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2022-04-14

Lecture 1: On Space Travel

tags: lecture

Intro

Over at Midnight Pub ~theoria says:

Tell me more about the astrophysics! I've always found promises of interplanetary travel unrealistic and irresponsible in regards to the planet we already inhabit. I can't imagine the logistics of shuttling a significant proportion of the first-world population (let alone the world population) off-planet. It's the vapid daydreaming of those wealthy enough to waste billions.

My original reply

Tell me more about Astrophysics

Astrophysics? Ok, well. You already found out that we will not leave this planet in our attached life form in numbers exceeding a few dozen. I have ranted about the fashionable escape elsewhere:

/en/2021/20210724-spaceflight.gmi

However, one can for a few minutes make a thought experiment, of the "what if" sort. What if we must ship a group of folks to Proxima Centauri (or near there) in a desperate attempt to keep human life afloat while the planet burns? Without much thinking:

How to gather and transport the amount of energy/momentum required to accelerate the space ship? This alone is gigantic. Tons of mass for each fraction of a ton of payload.
How to gather the energy required for the crew to live? It is dark out there, and once you "leave" the vicinity of Sol, its only getting darker. Solar panels are not an option any more.
How about producing food? I mean, nothing will grow without light, right?
The length in time of the journey will be many human life times. So the crew must consist of a group of male and female, able to reproduce. How many genetic lines must be present on board to survive such an adventure over the course of say 100 generations? This is a very interesting problem.
And I have not thought much about the delicate balance of humans and their symbiotic lifeforms (mostly in our intestines), which are absolutely necessary to survive on this planet. What if they deteriorate? What if their balance (there are several different ones needed) goes pear shaped? What if some disease spreads and kills about half of the crew? And how about the delicate genetic plan laid out in the section before?

Of course, there has been serious scientific work on all these. And of course, there has been literature written about some of the aspects mentioned. For example:

"To Conquer Chaos" by John Brunner --- this novel describes among other things the genetic aspect mentioned. A too small group of survivors on a place on Earth, which has been deliberately "cut off" from it's surrounding lands, is desperately trying to survive genetic degradation. The story brings two outsiders to the group. But imho the author was not brave enough to immediately have the girls of the survivors group mate with the two outsiders. Because tomorrow they could be dead due to some unforeseen incident. The story ends there, although I would be interested in the authors view, of what came after that.
"Echoes of Earth" by Sean Williams and Shane Dixon --- a very interesting collection of ideas. The crews of exploration ships are "virtual", they are neural copies of selected human beings. Another thing is that Earth has been destroyed by an army of nano robots, which got out of control.
"A Canticle for Leibowitz" by Walter M. Miller, Jr. --- a very thick book spanning a few centuries. One aspect is how to conserve knowledge of the time for future generations, and how that might work or fail. The story ends at the escape of the selected few to space.

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