In the book he discusses the shkadov thruster which reflects the energy so the shell would move, too. Obviously if it's not reflective you could absorb the ene

In the book he discusses the shkadov thruster which reflects the energy so the shell would move, too. Obviously if it's not reflective you could absorb the energy and use it as needed https://en.m.wikipedia.org/wiki/Stellar_engine https://en.m.wikipedia.org/wiki/Stellar_engine