[ExI] Dyson Sphere? Why? Just move planets into Habitable Zone.

[Gregory Jones]

OK.  Imagine a kind of a flattened donut shaped cloud of devices shaped
like a disc, about 100 micron diameter and 100 nanometer thickness.  These
devices have three patches on them, like a single pixel of an LCD on a
watch.  These can be either reflective or absorptive, so the light pressure
on them varies according to whether they are reflective or absorptive.
Having three of them spaced at 120 degrees equidistant from the CG of the
device means it can hold any orientation with respect to the star about
which it orbits.

Back to the donut shaped cloud of these devices, orbiting a small planet.
Imagine that planet is too close to its star and the orbiting devices want
to move it outboard.  The discs orient themselves to reflect photons in the
direction from which the planet has come, so that it directs momentum in
such a way as to cause the planet-particulate cloud system to gradually
accumulate angular momentum from the photons.

In a few million years, the planet has moved away from the star a few
million km, out to the more comfortable zone.

One can move a star that way too: orbiting refective discs, individually
steerable, forming a series of concentric spherical shells, reflecting
light in the same direction, so that the star accumulates the momentum of
its photons, and gradually accelerates in the opposite direction it
reflects its light.  Moving a star that way takes a while, a few tens of
millions of years perhaps.  But what's the hurry?

spike

spike

On Tue, Sep 26, 2023 at 2:15 PM Keith Henson via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Tue, Sep 26, 2023 at 12:23 PM BillK via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:>
>
> snip
>
> > The article and their paper “Making Habitable Worlds: Planets Versus
> > Megastructures,”   <https://arxiv.org/pdf/2309.06562.pdf>
> > does consider using laser arrays for moving planets.
> >
> > They make the point that to get enough material to build a Dyson
> > Sphere you would have to dismantle most of the planets anyway and move
> > the construction material to the habitable zone.
>
> Maybe, but I doubt it.  I have not seen or set up the model, but I
> suspect building in the computational zone is far more likely.
>
> > Compared with that
> > task, just moving a suitable sized planet or asteroid seems much
> > easier.
>
> Please try to keep track of the scales involved.  Earth is about 6 x
> 10 ^24.  The asteroid Bennu is around 7.3 x 10 ^10.
>
> Moving a planet with a laser is about 10 ^14 more difficult.
>
> > That also avoids all the problems associated with a Dyson
> > Sphere that they discuss.
> >
> > They seem to be considering expanding to multiple times the population
> > of Earth, so that would require a lot of real estate. Much more than a
> > few space colonies. Although they could have small colonies as well.
>
> The classic calculation about this is that O'Neill-type colonies
> constructed from asteroids could provide about 2,000 times the area of
> Earth.  That assumes, of course, human-type bodies that need air,
> gravity, food, etc.
>
> If you are trying to provide living space for biological humans,
> piling the matter up to provide gravity is just a horrible way to do
> it.  Using the tensile strength of materials to enclose spinning
> habitats is far more efficient.
>
> Keith
> >
> >
> > BillK
> >
> > _______________________________________________
> > extropy-chat mailing list
> > extropy-chat at lists.extropy.org
> > http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat
>
> _______________________________________________
> extropy-chat mailing list
> extropy-chat at lists.extropy.org
> http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20230926/be015691/attachment.htm>