In the ongoing human effort to understand the body's rhythms, independent researcher Rob ter Horst placed Apple's newest wearable against medical-grade equipment and found the gap between consumer technology and clinical precision narrowing in meaningful ways. The Apple Watch Series 12, redesigned to sample heart rate every five seconds without interruption, demonstrated near-perfect correlation with a Polar H10 chest strap across cycling, running, and weightlifting. This moment reflects something larger than a product review — it marks a quiet shift in who gets access to the kind of continuou