The Sum of All External Forces Art Is Equal to M A

The sum of all external forces art is equal to m a. Internal forces don't actually matter at all, he says. This is the reason why you can't jump and like, push yourself in a direction. It makes no senseit'so, not outo. The forces are all in the system, yo. It's all internal, so it doesn't matter. If the universe accelerates, what would that mean? He asks.