Do you ever get uncomfortable when your microwave clock is a minute or two off from your oven clock?
This mild time differential may not seem significant, but it provides a snapshot of how we regard the ethereal nature of time. Scientists in the field of Metrology (the science of measurement), however, see things in a different light. Using atomic clocks, they are able to measure time to a precision impossible with traditional elector-mechanical timepieces. These clocks have long been the standard by which any other timekeeper is measured, and they are only getting better.
The Atomic Clock
Atomic clocks work off the natural oscillation occurring within the atom. At all times, the nucleus engages in a never-ending dance with its electrons. This dance is measured and predictable. The atom’s mass sets the frequency of the oscillations, and it is through their steady, dependable rhythm that an atomic clock can harness unparalleled reliability.
Clocks have used some form of oscillation to keep their time reliably since the beginning of clock-making. What sets atomic clocks apart is that their oscillations are not subject to the natural whims of the environment. Clocks based on water pull, pendulums, chronometry, and the earth’s rotation will all lose time due to these changes. Because the inner rhythm of an atom remains unchanged, clocks that rely on their oscillation are the most accurate in the world.
Improving on Excellence
When you ask someone for the time, you’re probably happy if you can get an estimate within five minutes of the mark. Metrologists, however, are still working diligently to improve on the atomic clock. Today’s standard-bearing atomic clocks work by using cesium, an element that becomes agitated when microwave frequencies reach a certain state. Dr. Alan Madej of the Canadian National Research Council is just one scientist working on the next generation of atomic clocks. Through the research at Madej’s lab and others, atomic clocks are moving away from microwaves and into the use of laser light. Known as optical-lattice clocks, these new timepieces can split the second into smaller intervals. This increased dissection leads to even greater accuracy.
Madej and his associates have developed a single-ion clock which is able to measure the 430 trillion light waves per second it takes to energize a strontium atom. The clock converts the measurement of these light waves into individual ticks, allowing them to measure time at a microscopic level that surpasses any of the atomic clocks in current use.
Of course, Canada’s NRC is just one Metrology Lab of many. Labs around the world are focused on creating the next advances in atomic clock technology, and it is the spirit of competition between them that drives us to new heights in accuracy. A team working for the National Institute of Standards and Technology in Boulder, Colorado has developed what is now being called the most advanced clock in the world. Under the guiding research of physicist Jun Ye, the team was able to create an atomic clock that would stay accurate to the second for up to five billion years.
Technology and Theory
Jun Ye and his team may have accomplished greatness in developing their new clock, but the theoretical underpinnings that make the advancements possible have been around since the early 2000s. It was then that researchers realized that holding Sr atoms in optical latticework would prevent them from being agitated by outside factors. Unfortunately, laser stability was not reliable enough to make the clocks work until 2013. The research Ye and his team has conducted led directly to better laser technology that could then be applied to their new atomic clock.
Accurate Time and its Importance
Is there any practical reason to have a clock that will still be accurate after five billion years? Certainly, it is unlikely to have much affect on our day-to-day lives, a fact that the top Metrologists in the world readily admit.
That said, advances in clock technology have the potential to affect other technologies across a wide spectrum of fields. For instance, today’s advanced computer networks rely on precise atomic clocks to work correctly. The same can be said for the national GPS system, which couldn’t figure out your exact location without the reliability of atomic oscillation. Jun Ye is on record as envisioning a future where increasingly accurate atomic clocks can help scientists study quantum physics, look deeper into the space-time continuum, and explore theoretical concepts such as black holes.
A History of Progress
Of course, we weren’t always obsessed with timekeeping as a species. Up until the 17th century, people relied on general, inaccurate measures of time predicated on gravitational pull, the sun, and other methods that could not be reduced to minutes and seconds. It was not until Italian mathematician Tito Livio Burattini proposed a definition of the second in 1685 that Metrology got serious about getting accurate time. Burattini’s definition was 1/86,400 of a solar day, and it was based on the rotation of the earth on its axis. Though this definition was accurate enough for both laymen and scientists for hundreds of years, it fell short of providing scientists with the accuracy they needed for 20th century technology.
Einstein’s Theory of Relativity introduced new problems into the mix, and scientists immediately began conducting experiments that might lead to a more reliable unit of time. To study his theories, provide radio broadcasting, and distribute electricity effectively, society needed to rethink Burattini’s time measurements through steady oscillations the earth couldn’t provide. By 1955, scientists were using atoms to tap into a new cosmic pendulum, giving us the most accurate clocks the world had ever seen. Using these new methods, the scientific community redefined the second by using cesium atoms. By breaking the link between time and the earth’s rotations, science was able to define time in a way that wouldn’t degrade in the same manner.
The Present and the Future of Atomic Clock Research
Atomic clock research isn’t limited to the advances made by Jun Ye or Alan Medej. Other types of atomic clock technology have been developed using hydrogen, rupidium vapor, and of course cesium. Some advances are geared toward making the clocks smaller, decreasing their cost, and reducing the amount of power they need to function.
We live in a world governed by precise time. You may not care too much about the difference between 8:05 and 8:06, but without greater accuracy many of today’s technological wonders would be impossible. Everything from the stock market to mass transit depends on accurate time. In the future, there will almost certainly be new technologies and devices that require atomic accuracy to work properly. Until then, researchers at Canada’s NRC, America’s NIST, and other laboratories around the world will continue to push us forward into a brave new millennium.
By using your computer’s time settings, which are usually updated via time servers over the Internet, Online Clock is playing its own small part in helping to ensure accurate timekeeping!