Brown University researchers propose topological explanation for cosmological constant problem
7 reported
Scientists at Brown University have proposed a new explanation for why the universe is not expanding as fast as quantum theory predicts, linking quantum gravity to an exotic quantum state of matter. The study, published in Physical Review Letters, suggests that the topology of space-time may protect the cosmological constant from disruptive quantum effects. The cosmological constant, first introduced by Albert Einstein and later called his "biggest blunder," describes the energy driving the universe's accelerating expansion. Quantum field theory predicts the constant should be extraordinarily large, but observations show it is incredibly small. The researchers found that the mathematics behind the Chern-Simons-Kodama state, a proposed ground state of quantum gravity, resembles the mathematics describing the quantum Hall effect. In the quantum Hall effect, topological properties lock electrical conductance into stable values, and the researchers argue a similar process could lock the cosmological constant into stable values. The work was co-authored by Stephon Alexander, Aaron Hui, and Heliudson Bernardo of the Brown Theoretical Physics Center.
What’s reported
The cosmological constant describes the energy responsible for the universe's accelerating expansion.
Quantum field theory predicts the cosmological constant should be extraordinarily large, but observations show it is incredibly small.
Brown University researchers found a mathematical connection between quantum gravity and the quantum Hall effect.
The quantum Hall effect occurs when electricity flows through extremely thin materials exposed to a magnetic field, producing stable conductance values due to topology.
The researchers argue that the topology of space-time in the Chern-Simons-Kodama state could protect the cosmological constant from quantum fluctuations.
The study was published in Physical Review Letters on June 19, 2026.
Co-authors are Stephon Alexander, Aaron Hui, and Heliudson Bernardo.
Key figures
Stephon Alexander, professor of physics at Brown University and study co-author
Aaron Hui, assistant professor at Brown University and study co-author
Heliudson Bernardo, Brown Theoretical Physics Center colleague and study co-author
Albert Einstein, physicist who introduced the cosmological constant
Edwin Hubble, astronomer who discovered the universe was expanding in 1929
Sources: ScienceDaily
