It is less that they are being pushed away from each other, but that all the matter in the universe exploded from a single point a long time ago and is still expanding at that same speed according to Newton's first law (nothing to stop it, so it will stay at the same velocity). The particles are just moving at different speeds/velocities and so are expanding away from each other.
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Think of two cars starting a race. One is a very fast car, and the other is a slow car. When they start the race, they are very close to one another, but slowly, the distance between them increases. The big bang is the start of the race, and the cars are the particles.
The particles in any particular celestial object, however, are not distancing themselves from each other. The molecules on earth all hold themselves together and are moving as a single, very large particle moving away from everything else.
Resident_Smoothbrain t1_ixegbx3 wrote
Reply to comment by erkynator in Is space infinite or finite? by erkynator
It is less that they are being pushed away from each other, but that all the matter in the universe exploded from a single point a long time ago and is still expanding at that same speed according to Newton's first law (nothing to stop it, so it will stay at the same velocity). The particles are just moving at different speeds/velocities and so are expanding away from each other.
​
Think of two cars starting a race. One is a very fast car, and the other is a slow car. When they start the race, they are very close to one another, but slowly, the distance between them increases. The big bang is the start of the race, and the cars are the particles.
The particles in any particular celestial object, however, are not distancing themselves from each other. The molecules on earth all hold themselves together and are moving as a single, very large particle moving away from everything else.