A new device developed by Bertrand Selva utilizes a pair of gyroscopes to measure the Earth’s rotation, providing a compact alternative to traditional methods such as the Foucault pendulum. This innovative apparatus emerged from a conversation with a flat-earth believer, leading to a practical application of gyroscopic technology in a way that is both accessible and effective.
Selva’s device is built around two BMI160 MEMS gyroscopes, which can detect angular velocity changes as minor as 0.0038 degrees per second. In contrast, the Earth rotates at approximately 0.00416 degrees per second. To isolate this small measure from the surrounding noise, Selva designed the system to perform measurements in four distinct orientations. This approach helps to eliminate sensor bias and the impact of gravitational forces.
Before conducting tests, Selva carefully aligned the sensors to true north. A stepper motor then cycled the sensors through the four positions, while a Raspberry Pi Pico recorded 128 measurements at each position. The device can perform this cycle up to 200 times, with the error margin decreasing as the number of cycles increases. A Kalman filter processes the raw data, ultimately yielding results that are within two percent of the actual rotational velocity.
The accuracy of Selva’s system is closely tied to its alignment with true north. In fact, the alignment was so precise that he could utilize the setup as a compass. Despite its impressive capabilities, the device did not convince his neighbor of the Earth’s rotation, but it stands as a testament to the potential of simple technology in scientific exploration.
Beyond this gyroscopic approach, there are also alternative methods for measuring Earth’s rotation, including using gaming consoles such as the PlayStation. For those interested in higher precision, established standards organizations are actively involved in refining measurement techniques.
Selva’s work exemplifies how innovative thinking can lead to practical scientific tools, encouraging further exploration of geophysical principles with accessible technology.
