It’s about 10 times more accurate than the previous atomic clock – which means it’s so accurate that if it had been started at the beginning of the universe, about 13.8 billion years ago, it would have only lost one second. This is the National Institute of Standards and Technology’s (NIST) new atomic clock, the most precise device for measuring time that scientists have ever devised. Known as the ytterbium optical lattice clock, it’s so accurate that scientists believe they can use it to test Albert Einstein’s general theory of relativity.
How atomic clocks work
How can a clock be so accurate that it only loses a second in every multiple billions of years? First, let’s take a look at how clocks work. Inside any old clock is a mechanism that changes in a regular way, called an oscillator. This might be a pendulum in a grandfather clock or a crystal in a wrist watch. A specific number of times the oscillator travels back and forth is equal to one second.
What makes a clock accurate is the stability of its oscillator. NIST physicist Andrew Ludlow explained on NPR’s All Things Considered, transcribed by Adam Cole in the August 22, 2013 post “The world’s most precise clock could prove Einstein wrong,” if a toddler bumped into a grandfather clock, “that oscillation period could vary quite a bit. How much that ticking rate varies determines the precision with which you can measure the evolution of time.”
Atomic clocks use the speed of vibration of an atom — in the case of the new clock, an atom of ytterbium — as the oscillator. The speed of the vibration is consistent, accurate, and fast. To keep atoms in place, so that the clock can measure them accurately, a lattice of lasers traps the atoms and cools them down.
What is Ytterbium?
So what is ytterbium anyway? It’s a metal found on the periodic table. Here are some fast facts:
- Atomic number: 70
- Atomic weight: 173.054
- Phase at room temperature: solid
- Pronunciation: i-TUR-bee-em
- Named for: Ytterby, a village in Sweden
- Discovered by: Swedish chemist Carl Gustaf Mosander
- Discovered in 1843
Previous atomic clocks ran off of cesium, which was used in 1967 to define the rate of a second (“exactly 9,192,631,770 vibrations of a cesium 133 atom” according to Eoin O’Carroll of the Christian Science Monitor on August 23, 2013, in “Imperturbable ytterbium reverberates superbly, scientists say.”
What about Einstein?
For years, scientists have been poking at Einsten’s general theory of relativity, because they theorize that it’s incompatible with other physical theories. Einstein’s theory posits, among other things, that clocks in different gravitational fields would run at slightly different speeds. For example, a clock at the altitude of Boulder, Colorado would run at a different speed than a clock along the shoreline in Boston, Massachusetts. After about 200,000 years, the Boulder clock would be ahead by a second. Einsten also posited that certain physical properties should never change. Using the ytterbium optical lattice clock, scientists might be able to detect fluctuations in supposed constants like the “ratio of mass of electrons and protons,” according to Cole.
How does that impact you? The GPS in your car — or your cell phone — takes into account the difference in gravitational pull between where you are and where the GPS satellite is in orbit, where the gravitational pull is much weaker. “A more precise atomic clock could measure the correctional factors even better,” Elizabeth Landau reported on CNN.com in the August 23, 2013 article “New atomic clock’s precision ‘groundbreaking.’” She continued to suggest that there could be additional implications for navigation and communication systems. “But you probably won’t want one for your alarm clock,” Landau wrote. “Ludlow said the total cost ranges on the order of a half-million dollars.”
Do you think Einstein’s theory of relativity will be upheld? Tell us in the comments below!