Brian Tennyson ’11 is finishing up his Ph.D. in physics at Yale University this spring. Tennyson is part of a team trying to find dark matter using the LUX (Large Underground Xenon experiment)
particle detector at the bottom of a gold mine in Lead, South Dakota. Dark matter makes up 80% of the mass of universe, but we cannot see it.
“Scientists discovered indirect evidence of dark matter in the 1930s, and there are currently several competing theories about what it is, but no one has yet proven which one is correct,” Tennyson explained. “It is one of the oldest unsolved problems in physics.”
The LUX detector is a tank of cryogenic xenon liquid kept at 100 degrees below zero centigrade. The hope of Tennyson, and the approximately 150 other scientists who have worked on LUX over the last ten years, is that dark matter will pass through the liquid and that they will be able to see evidence of it having happened. As Tennyson explains it, the process would be similar to how an x-ray works, where the earth would be skin and the xenon would be the bone. The x-ray film would light up if dark matter passed through it.
The fact that it has not happened yet has almost as much meaning as if it had — as it has disproved one theory about how much dark matter weighs and how big it is. “If they were right, we would have seen a huge amount of light by now,” Tennyson explained.
But even if we can’t “see” it yet, we know dark matter is there, and Tennyson’s work is increasing our chances of finding it.