What is the minimum age to go to a California University?

Here is an example:

The California State University, Bakersfield will award a bachelor's degree to its youngest graduate ever at the School of Humanities and Social Sciences Commencement on Saturday, June 14 at 7:15 a.m.

At age 10, Christina Brown of Lancaster began taking community college classes at Antelope Valley Community College. Now 15, Brown completed her bachelors degree in psychology and on Saturday will become the youngest graduate in CSUB history. http://www.calstate.edu/newsline/Archive/02-03/030...

ALL of 15 years old, this whiz is set to begin graduate studies in computer science at the University of California-Santa Barbara in August. http://www.inq7.net/globalnation/sec_new/2005/jun/...

I've seen young kids there, but their parents have to be with them. They do have to pass an entrance exam, so they have to be smart enough for that.