A few years ago, this blog looked at some work examining the likely effect of dark matter on the human body. The thinking was that if dark matter fills the universe and the Earth is sweeping through vast oceans of the stuff, then our bodies would be constantly bombarded with dark matter particles, causing problems such as genetic mutations and cancer.
But after careful consideration, researchers decided that the risk was minimal. They calculated that although dark matter particles called WIMPs (weakly interacting massive particles) might be constantly hitting us, they were considerably less of a problem than cosmic rays, which also bombard us and are known to cause mutations of all kinds.
Today, Olga Chashchina from the Ecole Polytechnique in France and Zurab Silagadze from the Budker Institute of Nuclear Physics in Russia take another look at this problem. These guys make a different set of assumptions about the type of stuff that dark matter is made of.
And this time, their conclusion is much more dramatic. They say that the consequences of this kind of dark matter are much more serious and could lead to diseases associated with mutations, such as cancer.
The key difference between the earlier analysis and this one is the type of dark matter involved. Nobody knows what dark matter is made of or even whether it exists at all. Astronomers hypothesize its existence because it conveniently explains an otherwise puzzling observation.
Distant galaxies spin so rapidly that they require powerful gravitational forces to hold them together. But when astrophysicists add up all the matter they can see in galaxies, it cannot possibly generate the required pull.
That’s why they think these galaxies must be filled with other stuff they can’t see—dark matter—and that this generates the gravity that holds them together. Indeed, for the sums to add up, about 80 percent of galactic mass must be dark matter.
But what could this dark matter possibly be? Astronomers think it must interact only very weakly with ordinary mater, otherwise we would have already seen its effects. So a leading candidate is the WIMP, the subject of the first study.
But another idea is that the universe could have an invisible partner made of exact mirrors of all the particles known to exist today. In this view, there would be mirror protons, neutrons and electrons which interact to create form mirror atoms, rocks, meteorites, planets, stars and so on.