equalize the tidal streching
>with relativistic compression.

Relativistic compression as the name implies depends on the observer, to you
nothing special is happening you're not compressed at all. Tidal stretching
(and crushing) is absolute because every observer including you would notice
that your head and feet were in very different reference frames and that
could be uncomfortable.

On Tue, 14 Apr 1998 Reilly Jones <> Wrote:

>after publicly announcing that you think I and half my state should
>be guillotined because we don't want to turn our doctors into
>murderers of the old and sick

Neither publicly nor privately did I announce any such thing. I don't want to
turn anybody into a murderer. I did say that people should not be punished
for allowing an individual to make the most important decision a human can
make, ESPECIALLY if they're old and sick. I love life so I personally don't
care if you dislike euthanasia, I care a little more that you'd vote against
it, but not much because voting means almost nothing. Needless to say I have
no wish to send you or half your state to the guillotine.

However, if I decided to die and you felt so strongly about it you'd used
force to stop me, I would with a clear conscience do what I had to do to
defend my autonomy, and if that includes causing your head and shoulders to
become discontinuous so be it. Making a person live when they want to die is
the moral equivalent of murder.

Speaking of suicide, if a transhuman decided that eternity was just a little
bit too long there is a way he could go out in style. The quasar 3C273 almost
certainly has a black hole of 10 billion solar masses in it. At the event
horizon the tidal forces would be barely noticeable, even by a frail human,
and would not become lethal for almost an hour (your time), and by then you'd
literally be face to face with quantum gravity and a naked singularity.
Unfortunately you'd be unable to communicate your adventure to anyone but
you'd see things nobody has ever seen or imagined before. Actually you
couldn't even be sure it would kill you because what the singularity is like
is anybody's guess.

John K Clark

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