Average Randomness Thought experiment

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Discussion Overview

The discussion revolves around a thought experiment concerning the concept of "Average Randomness" and its implications in predicting the behavior of a particle subjected to random forces. Participants explore the statistical nature of randomness, its relation to concepts like diffusion and Brownian motion, and the mathematical modeling of such phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • One participant proposes that if a particle is acted upon by random forces, it may eventually average out to a predictable behavior over an extensive period.
  • Another participant counters that while individual pushes are unpredictable, one can predict the probability of certain pushes occurring, drawing parallels to quantum mechanics.
  • A participant introduces the concept of a "random walk," explaining that the average distance from the starting point increases over time, but the exact position remains uncertain.
  • One participant mentions that this phenomenon is related to diffusion or Brownian motion, suggesting that while individual paths are unpredictable, averages can become predictable over time.
  • Another participant clarifies that the total integrated movement is linear with time, but the expected distance from the origin grows with the square root of time, providing a probabilistic framework for understanding the particle's behavior.

Areas of Agreement / Disagreement

Participants express a range of views on the predictability of the particle's behavior under random forces. While some agree on the statistical nature of averaging out over time, others emphasize the inherent unpredictability of individual movements, indicating that multiple competing views remain in the discussion.

Contextual Notes

There are assumptions regarding the nature of randomness and the conditions under which predictions are made, such as the definition of "pushes" and the time scales involved. The discussion does not resolve these assumptions or the implications of the models presented.

ImaBeast
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"Average Randomness" Thought experiment

Please bear with my explanation, I am, by no means a Physicist.

During a recent theoretical thought experiment, I thought of a strange factor that I feel I should let out before it becomes forgotten by the constant wave of thought experiments that flow through my mind.

Lets say we have an object, that is being acted upon, by a random force.
For example a particle, in space, and the force would be someone pushing it slightly in any & all given (random) directions...
Just assume the force to be equal on each push.

So the particle would kind of wobble in a three dimensional "sphere".

Now, if this happens for billions100 of "pushes" per second, for billions100 of years, and each movement were documented, wouldn’t it average out (statistically) eventually? Ultimately becoming predictable?

I am open to any comments about this, as my understanding of physics is minimal at best.
 
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If the pushes were totally random, then by definition, you would never be able to predict the exact push. You could, however, begin to predict the probability that a certain push occurs.

Similarly, in quantum mechanics, the most information you can give about a particle prior to your observation is the probability of the particle being in a certain state, since wavefunction collapse is totally random.
 


In computer [STRIKE]programming[/STRIKE] science this is called a "random walk".

Simulating it results in the particle moving from its starting place and on average, increasing its distance from its starting location as time continues. (Because if two events combine to move it, it takes an exact combination of the same 2 events to put it back, and that doesn't likely happen).

All you can really predict is that "after N seconds, the ball is somewhere between X and Y distance of its start point" edit: Where X and Y are proportional to N.

Maybe the mathematicians on here can do better than me.
 


ImaBeast said:
Please bear with my explanation, I am, by no means a Physicist.

During a recent theoretical thought experiment, I thought of a strange factor that I feel I should let out before it becomes forgotten by the constant wave of thought experiments that flow through my mind.

Lets say we have an object, that is being acted upon, by a random force.
For example a particle, in space, and the force would be someone pushing it slightly in any & all given (random) directions...
Just assume the force to be equal on each push.

So the particle would kind of wobble in a three dimensional "sphere".

Now, if this happens for billions100 of "pushes" per second, for billions100 of years, and each movement were documented, wouldn’t it average out (statistically) eventually? Ultimately becoming predictable?

I am open to any comments about this, as my understanding of physics is minimal at best.
This actually happens in what is called "diffusion" or "Brownian motion". Yes, although the path of an individual particle at a given time is unpredictable, averaged out over a long time for one particle or over a shorter time for a lot of particles the average becomes predictable.
 


The total integrated movement based on all "pushs" is linear with time, but the average (expected) distance from the original position grows with the square root of time. This is the "predictable" part: Give it 10^1000 pushs, and you can expect to find it somewhere within 10^500 push-distances from the origin with a high probability.
 

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