  The effects of compact extra dimensions upon quantum stress tensor
fluctuations are discussed. It is argued that as the compactification volume
decrease, these fluctuations increase in magnitude. In principle, this would
have the potential to create observable effects, such as luminosity
fluctuations or angular blurring of distant sources, and lead to constraints
upon Kaluza-Klein theories. However, the dependence of the four-dimensional
Newton's constant upon the compactification volume causes the gravitational
effects of the stress tensor fluctuations to be finite in the limit of small
volume. Consequently, no observational constraints upon Kaluza-Klein theories
are obtained.
