Physics in Everyday Life: Simulating Collisions & Forces

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Discussion Overview

The discussion centers around the challenges of realistically simulating particle collisions and gravitational forces in computational models. Participants explore the complexities involved in simulating these physical phenomena, particularly in the context of chaotic systems and the limitations of current computational methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the clarity of the original inquiry regarding what specific simulations are being sought, suggesting that the complexity varies significantly between simple interactions and more complex systems like a human being.
  • One participant highlights the difficulty of the three-body problem, noting that finding an analytic solution without simplifications is impossible, and suggests that this complexity increases dramatically with more particles.
  • Another participant explains that simulating motion typically involves starting from an initial state and calculating future states in small time steps, but acknowledges that this method can accumulate errors due to machine precision and chaotic behavior.
  • A later reply raises the issue of predicting chaotic starting conditions without relying on error-prone approaches, indicating a concern about the limitations of current simulation techniques.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and focus on different aspects of the simulation challenges. There is no consensus on a singular approach or solution, and multiple viewpoints regarding the complexities and limitations of simulations remain present.

Contextual Notes

The discussion touches on unresolved mathematical steps related to chaotic systems and the implications of machine precision in simulations. There are also dependencies on definitions of what constitutes a realistic simulation.

Jam Smith
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Hello everyone,
Last night I was reading about gravity and I come across one debate. I tried to search about it but got confused. I hope some one can help me.

The question is:

Why is it so hard to realistically simulate the collisions of particles, gravity all the forces that go on around us daily in a computer?
 
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Jam Smith said:
Why is it so hard to realistically simulate the collisions of particles, gravity all the forces that go on around us daily in a computer?
Your question is completely unclear. EXACTLY what is it you want to see simulated? A single particle-pair interaction is one thing. Simulation of everything involved in, say, a single human being is quite another.
 
Jam Smith said:
Hello everyone,
Last night I was reading about gravity and I come across one debate. I tried to search about it but got confused. I hope some one can help me.

The question is:

Why is it so hard to realistically simulate the collisions of particles, gravity all the forces that go on around us daily in a computer?

Start with the 3-body problem and figure out why getting an analytic solution for the most general situation (i.e. without any kind of simplification or restriction) is impossible.

https://www.wired.com/2016/06/way-solve-three-body-problem/

Now imagine how this gets progressively more difficult with 4, 5, 6... Avogadro's number of particles.

Zz.
 
One way of simulating the motion is to start with an initial state and calculate the state a small time step in the future. Then repeat with the new state. Depending on how you do the time integration, you normally accumulate small errors which scale with some power of the size of the time step. In addition, you have a limited machine precision which introduces errors. These errors will cascade into your future states. The more chaotic your system is, the more sensitive you are to these errors.
 
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ZapperZ said:
Start with the 3-body problem and figure out why getting an analytic solution for the most general situation (i.e. without any kind of simplification or restriction) is impossible.

https://www.wired.com/2016/06/way-solve-three-body-problem/

Now imagine how this gets progressively more difficult with 4, 5, 6... Avogadro's number of particles.

Zz.

Hello Zz,
I am amazed after visiting this link. I found many books but this information is quite unique and also helps me to solve my doubts.
 
Khashishi said:
One way of simulating the motion is to start with an initial state and calculate the state a small time step in the future. Then repeat with the new state. Depending on how you do the time integration, you normally accumulate small errors which scale with some power of the size of the time step. In addition, you have a limited machine precision which introduces errors. These errors will cascade into your future states. The more chaotic your system is, the more sensitive you are to these errors.

How can we predict, these areas of chaotic starting conditions without an error approach?
 

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