expansion

[jjuris]

can there be a model of an expanding universe

[CaptainPanic]

There are lots of models of the expanding universe, and the model that seems to fit the current observations the best is about an accelerating expanding universe.

 

Please take some time to investigate the topic... I get the idea that you dump a question here to see what comes up. In stead of asking other people to invest time to answer your question, you can also invest some of your own time.

 

Use:

-google

-wikipedia

-the search function of this forum

[Martin]

can there be a model of an expanding universe

 

Modeling has gone thru many versions.

The earliest model was 1922, a simple differential equation model constructed by Alex Friedman. Published in the Zeitschrift für Physik of that year.

http://edocs.ub.uni-frankfurt.de/volltexte/2008/9863/pdf/E001554876.pdf

http://en.wikipedia.org/wiki/Friedmann_equations

 

By plugging in today's measurements, this model lets you calculate the approximate history back nearly to when expansion started. It is still the main model that cosmogists use, and a lot of effort is currently focused on improving Friedman's model so that it will go back further in time.

 

Probably the leading up-to-date models are the computer models being run by Ashtekar's group at Penn State. They can reproduce the good fit of the Friedman model, to current observation data. And they also don't break down near the start of expansion. They go back further. A lot of effort is now being devoted at various places around the world to finding ways to test the Ashtekar group's model observationally (to distinguish it from the older Friedman-type cosmology).

 

There is no popularization of the Penn State cosmo model, but if you aren't put off by technical writing you can scan over this list

http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2006&FORMAT=www&SEQUENCE=citecount%28d%29

 

This list has a cutoff date of 2006. If you change the cutoff date you can get earlier papers. If you use the same keyword and look for papers before like 1999 you will find stuff by Stephen Hawking, James Hartle, Alex Vilenkin, Andrei Linde, string theorists etc etc. They used to dominate the field. Now a different group of authors has taken precedence. I'm only interested in the recent research, so I use the "date > 2006" cutoff. The list is ranked by citation count (a rough measure of importance in the research community.)

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So the answer to your question is YES it can very definitely be modeled:D

and unless you have a historical interest and want to go back to the 1922 roots you should check out the post-2006 research literature.

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The standard Friedman cosmo model is implemented in a hands-on version in the Ned Wright calculator. Google "wright calculator". Play around with it. Put in various redshifts and see what you get. The calculator is programmed to run the Friedman differential equations and calculate the universe for you, in its broad outlines.

There is another online calculator that does the same thing, called "cosmos calculator". A SFN member called NowThat recently reported trying it out and getting some numbers. It has some nice features that "wright calculator" doesn't. If you want to try it, google "cosmos calculator".

Edited April 18, 2009 by Martin