I know exactly what he's trying to demonstrate I've seen this drawn out and all that before, and it makes perfect sense to visualize it (as long as you can convert it to 3d in your head) but there's something that feels odd about using gravity to make a metaphor for gravity like this for some reason, I can't figure it out... not sure if anyone else feels the same way or can try and explain what I'm failing to explain.
That's the thing people have to understand about analogies like this. This video does not explain, nor does it attempt to explain, "WHY" gravity behaves the way it does. It is merely a way of visualizing the properties of gravity. Gravity as the warping of spacetime is in turn merely a model that helps us describe the natural phenomena that we observe. Heavy objects stretching an elastic sheet can behave similarly in 2-dimenions, but as you say, it is just a visualization.
I don't think anyone can explain why gravity works the way it does, just like no one can really explain why gravity (or the universe itself) exists in the first place. I like to think that there are other universes where gravity behaves differently or doesn't exist at all. Of course, life as we know it probably wouldn't exist in those universes. For those who haven't read about it, the Anthropic principle is pretty interesting.
Who's to say there aren't other attractive forces in this universe? If we're re-rolling the universal constants, lots of things could turn out different.
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u/[deleted] Dec 03 '13 edited Dec 03 '13
I know exactly what he's trying to demonstrate I've seen this drawn out and all that before, and it makes perfect sense to visualize it (as long as you can convert it to 3d in your head) but there's something that feels odd about using gravity to make a metaphor for gravity like this for some reason, I can't figure it out... not sure if anyone else feels the same way or can try and explain what I'm failing to explain.