We show that perturbative quantum gravity based on the Einstein–Hilbert action, has a novel continuum limit. The renormalized trajectory emanates from the Gaussian fixed point along (marginally) relevant directions but enters the diffeomorphism invariant subspace only well below a dynamically generated scale. We show that for pure quantum gravity to second order in perturbation theory, and with vanishing cosmological constant, the result is the same as computed in the standard quantisation. Although this case is renormalizable at second order for kinematic reasons, the structure we uncover works in general. One possibility is that gravity has a genuine consistent continuum limit even though it has an infinite number couplings. However we also suggest a possible non-perturbative mechanism, based on the parabolic properties of these flow equations, which would fix all higher order couplings in terms of Newton’s constant and the cosmological constant.

我们表明基于爱因斯坦-希尔伯特作用的微扰量子引力具有新的连续极限。重整化轨迹沿（边缘）相关方向从高斯不动点发出，但进入微分同胚不变子空间仅远低于动态生成的尺度。我们表明，对于微扰理论中的二阶纯量子引力，并且随着宇宙学常数的消失，结果与标准量子化中计算的结果相同。尽管由于运动学原因，这种情况在二阶可重整，但我们发现的结构一般都有效。一种可能性是重力具有真正一致的连续极限，即使它具有无限数量的耦合。然而，我们也提出了一种可能的非微扰机制，基于这些流动方程的抛物线特性，