Question #54ee7
1 Answer
It was, and is, gravity.
Explanation:
The collapse of the origial nebula to form the Sun and the planets was diven by gravity. The same applies to the formation of all stars and their planetary systems. And gravity is what holds stars and planets together and gives them their rounded shape.
The reason gravity does this is because it can. To make stars and planets a fundamental force must do two things:
1) It has to act over a long range. Gravity does that, nuclear forces do not.
2) It must be able to draw in all matter with an attractive force. Gravity does that, electromagnetism doesn't. Electromagnetism is attractive only when you have unlike charges, and the unlike charges tend to neutralize each other in large masses.
They say love makes the world go round. In some contexts that's true, but gravity is what makes the world go round physically.
