Maybe if you thought about them, people never really disappeared. It sounded so corny, but there was a scientific explanation for it, too. If you believed that thoughts were energy and energy is matter and matter never disappears, then a person can never truly leave you unless you stop thinking about them. Everything you shared with a person is still there swirling around in the universe.
—Wendy Wunder in The Probability of Miracles
Wendy Wunder has the following books quoted on Quodid: