Not long ago I watched a TV show which said that objects drawn into a
black hole would first be ripped apart and stretched into a thin string
a matter -- the idea being that the atoms comprising the portion of the
body which is closest to the black hole are subject to greater
gravitational pull than the atoms farther away from the black
hole. This seems to comport with the fracturing of some objects
as they are pulled toward large objects, such as the asteroid or comet
which crashed into Saturn in 1994 but first broke into several large
pieces. It intrigues me that there might be enough of a
difference in gravity over such a short distance to do this, but at the
same time I am puzzled and, frankly, a bit skeptical about it necessarily applying in all cases for the
reasons I will give.
First, to whatever degree it influences the outcome, one must keep
in mind that the more distant portions of the body are subject to not
only the gravitational pull of the large celestial body, but are also
accelerated by the tensile strength of the body with the portion closer
to the pull of gravity helping to accelerate the rest of the
body. I reckon that this matters a lot while the gravitational
pull is not great enough to rip the body apart, but eventually becomes
insignificant as the gravitational pull becomes massive. I
initially speculated, regarding black holes, that this might be only in
very close proximity to the black hole, but then when I consider Saturn
and its relatively tiny gravity in comparison to a black hole, I
realize
that this process must begin much earlier, or at least when gravity is
not nearly as intense as a black hole. That is something that
I am trying to sort out and would appreciate any comments, such as ...
what is the formula for calculating gravitational pull between two
bodies, considering their masses and the distance between them (or
their centers of gravity). I presume that there is one.
Another related issue in this puzzle is Einstein's theoretical
maximum speed -- the speed of light -- and whether that velocity would
be reached by the entire body BEFORE the point at which the body can be
torn apart; if so, then there could be no further 'stretching', no
matter HOW much the difference in gravitational pull, because the
leading parts of the falling body can't move faster than the trailing
parts to move away from them. And what is
the effect of the increased mass of the falling body (my understanding
being that with increased velocity the body attains increased mass,
with mass approaching infinity as the speed of light is
approached)? Does the increased mass of the falling body,
especially in such close
proximity, not begin to exert its own gravitational pull on its own
parts which might be sufficent to counteract the 'stretching' effect of
the acceleration toward the celestial body? Trying to understand
such things freaks my mind a bit, so let me cut to the chase and start
using a hypothetical case for us to discuss, with a few basic
assumptions which I think are reasonable.
First, assume a human body is 'diving' toward a celestial body, with
hands over the head and fingertips extended, for a total length of 8'
from tip of fingers to toes.
Second, assume that the greatest stretching force is at the knuckles
-- because they are closest to the celestial body and subject to more
gravity -- which help to pull the rest of the body along behind it.
Third, assume a body weight of 150 pounds, and that the knuckles can
pull 450 pounds of weight before being ripped from the hand; I have no
idea how close to the maximum stress that might be, but with a world
record clean and jerk of 586 pound, 450 is more than reasonable and we
could possibly even go to 600 pounds (4x body weight).
Fourth, assume for the ease of calculations and discussion, that cross sections of the body are consistent from finger to toe.
That means that at the knuckles there are 3gs more due to
acceleration than the average acceleration for the rest of the body,
which I think would probably be represented at the mid-point -- about
four feet away -- at least is the effect is linear (which it probably
isn't). But my point is that if rate of acceleration increases at
a rate of 3gs (NOT three 'times'*) for every four feet of travel, then
in just a mile of travel the rate of acceleration would be 3,960 of
what it was to start. But I guess a solution is really going to
depend on finding a forumula for 'g', and possibly whether it is linear
or not.
Now let's see what some folks think.
Bill Velek
The Effect of Accelerating Toward a High-Gravity Body
Re: The Effect of Accelerating Toward a High-Gravity Body
