  We investigate correlations between the long wavelength fluctuations and the
small scale power in the Lyman alpha forest. We show that such correlations can
be used to discriminate between fluctuations induced by large scale structure
and those produced by non-gravitational processes such as fluctuations in the
continuum of the quasar or in the temperature of the gas. The correlations
observed in Q1422+231 are in agreement with the predictions of numerical
simulations, indicating that non-gravitational fluctuations on large scales
have to be small compared those induced by the large scale structure of the
universe, contributing less than 10 % (95 % confidence) of the observed power.
We also show the sensitivity of such statistics to the equation of state of the
gas and its mean temperature.
