A University of Queensland researcher has developed a mathematical framework that incorporates collapsing regions of matter and expanding cosmic voids to explain the universe's evolution in greater detail than the standard model allows.
Dr Leonardo Giani and colleagues used data from the Dark Energy Spectroscopic Instrument (DESI), which measures the structure of the universe across distan by Simon Mansfield
Sydney, Australia (SPX) Aug 20, 2025
A University of Queensland researcher has developed a mathematical framework that incorporates collapsing regions of matter and expanding cosmic voids to explain the universe's evolution in greater detail than the standard model allows.
Dr Leonardo Giani and colleagues used data from the Dark Energy Spectroscopic Instrument (DESI), which measures the structure of the universe across distances of up to 11 billion light years. Giani explained that unlike conventional models that treat matter particles as identical and non-interacting, his work accounts for stars, galaxies, black holes, and empty space continuously interacting through forces such as gravity.
"For 30 years scientists have tried to explain what is happening as this complex universe expands and there have been plenty of exotic attempts at solutions," Giani said. "We know voids and collapsing regions exist, but we didn't really know how to compute their impact on the measurements. My model gives a recipe to compute it, without the need for new physics."
The team defined two critical parameters: R_c, the minimum size a void must reach to influence cosmological measurements, and R_v, the minimum cluster size required to have the same effect. Comparing independent datasets with DESI data, they found that the results overlapped in unexpected regions. This suggests that large-scale voids could be driving anomalies seen in cosmological observations.
The model also engages with two of cosmology's biggest challenges: Hubble tension and dynamical dark energy. Hubble tension arises from different methods of measuring the universe's expansion rate, while dynamical dark energy proposes that dark energy changes or weakens over time.
"Our model has the richness to address both of these," Giani said. "If you assume that dark energy is weakening and then try to infer how fast the universe is expanding, you end up with an even lower rate. In our model, any apparent weakening is simply a detailed accounting of the universe's complexity."
According to Giani, the framework shows that the structure of matter can naturally explain discrepancies in cosmological data without resorting to exotic new physics. "Essentially when we asked if the complexity of the universe was showing up in the DESI data the result was that it was, and our framework can explain all of the observations," he noted.
Research Report:Novel Approach to Cosmological Nonlinearities as an Effective Fluid
Related Links
UQ's School of Mathematics and Physics
Understanding Time and Space