[ExI] Expansion of the Universe

[spike]

-----Original Message-----
From: extropy-chat-bounces at lists.extropy.org
[mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of Anders Sandberg

>...We can use Spike's reflecting Dyson shells to do it. I get a mass ratio
of sqrt[(1 + Delta v / c) / (1 - (Delta V/c)]. In our case it is
1.000533 (no stop) and 1.001 (stop). Quite acceptable!... Anders

>...
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Reminder of the time scales involved: I calculated about 20 million years
from here to the nearest star, which is about 4.5 yrs away.  To get to the
next galaxy, I came up with a scheme where you deflect off of other stars
and grab their galactic-center orbit velocity.  We can get a star to the
nearest galaxy in a billion years, which is enough time before our sun goes
off the main sequence.  But to move an entire galaxy that way requires just
light-pressure acceleration, which I calculated is about 300 meters per
square year.  Since M87 is about 50 Mly away, that's about 5e6* 1e16=5e22,
so t^2=1e23, t=3e11, about 300 billion years and we only have about 20
billion years before the Big Rip, and oh that is so sad.   However all is
not lost.  

Instead of hauling M87 here, we can leave it all out there, and take a good
bright young star from the Milky Way to M87 in about 15 billion years, which
may be within the life of a properly chosen star if we learn how to deal
with those difficult helium burning years which would occur along the way,
in the cold loneliness of intergalactic space.  

It fills one with a sense of urgency to realize that one has only 20 billion
years to live, and that's a best case scenario.  It causes one to be so much
more aware of the passing of each geological age, to learn to take one eon
at a time, to live in the millennium, to seize the century, that sort of
thing. 

spike