IronSmithFE t1_ix72zt3 wrote
Reply to comment by tigojones in Someone tell me how the Big Bang began 13 billion years ago, yet the *observable* universe is 83 billion light years apart? by novacks0001
i don't understand this. the universe is defined by everything within it.
glieseg t1_ix75gzd wrote
Imagine you have a balloon. Paint some dots on it and blow some air in it. All the dots move away from each other because the balloon (the universe) is expanding, despite the dots not moving physically on the balloon.
The surface of the balloon itself is curved 2 dimensions, but the analogy works for the universe, too.
Kiezeus t1_ix7523g wrote
Long story short i) >>c expansion (hyperinflation) at the beginning of universe and ii) space between matter in the universe is expanding constantly that causes faster-than-light expansion (new-born empty space also expanses so the expansion is exponential and not limited by the speed of light). So again, new emerging space between the objects or the universe cause the universe to expand faster than light, although all objects in that space are not able to move faster than light in relation to each other.
IronSmithFE t1_ix9tv1v wrote
> space between matter in the universe is expanding constantly that causes faster-than-light expansion
at best you'd only get 2x the speed of light in expansion assuming objects were traveling in exactly opposite directions at the speed of light. since nothing but photons and gravity waves are traveling at the speed of light and neither are observable parts of the universe as they travel outwards the universe could not have expanded nearly 80 billion lightyears. at best it could have expanded to a diameter of 26 billion lighyears and that would not be nearly true because no matter what we can observe from our vantage point travels nearly the speed of light.
so, if the observable universe is indeed more than 80billion lightyears in diameter the initial hyperinflation would need have been the vast majority of the expansion of the universe and must continue to be the majority of the expansion for the next 27 billion years. now, because i have no idea how or why matter could have expanded faster than the speed of light your "short story" makes no sense to me.
perhaps you could tell me how matter or protomater could have expanded a great deal faster than the speed of light before you expect me to believe your short story.
Kiezeus t1_ixb96pw wrote
There is new empty space emerging from nothingness, and this is different thing that two objects travelling from each other. Think it like this: you and I are located still 1 lightyear from each other, and suddenly 10 light-years worth of new space emerges between us. It would endeed SEEM to us that we would have broken law of relativity, but actually we have not moved faster than light (or in this case, ww havent moved at all!) - there just have becomw more empty space between us. (Edit: accidentally posted too early)
IronSmithFE t1_ixbdi8t wrote
> There is new empty space
prove it.
the best you can say for sure is that distant massive bodies are accelerating away from each other. there are a few flimsy theories as to why it is happening, one of which is that there is some kind of dark matter between normal matter which is pushing normal matter around. even if that were the case, the motivation of normal matter would never exceed the speed of light.
Kiezeus t1_ixbit9y wrote
Hi, most accepted Dark Energy theory is not based on material/dark particles pushing objects away from each other, you may mix it with Dark Matter theory (explaining "missing" mass of galaxies etc). However, I see that this thread was to explain the issue that universe is larger than light speed would allow, and for this purpose explaining the topic on the currently accepted hypothesis/theories is logical to keep the answers simple. Discussing proving of the dark energy theory and especially doscussiong alternative theories for sure deserve their own thread.
ElliosRile t1_ix75hdg wrote
Imagine you have a balloon, and you have a bunch of dots on it. Things can travel along the surface of the balloon up to a certain speed in any direction. You can define the balloon based on where all the dots are and the surface in between them. However, if someone starts inflating the balloon, then everything is going to spread out and the surface is going to stretch. Since the expansion of the balloon isn’t travel along the surface of the balloon, it’s not subject to the same speed limit, so your dots can move away from each other faster then things can travel along the surface if the balloon.
IronSmithFE t1_ix9sa75 wrote
k, but the stars don't and can't move at near the speed of light and even if they did and two stars were traveling in opposite directions the furthest they could have expanded from each other in the fastest scenario assuming they did each move at the speed of light would still only be 26 billion lightyears. in your balloon scenario, they wouldn't move near the speed of light except in relation to each other and even then they would be unlikely to reach the speed of light in relation to each other.
ElliosRile t1_ixa069r wrote
I want to clarify, this isn’t “my scenario”, it’s a non-mathematical explanation of what we actually observe right now. When we measure the speed of galaxies far away from us, they’re receding at faster then the speed of light. You have to keep in mind that we are not talking about movement “within” the universe, where stars and matter don’t move anywhere near the speeds of light, we’re talking about reality itself expanding in all directions. We can actually observe the light emitted from those distant galaxies change its color, as the expansion of space causes the actually wavelength of light to expand.
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