Dark Matter may have caused the extinction of Dinosaurs

It is estimated that more than 99% of the species that lived on the Earth are extinct today owing to the competition or inability to survive and others might have perished due to periodic cataclysmic events. New York University Biology Professor Micheal Rampino in his recent research article published in the Monthly Notices of the Royal Astronomical Society suggested that astrophysical findings could help us in understanding the biological phenomena occurring on the Earth. Fossil records show that Earth experienced periodic mass extinction cycles of 26-30 Million years over the past 250 Million year cycle. All these cataclysmic events are fall outs of collisions of either asteroids or comets and extended periods of volcanic emissions. The extinction of dinosaurs, 66 million years ago is one such most extensively researched events. Palaeontologists recognise five such humongous events wherein 90% of species were lost. Though there is an ambiguity over the periodicity of the events, the new postulates suggest that Cometary collisions might  have been triggered by the gravitational disruption of the Oort Cloud, where a repository of Comets reside in the outer edge of our solar system.

Every 250 million years the Sun with its entourage of planets makes a peregrination of our Milky Way. While orbiting, Solar System oscillates up and down through the galactic disc where the Galaxy’s dark matter is concentrated. During this process the Earth too passes through the galactic disc once in every 30 million years. Galactic disc is crowded with stars, clouds, dust and elusive sub-atomic particles whose existence can be detected by their gravitational effects. In this paper Prof. Rampino tries to shed light on the impact of the dark matter in the galactic disc on the periodicity of the terrestrial events. Interestingly the periods of gravitational effects of the dark matter on the Earth were found to be in congruent with the galactic dynamics.

Earlier he postulated Shiva Hypothesis named after Lord Shiva the God of destruction to explain how mass extinctions are caused by impact events. The hypothesis suggests that the gravitational disturbances are caused as the solar system crosses the plane of the Milky Way galaxy disturbing the comets in the Oort cloud surrounding the solar system. This results in raining of comets towards the inner solar system causing the impact. These impact events that occurred every 30 million years might have led to the cretaceous- paleogene extinction event.

While the composition of the dark matter is unknown, it is known to interact with visible matter and radiation under the influence of gravity. Modern theories suggest that dark matter is accounts for 23% of all mass in the universe, 73% of Universe is dark energy and the rest 4% includes regular matter such as planets, stars and people. The dark matter tends to interact with the regular matter as Earth passes through the galactic disc and eventually results in the disruption of Oort Cloud. The gravitational attraction between the dark matter and Earth will result in the accumulation of the dark matter at Earth’s core.

Rampino believes that as the dark matter particles build up, the particles will annihilate each other and release large amounts of energy. Approximately as earth passes through the galactic plane every 30 million years, internal heating of the Earth brings about massive changes in the Earth’s magnetic field, leads to cataclysmic events like tectonic shifting, eruption of volcanoes, rise of sea levels and climate.

Another study carried out by Harvard University team of theoretical physicists Rendall and Reece in their paper published in Physical Review Letters opined that dark matter is the source of the periodic Oort Cloud perturbation. Rampino believes that Earth’s cyclical movement through the thin, invisible, disc of dark matter would also lead to perturbations in the orbits of distant comets and results in heating up of Earth’s core. Thus the Cometary collisions and eruption of volcanoes might have led to the periodic mass extinction. The  astrophysical events caused by the oscillation of Earth around the galactic disc , results in consequent accumulation of the dark matter within the Earth’s core causing dramatic changes in the geological and biological phenomena on the Earth.

This model in fact opens up new vistas for understanding the impact of the astrophysical events on other planets in our solar system. It throws up new challenges for astrophysicists to extensively work on the excruciating details of the dark matter, whose composition is not yet clearly known. While the exact details of the sequence of events elucidated in the model are not scientifically worked out, it has eclectically linked the cycles of geological and biological evolution on the Earth to the rhythms of the Galactic dynamics.

 

 

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