The News:

Scientists in US have developed new ultra-precise clocks that may outsmart the existing atomic clocks in precision and economy and would render obsolete, the technology behind high precision clocks that reigned for 50 years. Moreover, eventually, it may force scientists to give a new definition to the second itself.

The Background:

Evolution of measurement is simply an engaging reading for even a person with a non-science background. People in ancient times are smart enough to naturally divide the flow of time based on the duration of day and night combined together. By the turn of eighteenth century, the modern measures of time are spreading around the world. The history and evolution of time measurement is beyond the scope of article.

We, humans need very precise measure of time many a time. For example, in sports, the hundredth of a second decides the winners in many athletic events. Apart from such things, which have a direct bearing on us or command our interest, there are matters that interest scientists and commonly pass unnoticed by most of us, where fractions of a second to the order of millions are important. For example, Earth and Astronomical studies, GPS (Geographical Positioning System), Inter-planetary Navigation etc command precisions of time beyond the need of every day life.

As the science progressed, very accurate clocks developed. The first atomic clock was built in 1949 at the U.S. National Bureau of Standards (NBS). The first accurate atomic clock, based on the transition of the caesium-133 atom, was built by Louis Essen in 1955 at the National Physical Laboratory in the UK. This led to the internationally agreed definition of the second being based on atomic time.

Conventional Atomic clock work by measuring the ticks of cesium atoms exposed to microwave radiation. When microwaves were tuned to the natural frequency of ionized cesium gas, the electrons iside them get excited to change states. These to and fro transitions constitute the ticks for atomic clock. In actual clocks, there are complex feedback and monitoring mechanisms to measure the cesium oscillator. After this innovation, in 1967 the International System of Units (SI) has defined the second as the “time required for 9,192,631,770 cycles of the radiation which corresponds to the transition between two energy levels of the ground state of the Caesium-133 atom”. Besides, other units like the volt and metre also depend on the definition of the second as part of their own definitions.

Now, everything may change soon, as the maser based microwave referencing of cesium atoms is giving way to laser based referencing of ions of atoms like Mercury, Strontium or Ytterbium. The laser referencing allows scientists to use frequencies of 100,000 times higher than microwaves.

For physicists, a billionth of a second is just too long a time between ticks of a clock. How else would it be, when their precise clocks shows a real dif¬ference between time shown by a clock in a hill station and another at sea level? Einstein’s theory of relativity shows that time itself passes more quickly when gravity is reduced! And rest assured, it is proved!

Current Scenario:

Mr. Bergquist, a physicist with the Na¬tional Institute of Standards and Technology in Boulder, Colora¬do, USA works with extremely accu¬rate device. He and others have demonstrated the current better way to make atomic clocks. The new clock could at least be 100 times more accurate than the standard clock could ever be.

Still, can’t fathom the effect of this accuracy? Take this: The current standard atomic clock, by their margin of error, will neither gain nor lose a sec¬ond in about 70 million years, whereas the new clock pushes that period out to a whopping 400 million years!