The results of observations done by astronomers indicate that there are not enough supernovas to justify an old galaxy. The numbers observed are consistent with a young galaxy of thousands of years old. The table below is a summary of the number and stage of observed supernovas.
|Supernova Remnant Stage||Number of predicted observable SNRs if our galaxy was billions of years old||Number of predicted observable SNRs if our galaxy was 7,000 years old||Number of SNRs actually observed|
First stage: The first stage starts with debris hurtling outwards at about 7,000 kilometers per second (about 4.3 miles per second). This stage lasts for about 300 years and expands to a diameter of about 23 light years (about 25,000 times the size of our solar system). To account for the number of stars in our galaxy, a supernova should occur every 25 years.
Second stage: This stage is predicted to last for about 120,000 years and reach a diameter of about 350 light years.
Third stage: This stage would theoretically begin after about 120,000 years, and would last for millions of years. The SNR would end its career when it either collided with another SNR or became so dispersed that it would be indistinguishable from the vacuum of space.
If the universe is billions of years old, there should be about 35,000 third stage SNRs in our galaxy. It is predicted that only about 14 percent (about 5,000) of these should be visible due to distances. However, if the universe is only about 7,000 years old, no SNRs should have reached this stage, so none should be observed.