For generations, the pacemaker has meant surgery — a device buried beneath skin, wires threaded into the beating heart. Researchers at the University of Southern California and MIT have now demonstrated, in animal models, that sound itself may one day serve as the stimulus, using focused ultrasound to coax genetically modified heart cells into rhythm without a single incision. The work, published in Nature Biomedical Engineering, does not yet promise a clinical revolution, but it asks a question that medicine has rarely been positioned to ask: what if the most intimate interventions no longer