Revolving around a sphere helically?

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Discussion Overview

The discussion revolves around the possibility of an entity revolving around a sphere in a helical path, constrained to maintain equal distance from the surface, with a focus on the mathematical and topological aspects of such a motion. Participants explore the implications of forces acting on the entity and the nature of the space required for this motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant questions whether a specific kind of space exists that allows an entity to revolve helically around a sphere while maintaining equal distance from its surface and only experiencing a force perpendicular to that surface.
  • Another participant argues that if the only force acting on the entity is radial, it will move along a great circle, as per Newton's second law, and cannot deviate from this path.
  • A participant emphasizes the mathematical aspects and suggests that the discussion should consider special topologies or reference spaces where such helical motion might be possible.
  • It is noted that mathematically, a spring cannot exist on the surface of a sphere while maintaining a constant distance from it, and changing coordinates does not alter this fundamental reality.
  • One participant introduces the idea of an infinitely-long cylinder of matter as a source of force, suggesting that helical orbits could exist around it, particularly if the cylinder is sufficiently long and dense.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of helical motion around a sphere, with some asserting that it is not possible under the given conditions, while others explore alternative configurations, such as cylindrical forces, that might allow for similar orbits.

Contextual Notes

The discussion includes unresolved mathematical implications and assumptions regarding the nature of forces and the geometry of space involved in the proposed motion.

ManDay
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Dumb question maybe, since I'm not a mathematician, but is there something like a specific kind of space in which an entity given a certain initial velocity parallel to the surface of a sphere and constrained to equal distance to the surface of it will revolve arround the square helically (not equatorially), without being exerted any force other than the one running perpendicular to the surface?
 
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ManDay said:
Dumb question maybe, since I'm not a mathematician, but is there something like a specific kind of space in which an entity given a certain initial velocity parallel to the surface of a sphere and constrained to equal distance to the surface of it will revolve arround the square helically (not equatorially), without being exerted any force other than the one running perpendicular to the surface?

Hi ManDay! :smile:

(btw, "helically" means like a spring … did you mean like a sort-of sine function?)

If the only force is radial, then good ol' Newton's second law means that the particle will have no reason to turn, and so will move along a great circle ("an equator").

The radial force may change the speed along that great circle, but can't make it deviate from the great circle. :smile:
 
Like a spring, yes.

Since this is the physics-forum I assume you can assume that everyone can presume at least a basic knowledge. Know about that "Newton-stuff" :D I'm concerning the mathematical aspects since this is the maths-subsection. I was asking for a sort of special topology or reference-space in this would be possible.
 
Last edited:
ManDay said:
Like a spring, yes.

Mathematically, you can't have a spring on the surface of a sphere, or "constrained to equal distance to the surface".
I was asking for a sort of special topology or reference-space in this would be possible.

Changing the coordinates won't alter this basic reality. :redface:
 
If you hand an infinitely-long cylinder of matter as the source of the force, then there would be helical orbits around it.

Consequently, for a finite cylinder, if it is sufficiently long and dense, and you stay near the center (away from the endpoints), then there are orbits which locally look like helices. But since the cylinder is finite, these orbits will distort as they get closer to the endpoints.
 

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