I checked on wikipedia:(adsbygoogle = window.adsbygoogle || []).push({});

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

and I found that the scale factor is related to the red shift, in FRW model, by:

[itex] 1+z(t) = \frac{a(t_{0})}{a(t)}[/itex]

How is that derived?

Also intuitively could you check this reasoning of mine?

Intuitively I can understand this relation, since the scale factor in the past was smaller, then the wavelengths were practically more compressed, so:

[itex] z=\frac{a(t_{0})}{a(t)}-1[/itex] was much bigger than 0 (I don't know why it happens to be 0 for today)

while as time passes, and the scale factor is raising more than a(t0) the redshift is going to get "smaller"...in fact there will be always new "normalization" on the nominator, just to keep it falling "asymptotically" to 0... (the wavelengths are stretched)

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# RedShift-scale factor (FRW)

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