The idea that the universe is a black hole is not new. However as stated in the link below the FRW gravitational field equations of General Relativity for a black hole do not perfectly match the observed properties of the universe.

Is the Big Bang a Black Hole

Arguments against the Black Hole Universe model:

- The Schwarzschild radius of a black hole applies only to the mass of a static body before it must collapse into a black hole and does not apply to a dynamic body of rapidly expanding matter.

- The singularity of the universe lies in the past but the singularity of a black hole lies in the future.

The book "Gravitation" details the FRW gravitation model for a black hole.

My counterarguments are that:

- If all the mass of a black hole was contained before expanding, then it was static and therefore the Schwarzschild limit applied at some time(t) prior to expansion.

- Matter forms clumps, in turn forming additional event horizons within the larger one, and the smaller they get the faster they evaporate, therefore there is no singularity either in the past or in the future. But this is my model of a black hole, not theirs.

Black Hole Inflation

Other conundrums that neither model seem to adequately address:

- Why does all the matter in the universe seem to occupy a volume much smaller than the 89.1 billion lightyear Schwarzschild radius in the past, even though extrapolating the observed expansion suggests that it would have nearly filled that radius and volume by now?

- My model suggests that all stellar-mass black holes will grow and envelope the universe, but my model does not suggest that matter captured by a black hole will be crushed into a volume smaller than the Schwarzschild radius, i.e. a singularity. Their model suggests that all matter in a black hole is crushed into a singularity, but no reason for the rupturing of that singularity is given, and therefore the universe is described as something other than a black hole.

- My model suggests that heat is captured by black holes as well as matter and that this would reduce the entropy of matter inside it. This heat may be converted into gravitational potential energy. Matter would then expand to fill the Schwarzschild volume of the universe as observed.

- The conversion of heat into gravitational potential energy by a black hole may solve the Black Hole Information Loss Problem and bring it into agreement with the second law of thermodynamics.

- The mechanism of formation of event horizons within the universe seems to be supernovas, but the mechanism of formation of nested event horizons within a stellar mass black hole, where matter may only exist as superdense quagma, is not clear. The relative scale of nested event horizons may be comparable, such that the next nested event horizon is billions or trillions of times smaller than its parent event horizon. The behaviour of quark-gluon plasma may not be understood well enough to suggest more than "collisions" as a possible formation mechanism.

- The mechanism of conversion of heat into gravitational potential energy by the Black Hole Universe is not clear. I like to think that Dark Matter is responsible, that Dark Matter and Dark Energy are related phenomena. It's conceivable, if implausible, that Dark Matter consists of exotic particles that only absorbs radiation and never emit, and that this is why the universe appears to be expanding, and also why Dark Matter isn't visible. But there is another explanation... The mass of the solar system is known with accuracy, and correponds to the observable matter. The mass of the galaxy is also known with accuracy, but there isn't enough visible matter to account for this mass. We assume that dark matter exists further out beyond the visible rim of the galaxy and that is why the inner visible disk appears to rotate with the same angular velocity, in unison, seemingly in violation of Newtonian gravity. I suggest that just as matter is differentiated in planets with denser elements sinking to the core, and just as superdense neutron stars migrate toward the center of the galaxy and lighter dwarf stars migrate outward, that the halo of matter existing beyond the visible rim of the galaxy must consist of extremely lightweight matter, perhaps so light that it would not even form stars. Dark matter is also perhaps without charge and does not absorb or emit radiation. But Dark Matter must have momentum, and interact gravitationally with the galaxy. Neutrinos are constantly being pumped out by fusion reactions in stars and this may be how the stars minimize their gravitational potential energy: heat may be absorbed by stars as momentum, which then produce neutrinos and transfer excess momentum to them before they escape the corona. Solar Neutrinos then migrate to intergalactic space where they act as accumulators of gravitational potential energy and push galactic groups apart. This may be the mechanism of expansion of matter in the universe.