Speaker
Dr
Verónica Errasti
Description
It is over 150 years since Ostrogradski noticed that higher-order Lagrangians generically lead to instabilities that render theories inconsistent and unphysical. Today, we call these ghosts. I will show that ghosts appear even in first-order Lagrangians and I will present a user-friendly method to spot them in such a simple scenario. I will briefly comment on higher-order extensions, including gravity.
