Space Search for a Variation of Fine Structure Constant with Atomic Clocks
Lute Maleki
Jet Propulsion Laboratory
Lute.Maleki@jpl.nasa.gov
Additional authors: John Prestage
We discuss a proposed space mission concept based on three high-precision clocks, each having a rate based on the atomic structure of different elements, to search for a possible variation of the fine structure constant, a. Measurement of the drift in ratios between the frequencies generated by each clock, will probe for the variation of a Since the response of each element to a change in a has a specific signature, this measurement will provide specific and unambiguous results. The sensitivity of this experiment to a change in a will be four orders of magnitude higher than recent results based on observational astronomy Thus, the experiment will provide a compelling reaffirmation or refutation of astronomical observations. The simplicity of the experiment and the measurement methodology provide for a test that has significant potential for success. The Standard Model requires that the dimensionless constants of nature be fixed with respect to locations in space and time. Changing constants also leads to a violation of one of the most venerable theories of physics, Einstein’s general relativity. This theory asserts that the gravitational field is a manifestation of the geometry of space and time. Thus, the rate of passage of time, as measured by all clocks, is universally affected by nearby matter. An observed deviation from this prediction will require modifications to general relativity, and all other metric theories of gravity. It will also test predictions of dilaton based string theories. The apparatus is a unique “tri-clock” instrument based on the linear ion trap standard developed at JPL in support of Deep Space navigation and science experiments. Singly ionized mercury, cadmium, and ytterbium provide the three clock transitions. The mission entails flying the tri-clock instrument to within six solar radii of the sun.
