Zenith Grant Awardee
Dr. Richard J. Easther
Yale University
Co-Investigators
Eugene Lim, <i>Yale University</i><br>Liam McAllister, <i>Princeton University </i>
Project Title
Possible Pasts in the Multiverse
Project Summary
The suggestion that our observable universe may be a single "pocket" in an infinite "multiverse" is one of the most profoundly exciting – and unsettling – possibilities offered by modern cosmology. However, attempts to calculate the probability of finding oneself inside a given type of pocket universe often yield ambiguous answers, which depend critically on the choice of coordinate system in the multiverse. This proposal tackles this problem by examining only quantities that can be computed without reference to any explicit coordinate system, and without making direct comparisons between hypothetical observers who could only communicate by using signals that travel faster than light. Secondly, much of theoretical support for the multiverse comes from the string landscape. This is a massively complicated, multidimensional surface with a vast number of valleys and paths – each of which represents a possible past for our (or any other) universe. The second goal of this proposal is to compute the properties of the landscape that follow directly from its dimensionality, as opposed to following from explicitly stringy considerations.
Technical Abstract
QSpace Latest
PressRelease: Precision experiment puts pressure on quantum collapse theories
Quantum mechanics, the theory governing the microscopic world, is famously counterintuitive. A particle can exist in a superposition of multiple states, such as different positions, until a measurement is performed. At that point, the wavefunction describing that particle appears to ‘collapse’ to a single outcome. This puzzle lies at the heart of the measurement problem, famously illustrated by Schrödinger’s cat, suspended between life and death until observed. The XENONnT detector, which was designed to be sensitive to rare physics events, has tightened constraints on one family of possible solutions to the measurement problem, known as ‘collapse theories.’ The work, which was partially funded by FQxI, was reported in Physical Review Letters in March 2026. Image credit: XENON Collaboration.