3 ms·

That would mean that we are (as in our galaxy is) in a very, very special position because we see all distant galaxies moving away from each other with velociti

That would mean that we are (as in our galaxy is) in a very, very special position because we see all distant galaxies moving away from each other with velocities proportional their distance from us. This is exactly what we would expect if the universe is expanding isotropically but under the "galaxies actually moving away from each other" hypothesis this is only possible if Earth is exactly at the center of a sort of "explosion of galaxies". A second issue with this theory is that we see objects with redshifts that would mean that if their apparent motion is actually real motion then they would be moving away from us faster than the speed of light. As far as we know this is completely impossible for actual motion but is exactly what we would expect from expansion.

scotty79 5y ago
Not really special. Try simulating this: Start with bunch of objects at coordinates 0,0,0. Give them random velocities from 0 to c. Then just let them move according to Newtons law. Now focus on single random object and narrow down your field of view so you won't see the edge. Look at other objects. They will seem to be moving away directly from the point you focused on with velocities proportional to distance from it. I made such simulation and made calculations to ensure that the velocities of other points face directly away from the point I'm observing. And they really do. Even in completely flat Newtonian universe there could have been a sort of Big Bang with epicenter and it could be as simple as "give matter random speeds" and we living on a one speck of matter would have no way to figure out that there is a center or where is it. When I asked about this on physics stack exchane I got a shurg that, yeah cosomology is basically that but with Einstein not Newton. All that talk about spacetime inflating is just a result of matter 'dragging' the spacetime along as it moves. The faster than light galaxies far away are not a problem because the speed of their movement that we measure is sum of their kinetic movement (which could be almost at light speed) and expansion of the space time between us and them as the spacetime is 'dragged' by them with GR. But you can equally well interpret the math and data as galaxies roughly at rest and all the speed coming from spacetime expansion and for I have no idea what reasons people actually prefer to do that.

scotty79 5y ago

Not really special. Try simulating this: Start with bunch of objects at coordinates 0,0,0. Give them random velocities from 0 to c. Then just let them move according to Newtons law. Now focus on single random object and narrow down your field of view so you won't see the edge. Look at other objects. They will seem to be moving away directly from the point you focused on with velocities proportional to distance from it. I made such simulation and made calculations to ensure that the velocities of other points face directly away from the point I'm observing. And they really do. Even in completely flat Newtonian universe there could have been a sort of Big Bang with epicenter and it could be as simple as "give matter random speeds" and we living on a one speck of matter would have no way to figure out that there is a center or where is it. When I asked about this on physics stack exchane I got a shurg that, yeah cosomology is basically that but with Einstein not Newton. All that talk about spacetime inflating is just a result of matter 'dragging' the spacetime along as it moves. The faster than light galaxies far away are not a problem because the speed of their movement that we measure is sum of their kinetic movement (which could be almost at light speed) and expansion of the space time between us and them as the spacetime is 'dragged' by them with GR. But you can equally well interpret the math and data as galaxies roughly at rest and all the speed coming from spacetime expansion and for I have no idea what reasons people actually prefer to do that.