« on: 09/08/2017 12:32:46 »
Quote from: Rlmdouglas
The contraction of the black hole is a kind of inward expansionThere is a suggestion that a black hole is like a "universe within a universe".
Current theories suggest that our usual concepts of time and space become twisted and even interchanged inside the event horizon of a black hole.
Unfortunately, as far as we know, no-one can peek inside the event horizon and then come back to tell us what it is like inside.
the processes of ... inward contraction of each galaxy or region of space towards its centre, would make it appear as though the universe were expanding in every direction, each galaxy or region of space rushing away from us.Gravity certainly does attract all stars of the galaxy in towards the center of the galaxy, just like the Sun attracts the planets, and the Earth attracts the orbiting satellites.
If our galaxy were contracting towards its center, we could look out farther in our galaxy, and see the outer parts of our galaxy collapsing inwards. But we don't see this.
This is because inertia makes matter continue in its previous direction. For the Solar System or a Galaxy, gravity and inertia are balanced so that the planets take elliptical orbits around the Sun, and the stars take elliptical orbits around the center of the galaxy.
The beautiful spiral arms of a galaxy suggest that the galaxy has maintained roughly its current rotating structure for several revolutions of the galaxy; for our Milky Way galaxy, that makes it a multiple of 250 million years. This is not the sort of timespan for which a collapsing galaxy could exist.
Could expansion and contraction of the universe be driven by the same processes?Most cosmologists agree that gravity act in the direction of contracting the universe; just what acts to drive an (accelerating) expansion of the universe is a bit mysterious, and is dubbed "Dark energy".
Einstein's General Theory of relativity describes the structure of a universe with gravity, and did allow for a "Cosmological Constant" which could drive expansion of the universe. So in this sense, I guess here is a unified description of forces in the universe which describes both a contracting and an expanding force.
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