Bang goes any excuse for ever being late ever again.

Physicists in the US have made a clock that is claimed to be so accurate that it won't lose or gain even a second in more than 200 million years (though who is still going to be around to test this claim is another question!).

The new atomic clock is vying for the title of world's most accurate.

It is currently up against another experimental clock developed in the same lab at the Joint Institute for Laboratory Astrophysics, which is a collaboration between NIST and the University of Colorado in Boulder.

However, it has already outperformed the official atomic clock used by the US Commerce Department's National Institute of Standards and Technology, which promises to keep accurate time down to the second for 80 million years.

High precise clocks are most important for deep space navigation, where any error in timing can cause a mission to be aborted.

Jun Ye developed the atomic clock at JILA and says that the secret to extreme accuracy is the number of time the clock ticks.

This latest clock has 430 trillion "ticks" per second.

Here's the science part - its pendulum uses thousands of strontium atoms suspended in grids of laser light. This allows the researchers to trap the atoms and measure the movement of energy inside.

"Essentially, we are probing the energy structure of the atom. We are probing how electrons make transitions between a set of energy levels", Ye said in an interview with Reuters.

"This is the time scale that was made by the universe. It is very stable."

The new clock was pitted against another optical atomic clock, which measures calcium atoms, but is only stable over shorter periods of time.

Next up, it is to be tested aginst a clock that measures a single ion of mercury, which was claimed to be accurate to about 1 second in 400 million years in 2006.

Developing super clocks like these is hoped to help physicists test basic questions about the nature of the universe.

But, added Ye, they may also be used for more day-to-day purposes, such as for synchronising telecommunications networks to support, for example, hands-free driving in satellite-guided cars.

"If we can navigate a vehicle on Mars and ask it to settle down on a particular runway, I'm sure we can navigate all the cars on Earth with satellites", Ye said.