Are galaxies really moving away from us or is space just expanding?
The Big Bang did not occur at a single point in space as an “explosion.” It is better thought of as the simultaneous appearance of space everywhere in the universe. That region of space that is within our present horizon was indeed no bigger than a point in the past. Nevertheless, if all of space both inside and outside our horizon is infinite now, it was born infinite. If it is closed and finite, then it was born with zero volume and grew from that. In neither case is there a “center of expansion” – a point from which the universe is expanding away from. In the ball analogy, the radius of the ball grows as the universe expands, but all points on the surface of the ball (the universe) recede from each other in an identical fashion. The interior of the ball should not be regarded as part of the universe in this analogy.
Related Questions
- For objects moving away but not directly away in our light of sight, could we take measurements from different parts of the Earth and compare the readings to figure out precise velocity?
- When the asteroid gets close to the Earth, it starts moving away again. Why doesn the Earths gravity pull it right in?
- Are galaxies really moving away from us or is space just expanding?
