The Search For Primordial Tensor Modes
  We review the prospects for detecting tensor modes generated during inflation by CMB polarization experiments and by searching for a stochastic gravitational wave background with laser interferometers in space. We tackle the following two questions: (i) what does inflation predict for the tensor fluctuations? (ii) is it really worth building experiments that can cover only a small range of tensor amplitudes? 
George Efstathiou, Sirichai Chongchitnan