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by roywiggins 2949 days ago
Reactionless drives are even "worse" than Epstein drives, since they break conservation of momentum entirely. Epstein drives just have wildly implausible characteristics- while they might break all known laws of, say, material and nuclear science, they don't break conservation laws since they require reaction mass.
3 comments
SolarNet 2949 days ago
If I remember correctly the authors stated it was based off of the theoretical limits of efficiency for a reaction mass drive (e.g. if we could turn mass into acceleration with very little waste energy). Which is a really great conceit in my opinion because it stays hard sci-fi where it matters (e.g. besides the aliens) while still being close enough to our time to be interesting.
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ben_w 2949 days ago
Given what appears on screen, the Epstein Drive doesn’t even have that problem. It “only” acts like an electrostatic confinement fusion reactor with a hole in the confinement, slight enough for only the fusion products to escape, where the nozzle points.

(Edit footnote: only seen s1/2, anything surprising in s3 is unknown to me).

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roywiggins 2949 days ago
The "Eros incident" does imply that the aliens have an interesting relationship with momentum, since ordinarily accelerating something that big that fast would grind everything to a pulp.
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sjburt 2949 days ago
I thought when they were "flying teakettle" they were using water as a reaction mass, and the Epstein drive was an unexplained reactionless drive? At least in the books, haven't seen the TV show.

Iirc, there's some mention of pre-Epstein fusion ships that needed even more water.

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roywiggins 2949 days ago
It's left intentionally vague, but at some point they do refuel the drive. It's meant to be an improbably efficient fusion drive.

The alien forces demonstrably have a reactionless capability though (see: Eros) that utterly outmatches the Epstein drive.

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jerrysievert 2949 days ago
you can read the novella Drive online: http://www.syfy.com/theexpanse/drive/prequel.php where it appears to be some sort of issue that occurs to his failing fusion drive, so definitely a more efficient fusion drive.
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