  The light element lithium is formed by nucleosynthesis during the Big Bang.
Its abundance can help to define the parameters of the early universe. To find
this primordial value, it is necessary to determine Li abundances in the oldest
stars because it is readily destroyed by nuclear reactions in stellar
interiors. We have made high-resolution (~45,000) spectroscopic observations of
five identical unevolved turn-off stars in the 13 Gyr old globular cluster M5.
In our analysis we find a range in Li abundance of a factor of two; the spread
is five times the individual error. The comparison of these results with those
for turn-off stars from five other globular clusters reveals similarly large
range in Li. Lithium in M5 and the other clusters all have stars above the
field star Li plateau, but none are as high as the predictions for primordial
Li. The maximum values for Li are the same in all six clusters. Multiple
generations of stars are found in many globular clusters; those later
generations are expected to have formed from Li-depleted gas. Such second- and
later-generation stars would have no Li. However, only one of the six clusters
has a few unevolved stars with upper limits on the Li abundance.
