How big is the universe truly.

How do we know that the universe expands faster than the speed of light? How do we know that there wasn't a universe already here when our big bang occurred?

 

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We can directly see low velocity masses (such as galaxies) moving away from each other at multiples of the speed of light. That's accomplished by adding many points of space between them at a rapid rate.

Nobody knows. Most big bang models only cover a few moments after T=0 to present. The implication of the original big bang model is that our universe existed as a single point of space-time and then began inflating (more points being added).

 

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i get there eventually.

 

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According to the conventional 'Expansion' hypothesis, 'local' expansion is 'currently' sub-luminal, even though the 'cumulative' observational artifact is 'superluminal' (according to certain assumptions) over great distance. The hypothetical 'Early Inflation' stage may have been of any 'speed/rate' (even multiples of lightspeed even 'locally' etc), since no-one can ascertain the actual value using the conventional hypothesis/theory for that earliest era of the hypothesized inflation-expansion scenario.

 

“Space, is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. Listen....”

- Douglas Adams, "Hitch Hikers Guide to the Galaxy".

 

Three Possibilities in Einstein's General Theory of Relativity:
flat - infinite and unbounded - "critical universe"
closed - positive curvature - finite (need not be bounded)
open - negative curvature - infinite and unbounded

we are in the first type of universe according to current models based on WMAP data.

http://www.pbs.org/wgbh/nova/physics/blog/2011/11/a-tour-of-the-multiverse/

givesw an explanation on what eternal inflation would look like.

 

That's not what cosmologists are telling us. WMAP results = flat universe. Infinite in extent means it continues to expand forever. The cosmology that has empirical support for predictions is Guth's Eternal Inflation.

The following brought cosmology into a predicable science. Where the predictions are tested in the great CMBR experiments.

Eternal inflation and it's implications
http://arxiv.org/abs/hep-th/0702178
Eternal Inflation w/pictures [power point].
http://online.itp.ucsb.edu/online/strings_c03/guth/

And the one I found a couple of days ago. Click on Level 5 and look at the author index. Huge resource.
INFLATIONARY COSMOLOGY:
EXPLORING THE UNIVERSE FROM THE SMALLEST TO THE LARGEST SCALES
http://ned.ipac.caltech.edu/level5/March05/Guth/frames.html
And the mind blower looking at the CMBR for Universe bumping into each other.
First Observational Tests of Eternal Inflation
http://arxiv.org/abs/1012.1995

 

Interesting. They didn't find any evidence of bubbles bumping but they did find some needlet significance and don't really know what it means.

 

It should be more revealing, for or against, with the > resolution of the Planck Experiment. Thanks for reading it. I must have linked that 50 times but it usually gets ignored. I understand Fraggle Rocker's view since it's the view we all had for so long. We always thought it would be impossible to know anything outside our own universe. Maybe that's still true depending on the future analysis of the CMBR.

 

The thing is nobody knows how big the entire Universe is, maybe it will never be known, it may even have infinite volume. Is possible to know how big the observable Universe is, it has a radius (in proper distance) of about 46 billion light years.