Thread | Brutkey

400 years to Proxima Centauri means velocity of roughly 1% of c. To accelerate to that, then decelerate, takes energy on the order of 1-2% of the ship's rest mass.

Ship is 36 miles (50km) long.

So it obviously masses many gigatonnes (1 cubic kilometer of water—0.15 the density of steel—masses 1 billion tonnes). Conservatively this masses 10-100gt.

Fusion bomb yield is about 2% of the payload mass. Our current 10,000 H-bombs probably contain 1000kg of fuel.

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https://spacey.space/@nyrath/114992789210759955

Charlie Stross
@cstross@wandering.shop

@nyrath@spacey.space Upshot: I think this thing will take 100-1000 years of our current worldwide civilizational energy budget to propel.

And at the other end? Congratulations: a colony of 2400 people is at least 3 orders of magnitude too small to sustain a self-training technology base able to service an autonomous space colony. (Because resupply with finished products is impossible at that range.)

TLDR: magic wands or scientific breakthroughs required.

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Dan Sugalski
@wordshaper@weatherishappening.network

@cstross@wandering.shop @nyrath@spacey.space I remember doing the math once, and I came away convinced that the overwhelming problem with any kind of interstellar travel is that space is big. (I didn't believe how vastly, hugely, mind-bogglingly big it was...)

Going anywhere in a reasonable amount of time requires impossible amounts of energy, and going anywhere with reasonable amounts of energy requires impossible amounts of time. And, more than that, impossible amounts of equipment life.

Poul-Henning Kamp
@bsdphk@fosstodon.org

@wordshaper@weatherishappening.network @cstross@wandering.shop @nyrath@spacey.space

The biggest problem is know where to go in that big space.

Humanity has only been easily detectable at a distance for the single century between discovering radio and spread-spectrum modulation.

If you only have a 100 year window in which to detect that there might be a civilization to visit, space just got a lot more lonely.

Angus McIntyre
@angusm@mastodon.social

@wordshaper@weatherishappening.network @cstross@wandering.shop @nyrath@spacey.space Maybe the ultimate answer to the Fermi Paradox is that every civilization eventually does the math and says “You know what? There's no way to make this thing work. Why would we even bother trying?” and resigns itself to a peaceful, low-energy retirement on its home planet. Until either its primary expands into a red giant or, more likely, the ecosystem goes tits-up as a result of previous bad decisions.