Re: Sinosauropteryx filament melanosomes challenged

[Erik Boehm <erikboehm07@yahoo.com>]

> Perhaps -- just perhaps, though we
> will be extraordinarily lucky to last long enough to develop
> the level of technology required (should this even be
> possible) before driving our civilization to the point of
> collapse. However, if the "space seed" hypotheses are
> correct, some extremely simple organisms may have "solved"
> the space travel problem billenia before we got here.

#1) The Space seed hypothesis is lacking, a LOT.
How is a bacteria even going to get to 0.0002c?
Ejecta from impacts won't do get going that fast, they won't even leave their 
system.
1/1000th of the speed a fusion powered craft could go, turns a few million year 
transit time, into a few billion, and 1/10,000th the speed of light is a lot to 
ask for a bacteria with no propulsion...
By the time you consider how fast they could reasonably go, you must conclude 
that 5 billion years isn't enough to cross the galaxy,
and that isn't even mentioning the extreme unlikeliness of it surviving even a 
thousand years drifting in space...
I don't buy the panspermia hypothesis.
At most I could see microscopic life getting from one planet to another within 
the same system.
I can't imagine any means by which a bacteria would reach escape velocity for 
its solar system.

Maybe a passing by massive option could send its planet careening through 
space... and then getting ejected from there but that would still result in 
velocities far too low to cross the galaxy in a hundred billion years.
Not to mention the low innoculum, the likelihood that such a bacteria would 
wind up on a suitable planet...

No, I will not seriously consider that bacteria are interstellar travelers.

#2) There is no question it is possible.
The question is how big of a fusion reactor you would need, and could a 
civilization unite "for the common good" to build such a vessel, that they will 
never see any benefit from (they'll be long dead before it gets anywhere).

Fusion is possible, if you doubt it, I suggest you go look outside at the sun 
(if it is day) or stars (if it is night).
And there is no question that with the energy released the exhaust velocity of 
the propellant could be high enough to attain well over 0.2c with a propellent 
mass to total mass ratio that is significantly less than the Saturn V rocket.

However, getting to 0.2c would take a long long time, and you'd need to 
decelerate from about that speed too (although 0.2c is actually conservative 
considering the theoretical max delta V of >100,000 km/s) with a mass ratio of 
10, compared to the mass ratio of 22 for the Saturn V).
It would still take a long long long time to get anywhere in terms of the human 
life span, but in "geologic time", it would be very fast.
100,000 light year diameter-> get to 0.1c, and then stay there for most of the 
journey, then decelerate (for a total delta V of about 0.2c) and you cross in 
about a million years.

Then of course there are more dubious technologies like bussard ramjets (which 
may not work, but a similar concept would at least work as a brake, and allow 
one to use more propellant to accelerate than to decelerate), which could half 
this time.
Even with a lot of inefficiency, and only proton-> boron fusion, a ship could 
still manage 0.02 and make the trip in a rather small 10 million years.

Colonizing the galaxy would not take that long, the problem would be getting 
self sustaining manufacturing facilities in space (as presumably, earth like 
planets are few and far in between, with large gaps where the only habitats 
would be asteroids and gas giants.