Our observations relating to the expansion of the universe demonstrate that we can assume that each point in the universe is at the center of the universe and that everything is expanding away from that point. This can be illustrated by a model of the universe that is like a gigantic star made of space-time liquid.
For comparison, let’s take two suction cups and push them together. The cups attract each other due to external air pressure, since there is no air inbetween them. Now, let’s take two protons (or neutrons) which attract each other with a nuclear force Pn. According to the space-time-mass unified theory, this force Pn is really the resulting external pressure of the universal space-time on these particles. The pressure exists because the space between the protons has vanished.