  We propose a testable alternative to inflation directly built in a very
general class of ultraviolet complete theories of quantum gravity enjoying Weyl
conformal invariance. After the latter is spontaneously broken, logarithmic
quantum corrections to the action make both the primordial tensor spectrum
(from graviton fluctuations) and the scalar spectrum (from thermal
fluctuations) quasi scale invariant. We predict a scalar spectral index $n_{\rm
s}$ which only depends on two parameters and is consistent with observations, a
tensor index $n_{\rm t} =1-n_{\rm s}>0$, a tensor-to-scalar ratio
$r_{0.05}\approx 0.01$ detectable by BICEP Array and LiteBIRD in the immediate
or near future, respectively, and a blue-tilted stochastic gravitational-wave
background observable by DECIGO in the further future.
