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Feb29-12, 07:06 PM
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Quote Quote by waterfall View Post
The thing is this (and to Dalespam too), we are taught that Big Bang is like the baloon expanding and the surface like spacetime, therefore everywhere expand at the same time, so how can any comparison be done when all is expanding together.

Going to the orange analogy (I'm familiar with the relativity of simultaneity and it's related to it). But if the entire orange expands, the orange-skin would expand too so we can describe it as "expanding orange-skin". Note that all circles you draw from the pole to the equator expands at the same time. So it has same relationship. It's like the earth expanding and every object, the ground, you and I expanding forever. Can we tell? No. Because we will have same relationship to each other. (btw.. some guy produced a theory where this is what produced gravity because the expanding earth and us keep us close to the ground.. of course I don't believe this but just mentioning this because I just recalled it).
My orange analogy is different from the balloon analogy.

In the expanding balloon analogy, the 3 dimensions of space are represented by the 2 dimensions of the balloon surface, and time is represented by time.

In my orange analogy, the 3 dimensions of space are represented by just one dimension (circumference) of a circle, and time is represented by the "latitude" of the circle. The 4 dimensions of spacetime are represented by the 2 dimensions of the orange skin. The "North Pole" represents the big bang. The circle expands as it moves down but the orange is static.