Quote:
Originally Posted by Peter Wilson
Whether light is a particle or wave was debated for centuries, and the argument was finally resolved by recognizing it is both. In a parallel manner, Einstein famously “solved” his equations of GR and discovered that every possible universe would either contract or expand, depending on its initial conditions. When giant telescopes were developed, pointed skyward and the Hubble expansion was unveiled, the reaction was, “Ah hah! The universe is expanding after all!” But this is a case of not seeing the forest for the trees.
When we look to distances of less than about 5 Mpc, we do not see expansion. We see contraction. The Andromeda galaxy is on a collision-course with the Milky Way, and all the mass within the entire Local Group is caught in the local gravitational grip, pirouetting about the local center of gravity, slowly spiraling inwards. Throughout this local region, gas is contracting in myriad regions, forming new stars; and virtually every visible point of light in the sky is a center of local gravitational contraction, furiously radiating away energy as the gravitational field continues crushing matter in its ever tightening grip.
What model includes this?
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The Andromeda and Milky Way galaxies are heading towards each other, it isn't a "collapse." But in any event, at the shorter scales, gravity dominates over cosmological expansion. If it didn't, we wouldn't exist. This quantitative issue certainly isn't ignored, and in fact, there is the idea of the
Big Rip where, if validated, there could come a time in the distant future when galaxies and even planets and living creatures would be ripped apart.