First proposed by physicist T. W. B. Kibble in 1976, cosmic strings are hypothetical one-dimensional objects. They are often compared to imperfections that arise during phase transitions in matter—similar to the cracks that form in ice as it freezes.
These intriguing objects are sources of Gravitational Waves (GWs) that can be potentially measured by LISA. The detection of cosmic strings would provide the key to unlocking the answers to questions about the earliest moments of the universe’s existence.