I was talking with a lecturer about friction between two objects and he said that he thinks that to have friction the objects need to deformable so you can have an impulse or something like that. Though he said he wasn't sure without doing the calculations, which he doesnt have the time. So I was wondering can you have friction, minus the 'sticking together' time with rigid bodies? thx also i saw an example with rigid spheres, where the person used an arbitrary impulse time...