The universe is more massive than it looks. Although it’s invisible to the eye, this extra mass, called dark matter, seems to interact with visible matter through gravity and the weak nuclear force. Some researchers hypothesize that dark matter consists of WIMPs, or weakly interacting massive particles, which form an invisible “sea” through which the Earth passes as our planet travels through space. While these WIMPs would ordinarily fly right through ordinary matter, we might be able to observe the rare occasions when one directly strikes a nucleus.
One big challenge to WIMP detection is proving that a collision was due to a WIMP, and not to another type of fly-by particle. Some projects are dealing with this problem by burying their detectors deep underground where no interfering radiation can reach; some are using the fact that the number of WIMP collisions is expected to change throughout each day and each year, as Earth’s position in the sea of WIMPS changes. (This approach is similar to the Michaelson-Morley experiment, which disproved the existence of luminiferous aether, another invisible “sea” we supposedly orbited through.) Now an interdisciplinary group of physicists and biologists has an idea to take the comparison of daily and annual measurements to the next level.
The researchers have proposed a DNA-based detector that they say could not only detect a WIMP but also measure the direction of its motion, which would show more specifically whether it came from where dark matter is expected to come from. To measure a WIMP’s direction, they would construct a multilayer detector where each layer is made from carefully ordered strands of DNA dangling from a thin gold sheet. When a particle of dark matter hits a gold atom, it would smash the nucleus the toward dangling strings of DNA, snipping various pieces as it goes (see image above). By collecting the fallen DNA strands, which will contain markers to reveal their positions on the detector, researchers will be able to reconstruct the path of the nucleus’s motion, and thus the particle’s initial direction.
Right now the proposal is just that, and there are many technical challenges to overcome before the detector could be realized. But if the researchers can pull this off, they say it could provide 1,000 times better resolution than current detectors at a reasonable cost (even accounting for the kilogram of gold that it would use).
And that is how one of the most important molecules in biology could help solve one of the biggest mysteries in physics.
[via Wired Science]
Image courtesy of Drukier et al / arXiv