Oct 03, 2020 22:58:00

The 'time dilation' of the theory of relativity occurs even at a height of only 30 cm

One of the general theories of relativity, '

time dilation, ' is a phenomenon in which when the gravity applied to two points is different, the time at the two points travels differently. When we say 'gravity is different', it seems that we need a difference between the earth and the universe, but in reality it has become clear that we can observe a time delay with a height difference of only 33 cm on the earth.

NIST Pair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale | NIST
https://www.nist.gov/news-events/news/2010/09/nist-pair-aluminum-atomic-clocks-reveal-einsteins-relativity-personal-scale

An experiment conducted in 2010 by a research team at the National Institute of Standards and Technology (NIST) revealed that even a height of only 33 cm causes a time delay. In the experiment, an atomic clock that measures time using spectral lines such as atoms is used. Atomic clock is a clock that can keep a very accurate time among many clocks, and it is said that the error that occurs during operation is about 1 second in 30 million years if it is highly accurate.

The NIST research team conducted an experiment by comparing the operation of two atomic clocks with the world's highest level of performance as of 2010. Both watches use the 1000 trillion or more vibrations that occur when the energy level of a charged aluminum atom changes to measure time. Each of the two watches was placed in a separate laboratory at NIST and was connected by an optical fiber about 75 meters long.

In the experiment, one of the atomic clocks was placed on the floor of the laboratory, and the other was placed about 33 cm above the floor to measure whether there was a difference in the progress of each time. As a result, it was found that the clock in the high position advances the time quickly by a very small difference, and the clock in the low position advances the time slowly, and the time delay occurs even with a difference of only 33 cm. It became clear.

The time delay observed in the experiment was so small that humans could not perceive it. According to the research team, 'The time delay that human beings experience in their lifetime on the earth is about 1/90 billion seconds if life is about 80 years.' James Chinwen Chow, a NIST researcher and lead author of the paper, was able to detect small changes demonstrating time dilation due to the extremely high accuracy of aluminum atomic clocks. It says that it was.

In 2020, experiments using an optical grid clock, which is a type of atomic clock, are being conducted to detect time delays, and even in Japan, the time generated between the observation deck of the Tokyo Sky Tree and the ground is being conducted. A research team at the University of Tokyo has reported that it succeeded in observing the delay.