Re: A newcomer here

On Sun, 11 Sep 2005 14:29:34 -0700, Brooks Moses
<bmoses-nospam@xxxxxxxxxxxxxxxxxx> wrote:

>Wilson Heydt wrote:
>> In article <1h2iifw.1fahmba1nptncwN%mbottorff@xxxxxxx>,
>> Michelle Bottorff <mbottorff@xxxxxxx> wrote:
>>>If we were talking science fiction, I rather thought we couldn't get a
>>>sun small enough that it had less mass than an "earthlike" planet.
>>>
>>>If anyone has a notion of how to get one, though, I'd love to hear about
>>>it. I could *do* stuff with that.
>>
>> Small enough diameter is easy enough. Use a white dwarf. Mass is
>> another issue altoghter, plus explaining how you have a habitable
>> planet orbiting a reasonable distance from the white dwarf, 'cause
>> it sure isn't going to be that way while the star gets that way.
>
>Well, it's possible to have a planet with earth-levels of gravity and
>arbitrarily high mass, so long as one doesn't mind having a hollow
>planet. (And, at some point way up in the "arbitrarily high" scale, the
>planet's crust starts becoming remarkably thin....)
>
>So, you could have this tremendous beach-ball of a planet, carefully
>constructed near a white dwarf, with the white dwarf orbiting around it
>in a manner very reminiscent of the sun-god's chariot driving by
>overhead. If the orbital distance is small enough relative to the
>diameter of the planet, you then get only a small swath of land under
>the sun's path that actually gets much sunlight, and the nights are much
>longer than the days. And there's this tremendous realm of dark cold
>land (or maybe ocean) outside the lit areas, which may or may not harbor
>monsters.
>
>Making a hollow beach-ball planet strong enough to avoid self-collapse
>and to avoid breaking apart with the tidal forces is, of course, an
>interesting exercise.

If the planet has greater-than-Earth mass, it will have
greater-than-Earth gravity. Hollowing out the interior of a planet
(while presumably using some sort of handwavium force field to keep it
from collapsing inward under its own weight) will result in less
gravity, not greater gravity.

I think that what you are probably intending is to have a hollow
planet of considerably-greater-than-Earth diameter, while using the
hollow interior as a way of keeping the mass down so that the surface
gravity will be similiar to that of Earth.

Have you read Tony Rothman's _The World is Round_, which uses such a
scheme (although with a normal star, not a white dwarf)?

--
John F. Eldredge -- john@xxxxxxxxxxxxxx
PGP key available from http://pgp.mit.edu
"Reserve your right to think, for even to think wrongly is better
than not to think at all." -- Hypatia of Alexandria
.

Relevant Pages

  • Re: Relativity predicts itself false !!!
    ... says gravitational acceleration and kinematic acceleration are ... one may see a planet by the reflected light of the sun. ... call it gravity not acceleration. ...
    (sci.physics.relativity)
  • Re: I love me some Pravda
    ... carefully concealed from outsiders somewhere close to the North Pole. ... a reliable edition reported that UFOs coming to this planet start ... existed inside planet Earth too. ... The idea of a hollow planet was very popular among science fiction writers ...
    (rec.sport.pro-wrestling)
  • [Tass (n.tass{n.Taz})] I love me some Pravda
    ... carefully concealed from outsiders somewhere close to the North Pole. ... a reliable edition reported that UFOs coming to this planet start ... existed inside planet Earth too. ... The idea of a hollow planet was very popular among science fiction writers ...
    (rec.sport.pro-wrestling)
  • Another human civilization may live inside Earths hollows
    ... Legends say that an entry to the underground realms was located somewhere in the North, and legendary ancient tribes living on the planet centuries ago used the entries to have a good shelter under the Earth's surface. ... Mystics believe that the entry to the legendary Hyperborea, Shambala and Plutonia is carefully concealed from outsiders somewhere close to the North Pole. ... Researcher Edmond Halley studied the magnetic field of the Earth and noticed that it slightly varied which suggested that there could be several magnetic fields at once. ... And even some researchers presented various estimations and experiments to prove that the planet could be actually hollow inside. ...
    (soc.retirement)
  • Re: Electo London Gravity ?
    ... Certainly pressure is a factor for a planet but could we not ... to calculate the gravity slope inside a body of any significant ... > gravity slopes for various planets. ... > | electron cloud half the e- minus would be on you right, ...
    (sci.physics.relativity)