Spacetime, like an isometric weather map?

[narrator]

Novice question

I've been reading Brian Greene's "The Hidden Reality".

It occurred to me that spacetime across the 2D analog of the U could be much like an isometric weather map. Could it be that the U isn't expanding, but that our region, like a High on a weather map is rushing to fill a Low pressure region outside our OU? The downhill slope of the High would account for acceleration.

What led to this line of thinking was the part in Green's book where he discusses densities in some patches of space, suggesting that whole regions, the size of our OU could be so dense that the whole region becomes a black hole. It made me think of the rubber mat, our OU on the crest of a bump, randomly surrounded by other Highs and Lows (OU size black holes) all feeding each other like a ginormous weather system. It would also go some way to explaining why no new galaxies have "appeared" (as their light finally reaches us).

 

[Chalnoth]

Novice question

I've been reading Brian Greene's "The Hidden Reality".

It occurred to me that spacetime across the 2D analog of the U could be much like an isometric weather map. Could it be that the U isn't expanding, but that our region, like a High on a weather map is rushing to fill a Low pressure region outside our OU? The downhill slope of the High would account for acceleration.

What led to this line of thinking was the part in Green's book where he discusses densities in some patches of space, suggesting that whole regions, the size of our OU could be so dense that the whole region becomes a black hole. It made me think of the rubber mat, our OU on the crest of a bump, randomly surrounded by other Highs and Lows (OU size black holes) all feeding each other like a ginormous weather system. It would also go some way to explaining why no new galaxies have "appeared" (as their light finally reaches us).

Normal matter feels no pressure whatsoever on cosmological scales. Furthermore, pressure itself is an energy density, and therefore acts as a source of gravity. So having positive pressure in our observable universe tends to slow down the expansion even faster.

That said, one of the possible explanations entertained a bit ago was that maybe our local region was just an underdense region of the universe, and we see an expansion not because of any sort of dark energy, but instead because there is a lot more matter further away than there is here, pulling everything away from us.

But this sort of idea simply doesn't hold up to detailed examination of the properties of expansion: our observations fit dark energy, not this "void model".

 

[narrator]

But this sort of idea simply doesn't hold up to detailed examination of the properties of expansion: our observations fit dark energy, not this "void model".

Thanks Chalnoth, I had thought more about this since posting, and while I like the idea that waves, motion and various pressures have analogs at different scales, further reading of Greene's book showed me how developed "expansion" theory is, negating my idea. On the other hand, it's nice to know someone had a similar idea at one point (I don't feel so silly.. lol).

Loving Greene's book.