The Tajmar anomaly is an unexplained acceleration observed by gyroscopes close to , but isolated from , rotating rings cooled to 5K .
The observed ratio between the gyroscope and ring accelerations was 3 \pm 1.2 \times 10 ^ { -8 } for clockwise rotations and about half this size for anticlockwise ones .
Here , this anomaly is predicted using a new model that assumes that the inertial mass of the gyroscope is caused by Unruh radiation that appears as the ring and the fixed stars accelerate relative to it , and that this radiation is subject to a Hubble-scale Casimir effect .
The model predicts that the sudden acceleration of the ring causes a slight increase in the inertial mass of the gyroscope , and , to conserve momentum the gyroscope must move with the ring with an acceleration ratio of 2.67 \pm 0.24 \times 10 ^ { -8 } for clockwise rotations and 1.34 \pm 0.12 \times 10 ^ { -8 } for anticlockwise ones , in agreement with the observations .
The model predicts that in the southern hemisphere the anomaly should be larger for anticlockwise rotations instead , and that with a significant reduction of the mass of the disc , the decay of the effect with vertical distance should become measurable .