- A movable clock accurate to the attosecond has measured relativity between the ground and the Tokyo Skytree.
- Albert Einstein's work is often used as a waypoint from which other science begins or extends.
- These researchers are excited to take their extremely good clock on the road for more experiments.
Using proprietary, cutting-edge optical lattice clocks, the researchers can see nano-scale time differences between something on the ground and something 450 meters up. They say doing this confirms—again—Einstein’s ideas about the way time bends with gravity. More importantly, the research team is excited to highlight a cutting-edge clock they say could revolutionize how distances and elevations are measured.
The group responsible for this clock technology is from Japan’s Institute of Physical and Chemical Research, shortened to Riken from its longer Japanese name.
“Performing a stringent test of the theory of relativity requires either a very precise clock or a large different in height,” the Riken scientists explained in a statement.
“However, such state-of-the-art clocks have been demonstrated only in well-conditioned laboratories,” they say in their paper. Indeed, their big step is in carrying the extraordinarily precise clock into the world and using it on the Tokyo Skytree tower.
Clocks tick in a way that’s consistent with the gravity they’re in. This is one of the key ideas of general relativity. Instead of experiments taking place using measurements from satellites, the Riken team used a much smaller altitude and a much finer clock.
“A clock at a higher altitude ticks faster than one at a lower altitude, in accordance with Einstein’s theory of general relativity,” the researchers explain, so with a clock that measures up to 10⁻¹⁸—an attosecond—they can measure a detectable difference in the just 450 meters from the ground to the observation deck of Tokyo Skytree.
These kinds of headlines about Einstein appear all the time: Some scientist is questioning Einstein, reinforcing his ideas, or “proving Einstein wrong.” But why is this such a key idea?
The easy answer is Einstein is a luminary and a legend, not just in science, but as a massive pop culture figure representing science. Like Mohandas Gandhi and Reverend Martin Luther King, Jr., Einstein is the butt end of reams of misattributed quotes, to the point where satirizing these has become its own meme. So repeating “Was Einstein Wrong?” is a cheap way to gather eyeballs.
But there’s a bigger issue at play in the science, and even a low-level physics student knows what it is.
Einstein put together huge theories about the nature of gravity and time, working with what he was able to know at the time. Since then, advances in the entire field known as quantum mechanics have called certain of Einstein’s ideas into question in certain contexts. These are almost all on the molecular or particular scale in a way Einstein simply had no way to observe—the same way he never had an optical lattice clock.
As we're able to look more and more closely at the tiniest particles in different gravities and contexts all around our galaxy, Einstein's work is still a fundamental frame for everything we find out.