Can Gravitational astronomy look beyond the CMB?
Yes. Gravitational wave observatories like the proposed eLISA laser interferometer may be able to detect gravitational waves that originate from the early moments of the big bang itself. If some part of the big bang energy goes into gravitational waves then those waves will be redshifted by expansion and waves produced in the first $&lt;10^{-10}$ s should be present in eLISA's frequency sensitivity window (Amaro-Seaone et al. 2012; Bartolo et al. 2016; Ricciardone et al. 2017). This might probe exotic physics like inflation, extra dimensions, phase transitions and cosmic strings.