[ExI] Moving Stars

[spike at rainier66.com]

-----Original Message-----
From: extropy-chat <extropy-chat-bounces at lists.extropy.org> On Behalf Of
Keith Henson
Sent: Thursday, June 21, 2018 9:55 AM
To: ExI chat list <extropy-chat at lists.extropy.org>
Subject: [ExI] Moving Stars

https://www.sciencenews.org/article/combat-expanding-universe-aliens-could-h
oard-stars?tgt=nr

What's a bit strange about this is that the way to move stars is obvious.
Eric Drexler and I discussed it way back in the 1970s.
There is even a nice painting of a star fixed up this way somewhere.
(The artwork even had a slice out of the light sails to keep planets
illuminated.)

For those who have not heard about it, you hover actively controlled solar
sails over one hemisphere of a star.  This makes the star into a
fusion/photon drive.  The acceleration isn't much, but a G type star looked
like it could cross the average distance between galaxies before it burned
out.

Keith

PS.  For your amusement, the word "extropic" shows up on page 67 of the Feb
2018 Scientific American.
_______________________________________________



Keith this is so cool!  I had not heard that you and the K.Eric had already
worked all this out while I was struggling thru grade school.  

If I offer any insight, it is that the reflectors need not hover: they can
be in orbit and still have the photon drive effect.  The reflectors slow
down on the warm side and speed up as they fall toward the cool side, thus
spending more time on the side from which they are gently tugging the star
gravitationally.  Granted it takes a bit of rethinking to recognize that the
usual orbit equations fail when photon pressure is no longer negligible.

Of course it requires a lot more mass to do it that way, but the orbiting
reflection notion pays off in other ways, specifically heat control.  Even
with orbiting reflectors, the warm side still gets really hot.

Explanation of how I am using the terms: imagine a star with skerjillions of
individual orbiting nodes which turn and reflect light to the left.  When
they are on the left side of the star, they turn sideways to let most of the
light pass them by.  When they are on the right side, they turn to reflect
most of the light to the left.  Result: several meters per square year
acceleration to the right. 15 million years later, we swoosh past where
Proxima Centauri is now (it won't be there anymore) at a rate about typical
of a Boeing 737.  Sure it takes a while, but I don't know how the heck else
to get to another star other than to bring along our own personal
multi-generation ship, which is our planet (since it also gets tugged along
with our power source.)

spike