Of Galactic Violence And Stellar Explosions

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Of Galactic Violence And Stellar Explosions
Of Galactic Violence And Stellar Explosions

“The Universe is in a state of violent explosion in which the great islands of stars known as galaxies are rushing apart at speeds approaching the speed of light. Further we can extrapolate this explosion backward in time and conclude that all the galaxies must have been much closer at the same time in the past—so close in fact that neither galaxies nor stars nor even atoms or atomic nuclei could have had a separate existence”—

Steven Weinberg in “The First Three Minutes.”

One morning a few years ago a scientist and his wife who were walking down a country road near their home,  in a small university town, somewhere in America were startled by the cacophony of sudden popping noises. They saw pods from weed were blowing themselves apart and scattering their seeds to the wind. The riot of small explosions which lasted barely a minute marked the end of one generation of weed. But the scientist knew that soon another would commence some­where across the field or near a grove or in a garden nearby.

Exploding seed pods, like volcanoes, giant geysers and supernovas, are one of the ways nature uses violence construc­tively. But for the eruptions the seeds would have remained locked inside their capsule. They might have eventually “seeded” the immediate area, but their spread across the countryside might not have taken place at all. Similarly, but for volcanic eruptions and giant geysers, water might have re­mained for ever deep inside the Earth and life might not have gained a foothold on its surface.

Therefore it should not be difficult to appreciate that cosmic violence is directly responsible for the creation of the stars including the sun and the planets and indirectly for the creation of all life forms. Our solar system would not have been formed out of the vast amorphous cloud of gas and dust, if a Supernova had not made the cloud collapse. In the absence of an interstellar shock, that primordial cloud would have re­mained a formless swirl.

Once, every 50 years, a massive star explodes in our galaxy as a supernova. The force of the explosion hurls vast quantities of radiation and matter into space, the “seeded” for future planetary systems and generates shockwaves that sweep through the arms of the galaxy. The waves heat interstellar gas, evaporate small clouds, and compress large ones to the point where they collapse under their own gravity to form new stars.

Supernovas are the detonations, that propel the galactic engine forward in its evolution. They seed the interstellar gas with heavy elements, heat it with the energy of their radiations, stir it up with the force of their blast waves, and cause new stars, some of them very massive, to form. In a fantastic chain of violence that links the rise of life on Earth to events billions of years and half a galaxy away, stars will rush through their lifecycle, explode, dump a new supply of heavy elements into the gas, and trigger the formation of other stars to make other supernovas.

The cloud that collapsed to form the solar system con­tained the legacy of stars that had exploded even longer ago. Though composed of mostly hydrogen and helium, the cloud was enriched with carbon, nitrogen and oxygen, the elements essential for life. All the elements heavier than helium are manufactured deep in the interior of stars and would in fact remain there if it were not for the supernovas in which giant stars blow themselves asunder.

Violence however is a double edged weapon. The process that creates the basic raw materials for the development of life on Earth would severely threaten life if it were to happen too close to home. A supernova occurring within a few light years of the Earth would immerse us in a deadly cloud of cosmic rays for hundreds of years, destroying life on Earth. Catastrophes such as the great die-offs of the past in which most species became extinct could have been caused by a supernova exploding in the vicinity if not by a large asteroid or comet crashing to Earth.

The centres of some galaxies are racked by explosions, that are perhaps millions of times as powerful as supernovas; these galaxies appear to have “blown their stacks”, converting their appearance from what might have once been a majestic stately spiral into a boiling source of high energy particles and radia­tion. Violence seems to be the natural tendency in the swarming, shoving, seething central regions of galaxies. At the centre of some of the swarms are the enigmatic extremely explosive “quasars” spewing out so much intense energy that we cannot say for sure whether the rest of the galaxy is even there.

Going back in time, we see evidence of more violence. The more distant galaxies and quasars whose light comes to us from long long ago are the most active. When we look back as far as we can, we find that space is pulsating with radiation and galaxies fleeing from one another at high speeds, apparently in response to an awesome explosion, the famous “Big Bang” that inaugurated the universe.

Some scientists are reluctant to use the term “creation of the universe” as they feel that it is too restrictive. “Creation” implies that the universe had a beginning,  whereas this according to some astrophysicists, might not be the case at all. It may have been expanding and contracting endlessly, and we may be in one of a countless number of expansion phases. Or our universe may be one of a many universes, and what appears to us as an expansion from a dense initial state may represent the eruption of matter from an adjacent Universe into our own. Our universe may not have had a beginning but it most certainly has had an extremely violent past without which we would not have been here today!

The question arises as to whether we cannot get along without violence? Is violence, intrinsic to our nature? On a small controlled scale, we do make good use of violence, in the internal combustion engines that drive our cars, in the explo­sives that clear the way for roads and tunnels and in the jet engines, that propel our aircraft across azure skies over the oceans.

However, violence in the universe as a whole seems to be on the wane. There are fewer violent galaxies around and the rate of supernovas has reduced steadily over the eons as the galaxy steadily runs out of gas. But this does not mean that the show is over and that all we can look forward to is a cold and lonely universe, an abandoned stage littered with the ashes and dust of burnt-out stars.

On the contrary some scientists are of the view that the real performance is just beginning and that soon the stage will be dominated by life, intelligent and mature life, born of violence, but free from it at last, that is free to thrive and soar through the cosmos, carrying messages that spread real human val­ues—truth, goodness and beauty.

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