[thedoc (OP)]

Marne Botha asked the Naked Scientists:
   If anti-matter is normal matter but with the opposite charge, why does anti-matter and normal matter annihilate each other instead of attracting each other like positive and negative magnets do?

What do you think?

[chiralSPO]

They do attract, and when they meet is when they annihilate.

[acsinuk]

Do you know how many times more powerful than gravity the attractive force is?

[chiralSPO]

The attractive force is essentially electrostatic (opposite charges attracting) so, for subatomic particles, the electrostatic attraction is at least 20 orders of magnitude greater than the gravitational attraction between the particles. I'm not sure, but I think protons and antiprotons may also be attracted by the strong force once they get close enough, which would be several orders of magnitude stronger than electrostatic attraction...

[Ethos_]

The attractive force is essentially electrostatic (opposite charges attracting) so, for subatomic particles, the electrostatic attraction is at least 20 orders of magnitude greater than the gravitational attraction between the particles. I'm not sure, but I think protons and antiprotons may also be attracted by the strong force once they get close enough, which would be several orders of magnitude stronger than electrostatic attraction...

Yes, I think the strong force is somewhere around 36 orders of magnitude stronger. This is however at a very short range of distance whereas the gravitational force is very long range, possible even infinite.

[acsinuk]

So if stars and our Sun were made of antimatter then there would be an extra force of attraction of more than 20 times gravity holding our planet in position. That would mean that the sun weighs less than a twentieth of is mass. This would be in line with the positioning of the Lagrange point  L1 discussed in an earlier thread

[Ethos_]

So if stars and our Sun were made of antimatter then there would be an extra force of attraction of more than 20 times gravity holding our planet in position.

NO...........because as was already stated, these forces are short range forces and can't compete with the long range force of gravity.