Weighing Heavy Objects and Communicating with Gravity

ASEG ACT Branch Tech Talk 27 October | 1:00 PM AEDT Speakers: Dr Charles Woffinden & Dr Andrew Groszek (University of Queensland) This Tech Talk explores two unconventional and innovative applications of gravimetry, highlighting its versatility beyond traditional geophysical use cases. Part 1: Weighing Vehicles with Gravimeters Conventional weighbridges measure mass by recording the downward force exerted by gravity. While effective, they are immobile and provide no information about how mass is distributed within an object. In this talk, we present a novel approach that uses high-precision gravimeters to map the gravitational field around a vehicle. By applying inversion techniques commonly used in geophysics, we can estimate both the total mass and mass distribution of the vehicle. This method offers the potential for a compact, portable alternative to weighbridges, with added insight into internal load distribution. We demonstrate that with only a limited number of gravimetry measurements, it is possible to reconstruct the approximate mass distribution of a truck and estimate its total mass with over 90% accuracy. Part 2: Communicating Using Gravity The second part of the talk introduces the concept of gravitational communication. In this scenario, a transmitter (“Alice”) broadcasts a binary message by moving a heavy mass between two positions, representing binary 0 and 1. A nearby receiver (“Bob”) detects the resulting changes in the local gravitational field using a gravimeter and decodes the message. Using a lift counterweight and a LaCoste & Romberg Model D gravimeter, we experimentally validate this concept by successfully transmitting and receiving binary messages through a wall. Unlike electromagnetic communication, gravity cannot be blocked by any known material, making it a fundamentally resilient communication channel. Speaker Information Dr Andrew Groszek Dr Groszek is a Research Fellow in the School of Mathematics and Physics at the University of Queensland. He completed his PhD at Monash University in 2018 and subsequently worked at Newcastle University (UK) before joining UQ in 2020. His research background is in computational modelling of superfluids, which exhibit exotic quantum mechanical behaviour. Since 2023, he has been part of a UQ research team developing methods to weigh heavy objects using high-precision gravimetry. Dr Charles Woffinden Dr Woffinden completed his PhD in experimental physics at the University of York in 2010 under Prof. Steve Tear, studying the electronic and magnetic properties of novel surfaces and nanomaterials. From 2009 to 2019, he worked at Teledyne e2v as an engineer and product development manager, developing imaging systems for space and scientific applications. In 2020, he joined the University of Queensland and is currently based in the Bose–Einstein Condensation Laboratory under Prof. Halina Rubinsztein-Dunlop.