Observational Limits
Since the universe must be at least as old as the oldest thing in it, there are a number of observations which put a lower limit on the age of the universe; these include the temperature of the coolest white dwarfs, which gradually cool as they age, and the dimmest turnoff point of main sequence stars in clusters (lower-mass stars spend a greater amount of time on the main sequence, so the lowest-mass stars that have evolved off of the main sequence set a minimum age).
Read more about this topic: Age Of The Universe
Famous quotes containing the word limits:
“Whatever appeals to the imagination, by transcending the ordinary limits of human ability, wonderfully encourages and liberates us.”
—Ralph Waldo Emerson (1803–1882)