Wednesday, April 05, 2017

Maybe The Physicists Will Start Coming Around on Dark Energy

James B. flags me:
Hey Marc, I know what you think of Dark Matter/Energy, so this should make you happy.

What might this be, this story?:
The ΛCDM model assumes a uniform expansion that progressively gets faster thanks to the increasing push of dark energy overcoming the pull of dark and normal matter distributed evenly throughout space.

Yet according to the physicists involved in this new research, the large scale structures – 'bubbles' of seemingly empty space and the galaxies surrounding them – would create zones where expansion occurs at different rates, almost like mini-universes.

By mathematically modelling the effect of gravity on millions of particles representing dark matter, the team managed to recreate the bunching up of matter in the early Universe in such a way that it looked like the large scale galaxy structures.

While the Universe in their model still expands, the individual differences in how these bubbles expand averages out to an overall acceleration.

"Our findings rely on a mathematical conjecture which permits the differential expansion of space, consistent with general relativity, and they show how the formation of complex structures of matter affects the expansion," said Dobos.

"These issues were previously swept under the rug but taking them into account can explain the acceleration without the need for dark energy."

The model makes its own necessary assumptions, but if it stands up to scrutiny it could explain why the Universe's expansion seems to be accelerating, all without the need for negative pressure.
This strikes me as more reasonable than a universal repulsion. The local, crowded universe appears to expand more slowly than distant empty parts of the universe, because gravity slows things down nearby, but you can see those distant empty places better, because they are empty. Thus, it appears as if there's a universal repulsion. It would be nice to know what caused the Big Bang in the first place.

Today, I've been reading papers on midge swarming behavior, which appears to be modulated by sound. Midges behave as if they have a gravitational attraction to each other, but biologic systems have saturation levels, so the attraction weakens as midges get close to each other. Nevertheless, they've been using cosmological models to study midge swarming behavior.

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