[TML] White Dwarfs, Black Holes & 100 Diameters

[Jerry W Barrington]

On 10/23/07 11:13 PM, Michael Jenkins wrote:

> To rephrase this, imagine the spherical object you've entered as a
> series of thin concentric shells with the same centre. Once you're
> inside any particular shell, it's gravitational forces on you cancel
> each other out exactly (if the shell is of even density). Only the
> shells you're still outside exert gravity on you. When you reach the
> centre of the sphere, nett G will be zero.
> 
> I recall working through the maths once that proves this, but that was
> a long time ago now.

Heh.  I went about proving this to myself in a totally different way.  I
assumed that a lens shaped volume near you would cancel itself out, and only
the further parts would pull you.  Then I set up a spreadsheet to calculate
the contribution of rings of matter at different distances and add them up
(effectively integrating over the volume).  Yes, this is only a
computational approximation, but it showed me the linear relation of gravity
inside a sphere.

More recently, I thought out why the gravity inside a spherical shell would
be zero.  Anywhere inside an infinitesimally thin shell, given small wedges
in opposite direction, the quantity of matter in that direction is
proportional to the square of the distance, which you divide by the square
of the distance for gravitation, so they're equal.  :)

[Note, I disappointed my High School Chemistry teacher by not taking Physics
my senior year.  As a result, most of my physics is self-taught.]



On 10/23/07 11:13 PM, Leonard Erickson wrote:

> Which would make finding one evidence of something *really* odd.
> 
> Possibilities (not an exhaustive list):
> 
> 1. it's been thrown back in time
> 2. it's slipped thru from an older universe
> 3. something removed the energy from it
> 4....
> 
> #3 is going to be of *great* interest to the military...

Actually, that would be of even more interest to *anybody* if you can remove
*useful* energy from it (or any generalized heat source).  :)



On 10/23/07 11:13 PM, Timothy Little wrote:

> It does actually conserve angular momentum.  In all reference frames,
> the angular momentum of the system before jump will equal that
> afterward.

Given that both masses are gone from *this* universe for approximately 1
week, and don't come to exactly where the other left (or jump exit variation
would go away), conservation fails.

Imagine, a mass pops into system A, because a ship is leaving tomorrow!