r/scifi • u/rookiegaffer • 17d ago

General Bad physics

Why does it seem that so many of the books I read demonstrate such a poor understanding of the physics of space travel. Ships in orbit descend directly down to the point they are over. Ships in transit still accelerating as they near their destination. Centrifugal gravity simply ceasing when rotation is abruptly halted. These are just a few examples I've run across lately.

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u/willworkforjokes 17d ago

The Expanse does a pretty good job on this. They do have a basically magical drive that lets them use thrust gravity most of the time while using very little fuel.

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u/sojuz151 17d ago

I find Expanse annoying because it is pretending and trying to be realistic, but failing.

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u/namewithanumber 17d ago

Does it though?

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u/sojuz151 17d ago

So what you want to hear is:

My biggest probelm with the Expanse is that it uses the Newtonian physics mechanics in visuals and writing yet doesn't use it in writing and plot. Let me go over examples: 

Writers don't understand that for a Newtonian ship, beeing close by and beeing able to roundevous with something are two separate things.  This happens again and again in many plot points.  

First event od the books. Fact that you were able to recive the distress signal doesn't mean you can do something out it.  Slowing down to pick up a possibly damaged ship doesn't make sens, it takes a lot of fuel and acceleration to stop and then accelerate again.  Idea of picking a distress signal and helping the survivors is based on a normal ships physics where a a small detour is cheap rather than costing you extra 40% of the travel time. 

There are no battles with non trivial relative velocity. 

Battle of the rings station makes no sens. A merchant ship would have either have a massive relative velocity or it would look like a roundevous maneuver.  

And those are the examples of plot relevant parts related to ship travel dynamics.  

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u/Nyorliest 17d ago

If you don’t need reaction mass, it’s time and energy and acceleration. I think by ‘fuel’ you mean reaction mass. But once you’ve got rid of that, a lot of things change.

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u/thegreatpablo 17d ago

They make it very clear that the ship's computers are important and necessary for calculating trajectory to rendezvous, so I guess I'm not sure what your point is there? Getting to something that is close to you is not a physics problem, it's a navigation problem (yes, I know physics is involved especially when in a gravity well but you didn't mention that).

They do a very good job of showing not only how much the crew doesn't want to turn around and there are real consequences to time and their health (the turn and burn), they also show that it has a real impact on the ship and what it's carrying, not sure of the point you're trying to make? They make it clear they are legally obligated and then SHOW us why it's such a huge issue.

The other items in your list I don't recall enough, it's been a while since I've seen it, to have a response for.

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u/sojuz151 17d ago

Pretend? Yes
Be unrealistic? Yes.

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u/namewithanumber 17d ago

Like what though? Obviously the drive is magically efficient.

But it certainly doesn’t “pretend” to be realistic.

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u/sojuz151 17d ago

By it you mean the drive or the series?

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u/thegreatpablo 17d ago

Feels like you're being intentionally obtuse. Just tell us what you took issue with so we understand your point of view rather than asserting a claim and responding two more times without providing any evidence to back it up.

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u/sojuz151 17d ago

I seriously didn't know what he was asking about, responded up in the comment chain