[Fred]

Chiq, to explain the expansion of the universe in a way you can visualise it is fairly easy. But lets look a little at the method by which was discovered first and the key is spectroscopy.

All mater when heated sufficiently emits light on characteristic quanta and, importantly, absorbs certain frequencies of light well. When light is taken from an object and split into a spectrum then these absorbtion lines can be noted. Now Hydrogen, and Heleium are sufficiently common elements that their absorption lines make handy reference sticks - especially given that the stars tend to made up largely of these two elements and are nicely radiant.

By looking at the light from various stars and galaxies you can get the absorption lines for them and when you compare the spectra with a similarly lumninous object that isn't moving relative to us you can see that the motion of the object has shifted the spectrum. (This process is a well known consequence of relativity and I won't go into it's hows and whys now.)

Edwin Hubble used this technique to study the night sky and noticed an interesting trend. Now distances in space are usually worked out, for any object above about 50 ly away from earth, by using reference objects of a known magnitude (brightness) and comparing their known magnitude with their absolute magnitdue (or observed brightness here on earth.). Certain objects are well known to have quite fixed magntiude relationships and (going from memory) these include Woolfe stars, Cephid variables, certain F0 primary stars, Quasars and one or two others that I forget.

Hubble noticed that when using these reference objects to get the distance to a galaxy that the further the object was away from the earth the more pronounced the red shift was in the spectra from that object. Red shifting only occurs when an object is speeding away from you - effectively elongating the wavelengths of light emitted. And the general relationship was that the further the object was away, the stronger the red shift and, here is the key bit, this occured in any direction you cared to look.

Now this has some interesting implications. If the universe was a nice more static place then you would expect that the 'soup' of galaxies out there would produce a heterogenous mix of shifts as some galaxies move towards us and some away. In essence we should see a pretty even mix of red, blue and marginal shifts irrespective of the distance.

Instead the further the distance then universally you get a more extreme red shift. There is some slight variation as some galaxies are 'fighting the flow' so to speak and trying to travel towards us but their motion is always less than the motion carrying them away.

One of the primary tennets of relativity is that our segment of the universe is not different from any other segment. This has lead to the assumption/expectation that even if we moved to another galaxy we would still see this motion carrying every other galaxy away from us. (There is a little more to the argument involving vector analysis of the motion to further reinforce this but it is more involved than I care to go into.)

That has lead to the inflationary model of thinking. The way to imagine it is picture a balloon half inflated. Draw on the surface of the balloon a set of concentric circles of dots with a dot at the centre of them all. The central dot is the earth. Keep inflating the balloon and you will see that as the inflation continues the further dots being to receed away from the center faster and faster.

This is effectively what is happening to us. The surface of the balloon is three dimensional space and we are on a hyper-sphere expanding at a fairly impressive clip.

|THAT|-fred
'fred is not dead, fred is resurrected!'