Is Quantum Knowability Subject to Spacetime Warping?

Grant #: FXQi 2013
Senior Scientist: Laurance Doyle

According to classical notions of light, interference between two light beams results from the wave nature of light. However, in quantum mechanics light is represented as particle–like photons, and interference depends on what can and cannot be known about the light; that is, it depends upon information. In brief, if the information about which path the light must have taken to reach the detector is knowable, then interference will not occur; if it is not knowable, interference will occur. We propose to send one component of a split radar beam to the planet Mercury and the other to Mars, thereby creating two possible paths for the light to take. When the beams arrive back at Earth, we will use Heisenberg’s uncertainty principle to force the which–path information to be unknowable, thereby determining when interference should occur. Since the beam to and from Mercury will pass close to the Sun, we will be able to analyze whether or not the knowability or unknowability of the information is affected by the curvature of spacetime resulting from the Sun’s gravity. This will also represent a rare test of whether or not quantum mechanics, via the uncertainty principle, “agrees” with general relativity.