For decades, the Lambda Cold Dark Matter (LCDM) model dominated cosmology, building on Big Bang theories. It proposed that the universe expanded from a hyperdense state, with spacetime expansion causing the Hubble redshift of light. The model integrated dark matter and dark energy to address the cosmic microwave background (CMB) and the unexpected dimness of distant supernovae.
However, cracks have begun to form in this once-reliable framework. Discoveries from the James Webb Space Telescope (JWST) show mature galaxies forming too soon after the universe's supposed origin. Other anomalies, like the “Hubble tension” and the late emergence of dark energy, suggest that cosmology might be facing a crisis.
A New Gravitational Perspective
While some scientists hope to tweak the LCDM model to fix these issues, findings in general relativity offer a completely different direction. In 2011, Jun Ni uncovered new solutions to the Einstein field equations for neutron stars, later expanded by Lubos Neslušan, Jorge deLyra, and others. These solutions—known as the Ni-Neslušan-deLyra configurations—challenge standard cosmological ideas.
Unlike conventional models, these solutions describe a shell-like structure with a central void, where a repulsive gravitational field causes matter to be attracted toward the shell. This setup produces gravitational redshifts and blueshifts, depending on the direction light travels within the shell, deviating from the standard flat Minkowski spacetime associated with spherical shells.
Resolving LCDM Tensions
All the tensions in the LCDM model, including Hubble tension and supernova dimming, might be explained if our observable universe were concentrated in a thick Ni shell. The Milky Way is near the centre in what is known as the KBC Void. Though this positioning conflicts with the cosmological principle, evidence from quasar counts and other observational anomalies might support it.
In this Ni shell universe, the Hubble redshift could be due to gravitational redshift caused by the shell, not just spacetime expansion. The Hubble tension would be explained by changes in gravitational forces as one moves away from the centre, and the concept of dark energy would no longer be necessary.
Hybrid Models and Beyond
The Ni solution could potentially merge with LCDM in a hybrid approach, similar to Rajendra Gupta’s “CCC + TL” model. Supernova dimming could result from Ni redshifts, making objects appear farther than they actually are. However, the Ni model may extend much deeper than just resolving current cosmological tensions.
Recent observations of high mass density at early stages of the universe suggest it may have so much mass that it resembles a black hole. In this scenario, a new cosmological model could arise, where spacetime consists of photonic filaments that interconnect all masses, an idea proposed by Arto Annila and colleagues. These filaments, composed of overlapping photon pairs, could play a key role in how gravity operates.
A Universe as a Black Hole?
In this black hole cosmology, all radiation would be confined within the cosmic interior. The CMB could have originated from gravitational energy trapped during the formation of the shell, possibly leading to a cosmological cycle for gravity and a force similar to Einstein’s cosmological constant, Λ.
Gravity, in this model, would arise from the absorption of CMB photon energy in spacetime filaments, pulling masses together. Meanwhile, the Λ force would return absorbed energy to photons, pushing masses apart. This setup matches the Ni solutions, where gravity and Λ are driven by inward-moving redshifted waves and outward-moving blue shifted waves, respectively.
A Ni shell black hole universe is also testable. If valid, the CMB temperature within the shell would be about 29 K, with the lowest temperature near the centre approaching 0 K. Our current CMB temperature of 2.73 K could indicate that the Milky Way is offset from the universe’s centre. Measuring CMB temperatures at different locations could provide a simple and direct test of this model.
A New Perspective on Black Holes
If the universe itself functions like a black hole, it suggests all black holes share the same structure, including a shell configuration and gravity/Λ cycles. Regardless of a black hole’s mass, they would produce the same “maximum luminosity,” irrespective of size.
For smaller black holes, this process would require more energy to prevent collapse. In rapidly rotating black holes, the Ni shell might collapse into a torus, which could explain the striking images of supermassive black holes.