In a new paper, theoretical physicists suggest that dark matter may have played a role in the mass extinction of dinosaurs from our planet. This paper which is titled Dark Matter as a Trigger for Periodic Comet Impacts was authored by Lisa Randall and Matthew Reece of Harvard University. These scientists have basically tried to answer two big questions that have eluded most who have dedicated their careers to study the origins of our universe. The first big question is about the nature of dark matter, particularly about what sort of particles constitute it and the second one is about trying to find out whether there are any patterns with regards to the manner in which comets have struck the Earth.
To set the record straight, even to this day scientists do not know what dark matter is. The word ‘dark’ has been attributed to the mysterious nature of these particles. What scientists are certain of is that dark matter does exist and that they exert a gravitational pull that influences the orbital motion within galaxies. This includes our solar system which orbits through the center of our galaxy, the Milky Way. Randall and Reece have hypothesized that dark matter exists as thin discs which are hidden either within our galaxy or they form a ring at an angle. It takes our solar system about 70 million years to complete it’s orbit through the Milky Way.
The nature of movement of the orbit of our solar system occurs not with a smooth sail but through a bobbing motion. Both scientists hypothesize that once in 35 million years, through this orbit, our solar system intersects with the disc of dark matter present in our galaxy. During this intersection, a greater gravitational tug is exerted over our solar system. Such a spike in gravitational force could disrupt the Oort cloud. This cloud is known to produce comets that head towards Earth. It is a formation of frozen material which surrounds our entire solar system. Such a comet that could have originated from a collision with dark matter may have struck our planet and led to the extinction of dinosaurs.
Coincidentally the time frame of 35 million years corresponds to when major comets have been known to make their way and collide with Earth. By comparing this cycle with the data on craters on Earth that are over 20km in length and more than 250 million years in age has proven to be inconclusive. There are many such comets that do correspond with the time period of a dark matter intersection and others that don’t. Many scientists believe that Randall and Reece’s theory is still worth scrutinizing. A consensus among astrophysicists is that this theory could also be subjected to astronomical observations which could test the disc of dark matter.
So far the data collected on the Chicxulub crater which has been linked with the extinction of dinosaurs 66 million years ago does not directly correspond with Randall and Reece’s dark matter theory but both scientists contend that there are many unanswered questions about this crater and that such a connection cannot be ruled out with further data from scientific experiments. Craters found on Earth can originate from collisions of either a comet or an asteroid and so far only comets are known to be come from the Oort cloud. Even if this new theory about dark matter is inconclusive in proving what exactly led to the extinction of dinosaurs, it will be helpful in understanding not only how large comets have made their way to Earth but also what we can expect from such collisions in the future.
By Unni K. Nair