Time-Warping Occurs in Daily Life

Time dilation arises in two situations. In one case, time appears to move slower the closer you are to a massive object, such as the Earth. So a person hovering in a hot-air balloon ages faster than someone standing below. Time also ticks by faster for someone at rest relative to someone moving.

Previous experiments with rockets and airplanes have demonstrated these odd aspects of general and special relativity. Now advances in laser technology and the field of quantum information science have allowed researchers to demonstrate Einstein’s theories at much more ordinary scales.

The researchers used two optical atomic clocks sitting atop steel tables in neighboring labs at the National Institute of Standards and Technology in Boulder, Colorado. Each clock has an electrically charged aluminum atom that vibrates between two energy levels more than a million billion times per second. A 75-meter-long optical cable connects the clocks, which allows the team to compare the instruments’ timekeeping.

In the first experiment, the researchers used a hydraulic jack to raise one of the tables about a foot. Sure enough, the lower clock ran slower than the elevated one — at the rate of a 90-billionth of a second in 79 years. In a second experiment the team applied an electric field to one clock, sending the aluminum ion moving back and forth. As predicted, the moving clock ran slower than the clock that was at rest.

Of course scientists are well aware of these relativistic effects. The clocks on GPS devices are also affected by relativity, and appropriate adjustments are made to keep them working properly.

The experiments have more implications for precision instrumentation than they do for relativity. But they are a nice reminder that relativity is always at hand. People tend to just ignore relativistic effects, but relativistic effects are everywhere. Every day, people are moving; they are doing things like climbing stairs. It’s interesting to think about — are frequent flyers getting younger [because they move so much] or aging faster [because they spend so much time in the air]?

• Source: Wired Science • See also: 80beats