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Offline Dick1038

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Big Bang & Inflation
« on: 10/11/2007 00:50:14 »
I'm confused over the extent of the "Inflation" of the universe right after the Big Bang. Is there any mathematical basis in the General Relativity theory to support inflation?

How large had  the universe supposedly gotten when inflation ceased?  I've read in various books and saw on PBS's NOVA estimates from about the size of a cantaloupe to many light years.  What is the most realistic estimate?



 

Offline Soul Surfer

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Big Bang & Inflation
« Reply #1 on: 10/11/2007 08:39:26 »
The quick answers are no,  and you've got it about right.

The inflationary theory is one of the hypotheses that have been put forward to explain the extreme smoothness of the big bang as it expanded to produce the cosmic microwave background radiation. 

Normally one would expect The surface of the cosmic microwave backround to look a bit like the surface if a star with turbulence, hot spots and cool spots that would be relatively easy to observe but the microwave background is incredibly even with only very tiny variations in it. This took many years of designing ever more sensitive devices to detect these variations.  One possible way of explaining this is that we are in fact only looking at a tiny piece of the overall universe which would have the sort of variation that one would expect from an expanding cloud of hot gas.

The best reason for the inflationary effect comes from the multidimensional properties of string theory in which some of the dimensions are very small and some very large. If, right at the beginning all dimensions were about equal and a lot of them contracted to allow some of them to expand  this would produce the sort of inflationary pressure that could produce very rapid expansion.

There are many other ideas around but inflation appears to be one of the most favoured or at least handles the problem well in models.

There is a very large very small symmetry in string theories that strongly suggests this is quite sensible bit that does not explain how it all starts.

My own pet fancy is as follows.

The dimensions are a bit like real and imaginary parts in real and imaginary numbers so when an object contracts down into a black hole to form a "singularity"  the real parts collapse and as this happens some of the imaginary parts expand to form a new universe inside the black hole.  This universe has some of the properties of the old universe embedded in it but may deviate slightly during the collapse process.  The whole process is scale invariant in the sense that the universe inside the black hole has an undefined size in its own right and this bears no relationship to the real size of the black hole where it originated.  the vacuum energy released during the collapse and expansion process also means that the amount of matter inside does not necessarily amount to the amount of matter in the original collapse and that any subsequent material falling into the hole is entirely insignificant after the initial colapse and expansion.

This produces universes which can evolve continuously and are scale invariant ans would tend to favour a set of physical laws which maximise the production of black holes within any universe and the physical properties of our universe are finely balanced to do this ( Lee Smolin's Life of the Cosmos ISBN 0 297 81727 2 )

However this is my own mad idea and not yet generally accepted

« Last Edit: 10/11/2007 09:03:11 by Soul Surfer »
 

Offline Dick1038

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Big Bang & Inflation
« Reply #2 on: 10/11/2007 17:54:12 »
Well, I like your mad idea.  Too bad it can't be verified.  I have my own theory about black holes.  Today, I made a separate post titled: "Temperature inside Black holes."
 

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Big Bang & Inflation
« Reply #2 on: 10/11/2007 17:54:12 »

 

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