If some of the many thousands of human volunteers needed to test coronavirus vaccines could have been replaced by digital replicas—one of this year's Top 10 Emerging Technologies—COVID-19 vaccines might have been developed even faster, saving untold lives. Soon virtual clinical trials could be a reality for testing new vaccines and therapies. Other technologies on the list could reduce greenhouse gas emissions by electrifying air travel and enabling sunlight to directly power the production of industrial chemicals. With “spatial” computing, the digital and physical worlds will be integrated in ways that go beyond the feats of virtual reality. And ultrasensitive sensors that exploit quantum processes will set the stage for such applications as wearable brain scanners and vehicles that can see around corners.