"Motion is impossible" claims modern Zeno

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Discussion Overview

The discussion revolves around a thought experiment involving a piano on a frictionless surface and the implications of work and energy in motion. Participants explore the paradox of whether it is possible to move the piano given certain assumptions about work and kinetic energy, questioning the relationship between force, work, and motion.

Discussion Character

  • Debate/contested
  • Exploratory
  • Conceptual clarification

Main Points Raised

  • One participant claims that the piano cannot be moved due to a circular reasoning involving work and kinetic energy, stating that work cannot be done unless the piano is moving, yet it cannot move without work being done.
  • Another participant challenges this reasoning by suggesting that a force can be applied to the piano without doing work if it remains stationary, implying that the piano must accelerate once a force is applied.
  • Some participants discuss the misinterpretation of relationships between variables, arguing that assuming a two-way causation leads to paradoxes in understanding motion and energy.
  • A participant expresses confusion about how energy is transferred to the piano, questioning the necessity of the piano having energy of motion before work can be done on it.
  • There is a discussion about the nature of movement, with participants questioning whether something must be moving at all times to be considered in motion.
  • One participant emphasizes that the relationship between force and energy is not straightforward, suggesting that force does not necessarily equate to energy expenditure at every moment.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the validity of the original claim regarding the immovability of the piano. Multiple competing views are presented, with some participants supporting the paradox while others challenge it through different interpretations of work, energy, and motion.

Contextual Notes

The discussion includes assumptions about the definitions of work and energy, as well as the implications of Newton's laws, which are not universally accepted or understood by all participants. The mathematical relationships presented are also subject to interpretation and may not be universally applicable in the context discussed.

  • #61
thinkandmull said:
So we must say that continuous motion has a special quality that is a "sum greater than its parts", so to speak.
No, it has nothing to with motion being special. You can divide any number like that. An it's not greater than the sum of its parts.
 
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  • #62
Than we are faced with the same paradox as Zeno's Arrow paradox. I think motion is "one step ahead" of matter so to speak. I don't know how else to say it. When you cross a finite segment, you pass over infinite points, and there is no final step. There are no discrete "one two three" steps to take and then wow! you are at your destination. I'm thinking that motion must be more mysterious, something about it that we are not getting straight from math, but can understand better with physics
 
  • #63
thinkandmull said:
Than we are faced with the same paradox as Zeno's Arrow paradox. I think motion is "one step ahead" of matter so to speak. I don't know how else to say it. When you cross a finite segment, you pass over infinite points, and there is no final step. There are no discrete "one two three" steps to take and then wow! you are at your destination. I'm thinking that motion must be more mysterious, something about it that we are not getting straight from math, but can understand better with physics

My steps are about 1m, so if I have to travel 3m, then it is "one, two, three" and I'm at my destination.

I never thought much of Zeno's paradox, I must admit. Here's my version:

The hare starts 1m behind the tortoise.
The hare starts 1m behind the tortoise.
The hare starts 1m behind the tortoise ...

Ergo, the hare never even moves let alone catches the tortoise.
 
  • #64
thinkandmull said:
Since I am using a line's quality as the bases for my understanding this, no I am not sure what a limit would be for infinite numbers or steps
This is the thing that you need to learn then. Once you have understood the limit of an infinite sum of real numbers then the mapping from the real numbers to a line is trivial.

As far as the infinite sum goes, this is actually straightforward. If you have ##\sum _{n=1}^k \frac{1}{2^n}## then you can fairly easily convince your self (simply by writing it out for a few small values of ##k##) that the answer is ##1-2^{-k}##. As ##k## becomes larger and larger the sum gets closer and closer to 1. In fact, you can specify any arbitrary ##0<\epsilon<<0.5## and calculate the ##k## necessary to make the sum closer to 1 than ##\epsilon##. This is what it means to have a limit. The limit of any finite series is less than 1, but as the finite series gets arbitrarily large the sum gets arbitrarily close to 1. So the infinite sum is equal to 1.

Please start with this website and think and mull it over a bit:
http://www.math.utah.edu/~carlson/teaching/calculus/series.html
 
Last edited:
  • #65
thinkandmull said:
...so to speak. I don't know how else to say it.
Use math.
 

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