Can Two Objects Move Opposite Directions?

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Discussion Overview

The discussion revolves around the question of whether two objects that have no empty space between them can move in opposite directions. Participants explore this concept through various scenarios, including rotation and sliding, and consider implications at different scales of physics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that two objects can rotate about a center point, allowing one to move left while the other moves right, even if they are stuck together.
  • Others argue that the concept of "empty space" is crucial to understanding how objects interact, questioning whether true contact exists between surfaces at a macroscopic versus microscopic level.
  • One participant suggests that the question may be conflating principles from different realms of physics, such as classical mechanics and quantum mechanics, which complicates the discussion.
  • There is a suggestion that examples like a marble on a glass table illustrate the idea of two objects moving without empty space between them, yet this raises further questions about the nature of contact and movement.

Areas of Agreement / Disagreement

Participants express differing views on the implications of "empty space" and the nature of contact between objects. There is no consensus on whether the original question can be meaningfully addressed within the frameworks being discussed.

Contextual Notes

Limitations include the ambiguity surrounding the definition of "empty space" and the varying interpretations of what constitutes an "object" at different scales, particularly when considering quantum mechanics.

Avgiu
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Can two objects that have no empty space between them move in opposite directoins?
 
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What if they rotate?
 
If there is nothing that separates the rotating objects, are they not attached?
 
They could be. But they can still rotate. Imagine two blocks stuck together. The system rotates about its center. So, one block goes left while the other goes right. (Momentarily.)

What are you getting at with this question? (I don't see any obvious physics here.)
 
Doc Al said:
They could be. But they can still rotate. Imagine two blocks stuck together. The system rotates about its center. So, one block goes left while the other goes right. (Momentarily.)

What are you getting at with this question? (I don't see any obvious physics here.)

Is there empty space between a marble and the glass table it moves across
 
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Avgiu said:
Is there empty space between a marble and the glass table it moves across
I would say no, at least macroscopically.

That's a much better example (of two things with no space between them moving in opposite directions) than my rotating object example! So I guess you answered your own question. Another example would be two things sliding across each other.
 
In first response your talking about a baton type of thing where one end is going against one way and the other is going another way. But you spoke of things sliding across each other. How can a thing slide across another thing without there being empty space, and if there is no empty space doesn't that change most of modern day physics?
 
I'm not sure what kind of answer you are looking for. It seems like you are hanging a lot on the meaning of "empty space". You slide a block of wood across a table. Is there "empty space" between the wood and the table? Macroscopically, I'd say no; but microscopically, there's plenty of empty space. After all, most things are mainly "empty" space. The only real "contact" between the surfaces is at the surface irregularities. I'm not seeing the issue. (And I certainly don't see the impact on modern day physics!)
 
This person also needs to clearly explain what is meant by an "object". By the time one gets to the extremely small scale, we have to invoke QM and all appearence of an "object" with definite spatial boundary is no longer valid.

So from where I'm looking, it looks like the question in this thread is using some rules from one realm of physics and mixing it with another set of rules from a different realm of physics. Such an exercise seldom produces anything meaningful.

Zz.
 

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