## Windscreen Wipers...

Ideas about how a world with more than three spatial dimensions would work - what laws of physics would be needed, how things would be built, how people would do things and so on.

### Windscreen Wipers...

Not sure if this situation has been raised before?
How would windscreen wipers work on a 4D car? Any thoughts?
gonegahgah
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### Re: Windscreen Wipers...

A 4D windshield would have to span a 3D hyper-area, so the analog of a windshield wiper would have to sweep out a 3D region. So my expectation is that the wipers would span 2D areas, so that when they sweep across the windshield they would clear away a 3D region of water. As to the exact shape and number of the wipers, that would depend on the shape of the windshield, which in turn depends on how the car is designed.
quickfur
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### Re: Windscreen Wipers...

Cool. That makes sense and provides food for thought.
Thanks quickfur.

I guess they could also even possibly spin as long as the spin describes a swiping process?
Perhaps like some sort of spinning offset plane?
Would that work?
gonegahgah
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### Re: Windscreen Wipers...

Spinning is a swiping/sweeping process. Think, for example, about surfaces of revolution in 3D that are commonly used in undergrad calculus classes. A wiper could be for example a square hinged on the X axis, say, so that it rotates around the X axis when activated. It would thus sweep out the volume of a 3D cylinder. So if a 4D windshield were in the shape of a cube, say, the wiper could be attached to one side, with the X axis running down the middle of a square face and the wiper being a rectangle occupying half of the square, then when it rotates it would sweep out a half-cylindrical region on the windshield.

You could also put the axis in the middle and have the wiper continuously sweep out a cylindrical region in the middle of the windshield (like extruded radar ); that would work if the driver's seat is offset to one side of the windshield, as would be the case in a wide, multi-seat vehicle. Less desirable for single-seat configurations because you'd have the wiper axle sticking through the middle of your view.
quickfur
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### Re: Windscreen Wipers...

Opens up possibilities...
Maybe you could also have multiple triangular blades that rotate themselves while also following each other around in a circle so that we don't get that unmoving centre?
I guess like 3 spinning planets in the same orbit around the sun, but with the planets being flat and wider (wider than where the sun would lay) with three different orientations so that they don't collide?
Wish I could animate that easily with the triangles.
gonegahgah
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### Re: Windscreen Wipers...

IMO that'd be too distracting to the driver.
quickfur
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### Re: Windscreen Wipers...

I was then also thinking about the windscreen shape...
Apart from the forward direction it could basically just form a cylinder to provide maximum view.
I then though maybe the sideways orientation of the driver wouldn't matter...
... but then I realised the driver would still need to have instruments close to each hand.

So would the windscreen be somewhat triangular then? Or, still cylindrical in the sideways direction?

The indicator would probably allow for different directions to be indicated so that you could indicate to turn into a particular sideways direction.
One hand could control that with a joystick style indicator.
The windscreen wipers would also be controlled by a separate hand; just like we do.
But what would an extra hand do? I'm guessing drivers would have preferred orientations to these controllers.

Seats we sit on tend to have a little hill between the legs for greater comfort so I guess there would still be a little hill between each of the legs of a 4D person.
The feet would have accelerate, brake, but perhaps also rotate?
gonegahgah
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### Re: Windscreen Wipers...

To sweep a chorid (3d solid) with wipers, you need the wiper to be hedrid (2d).

Given that the intent of wipers is to throw the water off some forward area, including a solid block where the driver sits, the motion would prolly be a prism-version of the 3d wiper, ie a square or something swept side to side in an arc. The driver's attention would then follow behind the sweep of the blade, where the view is clearest.
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