科学美国人60秒:Wanted: Gravitational Constant's True Value

[Audio from movie]

A scene from the movie Gravity. In real life, gravity is always bringing us down—particularly scientists who attempt to measure gravitational force. Try as they might, physicists cannot agree on a precise value of the constant called “Big G,” which denotes the strength of gravity. It’s tough to measure because gravity is incredibly weak compared to other fundamental forces.

“Big G is a fundamental constant of nature, and as such, I think it is important to measure its value precisely.” Stephan Schlamminger of the National Institute of Standards and Technology.  

The world’s best experiments keep turning up different answers that are incompatible with one another and diverge by about 40 times the uncertainty of the most precise experiment.

The discrepancy is not just embarrassing—knowing the true value of Big G is important in various fields. For example, in efforts to unify general relativity with quantum mechanics in a quantum theory of gravity.

 Aiming to solve the problem, Schlamminger is organizing an “Ideas Lab” gathering under the auspices of the National Science Foundation in July. Scientists from numerous disciplines will brainstorm new strategies for measuring Big G.

“First, I hope for a really good and new idea on how to measure big G. Completely new ideas are rare, and this wish may not get fulfilled. However, when you have a new idea, they can advance the solution to a given problem a lot…short of that, I hope that new collaborations form to tackle this problem…this will infuse new energy in the field, and there are many fascinating questions that need to be answered…and in the ideal best case we get a new, high-precision determination of big G.”

—Clara Moskowitz