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Post by abacus9900 on Mar 16, 2011 20:32:03 GMT 1
Yep, you lost.
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Post by speakertoanimals on Mar 16, 2011 22:43:17 GMT 1
Ah, there's your problem right there -- the rest of us are trying to have discussions about science, whereas you seem to be trying to play marbles........................and I think you've lost some of yours.........................
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Post by abacus9900 on Mar 22, 2011 15:00:20 GMT 1
Same nonsense you repeated before! Expandions does not NEED extra emptiness or extra dimensions, is not the same as saying there MAY be extra dimensions. There very well may be, but not because they are NEEDED for space to expand into/curve in, or any other of the obvious stuff you keep repeating from previous threads. This is nonsense because what you are proposing is that a possible multiverse model does not incorporate within it any connections between its various elements, which is a logical absurdity.
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Post by skeptic on Jan 15, 2012 12:52:18 GMT 1
What is the universe expanding (or should I say 'inflating') into? Inflation (which is an unproven idea) ended after a few seconds. The impossible singularity came about in a place where there was literally nothing else. The BB would make better sense if the present BB expanded into the remains of a collapsing universe from a previous BB. That way there would be ample "seeds" around which matter could coagulate and so quickly forms stars, black holes, galaxies, etc. The problem with expanding into literally nothing is that there is no bias. If you toss a penny two million times, there should be almost exactly a million heads and a million tails because random runs of one or the other should have been balanced out. So with the expanding universe where without running into anything it expands evenly in all directions. The idea of "little perturbations" forming galaxies after a few hundred million years and a two million solar mass quasar after just 770 million years with everything moving away from everything else is nonsense. One of a number of problems is that expansion works over very large distances, being less than 15 miles/sec over a million light years. So inflation ends and you have the whole universe so small you could hold it in your hands. Rounding out figures: A million light years is getting on 6 x 10^18 miles. Let’s call the cosmological constant 14 miles per second per million light years, so expansion is 1 part in 4.3 x 10^17 per second. 13.7 billion years is conveniently 4.3 x 10^17 seconds so in the lifetime of the universe, it would still fit inside a normal sized living room. And yet we are told that it is maybe 158 billion light years across. It needs a very big universe for expansion to work. Maybe the BB-ers have now changed it so that inflation ended last Thursday?
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Post by eamonnshute on Jan 15, 2012 13:00:57 GMT 1
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Post by skeptic on Jan 15, 2012 13:04:56 GMT 1
Well not really because you have not even brought possible additional dimensions into the discussion. It might be that our spacetime universe is an integral part of a higher dimensionality matrix which may be essential for inflation to take place. Not proven, no, but you can't just shrug off such ideas since the multiverse is no longer a joke among serious cosmologists. If there can be one universe (ours), there is no reason that there cannot be more but they would be beyond our universe in a strictly 3D direction. You cannot have two 3D objects occupying the same place. We have no evidence for extra dimensions (which does not mean that there are none) but expansion requires a fourth physical dimension as in a hypersphere. With just three dimensions, the universe would have a centre that we could find, which would be empty as everything moved away from it.
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Post by skeptic on Jan 15, 2012 13:18:18 GMT 1
For a universe to be infinite in size, it would have to be infinitely old. That would need a way of replenishing energy and matter and releasing what is inside black holes. You could say the universe is potentially infinite in size in that if it is expanding into literally nothing, then "nothing" has no bounds but is only defined by what occupies it. It does not matter if some imaginary boundary of the universe could expand at a zillion light years per second. The gravity, energy, matter, etc in it is limited by light speed so what we call the universe is of strictly limited size. We see this in looking at the furthest parts of the universe where (mutual) recession is said to be coming up to light speed, so we cannot see what is beyond that distance.
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Post by striker16 on Jan 15, 2012 13:30:50 GMT 1
I don't see the point in speculating about whether the universe is infinite in size in terms of endless layers of detail, rather like an infinite set of Russian dolls because no technological civilisation will ever possess the technology to determine this. It's rather like arguing about the existence of God, in my view, since however far you get you can always ask the question: 'But what if?' It's philosophy, not science.
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Post by eamonnshute on Jan 15, 2012 13:33:03 GMT 1
For a universe to be infinite in size, it would have to be infinitely old. That would need a way of replenishing energy and matter and releasing what is inside black holes. According to some theories the universe IS infinitely old, and the BB was not the beginning of the universe. As for replenishing, energy and matter etc, the total energy of the universe is zero, so there is nothing to replenish. That is what we think - the universe is infinite and so it has no boundary. Since there is no boundary it is not expanding into anything. I suggest you read the FAQs more closely. The VISIBLE UNIVERSE is finite in size, but we can only see a fraction of it, as you say.
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Post by skeptic on Jan 16, 2012 15:19:57 GMT 1
eamonnshute. While the total matter, energy, gravity, etc of the universe comes out to zero, all matter could end up tied up in black holes and much of the energy as little more than "background radiation" as in a heat death.
We need endlessly more material to make new stars, etc. I think there may be some way of replenishing fundamental particles and energy but it would mean that black holes can somehow break down (and I don't mean the ridiculous Hawking radiation).
The universe does have a boundary, beyond which there is no matter and beyond which no photons have travelled. You can say that boundary is forever growing larger but still an infinite distance from infinite.
We can only make assumptions about what is beyond what we can detect. They may be completely wrong.
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Post by striker16 on Feb 16, 2012 18:57:59 GMT 1
You have to be careful to define what is meant by 'the universe.'
Some people mean our 'spacetime' universe, which has a definite finite age and radius; some people are referring to whatever has existed prior to the big bang for as far back as we can conceive. Then there's the idea of the 'multiverse' of which our particular spacetime universe may be but one of a countless number. If what is meant is the second of these then I suppose one could argue that there must have been something or other that existed. But then again, what about the idea of acausal quantum fluctuation, which some people think gave rise to our universe? If this last alternative turns out to be the case then ultimately everything we see has no logical or consistent basis and all science can do is notice patterns which may last for as long as the universe 'chooses.'
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Post by skeptic on Feb 19, 2012 18:46:47 GMT 1
That's a lot of assumptions you have there.
I am more willing to believe in some form of acausal quantum fluctuation than a big bang. It could cause a universe to form over the present area of the universe without any need for expansion and solve a number of other problems (trace the present universe back in time and at some point the whole universe is dense enough to be a black hole, at which point expansion cannot happen.)
It is possible that the universe comes and goes every so many hundreds of billions of years or longer.
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