# More on gravitational memory

## TL;DR

This paper introduces two new results on gravitational memory, extending existing formulas to more general solutions and proposing a new observational effect related to spin memory as a time delay for free-falling observers.

## Contribution

It extends the gravitational memory formula to arbitrary boundary topologies and proposes a novel observational effect for spin memory as a time delay.

## Key findings

- Extended memory formula to arbitrary boundary topologies
- Derived memory effect for Robinson-Trautman solutions
- Proposed a new observational effect for spin memory as a time delay

## Abstract

Two novel results for the gravitational memory effect are presented in this paper. We first extend the formula for the memory effect to solutions with arbitrary two surface boundary topology. The memory effect for the Robinson-Trautman solution is obtained in its standard form. Then we propose a new observational effect for the spin memory. It is a time delay of time-like free falling observers.