Bijunath Patla’s experiment sounds like a real bore: Gather 12 of the most accurate clocks around the world, and watch them tick. It’s like a physicist’s version of watching paint dry. Patla’s team, based at the National Institute of Standards and Technology in Boulder, Colorado, began monitoring the clocks on November 11, 1999. And they’ve kept watching for some 450 million seconds*—over 14 years.

But their patience paid off. In a paper published in Nature Physics on Monday, Patla’s team reveal a profound result from an exceedingly monotonous experiment. The ticking of the clocks, Patla says, actually illustrates one of the most fundamental principles in the laws of physics: that no time or place in the universe is special. It’s one of the basic ideas in Einstein’s theory of general relativity, a set of rules that correctly describes how the planets orbit the sun and how neutron stars collide to produce gravitational waves. The laws of physics apply in the same way today as they did 4.5 billion years ago when the moon formed, or in 2000 when you were listening to Creed.

The principle seems obvious. Throw a ball today, and it lands in the same way it did yesterday. Duh. But how do we actually know that the laws of physics aren’t changing, ever so slightly, from day to day? It’s a hidden logical assumption that underpins all science, ever. We assume that an airplane will fly because it always does. We assume that baking soda and vinegar will make a frothy mess because it always has. But what if the laws of physics do change over time and in different locations, and we’re just too galumphing to perceive it?

“The modifications might be very, very small,” says physicist Nicolas Yunes of Montana State University, who was not involved in the experiment. Although all evidence so far indicates that the laws of physics don’t change, you can never be completely sure. “Everything we measure is approximate,” he says. “If you’re measuring distance with a ruler, you can only measure up to the accuracy of the ruler.”

To try to catch the laws of physics changing, you basically have to perform a task, over and over again, with painstaking precision, in as many locations as possible. If the outcome ever changes, that’s your hint that the laws of nature have switched it up on you. Patla’s task: watching clocks tick, ad nauseum, for over 14 years.