# Particle attraction

## Main Question or Discussion Point

If you have two particles of opposite electrical charge in proximity, what actually sets them in motion? As a an analogy, if you have two balls in either end of a tube and remove the air between them, outside pressure will push them together. What is the equivalent process at the particle level?

## Answers and Replies

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Drakkith
Staff Emeritus
Science Advisor
The particles exert an attractive electrical force on each other, resulting in an acceleration of each particle towards the other. In your example, the air molecules exerts a repulsive force on the balls when they collide with them, which pushes them together.

See here: http://en.wikipedia.org/wiki/Coulomb's_law

A.T.
Science Advisor
If you have two particles of opposite electrical charge in proximity, what actually sets them in motion? As a an analogy, if you have two balls in either end of a tube and remove the air between them, outside pressure will push them together.
That is not an analogy, but an example of the very same force. The electrons in the air atoms and the ball atoms are repelling each other.

The particles exert an attractive electrical force on each other, resulting in an acceleration of each particle towards the other. In your example, the air molecules exerts a repulsive force on the balls when they collide with them, which pushes them together.

See here: http://en.wikipedia.org/wiki/Coulomb's_law
The question is why do they accelerate. The provided some information on virtual particle exchange, that's what I'm trying to get my head around.

Drakkith
Staff Emeritus
Science Advisor
The question is why do they accelerate. The provided some information on virtual particle exchange, that's what I'm trying to get my head around.
Don't even try to wrap your head around virtual particle exchange. It's so far beyond your current level of physics that you have no hope of understanding it. Stick with the classical understanding for now. Not to mention that it really doesn't explain why particles accelerate any more than classical physics does, it only elaborates on how the interaction between two particles works and enables us to make more accurate predictions at the atomic and subatomic level.

In the end the two particles accelerate because they feel a force from each other. Applying a force to an object causes it to accelerate. It's literally as simple as that, and trying to find a "deeper" understanding is pointless. You won't find one because it doesn't exist, and not even understanding virtual particles will change this.