This is where our models hit a wall. When we run the film of cosmic expansion backward using Einstein’s general relativity, everything crunches down to an infinitely dense point—a singularity. But most physicists interpret a singularity not as a physically real thing, but as a bright red warning sign that the theory itself is breaking down under extreme conditions . It's a mathematical artifact, not a verified cosmic event.
Even official sources put it cautiously. NASA, for instance, is blunt about the limits of our knowledge: "Scientists aren’t sure what came before inflation or what powered it. It’s possible that energy during this period was just part of the fabric of space-time."
So, the question of a "before" the Big Bang, or whether spacetime itself came into being, is parked firmly at the edge of our confirmed models. Ideas range from eternal inflation to cyclical universes, but none are settled science.
For a clear, unassailable statement, you can say:
Consensus holds that our observable universe emerged from an extremely hot, dense early state and has been expanding ever since. It is not consensus that this indisputably proves space and time appeared out of absolute nothingness.