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Post by skeptic on Jan 20, 2012 18:01:56 GMT 1
If we trace expansion back we come to a point where the density of the universe is greater than that needed to make a black hole, and that is a long way from the BB. You have a black hole, you don't have expansion. A black hole can have any density - the mass is proportional to the radius, but the volume is proportional to the cube of the radius, so the greater the mass, the lower the density. You can have a black hole with lower density than the Earth. So you objection is invalid. You miss the point. Sure the whole universe will form a black hole at relatively low density, but it is a black hole nevertheless which means that at that point, it cannot expand. "Infinite size"? What does that mean? How does infinity expand? If what you claim was so, then nothing would ever have formed. Along with expansion there were no gravitational sources. Everything would have just drifted apart. The oldest galaxy found so far is believed to have formed around 300 million years after the BB. The oldest quasar which is two billion solar masses was found at 770 million years after the BB and probably formed hundreds of millions of years earlier.
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Post by skeptic on Jan 20, 2012 18:13:59 GMT 1
mak2. If you take it that all space is "connected", then wherever they are in the universe, all black holes would be busy sucking in space as they have been doing for billions of years.
This is like putting a vacuum hose into a room full of gas where the hose sucks in the gas near it, which is then replaced and sucked in, which is then replaced and sucked in, etc till there is no gas left. Except with space there seems to be a literal infinite amount of it since endless trillions of black holes have had no effect on it.
The idea is that there is no path out as light is curved by space it travels through and space is "infinitely curved".
I suspect something else but that seems to be the idea.
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Post by eamonnshute on Jan 20, 2012 18:24:55 GMT 1
You miss the point. Sure the whole universe will form a black hole at relatively low density, but it is a black hole nevertheless which means that at that point, it cannot expand. But the universe is nothing like a black hole. A black hole is a singularity with zero size and infinite duration, the BB was a singularity of infinite size and zero duration (near as dammit). Look at the illustration in the link - every point gets further away from every other point. For the universe to become non-uniform there must have been slight deviations from uniformity soon after the BB, which snowballed to become much less uniform. This means that there must be slight variations in the cosmic background, and this prediction has been confirmed by observation.
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Post by skeptic on Jan 22, 2012 17:56:03 GMT 1
eamonnshute. Long before you get back to the BB, the universe will be of sufficient density to form a black hole.
The illustration only works for a hypersphere, a four dimensional sphere, like the universe is a 3D skin on a 4D balloon. If expansion is in 3D only, then we have a slow motion explosion where everything moves away from a set spot and we are left with an empty area in the middle. It also means that while every part of it expands slowly compared to every other part, it builds up a cumulative speed so the outer edges are limited by light speed.
If you put evenly spaced dots on an elastic band and stretch it, each dot separates by the same amount, but the further from the centre, the faster the dots are moving away from the centre. This would give the universe a maximum diameter of 27.4 billion light years. In a 3D expansion this would mean objects moving backwards towards their point of origin for it to work.
As I understand it with the CMB, the temperature difference between "hot and cold" spots is 0.0002.K. We have some particles almost at absolute zero and we have some other particles almost at absolute zero. So what? What is to attract these particles to each other when they are all moving apart from each other over an ever larger area? The idea is like we have a gas at almost negligible pressure but the molecules start clumping together to form large structures. I cannot see why matter would clump under such conditions. It is too big a leap of faith.
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Post by Progenitor A on Jan 22, 2012 21:59:24 GMT 1
Who is this skeptic? Where has he been all my life?
I think I love him!! ;D
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Post by skeptic on Jan 24, 2012 8:47:20 GMT 1
naymissus. The real problems with the big bang is that most blandly accept it when nothing should be beyond question and that some accept it as they feel there is nothing else. It is a seriously flawed theory. Horizon recently did an hour long TV show on it which is worth watching: On the iPlayer: www.bbc.co.uk/programmes/b00rgg31Or download: thepiratebay.org/torrent/5429416It downloaded overnight for me. A lecturer said she teaches the big bang but does not believe in it herself. It also interviews Guth, the man who thought up the IDEA of inflation.
