Researchers led by the University of Warwick have proposed a unified framework to detect spacetime fluctuations - tiny, random distortions in the fabric of spacetime. Physicist John Wheeler first imagined them, and they appear in many quantum gravity models. Until now, experiments lacked clear directions because different gravity models predict varied fluctuations.
The framework sorts these fluctuations into three main types, based on how organized they are in space and time. For each type, it shows unique signs that can be measured in laser interferometers, devices that use laser beams to detect tiny changes in distance. Examples include the large 4-kilometer LIGO, which spots gravitational waves, and smaller lab systems like QUEST in the UK and GQuEST in the US.
The researchers explain that various gravity models predict different patterns in these random fluctuations, leaving experimenters without targets. This work turns abstract ideas into real signals testable with current interferometers, moving fundamental physics questions into experiments without needing new tech.
How interferometers perform in detection
Smaller tabletop interferometers like QUEST and GQuEST offer more details about fluctuation types due to their wide frequency range. They detect all key signatures. LIGO excels at confirming if fluctuations exist, thanks to its long arm cavities - tunnels where lasers bounce to boost sensitivity - though relevant frequencies are above public data ranges now.
The study resolves a debate: arm cavities improve sensitivity for some fluctuation types. The researchers note that interferometers measure spacetime precisely, and this framework predicts where to look and what signals expect for many theories, making them versatile for quantum gravity searches.
The framework ignores specific causes of fluctuations, needing only their math description and instrument shape. This helps not just quantum gravity but also hunting stochastic gravitational waves or dark matter signs.
The researchers say this method treats any fluctuation model consistently. Soon, it could help design better tabletop interferometers to test quantum or semiclassical gravity ideas, and explore dark matter or stochastic waves.
This research is published in Nature Communications.