I've been thinking about the balloon surface analogy and I want to ask some questions. Perhaps I am pushing it too far. But in that case it seems important to find its limits. My understanding is that the this analogy is used to illustrate the expansion of the universe and in particular how it is that even though (with the exception of a few close galaxies) everything in the universe is moving away from us. This does not mean that we are the center or source of the universe. It actually means that every point in the universe is moving away from every other point. Just like when you inflate a balloon. All points on the surface of the balloon move away from each other as it inflates. To the questions: 1. The balloon surface analogy is a two dimensional illustration of something that is happening in three dimensions. If so, can we talk about what that thing is? Would this image work: Say you have a highly compressed rubber ball and that there are tinny grains of sand randomly embedded in it. Then imagine that there is a mechanism by which we can uniformly increase the volume of all the rubber, gradually. In this scenario all the grains of sand would also be moving away from each other, but in three dimensions. Is that an accurate way to bring the analogy in to three dimensions? 2. We know that "all" galaxies are moving away from us because of red shift. We also know that the speed of recession is relative to distance from us. The farthest galaxies recede at a faster pace than the nearest ones. Taking both speed and distance into account we can "turn back" the clock and verify that all those galaxies meet back "here" at some point in the past, showing that the universe was once extremely dense. Now to my question: presumably we are also moving. If so, how come extra-galactic objects seem to be moving away from us? Shouldn't they be moving away from a different point since we are presumably not in a "direct line" with that denser state/place (we have since moved)? It doesn't seem possible for us to both be moving away from that core and still be in direct line with all the other objects that are moving away from it. This probably just shows that I con't get what is happening at all! One explanation might be that extra galactic objects have lateral speed which we cannot detect. But if this were the case we would not be able to measure a consistent speed to distance ratio in those objects. But we do. Therefore there is little lateral velocity in red shifted extra galactic objects (right?). 3. The other notion the balloon image is meant to express is that the universe itself (not simply the objects in it) is expanding. Are we to think, then, that objects are being "carried along" by "the universe" and that is why they are receding, not because of the "explosive" effect of the Big Bang. In any case, what exactly is "the universe" if it is not matter? What is mean by saying that "the universe" is expanding if that means something more than or other than the objects in the universe? Are we saying that there is no such thing as empty space or dimensions outside the universe? Thanks for reading. I'm looking forward to responses.