Expansion and Inflation of Universe
Date: Summer 2012
What is the difference between the concepts of inflation and expansion of the universe?
Inflation is a special type of expansion where the size of the universe grows exponentially with time,
size ~ exp ( t ).
A popular theory of cosmology suggests that the early universe underwent a very brief period of extremely rapid inflation. The rate of expansion then transitioned to a slower, power-law form,
size ~ t ^ #,
where the power, # is greater than zero, so the size continued to increase. Our universe is currently expanding in this power-law manner. However, many cosmologists believe that the universe is in the process of transitioning to a second period of exponential expansion (inflation), but with a much slower time scale.
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Update: December 2011