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# Astrophysics/Size of the universe through the ages

Question
Hi,
there is a diagram where i can see the dimension of universe in function of time ?
I know that the answer may be only theoretical because no one was there with a tape to measure ...
But if you want to answer, I would like something like this :
1) Big Bang -time=0 size=0
2) Start Inflaction time t=10^-35s size =?
3) Finish Inflaction time t=10^-32s size= ?
4) time = 1s size= ?
5) time when the light was free to expand(300.000years?) size =?

If you reply to me, please explain also what we intend with word -size- , diameter of universe or volume of universe ?

Hi Luca,

This is a very difficult question to answer, for three main reasons:
1) We don't know the current size of the universe, or even how to define "size", since it probably is not spherical and probably doesn't have an "edge".
2) We don't know the "shape of the universe (see http://en.wikipedia.org/wiki/Shape_of_the_universe)
3) We can only guess about the rate of expansion during the period of inflation and current expansion

That said, there are some guesses:

Although I can't post a graph, see the last graph in http://scienceblogs.com/startswithabang/2013/03/01/how-big-is-our-observable-uni

The 'size' relates to the 'diameter' of the universe (whatever that means!)

See also http://map.gsfc.nasa.gov/universe/uni_fate.html, which shows the relative size of the universe (today's size is "one", but we don't know the value in light-years!) with different models.

Another view on how the size of the universe evolved in the first three minutes is given in the book by Steven Weinberg entitled "The First Three Minutes". Although Dr. Weinberg is a brilliant physicist, I personally have a problem with the premise of the book. Time itself was undefined in the early universe, and there were no clocks (or orbital electrons) to measure its passing.

Your question implies Big Bang cosmology. It is 'generally' assumed that the Big Bang occurred some 13.7 billion years ago. Although this idea is believed to be valid by the majority of cosmologists, it is by no means universally accepted. The "Big Bang", based on Hubble's velocity-distance relation and the microwave background radiation, is very much still a theory, and there are alternative theories. Some observations do not support an expanding universe or the Big Bang. There are several references concerning this, but perhaps the most authoritative person is Halton Arp, a leading astronomer and researcher on galaxies, who wrote "Seeing Red". That book is highly recommended to get an alternative view.  Or read "A Different Approach to Cosmology" by Hoyle, Burbidge, and Narlikar.  That's another great book which gives a scientific view on how the universe has always been in a steady state. I've attached a few references from Amazon.co.uk. If you're interested, pick up one or more of these books. And please have an open mind. That's the way science progresses.

http://www.amazon.co.uk/Different-Approach-Cosmology-Universe-through/dp/0521019

http://www.amazon.co.uk/Quasars-Redshifts-Controversies-Halton-Arp/dp/0521363144

http://www.amazon.co.uk/Catalogue-Discordant-Redshift-Associations-Halton/dp/096

I hope this helps.

Prof. James Gort

Astrophysics

Volunteer

#### James Gort

##### Expertise

Questions on observational astronomy, optics, and astrophysics. Specializing in the evolution of stars, variable stars, supernovae, neuton stars/pulsars, black holes, quasars, and cosmology.

##### Experience

I was a professional astronomer (University of Texas, McDonald Observatory), lecturer at the Adler Planetarium, professor of astrophysics, and amateur astronomer for 42 years. I have made numerous telescopes, and I am currently building one of the largest private observatories in Canada.

Publications
StarDate, University of Texas, numerous Journal Publications

Education/Credentials
B.A. Physics and Astronomy M.Sc. Physics Ph.D. Astrophysics