Centripetal, Centrifugal, Coriolis effect and Pseudo-forces.

[TrippyHippy]

Taken from the other forum:

“Centrifugal force” (discussed in the Artificial Gravity section). Technically, there is no such thing as centrifugal forces. What you have is centripetal forces and their interaction with Newton’s 1st law.

‘Centripetal force' means the force pulled to the centre of a circle when the motion of an object is in a circular motion.

So, for example, a bucket of water being swung around an axis by a rope has a centripetal force acting to accelerate the bucket to the centre, and prevent it from flying off. However, the water in the bucket is trying to maintain Newton’s 1st Law of motion (to keep moving in a straight direction at a constant velocity). Hence, as the bucket turns in a circle, the water continues to push straight until it collides with the bottom/side of the bucket. It therefore it appears to be forced to the outside of the bucket which is termed ‘centrifugal’ (or 'avoiding the centre'). However, it doesn’t really exist - centrifugal forces are pseudo forces.

If we are going to do a hard Sci-fi game, then let's get the Newtonian Physics correct from the start.

 

[TrippyHippy]

The response from Sigtrygg was:
Centrifugal force is a perfectly acceptable pseudo-force - it all depend on you frame of reference.

Centrifugal force - Wikipedia​

en.wikipedia.org

If you are inside the rotating body then you experience a centrifugal pseudo-force. So very Newtonian.

the Coriolis force is also a pseudo force

Coriolis force - Wikipedia​

en.wikipedia.org

You'll be saying gravity isn't a force next...

 

[TrippyHippy]

My response was that a 'pseudo force' means it doesn’t exist (and is therefore not acceptable). Also the extra point that post-Einsteinian Physics suggest that Gravity is just an effect of warped space-time, but this was another debate.

Please continue....

 

[Sigtrygg]

Physicists are quite happy to use pseudo-force, virtual particles and all sorts of things that do not exist in the real universe but allow for descriptions and equations for what is going on.

Centrifugal force does exist if you are inside the rotating body.

 

[TrippyHippy]

Physicists are quite happy to use pseudo-force, virtual particles and all sorts of things that do not exist in the real universe but allow for descriptions and equations for what is going on.

Centrifugal force does exist if you are inside the rotating body.

A pseudoforce is not real and you don’t speak for all physicists. I’m a physics teacher and it bothers me!

What could be acceptable is a sidebar explanation though - indeed if this type of science explanation gets used in sidebars frequently it will add to the authenticity of the book. Know your audience.

 

[Sigtrygg]

If the audience doesn't know that centrifugal force is actually a pseudo-force they may have an opportunity to learn something about reference frames. Messing around with the maths in the back of the book may just stimulate enough interest for them to go and learn a bit more about orbital mechanics.

 

[TrippyHippy]

If the audience doesn't know that centrifugal force is actually a pseudo-force they may have an opportunity to learn something about reference frames. Messing around with the maths in the back of the book may just stimulate enough interest for them to go and learn a bit more about orbital mechanics.

Well, yes - but part of the appeal of doing a hard sci-fi setting is bring real science concepts into the writing. Like I say, including some sidebars about things like this actually adds to the appeal. You mentioned about Gravity before - another example of something that would make an interesting sidebar in the book. There may be a limit of wordcount, admittedly, but these types of discussion add authenticity to the design. Just ignoring an issue like pseudo-forces opens it up to criticism instead.

We have a NASA-employed writer making a hard-sci-fi game as a selling point - sell it!