“Reactionless” subluminal ships

[Starscapion]

An interesting read about how warp drives that are subluminal with spherical geometry could exist with positive mass.
https://arxiv.org/pdf/2102.06824

[Drashner1]

Thanks for sharing this.

I haven't had a chance to look at it yet (busy busy) but will aim to do so over the long weekend and post thoughts after that.

Thanks!

Todd

[Starscapion]

Thanks for sharing this.

I haven't had a chance to look at it yet (busy busy) but will aim to do so over the long weekend and post thoughts after that.

Thanks!

Todd

Epic

[Drashner1]

I gave this a light read thru (I am not a physicist, so the math elements are mostly over my head) and also googled on it a bit turning up some videos I still need to look at, but based on what I've seen so far...

This looks to be a 'warp drive' variant that doesn't actually propel the ship but instead encloses it (or some part of it) in a region of warped space-time that is then manipulated to either slow down the passage of time so that the trip seems shorter even if the ship isn't moving fast enough to experience significant time dilation. There is also a suggestion that such a bubble might also be manipulated to produce black hole like effects (possibly still requiring importing a lot of mass, even if less than normally required for a BH of a given size - not entirely clear on this bit) that would allow it to be used as an energy source via something like the Penrose Process.

At the end of the day, neither of these are 'drives' in the conventional sense of the word, although I understand why the terminology was used, at least up to a point. Anyway.

OA actually has a form of the first type of warp bubble - Stasis Bubbles - although they have various limitations that we deliberately included for various editorial reasons. These are actually based on a different paper I found somewhere (and should have held onto, drat!) that talked about creating exotic energy bubbles in which time could be slowed down, sped up, stopped, or even run backward. Introducing that level of messing with time into the setting (particularly running time backwards - what would that even look like?) seemed likely to cause various headaches, so I decided to just limit things to stasis bubbles.

I'm not initially feeling all that into the second variant - warp mediated BH creation - but need to read that section again and in more depth to get a better idea of what is actually being described. Maybe one of the videos will talk about it as well, which would be helpful.

More later once I have time to dig into this a bit more.

Todd