Shockwave cosmology, proposed by Joel Smoller and Blake Temple in 2003, presents a non-standard "big bang" where our observable universe originated from an explosion inside a black hole. This model integrates shock waves into Einstein's general relativity, producing a universe that "looks essentially identical" to the aftermath of the standard Big Bang, but with an unobservable shockwave at its leading edge, implying we are still within an expanding black hole.
Calculations suggest that this expanding volume will eventually decrease in density, leading the black hole's event horizon to vanish, potentially appearing as a white hole to an outside observer. Importantly, this theory offers an alternative to dark energy, proposing that the shockwave causes accelerated cosmic expansion due to a lower density in our region of the universe. While some aspects are proposed to be testable—such as a specific positive value (C = 0.359) for the cubic correction to redshift versus luminosity—the theory is generally considered to require significant further development to explain phenomena like big bang nucleosynthesis and cosmic microwave background anisotropies before it can challenge the standard Big Bang model.