Categories
astronomy Cosmology Creation/evolution

Is there definitive evidence for an expanding universe?

Evolution out of the ‘Dark Ages’

Expansion of the universe is fundamental to the big bang cosmology. No expansion means no big bang. By projecting cosmological expansion backwards in time, they assert, one will, hypothetically, come to a time where all points are the same. Since these points are all there is, then it logically follows that there is no space or time ‘before’ this moment. It is the singularity, and we cannot use language couched in concepts of time when no time (or space) exists.

Yet there are Christians who use this presumed fact as evidence in support of the Genesis 1 account and even for the existence of God Himself. They argue that only God could have started the big bang. Though it is true the universe does need a first cause it is an enormous leap into the unknown to suppose that the big bang story is that which is described in the Genesis 1 narrative. The sequence of events is nothing like it. See The big bang is not a Reason to Believe!

Redshift
Redshifted The spectral lines for this element still show the same distinctive pattern, but all have been shifted towards the red end of the spectrum.

At the end of the 1920s, Edwin Hubble made a significant discovery. He found a proportionality between the amount by which the spectral lines in the light coming from relatively nearby galaxies are redshifted(z) and their distances (r) from Earth. That relationship is now called the Hubble law c z = H0 r, where c is the speed of light and H0 is Hubble’s famous constant of proportionality.

The Hubble law has since been extended to very great redshifts (therefore by inference, distances) in the cosmos, via the redshift-distance relationship. At small redshifts, and by interpretation at small distances, this becomes precisely the Hubble law.

Redshifts have been interpreted as a velocity of recession, i.e. that galaxies are moving through space. And that the recession implies expansion of the universe. But Hubble, up to the time of his death, was not so convinced of this interpretation.  He was open to the possibility that there could be another mechanism to explain redshifts.