[ExI] Interstellar Travel is really hard

[Rafal Smigrodzki]

On Sun, Jan 9, 2022 at 6:41 AM BillK via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Sun, 9 Jan 2022 at 06:05, Rafal Smigrodzki via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
> >
> <big snip>
> >
> > ### As I said, just one group who likes to travel, out of thousands who
> like to navel-gaze, collapses this line of argument.
> >
> > It's just like when a bacterial culture in a small flask with 10e7 cells
> is exposed to antibiotic - even if 99.9999% are sensitive, you are
> guaranteed to have a thick broth of bacteria descended from the remaining
> 0.0001% filling the flask in a couple of days.
> >
> > Rafal
> > _______________________________________________
>
>
> Your example is correct for those circumstances, but I don't think it
> can be applied to existential crises on planetary populations or
> interstellar travel.
>

### Why not? Where does the analogy break?

--------------------------------


> Looking back over millions of years it appears to us that an asteroid
> wiped out the dinosaurs. But it wasn't really like that. The asteroid
> set off a chain of disasters that gradually over many years reduced
> numbers until survival became impossible.
> For an interstellar ship traveling at 20% of lightspeed the journey
> will be long, probably over 20 years just to the nearest star. A lot
> can go wrong in 20 years. Cosmic ray damage, supplies running out,
> machine breakdown, medical problems, etc.  Hitting a speck of dust at
> that speed is problematic. And it won't be just one speck of dust and
> some of the specks of dust might be small rocks.
>

### Are you saying the *every* starship sent out by millions of
civilizations over hundreds of millions of years will inevitably fail?
Because if you agree that even a small fraction survives, then the argument
is moot - all you need for a galaxy teeming with life is some starships
succeeding, not all of them, not even a majority, not even a small
minority. All you need is one civilization that develops a method for
sending enough ships to enough stellar neighbors to make on average more
than one self-sustaining and self-spreading colony from each parental
colony, and the rest is inevitable.

Also, cosmic ray damage? Supplies running out? Medical problems? How could
all civilizations everywhere always be defeated by such predictable and
manageable issues? Wouldn't some civilizations build starships designed to
withstand cosmic ray damage, with enough supplies and without live crews
susceptible to medical issues?


> That's what I mean when I say interstellar travel is really hard.
>
> ### If it's easier than beating the 2nd law of thermodynamics, it will
happen, somewhere.

Rafal
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