The latest Scientific American (February, 2012) has an article about the quantum universe. The story is about how Dr. Craig Hogan at Fermilab is planning to run an experiment to test the graininess of the universe. He figures that if space is not smooth, but consists of a quantum foam at the Planck level it should show up in an interferometer experiment. The interferometer will be similar to the one used by Michelson and Morley in their famous experiment looking for the ether drift. But in this case he will not be looking for a variation in the speed of light depending on which way the interferometer is moving, but will be looking for noise in the detected signal. He figures that if space is granular then light will take slightly different times to travel through the 2 interferometer branches. The difference between the 2 branches will vary with each measurement. So by looking for the noise level he hopes to be able to determine if space is granular. In order to reduce environmental noise he has 2 interferometers stacked on top of each other.
One thing that he talks about is that he does not have a theory about the granularity. He is just experimenting to find out whether it is there. It is also rather inexpensive, about $1,000,000. For a modern physics experiment that is practically nothing.
Bill Gill
