From: spike66 (spike66@attbi.com)
Date: Tue Jun 11 2002 - 23:17:38 MDT
Mike Lorrey wrote:
>spike66 wrote: ...a very advanced civilization might manage to cross
>interstellar distances of a few light years but not be able to
>manage the 10K or so light years of emptiness between
>the Milky Way and even the closer dwarf galaxies.
>
>
>I'd have to disagree with you here, Spike. If the propulsion of said
>civilization travels at near relativistic velocities (.9c+) and can
>accelerate to such velocities within a few years of voyage launch, then
>they can also reach velocities which will dilate the duration of
>intergalactic journeys with just a few more years of acceleration.
>
>When it comes to relativistic interstellar travel, if you can get
>anywhere, then you can get everywhere.
>
Let us imagine the scenario where a significant portion of mankind
recognizes that the singularity is coming. They wish to attempt to
outrun it by fleeing to the nearest stars and hoping there is some
dirt and water to be found out there.
We have about 50 years. Go.
Assume today's tech or tech that will be ready very soon:
no suspended animation, no controlled fusion, no uploading,
no wildly extended life spans.
But also assume we have a lot of rich people willing to kick
in resources. Looks to me like we have a situation where
we *almost can* cross interstellar space. But any intergalactic
crossing is out of the question, waaay out. This is a case where
we can get somewhere, but not everywhere.
Image a scenario where intelligent populations routinely
have 50 to 100 years between the time that space travel is
first attempted to the time that singularities occur, not so
different from what humanity is facing today. Imagine that
there is always a subset of the intelligent species that wishes
to flee from the singularity. These would quite typically be
in a state of technology where they can just barely cross
interstellar space, but not intergalactic space, not even close.
This is not so hard to imagine, when one realizes that with
the constraints of today's tech, velocity change is *always*
dearly bought. The amount of propellant needed increases
exponentially with linearly increasing velocity, whereas the
amount of power storage required to keep a multigeneration
crew alive increases only *linearly* with the length of time
needed for a trip. The best way to do the trip might be at
a leisurely pace, by science fiction standards.
Think of it this way: any interstellar trip using today's tech
would require a multigeneration ship. If it takes 10 tons
of plutonium to sustain a 10 person colony for 100
years, then it only takes 20 tons to sustain 10 people
for 200. Anyone who is still reading already knows the
rocket equation. So do the math.
Ignoring for the moment the fact that the erosion due to
interstellar gas and dust increases as the square of the
velocity, I can imagine that the galaxy could be lightly
scattered with smallish multigeneration ships of not so
exceedingly advanced intelligent beings fleeing singularities,
the vast majority of which are doomed to find the destination
star deficient in metals.
It is far easier for me to imagine these interstellar ships
travelling at a milli-c, enduring a desperate few thousand
year journey, than it is for me to imagine some civilization
figuring out how to somehow accelerate to several
hundred milli-c and back, and still managing to withstand
the friction from the tenuous interstellar debris.
These refugees would form an example of those who
can go somewhere but not anywhere. These would
form examples of space travellers for whom the edge
of the galaxy forms an impenetrable barrier, far more
formidible than the open oceans did for early humans.
This is a possibility: that there really are no magic discoveries
in physics yet to be conceived, that there are no terrific
shortcuts to space travel, that Newton's laws really do
hold true always and forever. But the Singularity is
coming, and we do not know what will happen when
it does. With today's tech and sufficient motivation,
we have a faint hope of surviving an attempt at the
crossing to the nearest star. spike
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