Systems and methods are provided for determining a property, e.g., density, of a geological formation based on Einstein's theory of gravitation. A gravitational potential difference is determined between two positions of the geological formation by measuring a frequency shift of a radiation travelling from a source to an absorber of a differential gravimeter. The gravitational potential difference determined can be converted to a density of the geological formation, e.g., based on a concentric spherical shell model. The systems can be a part of a downhole tool.