Even decades after its formulation, the dark matter hypothesis remains one of the most baffling mysteries in science. This invisible, hypothetical material is known to neither emit nor absorb light, which is why scientists are yet to detect its presence directly. However, it is generally believed that dark matter exists because experiments and calculations have shown that it exerts gravitational force on visible matter. According to a new study, by a NASA scientist, our planet might be engulfed in long, hair-like strings of dark matter.
Although invisible, dark matter is said to constitute 27-percent of all matter and energy in the universe. By contrast, regular, visible matter makes up only 5-percent of the universe. Scientists believe that dark matter is “cold”, since it does not move around all that much. It is “dark” because it neither emanates nor absorbs light or, for that matter, any other kind of electromagnetic radiation. Previous studies have shown that dark matter tends to arrange itself into “fine-grained streams”, in which all the particles move at the same speed. These streams orbit galaxies, which are in turn formed as a result of fluctuations in the density of dark matter. Gary Prézeau, the NASA scientist who conducted the study, said:
A stream can be much larger than the solar system itself, and there are many different streams crisscrossing our galactic neighborhood. When gravity interacts with the cold dark matter gas during galaxy formation, all particles within a stream continue traveling at the same velocity.
In the study, recently published in the Astrophysical Journal, Prézeau used advanced computer simulations to find out how these streams of dark matter behave in the vicinity of a planet, like Earth. Unlike regular matter, which would bounce right off the surface of the Earth, dark matter seems to be capable of going right through the planet. When approaching Earth, the streams of dark matter would be focused and bent into thin, dense hair-like filaments, by our planet’s gravity. Earth’s density poses no significant obstacle to these invisible filaments, which can pass right through the planet and emerge from the other side.
The computer simulations further suggest that these filaments have “roots” (that is, points with the highest concentrations of dark matter particles) and “tips”, where the hair-like threads end. When a stream of dark matter passes through Earth, its root would likely be present at around 600,000 miles (approx. 1 million kilometers) from our planet. The density of dark matter particles at this point, the scientist believes, would be nearly 1 billion times higher than the average. Prézeau added:
If we could pinpoint the location of the root of these hairs, we could potentially send a probe there and get a bonanza of data about dark matter.
A stream traveling through Jupiter, for instance, would have a root, where the density of dark matter particles is almost 1 trillion times more than the average, the computer models predict. According to the simulations, the changes in the density of the dark matter filaments would be similar to the changes in Earth’s density, from the core to the mantle and finally to the crust. Prézeau believes that the study could help unlock some of the mysteries surrounding dark matter. Speaking about the find, Charles Lawrence of NASA’s Jet Propulsion Laboratory said:
Dark matter has eluded all attempts at direct detection for over 30 years. The roots of dark matter hairs would be an attractive place to look, given how dense they are thought to be.