Schild's Ladder by Greg Egan

In a near-future hard-SF tale, a team of scientists accidentally creates a self-propagating new phase of vacuum that threatens to rewrite local physics, and must race to understand its strange mathematics and develop unprecedented, large-scale interventions to contain it. The novel follows their technical and ethical struggles as they confront the limits of scientific knowledge, the costs of radical experiments, and the shifting identities of posthuman society while exploring deep questions about reality, causality and the responsibilities of those who can reshape the cosmos.