What does the "(29)" in "1.000051(29) c" mean?
So 1.000051(29) would be equivalent to 1.000051 +- 0.000029.
For example, they measured 1.00005129c, but maybe their uncertainty is +-0.0000001c. The last digits are unreliable, but are the measurements they got
EDIT: below, its claimed that those digits ARE the uncertainty. That quite possibly is it; my answer is from what i remember from uncertainty in my 1st year Physics course.
edit: sorry if that's incorrect in this case. "1.000051(29)" is one of the formats of indicating repeating decimals, per http://en.wikipedia.org/wiki/Repeating_decimal#Notation