Reasons to Believe

Extraordinary Test of Relativity

General relativity and quantum mechanics represent the two most fundamental and important theories in all of physics. The former describes the large-scale structure of the universe, while the latter deals with fine-scale structure. Scientists discovered the key ideas that characterize these theories in the early twentieth century by pushing the limits of measurement and understanding until discrepancies were observed. In the process of trying to account for these discrepancies, physicists had to totally revamp their thinking, leading to paradigm shifts in both areas of physics.

The possibility of further groundbreaking discoveries motivates scientists to continue pushing the limits of measurement and understanding. There is the hope of finding a new area where present theories do not properly account for the observations. Even though, for example, general relativity is the most thoroughly tested theory in all of physics, researchers continue performing new experiments to check its validity at still higher accuracies.

A paper by Holger Muller, Achim Peters, and Steven Chu in the journal Nature provides a recent example of such experimentation. These researchers made the most precise measurement, to date, of the gravitational redshift predicted by general relativity. What is of particular interest is that their work was done using equipment that could fit on a tabletop yet has improved the accuracy of such measurements by a factor of 10,000!

The basic approach taken by these researchers is similar to a well-known experiment performed about 30 years ago where a hydrogen maser clock was “flown” at an altitude of 10,000 km and compared with a similar clock on the ground. For the new experiment, two clocks were also used, where one was flown above the other by only 0.1 millimeters. Improvement in the precision and comparison of clocks provided the opportunity for this updated experiment.

Over a decade ago, Chu’s Nobel Prize-winning work in the cooling and trapping of atoms with laser light paved the way for the new clock experiment. His research led to the development of an atom interferometer, an apparatus that compares the natural oscillations of cesium atoms traveling two different paths and determines the difference to extremely high accuracy. (For those interested in the details, see this Google group discussion.) The end result is that Muller, Peters, and Chu tested gravity’s effect on time to be predictable by Einstein’s theory to 7 parts per billion. While they did not find a discrepancy that could lead to a new breakthrough, they did establish this aspect of general relativity to a remarkable degree of precision.

Our universe’s big bang beginning and its continued expansion form two critical components of the RTB creation model. Because Einstein’s theory is foundational to our understanding of these phenomena, experiments testing relativity are vital in establishing its validity. Here at Reasons To Believe we have written previously about the benefits of this kind of work to our creation model. (For example, see this article on other tests of general relativity.) Of equal interest is the question of why evolutionists do not encourage similar testing of their basic theories and assumptions.

Subjects: Einstein / Relativity

Dr. David Rogstad

Dr. Dave Rogstad received his PhD in physics from Caltech and worked over 30 years for NASA’s Jet Propulsion Laboratory. Though now retired, Dave continues to serve as an RTB board member and participates regularly in several RTB podcasts.