It wasn’t easy, and we liked it that way. So now, along comes an analog clock that’s nothing but the hands — no dial, no numbers, just hands. How is such a thing possible?

Less obvious was how two volunteer clock hobbyists -- working in their basements on the intricate pieces that make the giant hands move -- had restarted time.

That’s where the National Institute of Standards and Technology (NIST) keeps an atomic clock known as the NIST-F2, which tosses cesium atoms in the air in a routine repeated thousands of times ...