![]() These clocks are lower in cost (as little as 50 USD), smaller in size, and can last for about 10 years. Rubidium atomic clocks utilize a glass vapor cell containing Rubidium-87 gas that both emits and absorbs light in reaction to microwave stimulation. ![]() Feedback from the detector is used to fine tune the radio waves and create a consistent flow of oscillating cesium atoms. Cesium atoms pass through radio waves and then into a detector that measures the microwave emissions that occur when the atoms return to their unexcited or ground state. Cesium was used in the first atomic clocks, and is still in use today. Types of Atomic ClocksĪtomic clocks come in several varieties. This energy change or resonance occurs at very consistent and specific frequencies to deliver a level of timekeeping accuracy that’s in a league of its own: Since 1967, the International System of Units (SI) has defined a second as the exact time required for a Cesium-133 atom to oscillate. In an atomic clock, the negative subatomic particles (electrons) that orbit an atom’s nucleus are subjected to a form of radiation, like radio waves, which causes these electrons to move back and forth between energy states. The natural oscillations (or resonant frequency) of atomic particles, which provide the basis for atomic clocks, essentially serve the same purpose as a pendulum - but with far greater accuracy. But pendulums and springs are affected by their physical environment, which introduces variables that make this traditional method for measuring time inherently imprecise. ![]() The functioning of traditional timekeeping devices is based on some measurable, repetitive movement or activity, like the back-and-forth motion of a pendulum. While all clocks tell time, how they do so varies by design. ![]() And it is, give or take a nanosecond, thanks to the precision of atomic clocks. We rely on the countdown to midnight every New Year’s Eve to be 100 percent accurate. ![]()
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