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Post by mak2 on Jan 24, 2012 15:09:28 GMT 1
"Is everything we know about the universe wrong?" No. The fact that we do not know everything is not evidence that everything we know is wrong. The producers of Horizon should take lessons in logic.
But thanks for the links.
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Post by skeptic on Feb 4, 2012 16:25:06 GMT 1
"Is everything we know about the universe wrong?" No. The fact that we do not know everything is not evidence that everything we know is wrong. The producers of Horizon should take lessons in logic. But thanks for the links. It's a question being asked and not a statement of fact. Yes, everything may be right, but it may be wrong so an open mind should be used on some aspects of the big bang which are no more than speculation.
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Post by mak2 on Feb 4, 2012 22:09:56 GMT 1
"Have you stopped beating your wife?", is a question but it has implications!
"Is everything we know about the universe wrong?" falsely implies that there is some reasonable likelihood of the answer being "yes".
The BBC has a nasty habit of asking questions of this type. It allows them to pretend to be impartial when they are not.
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Post by skeptic on Feb 9, 2012 14:41:15 GMT 1
You would only ask the question about beating your wife if it were possible that it was happening.
The programme pointed out that inflation and dark energy, two mainstays of the big bang theory are nothing more than ideas which were made up because the maths and observations did not support the BB theory.
It's like saying "I know you are in prison but I still think that you are beating your wife."
Of course the BBC are not impartial. They never have been. Neither is Horizon impartial. You have to look at the programme and judge for yourself as you do on anything to do with the media.
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Post by mak2 on Feb 9, 2012 21:00:17 GMT 1
At least we are agreed that the BBC is not impartial, as they claim to be.
My point is that asking a question can be used to create doubt, where none existed before.
It is quite likely that some details of the big bang are wrong. It is very unlikely, in my opinion, that the whole idea of the big bang is wrong. What I really object to is the sensationalist question "Is everything we know about the universe wrong?" Everything!! Not just some details of the big bang, not just the big bang, not just the expansion of the universe, the existence of other galaxies, ....everything. They cannot be serious .... but Horizon is supposed to be a serious scientific program.
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Post by skeptic on Feb 11, 2012 19:12:42 GMT 1
Is anything about the BB right? Most of it is doubtful and ranges from unproven to just plain imagination. Not my idea of a "theory".
This programme does present the evidence and casts some doubts but at the end you believe what you will.
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Post by striker16 on Feb 16, 2012 18:40:48 GMT 1
Is anything about the BB right? Most of it is doubtful and ranges from unproven to just plain imagination. Not my idea of a "theory". This programme does present the evidence and casts some doubts but at the end you believe what you will. You're being unreasonably sceptical (hence your name I suppose) because all the scientific evidence thus far supports the BB model. However, this does not mean the BB idea is the final word because science can only draw conclusions based on what evidence has been collected up till now. It might turn out that our 'commonsense' approach to the evidence is rather naive since there still remain some problems with the BB model which might only be able to be resolved by greater insights into the nature of the cosmos. Note I used the word model. A model is something which is just a representation of something, not the thing itself, so a model is always open to modification in the future when we obtain more understanding of the thing we are studying.
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Post by skeptic on Feb 19, 2012 17:33:02 GMT 1
The scientific evidence? A model with no credible origin and many serious faults?
One interpretation of the red shift and one interpretation of the CMB support it and that's about it.
Time dilation only works out to six billion light years.
Inflation and Dark Energy are nothing more than ideas.
The BB failed the Afterglow test.
Contraction of the universe has been observed over a billion light year area (Dark Flow).
There are no explanations of what space is and how it can infinitely expand without changing in any way.
And so on.
If we had any actual hard evidence for the BB, I'd believe it but we don't. It is little more than an idea.
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